Bruce L. Morin

Pratt & Whitney, East Hartford, Connecticut

Broadband Fan Noise Prediction System for 

Turbofan Engines

Volume 2: BFaNS User’s Manual and Developer’s Guide

NASA/CR—2010-216898/VOL2

November 2010
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Bruce L. Morin

Pratt & Whitney, East Hartford, Connecticut

Broadband Fan Noise Prediction System for 

Turbofan Engines

Volume 2: BFaNS User’s Manual and Developer’s Guide

NASA/CR—2010-216898/VOL2

November 2010

National Aeronautics and

Space Administration

Glenn Research Center

Cleveland, Ohio 44135

Prepared under Contract NAS3–27727
Acknowledgments

This work was performed under Contract NAS3-27727 (AST Task 13) from the NASA Glenn Research Center (GRC) with Dennis 

Huff as contract monitor. The author greatly appreciates the following contributions: Dennis Huff (GRC) and Edmane Envia (GRC) 

for overall direction and coordination the AST Noise Program; Donald Hanson (P&W, retired) and Stewart Glegg (Florida Atlantic 

University) for providing the noise prediction routines used in BFaNS; Ramons Reba (United Technologies Research Center) for 

his work on the cascade-response subroutines; Gary Podboy (GRC), Richard Woodward (GRC) and Christopher Hughes (GRC) 

for providing noise, performance and fl ow-fi eld data from the Pratt & Whitney and General Electric 22 in. diameter fan rigs that 

were tested at GRC; Ulrich Ganz (Boeing), John Premo (Boeing) and Timothy Patten (Boeing) for providing noise, performance 

and fl ow-fi eld data from the Boeing 18 in.diameter fan rig that was tested at Boeing; Tony Hoang (United Technologies Research 

Center) for his assistance with computer programming and running test cases; Jon Gilson (P&W), Aaron Farbo (P&W Intern) 

and Gary Willett (P&W retired) for their assistance with data reduction and analysis; Clint Ingram (formerly P&W) and Mark 

Stephens (P&W) for providing CFD predictions for the Pratt & Whitney 22 in. diameter fan rig; Wesley Lord (P&W), Douglas 

Mathews (P&W) and David Topol (P&W) for their helpful comments and suggestions regarding this work.

Available from

NASA Center for Aerospace Information

7115 Standard Drive

Hanover, MD 21076–1320

National Technical Information Service

5301 Shawnee Road

Alexandria, VA 22312

Available electronically at http://gltrs.grc.nasa.gov

Trade names and trademarks are used in this report for identifi cation 

only. Their usage does not constitute an offi cial endorsement, 

either expressed or implied, by the National Aeronautics and 

Space Administration.

This work was sponsored by the Fundamental Aeronautics Program 

at the NASA Glenn Research Center.

Level of Review: This material has been technically reviewed by expert reviewer(s).
NASA/CR—2010-216898/VOL2 iii

Summary

Pratt & Whitney has developed a Broadband Fan Noise Prediction System (BFaNS) for turbofan 

engines. This system computes the noise generated by turbulence impinging on the leading edges of the 

fan and fan exit guide vane, and noise generated by boundary-layer turbulence passing over the fan 

trailing edge. BFaNS has been validated on three fan rigs that were tested during the NASA Advanced 

Subsonic Technology Program (AST). The predicted noise spectra agreed well with measured data. The 

predicted effects of fan speed, vane count, and vane sweep also agreed well with measurements.

The noise prediction system consists of two computer programs: Setup_BFaNS and BFaNS.

Setup_BFaNS converts user-specified geometry and flow-field information into a BFaNS input file. From 

this input file, BFaNS computes the inlet and aft broadband sound power spectra generated by the fan and 

FEGV. The output file from BFaNS contains the inlet, aft and total sound power spectra from each noise 

source.

This report is the second volume of a three-volume set documenting the Broadband Fan Noise 

Prediction System:

Volume 1: Setup_BFaNS User’s Manual and Developer’s Guide

Volume 2: BFaNS User’s Manual and Developer’s Guide

Volume 3: Validation and Test Cases

The present volume begins with an overview of the Broadband Fan Noise Prediction System, 

followed by step-by-step instructions for installing and running BFaNS. It concludes with technical 

documentation of the BFaNS computer program. 

NASA/CR—2010-216898/VOL2 v

Contents

Summary......................................................................................................................................................iii

1.0 Introduction ..........................................................................................................................................1

2.0 Noise-Prediction Methodology ............................................................................................................2

2.1 Turbulent Inflow Noise...............................................................................................................2

2.2 Self Noise....................................................................................................................................3

3.0 Installation and Execution of BFaNS...................................................................................................3

3.1 Installation...................................................................................................................................3

3.2 Run Procedure.............................................................................................................................3

3.2.1 Create BFaNS Input File............................................................................................... 3

3.2.2 Create BFaNS Author File............................................................................................ 3

3.2.3 Execute BFaNS............................................................................................................. 5

4.0 Program Documentation.......................................................................................................................5

4.1 Units............................................................................................................................................5

4.2 Restart File..................................................................................................................................5

4.3 Model Scale ................................................................................................................................5

4.4 Frequency Range ........................................................................................................................5

4.5 Turbulent Inflow Noise...............................................................................................................7

4.5.1 BBCascade.................................................................................................................... 7

4.5.2 BBCascade Input........................................................................................................... 7

4.5.3 BBCascade Modifications............................................................................................. 8

4.5.4 Mach-Number Limitation ............................................................................................. 9

4.5.5 Turbulence Spectrum.................................................................................................... 9

4.5.6 Blade Tip Noise ............................................................................................................ 9

4.5.7 Blade Hub Noise ........................................................................................................... 9

4.5.8 Vane Tip Noise ........................................................................................................... 10

4.5.9 Vane Hub Noise .......................................................................................................... 10

4.5.10 Vane-Wake Interaction Noise ..................................................................................... 10

4.6 Self Noise..................................................................................................................................10

4.6.1 Self-Noise Input .......................................................................................................... 10

4.6.2 Self-Noise Modifications............................................................................................ 11

4.6.3 Mach-Number Limitation ........................................................................................... 11

4.6.4 Frequency Limitation.................................................................................................. 11

4.6.5 Blade Self Noise.......................................................................................................... 12

4.6.6 Vane Self Noise (Not Recommended)........................................................................ 12

4.7 Output File ................................................................................................................................12

5.0 Concluding Remarks..........................................................................................................................12

Appendix A .—Symbols.............................................................................................................................13

A.1 Variables...................................................................................................................................13

A.2 Greek Symbols..........................................................................................................................13

A.3 Subscripts..................................................................................................................................14

Appendix B .—Installing the BFaNS System.............................................................................................15

B.1 Step Number I: Setting Up the Directory Structure..................................................................15

B.2 Step Number II: Setting Up the Graphics Library (GRAFIC)..................................................15

B.3 Step Number III: Compiling Setup_BFaNS .............................................................................15

B.4 Step Number IV: Compiling BFaNS ........................................................................................16

B.5 Step Number V: Setting Up Aliases .........................................................................................16

Appendix C .—Running the Test Case.......................................................................................................17

C.1 Step Number I: Setting Up the Test Case .................................................................................17

C.2 Step Number II: Running a Test Case for Setup_BFaNS.........................................................17
NASA/CR—2010-216898/VOL2 vi

C.3 Step Number III: Running a Test Case for BFaNS...................................................................18

Appendix D .—Sample BFaNS Author File...............................................................................................19

Appendix E .—Directory Structure of ~/Codes/fans_nasa .........................................................................21

Appendix F .—BFaNS Subroutine Hierarchy ............................................................................................23

Appendix G .—Modification to BBCascade Input File..............................................................................25

Appendix H .—BBCascade Test Case - Stator...........................................................................................27

Appendix I .—BBCascade Test Case—Rotor............................................................................................29

Appendix J .—Sample Self-Noise Input File..............................................................................................31

Appendix K .—Self-Noise Test Case .........................................................................................................33

Appendix L .—Sample BFaNS Output File ...............................................................................................35

References...................................................................................................................................................39

List of Figures

Figure 1.—Fan broadband noise sources predicted by BFaNS. ..................................................... 1

Figure 2.—Organization of BFaNS. ............................................................................................... 2

Figure 3.—Cascade studied by Hanson.......................................................................................... 2

List of Tables

Table 1.—Run Procedure for BFaNS ............................................................................................. 3

Table 2.—Format of BFaNS Author File ....................................................................................... 4

Table 3.—Executing BFaNS .......................................................................................................... 5

Table 4.—ANSI Standard One-Third Octave Bands (Refs. 13 and 14)......................................... 6
NASA/CR—2010-216898/VOL2 1

Broadband Fan Noise Prediction System for Turbofan Engines

Volume 2: BFaNS User’s Manual and Developer’s Guide

Bruce L. Morin

Pratt & Whitney

East Hartford, Connecticut 06108

1.0 Introduction

In early turbofan engines, the fan blade passage tone and higher harmonics dominated the fan noise 

level when compared to fan broadband noise. However, engine makers have been very successful at 

reducing fan tone noise by decreasing fan tip speed, providing ample spacing between airfoil rows, 

carefully selecting the airfoil counts, and acoustically treating the fan duct. In fact, tone noise reduction 

has been so great that fan broadband noise is now a major contributor to the overall engine noise level.

Under NASA funding, Pratt & Whitney has developed a Broadband Fan Noise Prediction System 

(BFaNS) for turbofan engines. This prediction system is built around acoustic theories developed by 

Hanson (Refs. 1 to 4) and Glegg (Refs. 5 to 7). These theories account for noise generated by turbulence 

impinging on the leading edges of the fan and fan exit guide vane (FEGV), and noise generated by 

boundary-layer turbulence passing over the fan trailing edge.

Figure 1 shows the fan broadband noise sources that can be calculated with BFaNS. The blade tipnoise and blade self-noise calculations are limited to subsonic blade-tip relative Mach numbers. There are 

no limitations on the other sources.

Figure 2 shows the organization of the Broadband Fan Noise Prediction System, which consists of 

two computer programs: Setup_BFaNS and BFaNS. Setup_BFaNS converts user-provided geometry and 

flow-field information into a BFaNS input file (bfans.input). From this input file, BFaNS computes the 

inlet and aft broadband sound power spectra generated by the fan and FEGV. The output file 

(bfans.output) contains the inlet, aft and total sound power spectra from each noise source shown in 

Figure 1, along with the combined sound power spectra from all sources. Both Setup_BFaNS and BFaNS 

use control files (also referred to as author files) that allow the user to modify the way the programs 

operate.

This report is the second volume of a three-volume set. The present volume begins with an overview 

of the noise-prediction methodology, followed by step-by-step instructions for installing and running 

BFaNS. It concludes with technical documentation of the BFaNS computer program. Volume 1 provides 

instructions for running Setup_BFaNS, and Volume 3 provides validation and test cases.

Figure 1.—Fan broadband noise sources predicted by BFaNS.
NASA/CR—2010-216898/VOL2 2

Figure 2.—Organization of BFaNS.

Figure 3.—Cascade studied by Hanson.

2.0 Noise-Prediction Methodology

Fan broadband noise can result from turbulence impinging on leading edges (turbulent inflow noise), 

and turbulence convecting past trailing edges (self noise). This section summarizes the methods used in 

BFANS to compute turbulent inflow noise and self noise. Papers and reports by Hanson (Refs. 1 to 4) and 

Glegg (Refs. 5 to 7) provide more detailed discussions of the theory.

2.1 Turbulent Inflow Noise

The interaction of turbulence with the rotor and stator leading edges can be a major source of 

broadband noise in turbofan engines. For this noise source, Hanson (Ref. 4) derived an expression that 

relates sound power to the inflow turbulence characteristics and cascade geometry. This was done by 

formally adapting Glegg’s harmonic cascade theory (Ref. 8) to the random inflow problem. In later work, 

Hanson included the effects of blade row reflection and transmission (Refs. 9 and 10), though these 

effects have yet to be incorporated into BFaNS.

Using his theory, Hanson developed a computer program (BBCascade) that predicts the noise 

generated by a band of turbulence impinging on a cascade, as shown in Figure 3. The geometry consists 

of a rectilinear cascade of flat plates aligned with the mean flow direction (i.e., zero steady loading). The 

cascade span is assumed to be infinite. The mean flow is assumed to be uniform, and the boundaries far 

upstream and far downstream are assumed to be non-reflecting.

Within BFANS, BBCascade is applied to the rotor and stator in a stripwise manner. The inflows to 

the rotor and stator are divided into several turbulent bands. The bands are non-uniformly spaced, and are 

concentrated in regions of strong gradients in the turbulence profile. BFaNS computes the upstream and 

downstream sound power produced by the interaction of each turbulent band with the rotor or stator. The 

sound power from each band is then summed to yield the total upstream and downstream sound power.

Flow Path Geometry

Blade Geometry

Vane Geometry

Flow Field Description

Setup_BFaNS bfans.input BFaNS bfans.output

Setup_BFaNS

Control File

BFaNS

Control File
NASA/CR—2010-216898/VOL2 3

2.2 Self Noise

Broadband noise is also generated when boundary-layer turbulence convects past the rotor and stator 

trailing edges. This source has been studied extensively for isolated airfoils and helicopter rotors, and 

Glegg recently extended these theories to trailing edge noise from semi-infinite cascades (Refs. 5 to 7). 

Glegg developed a computer program to predict fan self noise (but not FEGV self noise), and that 

program has been incorporated into BFaNS.

Glegg’s approach relies on an experimental database of self noise from isolated NACA0012 airfoils 

(Ref. 11). This database is used to estimate the unsteady loading spectrum on the cascade for a given inlet 

Mach number, chord Reynolds number, and angle-of-attack. Given the unsteady loading spectrum, Glegg 

computes the noise that would be radiated by the cascade, including the scattering effect of the adjacent 

blades. The calculation is coupled to the radial modes of the annular duct (assuming uniform axial flow).

In Glegg’s computer program, the rotor is divided into several uniformly spaced segments. The 

program computes the upstream and downstream sound power produced by each strip. The sound power 

from each strip is then summed to yield the total upstream and downstream sound power.

3.0 Installation and Execution of BFaNS

This section provides instructions for installing and running BFaNS. Refer to Section 4.0 for technical 

documentation of the computer program.

3.1 Installation

Appendix B provides instructions for installing the Broadband Fan Noise Prediction System 

(Setup_BFaNS and BFaNS) on Unix-based computers. Both computer programs are written in 

FORTRAN 77. Appendix C explains how to run the BFaNS test case.

3.2 Run Procedure

Table 1 shows the step-by-step process for running BFaNS. Sections 3.2.1 through 3.2.3 describe the 

details of each step.

TABLE 1.—RUN PROCEDURE FOR BFANS

Step 1 Create BFaNS input file

Step 2 Create BFaNS author file

Step 3 Execute BFaNS

3.2.1 Create BFaNS Input File

To generate a BFaNS input file, the user must follow the instructions in the Setup_BFaNS Users’

Manual and Developer’s Guide (Ref. 12).

3.2.2 Create BFaNS Author File

The author file allows the user to change default values that are hardcoded in BFaNS. BFaNS will 

search the working directory for a file named “bfans.author”. If this file exists, BFaNS will use it to override the internal defaults for various options. Appendix D shows a sample BFaNS author file. The 

MATLAB (The MathWorks, Inc.) program “bf_author.m” creates an author-file template. This program 

is located in the BFaNS source code directory.

The author file has distinct blocks of input referred to as cards, with each card beginning on a new 

line. A negative card number indicates that the card is turned off. A positive card number indicates that a 

card is turned on. This feature allows the user to activate/deactivate various options in BFaNS. Each card 
NASA/CR—2010-216898/VOL2 4

has five input parameters (two integer, two real and one alphanumeric), which are provided at the end of 

the line. When a card is turned on, its input parameters are accessible to most subroutines within BFaNS.

Table 2 describes the various options in BFaNS. These options are also described in Section 4.0.

TABLE 2.—FORMAT OF BFANS AUTHOR FILE

Card Description

5000 If turned on, this card specifies the file name of the BFaNS input file, and the 

user will not be prompted to enter the file name.

500

through

5048

Reserved for future use

5050 If turned on, this card over-rides the default model scale (i.e. model fan diameter 

divided by full-scale fan diameter). The default model scale is 1.000.

5052 If turned on, BFaNS will compute narrowband spectra. The default is to compute 

1/3-octave spectra.

5054 If computing 1/3-octave spectra (see Card 5052), this card over-rides the default 

first 1/3-octave band (default is 17, i.e. 50 Hz).

5056 If computing 1/3-octave spectra (see Card 5052), this card over-rides the default 

last 1/3-octave band (default is 40, i.e. 10,000 Hz).

5058 If computing narrowband spectra (see Card 5052), this card over-rides the default 

number of frequencies (default is 100)

5060 If computing narrowband spectra (see Card 5052), this card over-rides the default 

first narrowband frequency (default is 100).

5062 If computing narrowband spectra (see Card 5052), this card over-rides the default 

last narrowband frequency (default is 10000).

5064 If computing narrowband spectra (see Card 5052), this card over-rides the default 

bandwidth. To automatically compute the bandwidth, enter 0.0. This automatic 

option will set the bandwidth equal to the frequency step. The default is to 

automatically calculate the bandwidth.

5066 If turned on, this card over-rides the default ambient density at the observer 

location (default is 0.0765 lbm/ft**3). Note: the ambient density at the observer 

is currently not used by BFaNS.

5068 If turned on, this card over-rides the default ambient speed of sound at the 

observer location (default is 1116 ft/sec). Note: the ambient speed of sound at the 

observer is currently not used by BFaNS.

5070 If turned on, BFaNS will not compute blade tip noise

5072 If turned on, BFaNS will not compute blade hub noise

5074 If turned on, BFaNS will not compute blade self noise

5076 If turned on, BFaNS will not compute vane tip noise

5078 If turned on, BFaNS will not compute vane hub noise

5080 If turned on, BFaNS will compute vane self noise

5082 If turned on, BFaNS will not compute vane-wake interaction noise

5084 If turned on, this card over-rides the default ratio between the transverse and 

longitudinal integral length scale in the blade inlet boundary layers (default is 

1.0)

5086

through

5090

These cards are used to control the duct eigenvalue and eigenmode calculation for 

the self-noise calculation. Do not use these.

5092 If turned on, this card over-rides the default number of turbulent bands in the 

blade tip region, blade hub region, vane tip region and vane hub region (default 

value is 4)

5094 If turned on, this card over-rides the default number of turbulent bands in the 

vane-wake interaction region (default value is 8)

5096 If turned on, this card over-rides the default number of radial segments to use in 

the self-noise calculation (default value is 10)

5098 If turned on, this card over-rides the default number of turbulent sub-bands to use 

in the turbulent inflow calculation (default is 10)

5100

through

5108

These cards are used to control the duct eigenvalue and eigenmode calculation for 

the self-noise calculation. Do not use these.

5110 If turned on, this card over-rides the default the Mach-number limit for BBCascade 

(default is 0.93) 

5112 If turned on, this card over-rides the default Mach-number limit for the self noise 

calculation (default is 0.97)

5114

through

5120

These cards are used to control the self-noise calculation. Do not use these.
NASA/CR—2010-216898/VOL2 5

TABLE 2.—FORMAT OF BFANS AUTHOR FILE

Card Description

5122 If turned on, this card over-rides the default value of inf in the jsplit routine. 

The value entered is the number of terms in thousands (i.e. enter 2 for 2000 

terms). Default is 2 (i.e. 2000 terms).

5124 If turned on, this card over-rides the default value of err in the jsplit routine. 

Default is 0.0005.

9999 Indicates end of author file.

3.2.3 Execute BFaNS

Table 3 shows the procedure for executing BFaNS.

TABLE 3.—EXECUTING BFANS

Step 1 Follow the instruction in Sections 3.2.1 through 3.2.2.

Step 2 Go to the working directory.

Step 3 Execute BFaNS using the alias bf.

Step 4 After execution is complete, confirm that the output file "bfans.output" has been 

created in the working directory.

4.0 Program Documentation

This section provides technical documentation for the BFaNS computer program, which is written in 

FORTRAN 77. Appendix F shows the subroutine hierarchy.

4.1 Units

Program inputs and outputs are in English units. Subroutine “read_input” reads the input file, and 

converts everything to SI units. The default name for the input file is “bfans.input”, but the user can 

change the name using Card 5000 in the author file. All internal calculations are done in SI units. 

4.2 Restart File

As BFaNS executes, it writes to a restart file (bfans.restart) that allows the BFaNS session to be 

terminated and restarted at a later time. The restart file is especially valuable for long runs, which have a 

greater chance of being terminated due to network problems, power failures or other unexpected reasons.

Upon execution, BFaNS checks the working directory to see if the restart file exists. If it does, then 

BFaNS reads the restart file and continues the calculation where it left off. If the restart file does not exist, 

then BFaNS starts the calculation from scratch.

BFaNS deletes the restart file after the BFaNS output file has been created.

4.3 Model Scale

The model scale is defined as the ratio of the model fan diameter to the full-scale fan diameter. For 

example, to scale predictions for a 22 in. diameter fan rig to a 112 in. diameter engine, the model scale is 

(22/112) or 0.196. The model scale is specified in Card 5050 of the author file. When Card 5050 is turned 

off, BFaNS uses a model scale of one.

4.4 Frequency Range

By default, BFaNS will compute 1/3-octave spectra from 50 to 10 kHz. However, the user can change 

the frequency limits in the following manner:

• Turn off Card 5052 in the author file (or remove this card completely).
NASA/CR—2010-216898/VOL2 6

• Specify the first 1/3-octave band number in Card 5054 (see Error! Reference source not found.

for standard 1/3-octave bands).

• Specify the last 1/3-octave band number in Card 5056 (see Error! Reference source not found.

for standard 1/3-octave bands).

To compute narrowband spectra, 

• Turn on Card 5052 in the author file.

• Specify the number of frequencies (nfreq) in Card 5058.

• Specify the first frequency (fmin) in Hz in Card 5060.

• Specify the last frequency (fmax) in Hz in Card 5062.

• Specify the bandwidth (BW) in Hz in Card 5064. If zero is entered, the bandwidth is 

automatically calculated via,

1

max min

−

− = n freq

f f BW

The frequency information provided by Cards 5052, 5054, 5056, 5058, 5060, 5062 and 5064 must 

correspond to the desired frequencies for the full-scale engine. The model-scale frequencies are 

determined via,

Model Scale

f f engine

model =

TABLE 4.—ANSI STANDARD ONE-THIRD OCTAVE BANDS (REFS. 13 AND 14)

Band

number

Center

frequency

(Hz)

Bandwidth

(Hz)

Band

number

Center

frequency

(Hz)

Bandwidth

(Hz)

1 1.25 0.292 25 315 73.2

2 1.6 0.367 26 400 92.2

3 2 0.462 27 500 116

4 2.5 0.582 28 630 146

5 3.15 0.732 29 800 184

6 4 0.922 30 1000 232

7 5 1.16 31 1250 292

8 6.3 1.46 32 1600 367

9 8 1.84 33 2000 462

10 10 2.32 34 2500 582

11 12.5 2.92 35 3150 732

12 16 3.67 36 4000 922

13 20 4.62 37 5000 1161

14 25 5.82 38 6300 1461

15 31.5 7.32 39 8000 1839

16 40 9.22 40 10000 2316

17 50 11.6 41 12500 2915

18 63 14.6 42 16000 3670

19 80 18.4 43 20000 4620

20 100 23.2 44 25000 5817

21 125 29.2 45 31500 7323

22 160 36.7 46 40000 9219

23 200 46.2 47 50000 11606

24 250 58.2 48 63000 14611
NASA/CR—2010-216898/VOL2 7

All calculations in BFaNS are done at the model-scale frequencies. At each frequency (fmodel), BFaNS 

compute the power spectral density of the sound power. From the power spectral density, BFaNS then 

computes the power spectrum via,

( ) ( ) model model model PWL = 10log10 PSD +10log10 BW

The full-scale power spectra are then computed via,

PWL PWL (Model Scale) engine model 10 = − 20log

f f (Model Scale) engine = model

4.5 Turbulent Inflow Noise

BBCascade is applied to the rotor and stator in a stripwise manner. The inflows to the rotor and stator 

are divided into several turbulent bands. The bands are non-uniformly spaced, and are usually 

concentrated in regions of strong gradients in the turbulence profile (the distribution of bands can be set 

by the user – see below). BBCascade computes the upstream and downstream sound power produced by 

the interaction of each turbulent band with the rotor or stator. The sound power from each band is then 

summed to yield the total upstream and downstream sound power.

4.5.1 BBCascade

Hanson derived the following equation for the sound power generated by a band of turbulence 

interacting with a cascade (Ref. 4),

= α υ φ α υ ∫∫ ± ∑ ±

constant F d d

PWR

PWR

k ref

22 ( , )

where

( ) 













 ∆

β +

π ω∆ω = e T ref

stat

PWR

Pr ra

s M Q M Q

BM

constant

2 1.4

12 33

2 2

This equation relates sound power to the cascade geometry, the mean flow field and the turbulence 

characteristics. The geometry consists of a rectilinear cascade of flat plates aligned with the mean flow 

direction (i.e., zero steady loading). The cascade span is assumed to be infinite. The mean flow is 

assumed to be uniform, and the boundaries far upstream and far downstream are assumed to be nonreflecting. Also, the turbulence characteristics are assumed to be constant over the band of turbulence.

Using his theory, Hanson developed the BBCascade computer program to predict the noise due to 

turbulent inflow interacting with a rotor or stator cascade.

4.5.2 BBCascade Input

Appendix G shows an example of a BBCascade input file. For each turbulent band, BBCascade 

requires the following information about the cascade geometry and the flow field:

Cascade geometry.—Airfoil count, gap-to-chord ratio, lean angle, sweep angle, and average 

radius
NASA/CR—2010-216898/VOL2 8

Steady flow.—Mach number in the stationary frame, flow angle in the stationary frame, static 

pressure and speed of sound

Turbulence.—Integral length scale, turbulence intensity and radial span of turbulent band

Most of this information is available from the “bfans.input” file. However, the static pressure, 

stationary-frame Mach number and stationary-frame flow angle must be computed from the “bfans.input”

file via,

where 1.4

2

γ = γ

ρ = a P

a

C C C

M z r 2 2 2

θ + + =

θ

+

α = C

Cz Cr 2 2

tan

For the radially dependent quantities, BFaNS computes a spanwise average over each turbulent band via,

∫ − =

hi

lo

r

r hi lo

avg Qdr

r r

Q 1

The Q variable can represent gap-to-chord ratio, lean angle, sweep angle, Mach number, flow angle, static 

pressure, speed of sound, integral scale or turbulence intensity, and (rlo, rhi) indicate the edges of the 

turbulent strip. The average radius and average airfoil rotational Mach number are defined as,

avg

avg

T avg

lo hi

avg

a

r

M

r r

r

Ω=

+ =

,

2

For the stator, the rotational speed (Ω) is zero.

4.5.3 BBCascade Modifications

Calculating the cascade response (F±

) is computationally intensive because it includes a slowly 

converging infinite product. To minimize the number of times that F± is calculated, BBCascade was 

modified to compute,

α υ





















= α υ φ constant∫∫ F± ∫∑ dr d d

PWR

PWR hi

lo

r

r k ref

22 ( , )

where

( ) 















β +

π ω∆ω = e T ref

stat

PWR

Pra

s M Q M Q

BM

constant

2 1.4

12 33

2 2
NASA/CR—2010-216898/VOL2 9

Note that the turbulence spectrum is now integrated over the span of the turbulent band, and the Δr term 

has been removed from the constant. In this manner, we only need to compute the cascade response once 

as long as the geometry and mean flow field are constant across the span of the cascade, even if the 

turbulence is non-uniform. If we were to use the original formulation of BBCascade on a non-uniform 

turbulence field, we would end up computing F± for every turbulent band, even if the cascade response 

were constant.

Appendix G compares the format of new BBCascade input file to that of the original BBCascade 

input file. Appendix H compares results from the new version of BBCascade to those from the original 

version for a stator cascade. Likewise, Appendix I compares results from the two versions of BBCascade 

for a rotor cascade. In general, agreement is very good between the two versions. The small differences 

are due to different steps being used in the wavenumber integration.

4.5.4 Mach-Number Limitation

Hanson’s theory for turbulent inflow noise is not valid when the relative Mach number is sonic or 

greater. In addition, high subsonic Mach numbers cause numerical problems. Therefore, BFaNS will 

terminate the calculation when the relative Mach number exceeds 0.93 on any segment. The user can 

change this limit with Card 5110 in the author file.

4.5.5 Turbulence Spectrum

Hanson’s theory formally accounts for anisotropic, non-homogeneous turbulence through the 3–D 

turbulent upwash spectrum. Unfortunately, this quantity is usually not available from measurements or 

computations. Consequently, we must rely on models that specify the 3–D upwash spectrum in terms of 

two readily available quantities, namely the intensity and length scale.

BBCascade has two options for the turbulence spectrum model:

(1) Isotropic turbulence via the Liepmann spectrum (Ref. 15), or

(2) Axisymmetric turbulence (Ref. 16)

BBCascade uses the Liepmann spectrum when the lateral and longitudinal intensities and length 

scales are equal. BBCascade uses the axisymmetric spectrum for all other cases.

The BFaNS input file only contains the longitudinal intensity and length scale. Therefore, the BFaNS 

default is to use the Liepmann spectrum. However, in Reference 4, Hanson showed the importance of 

anisotropy for noise generated by the inlet boundary interacting with the blade tip. Therefore, BFaNS has 

the option to set the ratio between the lateral and longitudinal length scales in the inlet boundary layer via 

Card 5084 in the author file.

4.5.6 Blade Tip Noise

By default, BFaNS will computes blade tip noise unless Card 5070 is turned on in the author file. The 

extent of the blade-tip region is determined by the boundary-layer thickness at the leading edge of the 

blade tip. By default, BFaNS divides the tip region into four equal bands. The user can change the number 

of bands using Card 5092 in the author file (warning—changing Card 5092 also changes the number of 

bands in the blade hub region, vane tip region and vane hub region).

4.5.7 Blade Hub Noise

By default, BFaNS will compute blade hub noise unless Card 5072 is turned on in the author file. The 

extent of the blade-hub region is determined by the boundary-layer thickness at the leading edge of the 

blade hub. By default, BFaNS divides the hub region into four equal bands. The user can change the 

number of bands using Card 5092 in the author file (warning—changing Card 5092 also changes the 

number of bands in the blade tip region, vane tip region and vane hub region).
NASA/CR—2010-216898/VOL2 10

4.5.8 Vane Tip Noise

By default, BFaNS will compute vane tip noise unless Card 5076 is turned on in the author file. The 

extent of the vane-tip region is determined by the boundary-layer thickness at the leading edge of the vane 

tip. By default, BFaNS divides the tip region into four equal bands. The user can change the number of 

bands using Card 5092 in the author file (warning—changing Card 5092 also changes the number of 

bands in the blade tip region, blade hub region and vane hub region).

4.5.9 Vane Hub Noise

By default, BFaNS will compute vane hub noise unless Card 5078 is turned on in the author file. The 

extent of the vane-hub region is determined by the boundary-layer thickness at the leading edge of the 

vane hub. By default, BFaNS divides the tip region into four equal bands. The user can change the 

number of bands using Card 5092 in the author file (warning—changing Card 5092 also changes the 

number of bands in the blade tip region, blade hub region and vane tip region).

4.5.10 Vane-Wake Interaction Noise

By default, BFaNS will compute vane-wake interaction noise unless Card 5082 is turned on in the 

author file. The extent of the vane-wake interaction region is determined by the boundary-layer thickness 

at the leading edge of the vane hub and vane tip. By default, BFaNS divides this region into eight equal 

bands. The user can change the number of bands using Card 5094 in the author file.

4.6 Self Noise

BFaNS uses a computer program that was developed by Glegg to predict fan self noise (but not 

FEGV self noise). Glegg’s approach relies on an experimental database of self noise from isolated 

NACA0012 airfoils (Ref. 11). This database is used to estimate the unsteady loading spectrum on the 

cascade for a given inlet Mach number, chord Reynolds number, and angle-of-attack. Given the unsteady

loading spectrum, Glegg computes the noise that would be radiated by the cascade, including the 

scattering effect of the adjacent blades. The calculation is coupled to the radial modes of the annular duct 

(assuming uniform axial flow).

In Glegg’s computer program, the rotor is divided into several uniformly spaced segments. The 

program computes the upstream and downstream sound power produced by each strip. The sound power 

from each strip is then summed to yield the total upstream and downstream sound power.

4.6.1 Self-Noise Input

The original self-noise computer program requires the following information about the cascade geometry 

and the flow field:

Cascade geometry.—Blade count, tip radius, root radius and spanwise chord distribution

Steady flow.—Blade rotational speed, speed of sound, density, axial flow speed, and spanwise 

angle-of-attack distribution 

The axial flow speed, speed of sound and density are assumed to be uniform. The blade is uniformly 

divided into several segments, the number of which is specified by the user. From this input, the program 

computes the following,

U = Ωr





 



 β = −

U

1 Cz tan
NASA/CR—2010-216898/VOL2 11

2 2 W = U +Cx

a

W M =

4.6.2 Self-Noise Modifications

Glegg’s self-noise computer program was originally written in MATLAB. It was converted to a set of 

FORTRAN subroutines that are called within BFaNS. The FORTRAN code requires an input file that 

contains the following cascade and flow-field information:

Cascade geometry.—Blade count, tip radius, root radius, radii for each segment, and spanwise 

chord distribution

Steady flow.—Blade rotational speed, average speed of sound, average density, and spanwise 

distribution of: meridional flow speed, angle-of-attack, relative flow speed and relative flow angle

BFaNS creates this input file based on the information contained in “bfans.input”. This new input 

format (see 0) eliminates the requirement for uniform axial flow speed (except when coupling to the duct 

modes, in which case the average axial flow speed is used). Note that the axial flow speed in the original 

file has been replaced with meridional flow speed to account for the non-zero component of radial 

velocity. Also, to account for swirl, the relative flow angle and relative flow speed are computed from,















 β = θ

−

W

1 Wm tan

2 2

θ W = Wm +W

This latter change allows the possibility of using the program to compute vane self noise (though it is not 

recommended).

For simplicity, the angle of attack is assumed to be uniform, and equal to the spanwise average angle 

of attack. However, the actual angle of attack distribution will be used when Card 5120 is turned on.

In addition to the above changes, the duct eigenvalue and eigenmode calculation was replaced with a 

faster method that was used by Glegg in some of his earlier work (Ref. 17). Appendix K compares results 

from the new version of the self-noise program to those from the original version. Agreement is very 

good between the two versions.

4.6.3 Mach-Number Limitation

Glegg’s self-noise theory is not valid when the relative Mach number is sonic or greater. In addition, 

high subsonic Mach numbers cause numerical problems. Therefore, BFaNS will terminate the calculation 

when the relative Mach number exceeds 0.97 on any segment. The user can change this limit with Card 

5112 in the author file.

4.6.4 Frequency Limitation

The self-noise prediction relies on an experimental database of self noise measured from isolated 

NACA0012 airfoils (Ref. 11). If the requested frequency exceeds the maximum frequency available in the 

database, BFaNS prints a warning to the screen, and enters zeroes in the output file.
NASA/CR—2010-216898/VOL2 12

4.6.5 Blade Self Noise

By default, BFaNS will compute blade self noise unless Card 5074 is turned on in the author file. Self 

noise is computed only for the portion of the blade span that is between the endwall boundary layers. By 

default, BFaNS divides this region into eight equal bands. The user can change the number of bands using 

Card 5096 in the author file (warning: changing Card 5096 also changes the number of segments in the 

vane self-noise calculation).

4.6.6 Vane Self Noise (Not Recommended)

By default, BFaNS will not compute vane self noise unless Card 5080 is turned on in the author file. 

Self noise is computed only for the portion of the vane span that is between the endwall boundary layers. 

By default, BFaNS divides this region into eight equal bands. The user can change the number of bands 

using Card 5096 in the author file (warning: changing Card 5096 also changes the number of segments in 

the blade self-noise calculation).

4.7 Output File

Appendix L shows a sample output file from BFaNS. The output file contains the upstream, 

downstream and total sound power spectra for each source, in addition to the spectra for all sources 

combined. The spectra apply to the full-scale engine (as determined by Card 5050 in the author file). 

Zeroes in the sound-power columns denote frequencies at which calculations were not performed (either 

by request, or due to program limitations). Although not shown in Appendix L, the end of the output file 

contains copies of the input and author files.

5.0 Concluding Remarks

Pratt & Whitney has developed a Broadband Fan Noise Prediction System (BFaNS) for turbofan 

engines. The noise prediction system consists of two computer programs: Setup_BFaNS and BFaNS.

Setup_BFaNS converts user-specified geometry and flow-field information into a BFaNS input file. From 

this input file, BFaNS computes the inlet and aft broadband sound power spectra generated by the fan and 

FEGV. The output file from BFaNS contains the inlet, aft and total sound power spectra from each noise 

source.

The Broadband Fan Noise Prediction System has been documented in a three-volume report. The 

present volume provides detailed instructions and technical documentation for BFaNS. Volume 1 

provides detailed instructions and technical documentation for Setup_BFaNS. Volume 3 provides 

validation and test cases for the prediction system.
NASA/CR—2010-216898/VOL2 13

Appendix A.—Symbols

A.1 Variables

a speed of sound

B airfoil count

BW bandwidth

b airfoil chord

C absolute velocity vector 

F± upstream (-) and downstream (+) cascade response (see Ref. 4)

f frequency

k scattering index (see Ref. 4)

M chordwise Mach number (see Ref. 4)

Mstat stationary-frame Mach number (see Ref. 4)

MT airfoil rotational Mach number (see Ref. 4)

nfreq number of frequencies

P static pressure

PSD power spectral density

PWR± upstream (-) and downstream (+) sound power (see Ref. 4)

PWRref reference sound power (1×10–12 W)

Qij transformation matrix from duct to cascade coordinates (see Ref. 4)

r radius

se see Reference 4

U blade velocity vector

W relative velocity vector 

x horizontal coordinate viewed from rear of engine

y vertical coordinate viewed from rear of engine

z axial coordinate

A.2 Greek Symbols

α absolute flow angle; effective angle-of-attack

α, υ lateral wavenumber components (see Ref. 4)

β relative flow angle; 2 1− M (see Ref. 4)

γ specific-heat ratio

θ tangential location

Λ turbulent length scale

ρ density

φ22 upwash spectrum tensor

Ω rotational speed of airfoil

ω radian frequency
NASA/CR—2010-216898/VOL2 14

A.3 Subscripts

engine engine scale

x horizontal component

y vertical component

z axial component

r radial component

θ tangential component

m meridional component

model model scale

max maximum

min minimum

lo lower edge of turbulent band

hi upper edge of turbulent band
NASA/CR—2010-216898/VOL2 15

Appendix B.—Installing the BFaNS System

The BFaNS system can be downloaded from the following web site: 

http://www.grc.nasa.gov/WWW/5900/5940/code/BFANS/

B.1 Step Number I: Setting Up the Directory Structure

1. In your home directory, create a directory called Codes.

2. Copy the file fans_nasa.tar to your ~/Codes directory.

3. In your ~/Codes directory, extract the files using the following command:

tar -xvf fans_nasa.tar

4. After executing this command, you will have a ~/Codes/fans_nasa directory. This directory will 

contain the following sub-directories:

setup_bfans: contains source code and make files for Setup_BFaNS

bfans: contains source code and make files for BFaNS

lib: contains source code and make files for GRAFIC (a freely distributed graphics library created 

by MIT)

makeflags: contains compiler options for Sun, SGI, and IBM workstations

5. Appendix E lists the files contained in each directory

B.2 Step Number II: Setting Up the Graphics Library (GRAFIC)

1. Go to the ~/Codes/fans_nasa/lib directory. There you will find libraries compiled for an SGI 

workstation (libgrafic.a.Iris), a Sun workstation (libgrafic.a.Sun4), and an IBM workstation 

(libgrafic.a.Ibm6000). You can use one of these existing libraries, or compile the library yourself. If 

you choose to use an existing library, proceed to step no. 2. If you choose to compile the library 

yourself, proceed to step no. 3.

2. If you are working on an SGI workstation (with iris architecture), type the command:

cp libgrafic.a.Iris libgrafic.a

If you are working on a Sun workstation (with svr4 architecture), type the command:

cp libgrafic.a.Sun4 libgrafic.a

If you are working on an IBM workstation (with rs6 architecture), type the command:

cp libgrafic.a.Ibm6000 libgrafic.a

For all the above workstations, proceed to Step no. III to compile Setup_BfaNS.

3. Go to the ~/Codes/fans_nasa/lib/grafic directory.

4. If you are working on an SGI workstation (with iris architecture), type the command:

make -f Makefile.Iris

If you are working on a Sun workstation (with svr4 architecture), type the command:

make -f Makefile.Sun4

If you are working on an IBM workstation (with rs6 architecture), type the command:

make -f Makefile.Ibm6000

The above commands will create a file called libgrafic.a in your ~/Codes/fans_nasa/lib directory. If 

you have problems compiling, go to the ~/Codes/fans_nasa/makeflags directory and check the 

compiler options that are set for your workstation (i.e., makeflags.Iris, makeflags.Sun4, or 

makeflags.Ibm6000).

B.3 Step Number III: Compiling Setup_BFaNS

1. Go to the ~/Codes/fans_nasa/setup_bfans directory.

2. If you are working on an SGI workstation (with iris architecture), type the command:

make -f Makefile.Iris
NASA/CR—2010-216898/VOL2 16

If you are working on a Sun workstation (with svr4 architecture), type the command:

make -f Makefile.Sun4

If you are working on an IBM workstation (with rs6 architecture), type the command:

make -f Makefile.Ibm6000

The above commands will create an executable file called setup_bfans.x in your 

~/Codes/fans_nasa/setup_bfans directory. If you have problems compiling, go to the 

~/Codes/fans_nasa/makeflags directory and check the compiler options that are set for your 

workstation (i.e., makeflags.Iris, makeflags.Sun4, or makeflags.Ibm6000).

3. If you want to change the compiler optimization (or other options), edit the appropriate makeflags file 

and repeat step no. 2 in this section.

B.4 Step Number IV: Compiling BFaNS

1. Go to the ~/Codes/fans_nasa/bfans directory.

2. If you are working on an SGI workstation (with iris architecture), type the command:

make -f Makefile.Iris

If you are working on a Sun workstation (with svr4 architecture), type the command:

make -f Makefile.Sun4

If you are working on an IBM workstation (with rs6 architecture), type the command:

make -f Makefile.Ibm6000

The above commands will create an executable file called bfans.x in your ~/Codes/fans_nasa/bfans

directory. If you have problems compiling, go to the ~/Codes/fans_nasa/makeflags directory and 

check the compiler options that are set for your workstation (i.e., makeflags.Iris, makeflags.Sun4, or 

makeflags.Ibm6000).

3. If you want to change the compiler optimization (or other options), edit the appropriate makeflags file 

and repeat step no. 2 in this section.

B.5 Step Number V: Setting Up Aliases

1. Inside your .cshrc file, create the following aliases:

alias sbf ~/Codes/fans_nasa/setup_bfans/setup_bfans.x

alias bf ~/Codes/fans_nasa/bfans/bfans.x

2. In your home directory, type source .cshrc

3. These aliases are not required, but they make running much easier.
NASA/CR—2010-216898/VOL2 17

Appendix C.—Running the Test Case

The BFaNS test case can be downloaded from the following web site: 

http://www.grc.nasa.gov/WWW/5900/5940/code/BFANS/

C.1 Step Number I: Setting Up the Test Case

1. In your home directory, create a directory called bbchallenge.

2. Copy the file bbchallenge.tar to your ~/bbchallenge directory.

3. In your ~/bbchallenge directory, extract the files using the following command:

tar -xvf bbchallenge.tar

After executing this command, you will have the following 13 sub-directories inside 

~/bbchallenge:

bfans_geometry: contains files that describe the flow path, blade, and vane geometry

bfans_cfd: contains files that describe viscous CFD-predicted flow field near blade l.e., blade 

t.e., vane l.e., and vane t.e. for each configuration and operating point

bfans_data: not used (normally contains files that describe measured flow field near blade l.e., 

blade t.e., vane l.e., and vane t.e. for each configuration and operating point)

bfans_sline: not used (normally contains files that describe inviscid streamline-predicted flow 

field near blade l.e., blade t.e., vane l.e., and vane t.e. for each configuration and operating point)

54vr_spd1: contains test case for 54 radial vanes, sideline power

54vr_spd2: contains test case for 54 radial vanes, cutback power

54vr_spd3: contains test case for 54 radial vanes, approach power

26vr_spd1: contains test case for 26 radial vanes, sideline power

26vr_spd2: contains test case for 26 radial vanes, cutback power

26vr_spd3: contains test case for 26 radial vanes, approach power

26vs_spd1: contains test case for 26 radial vanes, sideline power

26vs_spd2: contains test case for 26 radial vanes, cutback power

26vs_spd3: contains test case for 26 radial vanes, approach power

C.2 Step Number II: Running a Test Case for Setup_BFaNS

1. Inside your ~/bbchallenge/54vr_spd3 directory, type the command sbf or 

~/Codes/fans_nasa/setup_bfans/setup_bfans.x. This command will run Setup_BFaNS in the current 

directory.

2. When prompted for the name of the input file, enter setupbfans.input. This file contains the file 

names that describe the geometry and flow field (these files are located in the bfans_geometry and 

bfans_cfd sub-directories under ~/bbchallenge), along with some additional information.

3. A figure will be displayed on the screen showing the blade velocity triangles. Look at the figure and 

confirm that the velocity triangles are correct relative to the blade orientation. Once satisfied, place 

your cursor inside this window, and type the letter x on your keyboard. Typing x will continue 

program execution.

4. A figure will be displayed on the screen showing the vane velocity triangles. Look at the figure and 

confirm that the velocity triangles are correct relative to the vane orientation. Once satisfied, place 

your cursor inside this window, and type the letter x on your keyboard. Typing x will continue 

program execution.

5. A figure will be displayed on the screen showing the fan-duct configuration. Look at the figure and 

confirm that the configuration is correct. Once satisfied, place your cursor inside this window, and 

type the letter x on your keyboard. Typing x will continue program execution.

6. A menu will be displayed to allow you to change the geometry. If you wish to change something, 

type in the number corresponding to your selection and press return. Then provide the requested 
NASA/CR—2010-216898/VOL2 18

input. The old and new geometry will now be shown on the screen. Place your cursor inside the figure 

window, and type the letter x on your keyboard. Typing x will continue program execution, allowing 

you to make more changes to the geometry.

7. Type 99 to finish running Setup_BFANS.

8. You will now have a file named bfans.input in the ~/bbchallenge/54vr_spd3 directory. If you didn’t 

make any changes to the geometry, then bfans.input should be nearly identical to bfans.input.Sun4

which was created on a Sun workstation at P&W (there might be some very small differences 

depending on the compiler). To confirm that the two files are nearly identical, type the following 

command:

diff bfans.input bfans.input.Sun4

This command will show all differences between the two files.

C.3 Step Number III: Running a Test Case for BFaNS

1. Inside your ~/bbchallenge/54vr_spd3 directory, type the command bf or ~/Codes/ 

fans_nasa/bfans/bfans.x. This command will run BFaNS inside the current directory (note: to save 

time during code checkout, you might want to edit the bfans.author file to reduce the number of 

frequencies calculated).

2. When prompted for the name of the input file, enter bfans.input. This file contains the output from 

Setup_BFaNS. 

3. When done, BFaNS will display “calculation completed” on the screen. You will now have a file 

named bfans.output in the ~/bbchallenge/54vr_spd3 directory. If you didn’t make any changes to 

the geometry, then bfans.output should be nearly identical to bfans.output.Sun4 which was created 

on a Sun workstation at P&W (there might be some very small differences depending on the 

compiler). To confirm that the two files are nearly identical, type the following command:

diff bfans.output bfans.output.Sun4

This command will show all differences between the two files.
NASA/CR—2010-216898/VOL2 19

Appendix D.—Sample BFaNS Author File

c-------------------------------------------------------------------------------

c author file for bfans

c-------------------------------------------------------------------------------

c section #1: read format is (a1,i5,a20,a54)

c-------------------------------------------------------------------------------

c card description : a54

c-------------------------------------------------------------------------------

-5000 input file name : bfans.input

-5002 through 5048 : reserved for future development

c-------------------------------------------------------------------------------

c section #2: read format is (a1,i5,a45,2i4,2f8,a5)

c-------------------------------------------------------------------------------

c card description : i4 i4 f8 f8 a5

c-------------------------------------------------------------------------------

-5050 over-ride default model scale : 1.0

 -1 (default = 1.0) :

-5052 compute narrowband spectra :

-5054 over-ride first 1/3 octave band : 17

 -1 default = 17 (50 Hz) :

-5056 over-ride last 1/3 octave band : 40

 -1 default = 40 (10,000 Hz) :

-5058 over-ride number of narrowband frequencies : 100

 -1 default = 100 :

-5060 over-ride first narrowband frequency (hz) : 100.0

 -1 default = 100.0 :

-5062 over-ride last narrowband frequency (hz) : 10000.0

 -1 default = 10000. :

-5064 over-ride bandwidth (hz) for narrowband : 0.0

 -1 default = 0.0 (i.e. autocalculate) :

-5066 over-ride ambient density (lbm/ft^3) : 0.0765

 -1 default = 0.0765 :

-5068 over-ride ambient speed of sound (ft/s) : 1116.

 -1 default = 1116. :

-5070 do not compute blade tip noise :

-5072 do not compute blade hub noise :

-5074 do not compute blade self noise :

-5076 do not compute vane tip noise :

-5078 do not compute vane hub noise :

-5080 compute vane self noise :

-5082 do not compute wake noise :

-5084 over-ride inlet boundary layer anisotropy : 1.0

 -1 rmoda = transverse/longitudinal :

 -1 default = 1.0 :

-5086 over-ride approx. number of segments per : 5

 -1 wavelength for computing radial mode shape :

 -1 default = 5 :

-5088 over-ride minimum # of radial points : 30

 -1 default = 30 :

-5090 over-ride maximum eigenvalue multiplier : 1.1

 -1 default = 1.1 :

-5092 over-ride number of turbulent bands : 4

 -1 to use in boundary layers :

 -1 default = 4 :

-5094 over-ride number of turbulent band : 8

 -1 to use between boundary layers :

 -1 default = 8 :

-5096 over-ride number of radial segments to use : 10

 -1 in self-noise calculation :

 -1 default = 10 :

-5098 over-ride number of turbulent sub-bands : 10

 -1 in each turbulent band :
NASA/CR—2010-216898/VOL2 20

 -1 default = 10 :

-5100 over-ride eigenvalue tolerance : 1d-11

 -1 default = 1d-11 :

-5102 over-ride eigenfunction tolerance : 1d-06

 -1 default = 1d-6 :

-5104 over-ride tolerance on eigenvalue file : 1d-06

 -1 default = 1d-6 :

-5106 over-ride 1st eigenvalue for mode 0,0 : 1d-10

 -1 default = 1d-10 :

-5108 over-ride initial step in eigenval solver : 2.4

 -1 default = 2.4 :

-5110 over-ride maximum allowable mach number : 0.93

 -1 in bbcascade :

 -1 default = 0.93 :

-5112 over-ride maximum allowable mach # : 0.97

 -1 for self noise :

 -1 default = 0.97 :

-5114 do not use any cascade correction when :

 -1 computing selfnoise :

-5116 use approximate cascade correction when :

 -1 computing selfnoise :

-5118 use glegg routine for computing modes :

-5120 allow non-uniform a-o-a for selfnoise :

-5122 over-ride default inf in jsplit() : 2

 -1 imoda = # terms (thousands) :

 -1 default = 2 (for 2000 terms) :

-5124 over-ride default err in jsplit() : 5d-4

 -1 default = 5d-4 :

-5126 use fast version of jsplit() :

 -1 might create overflow :

 9999 end of author file
NASA/CR—2010-216898/VOL2 21

Appendix E.—Directory Structure of ~/Codes/fans_nasa

~/Codes/fans_nasa/

bfans/ lib/ lib/grafic/ setup_bfans/

Makefile.Ibm6000 libgrafic.a.Ibm600

0

Apollo.m4 grflip.m4 Makefile.Ibm6000

Makefile.Iris libgrafic.a.Iris Athena.m4 grgrey.m4 Makefile.Iris

Makefile.Sun4 libgrafic.a.Sun4 Aviion.m4 grgri1.m4 Makefile.Sun4

Makefile.wnt Dec.m4 grgrid.m4 add_points.F

angles.F makeflags/ Hp9000.m4 grinit.m4 angles.F

author.def makeflags.Ibm6000 Ibm6000.m4 grinpa.m4 arrowhead.F

bbcascade.F makeflags.Iris Iris.m4 grinpf.m4 author.def

bf_author.m makeflags.Sun4 Makefile.Ibm6000 grinpi.m4 cal_coeff.F

bfans_ibm6000.F makeflags.wnt Makefile.Iris grkey1.m4 calc_bl.F

bfans_iris.F Makefile.Sun4 grkey2.m4 calc_rotor_wake.F

bfans_sun4.F Newsys.m4 grkey3.m4 cascade.F

bfans_wnt.F Stellar.m4 grkli1.m4 chan_duct_geom.F

capz.F Sun4.m4 grklin.m4 circum_average.F

cascade2.F Titan.m4 grklst.m4 constants.def

constants.def Vapor.m4 grkpla.m4 converts.def

converts.def Vax.m4 grlin1.m4 cross_ref.F

cross_ref.F XApollo.c grline.m4 debug_add_points.F

dateandtime.F XAthena.c grloc2.m4 debug_calc_bl.F

error.F XAviion.c grloct.m4 debug_calc_rotor_wake.

F

exact_sol_hub.F XDec.c grmesg.m4 debug_estimate.F

f_ex.F XHp9000.c grmode.m4 debug_geom.F

f_ex2.F XIbm6000.c grmon2.m4 debug_get_bl.F

f_plus_minus2.F XIris.c grmon3.m4 debug_get_duct_geom.F

fbessj.F XNewsys.c grmov1.m4 debug_get_flow_data.F

fbessj0.F XStellar.c grmov2.m4 debug_get_geom.F

fbessj1.F XSun4.c grmov3.m4 debug_get_rotor_wake.F

fbessy.F XTitan.c grmovy.m4 debug_get_row_geom.F

fbessy0.F XVapor.c grnear.m4 debug_intersect.F

fbessy1.F contng.m4 grper1.m4 debug_normalize.F

fgen.F conxch.m4 grpers.m4 debug_scales.F

get_alpha_range.F gr2alst.m4 grplst.m4 debug_stream_line.F

get_freqs.F gr2axes.m4 grply2.m4 disp.F

get_input.F gr2ctrl.m4 grply3.m4 error.F

get_nu_range.F gr2curs.m4 grprnt.m4 estimate2.F

get_pratios_reba.F gr2get.m4 grscal.m4 flow.F

getalphas.F gr2lin1.m4 grscpt.m4 geom.F

getdeltas.F gr2line.m4 grsfac.m4 get_bl.F

input_bb.F gr2plst.m4 grsset.m4 get_duct_geom.F

input_new.F gr2set.m4 grsymb.m4 get_file_name.F

interp.F gr2sfac.m4 grthr1.m4 get_flow_data.F

jsp_te.F gr2sset.m4 grthre.m4 get_geom.F

jsplit.F grafic.doc grtime.m4 get_mesh_data.F

lusolve.F gralst.m4 grtran.m4 get_rho_sound.F

modes.F granot.m4 grvalu.m4 get_rotor_wake.F

mysqrt.F graxes.m4 grvec1.m4 get_row_geom.F

nasa_s.F grcfil.m4 grvect.m4 get_velocity_data.F

parameters.def grcler.m4 mrcon1.m4 interp.F

parameters.fgen.def grclos.m4 mrcont.m4 intersect2.F

power_ratio.F grcnew.inc leasqr.F

read_author.F grcntr.m4 ludcmq.F

read_input.F grcol2.m4 mkdir_matlab.F

response.F grcol3.m4 naca0012.F

run_bbcasc.F grcolr.m4 normalize.F

s_pred.F grcomn.inc parabola.F

s_spec.F grcon1.m4 parameters.def

trapezoid.F grcon2.m4 plot_bl.m

turbspect.F grcont.m4 plot_bv.F

zeros_ex_sub.F grctrl.m4 plot_geom.F

grcube.m4 plot_wake.m

grcurs.m4 read_author.F

grcutt.m4 reduce.m
NASA/CR—2010-216898/VOL2 22

~/Codes/fans_nasa/

bfans/ lib/ lib/grafic/ setup_bfans/

grdash.m4 save_get_bl.F

grdrw2.m4 sbf_author.m

grdrw3.m4 scales.F

grdump.m4 setupbfans.F

gredi1.m4 solnq.F

gredit.m4 sort.F

greror.m4 stream_function.F

grfil2.m4 stream_line.F

grfil3.m4 stress.F

stress.m

triangle.F

upwash.F

vect_comp.F

wake_lean.F

write_file.F
NASA/CR—2010-216898/VOL2 23

Appendix F.—BFaNS Subroutine Hierarchy

Bold items are called by multiple routines 

I. bfans

A. read_author

1. cross_ref

B. read_input

1. error

C. error

D. run_bbcasc

1. error

2. trapezoid

a. interp

3. bbcascade

a. input_bb

i. get_freqs

ii. angles

b. power_ratio

i. getdeltas

ii. get_nu_range

iii. get_pratios_reba

A) get_alpha_range

B) getalphas

C) f_plus_minus2

1) cascade2

a) jsplit

b) lusolve

D) turbspect

E. fgen

F. modes

1. error

G. input

1. error

2. trapezoid

3. interp

H. s_pred

1. error

2. get_input

a. error

3. s_spec

4. nasa_s

5. response

a. interp

b. jsp_te

6. interp

Appendix G.—Modification to BBCascade Input File

Original Format

'bbcascade input file' title

22 0.833E+00 0.239E+00 0.856E-02 -0.666E+00 b, gap/chord, machstat, thetastat, machtip

1 0.536E+01 -0.241E+00 * angleconvention, lean (deg), sweep (deg)

0.641E-01 0.641E-01 0.832E-02 0.832E-02 intensity (long), intensity (lat), scale/r (long), sc

0.203E+04 0.112E+04 0.912E+00 0.787E-02 po, ao, r, delr

3 ** spectrum type: 1 or 3 (1 for const BW, 3 for 1/3 O

0.250E+03 0.630E+05 ** see below for this line

0. 0. *** deltaalf, deltanu

* 0 for cascade system, 1 for duct system

** type = 1, const bw, input: f1 delfreq nfreq bw

** type = 3, 1/3 ob, input: first freq, last freq (e.g. 63. 500.)

*** (deltaalf = 0. => default values)

Modified Format

'bbcascade input file' title

 22 b 

 1 * angleconvention 

 0.203E+04 po 

 3 ** spectrum type: 1 or 3

 0.250E+03 0.630E+05 ** see below for this line

 0. 0. *** deltaalf, deltanu

 

* 0 for cascade system, 1 for duct system

** type = 1, const bw, input: f1 delfreq nfreq bw

** type = 3, 1/3 ob, input: first freq, last freq (e.g. 63. 500.)

*** (deltaalf = 0. => default values)

 

 10 nsubseg 

0.829E+00 0.830E+00 0.831E+00 0.832E+00 0.833E+00 0.834E+00 0.835E+00 0.835E+00 0.836E+00 0.837E+00 ga

0.281E+00 0.277E+00 0.272E+00 0.265E+00 0.257E+00 0.248E+00 0.237E+00 0.224E+00 0.203E+00 0.125E+00 ma

0.332E-01 0.337E-01 0.340E-01 0.332E-01 0.319E-01 0.292E-01 0.244E-01 0.146E-01 -0.125E-01 -0.136E+00 th

-0.663E+00 -0.664E+00 -0.664E+00 -0.665E+00 -0.666E+00 -0.666E+00 -0.667E+00 -0.668E+00 -0.669E+00 -0.671E+00 ma

0.523E+01 0.526E+01 0.529E+01 0.532E+01 0.535E+01 0.537E+01 0.539E+01 0.542E+01 0.545E+01 0.547E+01 le

-0.623E+00 -0.541E+00 -0.457E+00 -0.367E+00 -0.275E+00 -0.184E+00 -0.966E-01 -0.158E-01 0.541E-01 0.941E-01 sw

0.295E-01 0.351E-01 0.407E-01 0.478E-01 0.552E-01 0.631E-01 0.719E-01 0.831E-01 0.103E+00 0.156E+00 in

0.295E-01 0.351E-01 0.407E-01 0.478E-01 0.552E-01 0.631E-01 0.719E-01 0.831E-01 0.103E+00 0.156E+00 in

0.991E-02 0.985E-02 0.982E-02 0.986E-02 0.981E-02 0.945E-02 0.874E-02 0.763E-02 0.587E-02 0.229E-02 sc

0.991E-02 0.985E-02 0.982E-02 0.986E-02 0.981E-02 0.945E-02 0.874E-02 0.763E-02 0.587E-02 0.229E-02 sc

0.908E+00 0.909E+00 0.910E+00 0.911E+00 0.912E+00 0.912E+00 0.913E+00 0.914E+00 0.915E+00 0.916E+00 r 

0.787E-03 0.787E-03 0.787E-03 0.787E-03 0.787E-03 0.787E-03 0.787E-03 0.787E-03 0.787E-03 0.787E-03 de

0.112E+04 0.112E+04 0.112E+04 0.112E+04 0.112E+04 0.112E+04 0.112E+04 0.112E+04 0.112E+04 0.112E+04 ao 

NASA/CR—2010-216898/VOL2 2

NASA/CR—2010-216898/VOL2 27

Appendix H.—BBCascade Test Case - Stator

Original Input File

'Stator Case to Check BBCascade '

54 1.000 0.536 30.908 0.000 B, G, MachTotStat, Theta, MachTip

0 0.0 0.0 Angle Convention, Lean, Sweep

0.01 0.01 0.01 0.01 Intens1, Intens2, Scale1, Scale2

2262.0 1127.2 0.917 0.458 Po, A0, R, DelR

1 1 for const BW, 3 for 1/3 OB

1492.595 1492.595 30 100.0 see below *

1.0 1.0 DeltaAlf, DeltaNu

* For const BW, next line is first freq, freq step, Num freqs, BW

* For 1/3 OB , next line is first freq, last freq

Original Output File

Stator Case to Check BBCascade 

Month/Day/Year: 7/ 9/2003, Time: 10:16:24

Blade or Vane Count = 54, Gap/Chord = 1.000

Input values for mean flow in stator frame:

 Mach Number = 0.536 Flow angle = 30.9

 Rotor rotational Mach number = 0.000

Computed values:

 Relative Mach (rotor or stator) = 0.536, Stagger = 30.9

 Angles (degrees) Stagger Lean Sweep

In cascade system 30.9 0.0 0.0 - L&S input

In duct system 30.9 0.0 0.0 - L&S computed

Turbulence properties:

 I(axial)/W = 0.01000, I(trans)/W = 0.01000

 L(axial)/R = 0.01000, L(trans)/R = 0.01000

Po=2262.0 lb/sq ft, A0= 1127.2 ft/sec

Fan Radius= 0.917 ft, Span of Turbulent Band= 0.458 ft

DeltaAlf= 1.000, DeltaNu= 1.000

jfreq freq PWLup PWLdn 

 1 1492.6 73.6 78.1

 2 2985.2 83.3 86.9

 3 4477.8 88.1 91.3

 4 5970.4 87.4 94.1

 5 7463.0 89.7 96.0

 6 8955.6 90.0 95.5

 7 10448.2 89.3 94.4

 8 11940.8 89.1 95.0

 9 13433.4 89.0 95.0

 10 14925.9 88.1 94.3

 11 16418.5 87.2 94.1

 12 17911.1 86.8 93.5

 13 19403.7 86.2 92.8

 14 20896.3 85.1 91.8

 15 22388.9 84.7 91.7

 16 23881.5 84.2 91.4

 17 25374.1 83.5 90.6

 18 26866.7 82.8 90.2

 19 28359.3 82.4 89.8

 20 29851.9 82.1 89.2

 21 31344.5 81.1 88.4

 22 32837.1 80.7 88.3

 23 34329.7 80.3 87.8

 24 35822.3 79.8 87.1

 25 37314.9 79.0 86.8

 26 38807.5 79.0 86.5

 27 40300.1 78.6 85.9

 28 41792.7 77.9 85.3

 29 43285.3 77.6 85.2

 30 44777.8 77.2 84.7

Modified BBCascade

 freq PWLup PWLdn

 1492.6 73.9 78.3

 2985.2 83.3 86.9

 4477.8 88.0 91.2

 5970.4 87.4 94.1

 7463.0 89.6 96.1

 8955.6 89.9 95.6

10448.2 89.2 94.5

11940.8 89.0 95.0

13433.4 88.9 95.0

14925.9 88.0 94.4

16418.5 87.1 94.2

17911.1 86.7 93.5

19403.7 86.1 92.8

20896.3 85.0 91.8

22388.9 84.6 91.7

23881.5 84.2 91.4

25374.1 83.4 90.6

26866.7 82.7 90.3

28359.3 82.4 89.9

29851.9 82.0 89.2

31344.5 81.1 88.4

32837.1 80.7 88.3

34329.7 80.3 87.9

35822.3 79.7 87.2

37314.9 79.0 86.8

38807.5 79.0 86.5

40300.1 78.5 85.9

41792.7 77.8 85.3

43285.3 77.5 85.2

44777.8 77.1 84.8

NASA/CR—2010-216898/VOL2 29

Appendix I.—BBCascade Test Case—Rotor

Original Input File

'Rotor Case to Check BBCascade '

22 0.600 0.300 0.197 0.706 B, G, MachTotStat, Theta, MachTip

0 0.0 0.0 Angle Convention, Lean, Sweep

0.01 0.01 0.01 0.01 Intens1, Intens2, Scale1, Scale2

1991.2 1105.9 0.917 0.458 Po, A0, R, DelR

1 1 for const BW, 3 for 1/3 OB

1492.595 1492.595 30 100.0 see below *

1.0 1.0 DeltaAlf, DeltaNu

* For const BW, next line is first freq, freq step, Num freqs, BW

* For 1/3 OB , next line is first freq, last freq

OriginalOutput File

Rotor Case to Check BBCascade 

Month/Day/Year: 7/ 9/2003, Time: 11: 0:35

Blade or Vane Count = 22, Gap/Chord = 0.600

Input values for mean flow in stator frame:

 Mach Number = 0.300 Flow angle = 0.2

 Rotor rotational Mach number = 0.706

Computed values:

 Relative Mach (rotor or stator) = 0.766, Stagger = -66.9

 Angles (degrees) Stagger Lean Sweep

In cascade system -66.9 0.0 0.0 - L&S input

In duct system -66.9 0.0 0.0 - L&S computed

Turbulence properties:

 I(axial)/W = 0.01000, I(trans)/W = 0.01000

 L(axial)/R = 0.01000, L(trans)/R = 0.01000

Po=1991.2 lb/sq ft, A0= 1105.9 ft/sec

Fan Radius= 0.917 ft, Span of Turbulent Band= 0.458 ft

DeltaAlf= 1.000, DeltaNu= 1.000

BPF = 2981.2 Hz

jfreq freq PWLup PWLdn 

 1 1492.6 76.7 73.5

 2 2985.2 80.4 78.1

 3 4477.8 83.5 83.7

 4 5970.4 85.0 86.1

 5 7463.0 85.9 88.1

 6 8955.6 86.2 89.3

 7 10448.2 86.2 89.9

 8 11940.8 86.1 89.8

 9 13433.4 85.9 89.2

 10 14925.9 85.6 88.7

 11 16418.5 85.3 88.6

 12 17911.1 84.9 88.6

 13 19403.7 84.6 88.5

 14 20896.3 84.2 87.8

 15 22388.9 83.8 87.3

 16 23881.5 83.5 87.1

 17 25374.1 83.1 87.1

 18 26866.7 82.7 86.8

 19 28359.3 82.3 86.2

 20 29851.9 82.0 85.5

 21 31344.5 81.6 85.3

 22 32837.1 81.3 85.0

 23 34329.7 81.0 84.7

 24 35822.3 80.6 84.0

 25 37314.9 80.3 83.7

 26 38807.5 80.0 83.3

 27 40300.1 79.7 83.2

 28 41792.7 79.4 82.9

 29 43285.3 79.0 82.5

 30 44777.8 78.8 82.0

Modified BBCascade

 freq PWLup PWLdn

 1492.6 76.4 73.4

 2985.2 80.3 78.2

 4477.8 83.6 83.2

 5970.4 85.1 86.0

 7463.0 85.9 87.7

 8955.6 86.0 89.7

10448.2 85.6 90.6

11940.8 86.2 89.6

13433.4 86.0 89.4

14925.9 85.6 89.0

16418.5 85.1 88.8

17911.1 84.8 88.8

19403.7 84.5 88.5

20896.3 84.1 87.9

22388.9 83.7 87.3

23881.5 83.4 87.3

25374.1 83.1 87.2

26866.7 82.7 86.9

28359.3 82.3 86.2

29851.9 82.0 85.6

31344.5 81.6 85.4

32837.1 81.3 85.2

34329.7 80.9 84.8

35822.3 80.6 84.3

37314.9 80.3 83.9

38807.5 80.0 83.5

40300.1 79.7 83.4

41792.7 79.3 83.0

43285.3 79.0 82.7

44777.8 78.7 82.2

NASA/CR—2010-216898/VOL2 31

Appendix J.—Sample Self-Noise Input File

sound power type (1=upstream, -1=downstream) : updown = -1

1 for if apprx. downstream blade response used : res_opt = 0

sound power reference level (watts) : wref = 1.E-12

ambient density (kg/m^3) : roe = 1.184

ambient sound (m/s) : co = 346.143

rotational speed (rad/s) : om = 817.652

number of blades or vanes : b = 22

number of radial segments : nseg = 11

tip radius (m) : a = 0.279

hub radius (m) : hub = 0.084

radius (m) hub to tip : r = 0.084

radius (m) hub to tip : r = 0.103

radius (m) hub to tip : r = 0.123

radius (m) hub to tip : r = 0.142

radius (m) hub to tip : r = 0.162

radius (m) hub to tip : r = 0.182

radius (m) hub to tip : r = 0.201

radius (m) hub to tip : r = 0.221

radius (m) hub to tip : r = 0.240

radius (m) hub to tip : r = 0.260

radius (m) hub to tip : r = 0.279

chord (m) hub to tip : c = 0.075

chord (m) hub to tip : c = 0.079

chord (m) hub to tip : c = 0.083

chord (m) hub to tip : c = 0.084

chord (m) hub to tip : c = 0.086

chord (m) hub to tip : c = 0.089

chord (m) hub to tip : c = 0.092

chord (m) hub to tip : c = 0.096

chord (m) hub to tip : c = 0.097

chord (m) hub to tip : c = 0.095

chord (m) hub to tip : c = 0.095

angle of attack (deg) hub to tip : ang = 6.016

angle of attack (deg) hub to tip : ang = 6.016

angle of attack (deg) hub to tip : ang = 6.016

angle of attack (deg) hub to tip : ang = 6.016

angle of attack (deg) hub to tip : ang = 6.016

angle of attack (deg) hub to tip : ang = 6.016

angle of attack (deg) hub to tip : ang = 6.016

angle of attack (deg) hub to tip : ang = 6.016

angle of attack (deg) hub to tip : ang = 6.016

angle of attack (deg) hub to tip : ang = 6.016

angle of attack (deg) hub to tip : ang = 6.016

blade or vane angle (rad) hub to tip : beta = 0.988

blade or vane angle (rad) hub to tip : beta = 0.888

blade or vane angle (rad) hub to tip : beta = 0.802

blade or vane angle (rad) hub to tip : beta = 0.729

blade or vane angle (rad) hub to tip : beta = 0.665

blade or vane angle (rad) hub to tip : beta = 0.611

blade or vane angle (rad) hub to tip : beta = 0.564

blade or vane angle (rad) hub to tip : beta = 0.523

blade or vane angle (rad) hub to tip : beta = 0.487

blade or vane angle (rad) hub to tip : beta = 0.455

blade or vane angle (rad) hub to tip : beta = 0.427

meridional flow speed (m/s) hub to tip : u = 103.948

meridional flow speed (m/s) hub to tip : u = 103.948

meridional flow speed (m/s) hub to tip : u = 103.948

meridional flow speed (m/s) hub to tip : u = 103.948

meridional flow speed (m/s) hub to tip : u = 103.948

meridional flow speed (m/s) hub to tip : u = 103.948

meridional flow speed (m/s) hub to tip : u = 103.948
NASA/CR—2010-216898/VOL2 32

meridional flow speed (m/s) hub to tip : u = 103.948

meridional flow speed (m/s) hub to tip : u = 103.948

meridional flow speed (m/s) hub to tip : u = 103.948

meridional flow speed (m/s) hub to tip : u = 103.948

relative flow speed (m/s) hub to tip : ue = 124.522

relative flow speed (m/s) hub to tip : ue = 133.981

relative flow speed (m/s) hub to tip : ue = 144.590

relative flow speed (m/s) hub to tip : ue = 156.115

relative flow speed (m/s) hub to tip : ue = 168.367

relative flow speed (m/s) hub to tip : ue = 181.200

relative flow speed (m/s) hub to tip : ue = 194.498

relative flow speed (m/s) hub to tip : ue = 208.173

relative flow speed (m/s) hub to tip : ue = 222.154

relative flow speed (m/s) hub to tip : ue = 236.387

relative flow speed (m/s) hub to tip : ue = 250.830

integration step parameter : nintstep = 0

turbulent boundary layer calculation : turb = 1

laminar boundary layer calculation : lam = 0
NASA/CR—2010-216898/VOL2 33

Appendix K.—Self-Noise Test Case

Input file for original FAU MATLAB code:

outfile='OUTPUT'; %output file name

updown=-1; %updown=1 for upstream sound power

%updown=-1 for downstream sound power

fmin=1000; %input minimum frequency

fmax=15000; %input maximum frequency

N=15; %input number of points in spectrum

dfreq=15.6; %input freq. analysis bandwidth

%

U=93; %input axial flow speed

a=0.2286; %input duct radius

hub=0.1; %input hub radius

rpm=9120;Om=rpm*2*pi/60; %input rotor rpm

c=0.081+0*(1:10); %input blade chord(hub to tip)

ang=7+0*(1:10); %input angle of attack(degrees)(hub to tip)

B=20; %number of blades

Nintstep=5; %integration step parameter

%

%%%%%%%%%% OPTIONS %%%%%%%%%%%%

option=1; %option1=1 if NASA self noise code is to be used

%option1=2 if default blade self noise spectra are to be used

%option1=3 if data set in SLTdata.mat is to be used

%

res_opt=0; %res_opt=1 if approximate downstream blade response used

Turb=1; % TBL calc.

Lam=0; % LBL calc.

modeplot=1; % Mode plot displayed if modeplot==1

jjmax=100; % max number of modes to be displayed

%

plot_opt1=0; % plot_option1=1 displays the wavenumbers, response 

%function and and source level for tip region

plot_opt2=0; % plot_option2=1 displays the mode amplitudes vs duct 

%axial wavenumber

%

Nseg=length(c) %number of points used to interpolate source level

if length(ang)~=Nseg;disp('ang and c must have same number of points');return;end

Wref=1e-12; % sound power reference level

co=340; % speed of sound

roe=1.2; % density of air

%

FAU P&W P&W MATLAB P&W FORTRAN

Frequency D.S. Sound Power D.S. Sound Power P&W - FAU D.S. Sound Power D.S. Sound Power FORTRAN - MATLAB

(Hz) (dB) (dB) (dB) (dB) (dB) (dB)

1000 69.7423 69.7421 -0.0002 69.7418 69.7418 0.0000

2000 73.2749 73.2747 -0.0002 73.2744 73.2743 -0.0001

3000 76.2848 76.2848 0.0000 76.2847 76.2846 -0.0001

4000 81.4445 81.4445 0.0000 81.4445 81.4445 0.0000

5000 84.1604 84.1604 0.0000 84.1604 84.1604 0.0000

6000 85.0033 85.0033 0.0000 85.0033 85.0032 -0.0001

7000 84.5942 84.5942 0.0000 84.5942 84.5941 -0.0001

8000 83.1250 83.1248 -0.0002 83.1249 83.1248 -0.0001

9000 82.2663 82.2661 -0.0002 82.2661 82.2661 0.0000

10000 84.0167 84.0167 0.0000 84.0167 84.0166 -0.0001

11000 86.1071 86.1070 -0.0001 86.1070 86.1070 0.0000

12000 86.9741 86.9740 -0.0001 86.9739 86.9739 0.0000

13000 86.8632 86.8630 -0.0002 86.8630 86.8629 -0.0001

14000 86.0530 86.0528 -0.0002 86.0528 86.0528 0.0000

15000 84.5503 84.5499 -0.0004 84.5499 84.5499 0.0000

Notes:

 1. in comparing MATLAB codes, both versions used MATLAB-generated eigenvalues

 2. in comparing MATLAB to FORTRAN codes, both versions used FORTRAN-generated eigenvalues

 3. the FORTRAN-generated eigenvalues are more accurate than the MATLAB-generated eigenvalues due to the eigenvalue solver used

Comparison of MATLAB Versions (see note #1) Comparison of FORTRAN and MATLAB Versions (see note #2,3)

NASA/CR—2010-216898/VOL2 35

Appendix L.—Sample BFaNS Output File

54-Vane Radial Stator 

Approach Condition (7,808 rpm

blade tip noise (full scale)

 hz up dn tot

----------------------------

 250. 0.0 0.0 0.0

 315. 0.0 0.0 0.0

 400. 0.0 0.0 0.0

 500. 0.0 0.0 0.0

 630. 0.0 0.0 0.0

 800. 0.0 0.0 0.0

 1000. 0.0 0.0 0.0

 1250. 0.0 0.0 0.0

 1600. 0.0 0.0 0.0

 2000. 0.0 0.0 0.0

 2500. 0.0 0.0 0.0

 3150. 0.0 0.0 0.0

 4000. 0.0 0.0 0.0

 5000. 0.0 0.0 0.0

 6300. 0.0 0.0 0.0

 8000. 0.0 0.0 0.0

10000. 0.0 0.0 0.0

12500. 0.0 0.0 0.0

16000. 0.0 0.0 0.0

20000. 0.0 0.0 0.0

25000. 0.0 0.0 0.0

31500. 0.0 0.0 0.0

40000. 0.0 0.0 0.0

50000. 0.0 0.0 0.0

63000. 0.0 0.0 0.0

blade hub noise (full scale)

 hz up dn tot

----------------------------

 250. 0.0 0.0 0.0

 315. 0.0 0.0 0.0

 400. 0.0 0.0 0.0

 500. 0.0 0.0 0.0

 630. 0.0 0.0 0.0

 800. 0.0 0.0 0.0

 1000. 0.0 0.0 0.0

 1250. 0.0 0.0 0.0

 1600. 0.0 0.0 0.0

 2000. 0.0 0.0 0.0

 2500. 0.0 0.0 0.0

 3150. 0.0 0.0 0.0

 4000. 0.0 0.0 0.0

 5000. 0.0 0.0 0.0

 6300. 0.0 0.0 0.0

 8000. 0.0 0.0 0.0

10000. 0.0 0.0 0.0

12500. 0.0 0.0 0.0

16000. 0.0 0.0 0.0

20000. 0.0 0.0 0.0

25000. 0.0 0.0 0.0

31500. 0.0 0.0 0.0

40000. 0.0 0.0 0.0

50000. 0.0 0.0 0.0

63000. 0.0 0.0 0.0
NASA/CR—2010-216898/VOL2 36

blade self noise (full scale)

 hz up dn tot

----------------------------

 250. 66.8 58.8 67.4

 315. 0.0 0.0 0.0

 400. 75.9 68.6 76.6

 500. 75.9 71.8 77.3

 630. 80.1 76.5 81.7

 800. 83.6 80.4 85.3

 1000. 95.9 83.1 96.1

 1250. 86.2 86.2 89.2

 1600. 87.4 88.8 91.2

 2000. 90.1 90.0 93.1

 2500. 93.3 92.3 95.8

 3150. 96.5 96.8 99.7

 4000. 100.2 101.5 103.9

 5000. 101.9 103.9 106.0

 6300. 104.0 104.8 107.4

 8000. 104.9 104.1 107.6

10000. 104.8 109.1 110.5

12500. 105.2 109.8 111.1

16000. 104.7 108.6 110.1

20000. 103.6 107.5 109.0

25000. 0.0 0.0 0.0

31500. 0.0 0.0 0.0

40000. 0.0 0.0 0.0

50000. 0.0 0.0 0.0

63000. 0.0 0.0 0.0

vane tip noise (full scale)

 hz up dn tot

---------------------------

 250. 0.0 0.0 0.0

 315. 0.0 0.0 0.0

 400. 0.0 0.0 0.0

 500. 0.0 0.0 0.0

 630. 0.0 0.0 0.0

 800. 0.0 0.0 0.0

 1000. 0.0 0.0 0.0

 1250. 0.0 0.0 0.0

 1600. 0.0 0.0 0.0

 2000. 0.0 0.0 0.0

 2500. 0.0 0.0 0.0

 3150. 0.0 0.0 0.0

 4000. 0.0 0.0 0.0

 5000. 0.0 0.0 0.0

 6300. 0.0 0.0 0.0

 8000. 0.0 0.0 0.0

10000. 0.0 0.0 0.0

12500. 0.0 0.0 0.0

16000. 0.0 0.0 0.0

20000. 0.0 0.0 0.0

25000. 0.0 0.0 0.0

31500. 0.0 0.0 0.0

40000. 0.0 0.0 0.0

50000. 0.0 0.0 0.0

63000. 0.0 0.0 0.0

vane hub noise (full scale)

 hz up dn tot

---------------------------

 250. 0.0 0.0 0.0

 315. 0.0 0.0 0.0
NASA/CR—2010-216898/VOL2 37

 400. 0.0 0.0 0.0

 500. 0.0 0.0 0.0

 630. 0.0 0.0 0.0

 800. 0.0 0.0 0.0

 1000. 0.0 0.0 0.0

 1250. 0.0 0.0 0.0

 1600. 0.0 0.0 0.0

 2000. 0.0 0.0 0.0

 2500. 0.0 0.0 0.0

 3150. 0.0 0.0 0.0

 4000. 0.0 0.0 0.0

 5000. 0.0 0.0 0.0

 6300. 0.0 0.0 0.0

 8000. 0.0 0.0 0.0

10000. 0.0 0.0 0.0

12500. 0.0 0.0 0.0

16000. 0.0 0.0 0.0

20000. 0.0 0.0 0.0

25000. 0.0 0.0 0.0

31500. 0.0 0.0 0.0

40000. 0.0 0.0 0.0

50000. 0.0 0.0 0.0

63000. 0.0 0.0 0.0

vane self noise (full scale)

 hz up dn tot

---------------------------

 250. 0.0 0.0 0.0

 315. 0.0 0.0 0.0

 400. 0.0 0.0 0.0

 500. 0.0 0.0 0.0

 630. 0.0 0.0 0.0

 800. 0.0 0.0 0.0

 1000. 0.0 0.0 0.0

 1250. 0.0 0.0 0.0

 1600. 0.0 0.0 0.0

 2000. 0.0 0.0 0.0

 2500. 0.0 0.0 0.0

 3150. 0.0 0.0 0.0

 4000. 0.0 0.0 0.0

 5000. 0.0 0.0 0.0

 6300. 0.0 0.0 0.0

 8000. 0.0 0.0 0.0

10000. 0.0 0.0 0.0

12500. 0.0 0.0 0.0

16000. 0.0 0.0 0.0

20000. 0.0 0.0 0.0

25000. 0.0 0.0 0.0

31500. 0.0 0.0 0.0

40000. 0.0 0.0 0.0

50000. 0.0 0.0 0.0

63000. 0.0 0.0 0.0

vane-wake interaction noise (full scale)

 hz up dn tot

----------------------------------------

 250. 0.0 0.0 0.0

 315. 0.0 0.0 0.0

 400. 0.0 0.0 0.0

 500. 0.0 0.0 0.0

 630. 0.0 0.0 0.0

 800. 0.0 0.0 0.0

 1000. 0.0 0.0 0.0
NASA/CR—2010-216898/VOL2 38

 1250. 0.0 0.0 0.0

 1600. 0.0 0.0 0.0

 2000. 0.0 0.0 0.0

 2500. 0.0 0.0 0.0

 3150. 0.0 0.0 0.0

 4000. 0.0 0.0 0.0

 5000. 0.0 0.0 0.0

 6300. 0.0 0.0 0.0

 8000. 0.0 0.0 0.0

10000. 0.0 0.0 0.0

12500. 0.0 0.0 0.0

16000. 0.0 0.0 0.0

20000. 0.0 0.0 0.0

25000. 0.0 0.0 0.0

31500. 0.0 0.0 0.0

40000. 0.0 0.0 0.0

50000. 0.0 0.0 0.0

63000. 0.0 0.0 0.0

total noise (full scale)

 hz up dn tot

------------------------

 250. 66.8 58.8 67.4

 315. 0.0 0.0 0.0

 400. 75.9 68.6 76.6

 500. 75.9 71.8 77.3

 630. 80.1 76.5 81.7

 800. 83.6 80.4 85.3

 1000. 95.9 83.1 96.1

 1250. 86.2 86.2 89.2

 1600. 87.4 88.8 91.2

 2000. 90.1 90.0 93.1

 2500. 93.3 92.3 95.8

 3150. 96.5 96.8 99.7

 4000. 100.2 101.5 103.9

 5000. 101.9 103.9 106.0

 6300. 104.0 104.8 107.4

 8000. 104.9 104.1 107.6

10000. 104.8 109.1 110.5

12500. 105.2 109.8 111.1

16000. 104.7 108.6 110.1

20000. 103.6 107.5 109.0

25000. 0.0 0.0 0.0

31500. 0.0 0.0 0.0

40000. 0.0 0.0 0.0

50000. 0.0 0.0 0.0

63000. 0.0 0.0 0.0
NASA/CR—2010-216898/VOL2 39

References

1. Hanson, D.B., “Quantification of Inflow Turbulence for Prediction of Cascade Broadband Noise,” 

Paper No. 990544, presented at the 5th International Congress on Sound and Vibration, Adelaide, 

Australia, Dec 15–18, 1997.

2. Hanson, D.B., and Horan, K.P., “Turbulence/Cascade Interaction: Spectra of Inflow, Cascade 

Response, and Noise,” Paper No. 98–2319, presented at the 4th AIAA/CEAS Aeroacoustics 

Conference, Toulouse, France, June 2–4, 1998.

3. Hanson, D.B., “Influence of Lean and Sweep on Noise of Cascades With Turbulent Inflow,” Paper 

No. 99–1863, presented at the 5th AIAA/CEAS Aeroacoustics Conference, Seattle, Washington, May 

10–12, 1999.

4. Hanson, D.B., “Theory for Broadband Noise of Rotor and Stator Cascades With Inhomogeneous 

Inflow Turbulence Including Effects of Lean and Sweep,” NASA/CR—2001-210762, May 2001.

5. Glegg, S.A.L., “Airfoil Self Noise Generated in a Cascade,” AIAA Paper 96–1739, presented at the 

2nd AIAA/CEAS Aeroacoustics Conference, State College, PA, May 6–8, 1996.

6. Glegg, S.A.L., and Jochault, C., “Broadband Self Noise from a Ducted Fan,” presented at the 3rd

AIAA/CEAS Aeroacoustics Conference, Atlanta, GA, May 12–14, 1997.

7. Glegg, S.A.L, and Jochault, C., “Fan Self Noise Prediction,” Florida Atlantic University Report, April 

1997.

8. Glegg, S.A.L., “The Response of a Swept Blade Row to a Three-Dimensional Gust,” J. Sound and 

Vibration, Vol. 227 (1), pp. 29–64, 1999.

9. Hanson, D.B., “Broadband Noise of Fans – With Unsteady Coupling Theory to Account for Rotor 

and Stator Reflection/Transmission Effects,” NASA/CR—2001-211136-Revised, November 2001 

(reprinted January 2003).

10. Hanson, D.B., “Broadband Theory for Coupled Fan Stages Including Blade Row 

Reflection/Transmission Effects,” AIAA–2002–2488, presented at the 8th AIAA/CEAS Aeroacoustics 

Conference, Breckenridge, Colorado, June 17–19, 2002.

11. Brooks, T.M., Pope, D.S. and Marcolini, M.A., “Airfoil Self Noise and Prediction,” NASA RP–1218, 

1989.

12. Morin, B.L., “Broadband Fan Noise Prediction System for Turbofan Engines: Volume 1: 

Setup_BFaNS User’s Manual and Developer’s Guide,” NASA/CR—2010-216898/VOL1, 

November 2010.

13. ANSI, “Preferred Frequencies, Frequency Levels, and Band Numbers for Acoustical Measurements,” 

ANSI S1.6–1984, Published by the American Institute of Physics for the Acoustical Society of 

America, 1984.

14. ANSI, “Specification for Octave, Half-Octave, and Third-Octave Band Filter Sets,” ANSI S1.11–

1966 (R1975), 1975.

15. Liepmann H. W., “Extension of the Statistical Approach to Buffeting and Gust Response of Wings of 

Finite Span,” Journal of the Aeronautical Sciences, March 1955.

16. Kerschen, E.J., and Gliebe, P.R., “Fan Noise Caused by the Ingestion of Anisotropic Turbulence – A 

Model Based on Axisymmetric Turbulence Theory,” AIAA Paper 80–1021, presented at the 6th

AIAA Aeroacoustics Conference, Hartford, CT, June 4–6, 1980.

17. Glegg, S.A.L., “Broadband Noise From Ducted Prop Fans,” AIAA 93–4402, presented at the 15th

AIAA Aeroacoustics Conference, Long Beach, CA, October 25–27, 1993.
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4. TITLE AND SUBTITLE

Broadband Fan Noise Prediction System for Turbofan Engines 

Volume 2: BFaNS User’s Manual and Developer’s Guide

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Morin, Bruce, L. 

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13. SUPPLEMENTARY NOTES

14. ABSTRACT

Pratt & Whitney has developed a Broadband Fan Noise Prediction System (BFaNS) for turbofan engines. This system computes the noise generated by turbulence impinging 

on the leading edges of the fan and fan exit guide vane, and noise generated by boundary-layer turbulence passing over the fan trailing edge. BFaNS has been validated on three 

fan rigs that were tested during the NASA Advanced Subsonic Technology Program (AST). The predicted noise spectra agreed well with measured data. The predicted effects 

of fan speed, vane count, and vane sweep also agreed well with measurements. The noise prediction system consists of two computer programs: Setup_BFaNS and BFaNS. 

Setup_BFaNS converts user-specified geometry and flow-field information into a BFaNS input file. From this input file, BFaNS computes the inlet and aft broadband sound 

power spectra generated by the fan and FEGV. The output file from BFaNS contains the inlet, aft and total sound power spectra from each noise source. This report is the 

second volume of a three-volume set documenting the Broadband Fan Noise Prediction System: Volume 1: Setup_BFaNS User’s Manual and Developer’s Guide; Volume 2: 

BFaNS User’s Manual and Developer’s Guide; and Volume 3: Validation and Test Cases. The present volume begins with an overview of the Broadband Fan Noise Prediction 

System, followed by step-by-step instructions for installing and running BFaNS. It concludes with technical documentation of the BFaNS computer program. 

15. SUBJECT TERMS

Fan blades; Vanes; Broadband; Turbulence; Rotor stator interactions 

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