Christopher E. Hughes

Glenn Research Center, Cleveland, Ohio

John A. Gazzaniga

ASRC Aerospace Corporation

Effect of Two Advanced Noise Reduction 

Technologies on the Aerodynamic Performance 

of an Ultra High Bypass Ratio Fan

NASA/TM—2013-216073

November 2013
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Christopher E. Hughes

Glenn Research Center, Cleveland, Ohio

John A. Gazzaniga

ASRC Aerospace Corporation

Effect of Two Advanced Noise Reduction 

Technologies on the Aerodynamic Performance 

of an Ultra High Bypass Ratio Fan

NASA/TM—2013-216073

November 2013

National Aeronautics and

Space Administration

Glenn Research Center

Cleveland, Ohio 44135
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Acknowledgments

This work was performed under the support of the NASA Subsonic Fixed Wing Project in the Fundamental Aeronautics 

Program. The results obtained in the research described in this paper directly addresses Subsonic Fixed Wing Project 

goals to reduce Generation N+1 aircraft noise, fuel burn and NOx environmental emissions. The authors would like 

to acknowledge the dedicated efforts of the Test Engineers in the Wind Tunnel and Propulsion Test Branch and the 

support crew at the 9 - by 15-Foot Low-Speed Wind Tunnel at the NASA Glenn Research Center.

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 technical management. 

Available electronically at http://www.sti.nasa.gov
Effect of Two Advanced Noise Reduction Technologies 

on the Aerodynamic Performance of an 

Ultra High Bypass Ratio Fan 

Christopher E. Hughes 

National Aeronautics and Space Administration 

Glenn Research Center 

Cleveland, Ohio 44135 

John A. Gazzaniga 

ASRC Aerospace Corporation 

Cleveland, Ohio 44135 

Abstract 

A wind tunnel experiment was conducted in the NASA Glenn Research Center anechoic 9- by 15-Foot LowSpeed Wind Tunnel to investigate two new advanced noise reduction technologies in support of the NASA 

Fundamental Aeronautics Program Subsonic Fixed Wing Project. The goal of the experiment was to demonstrate the 

noise reduction potential and effect on fan model performance of the two noise reduction technologies in a scale 

model Ultra High Bypass turbofan at simulated takeoff and approach aircraft flight speeds. The two novel noise 

reduction technologies are called Over-the-Rotor acoustic treatment and Soft Vanes. Both technologies were aimed 

at modifying the local noise source mechanisms of the fan tip vortex/fan case interaction and the rotor wake-stator 

interaction. For the Over-the-Rotor acoustic treatment, two noise reduction configurations were investigated. The 

results showed that the two noise reduction technologies, Over-the-Rotor and Soft Vanes, were able to reduce the 

noise level of the fan model, but the Over-the-Rotor configurations had a significant negative impact on the fan 

aerodynamic performance; the loss in fan aerodynamic efficiency was between 2.75% to 8.75%, depending on 

configuration, compared to the conventional solid baseline fan case rubstrip also tested. Performance results with the 

Soft Vanes showed that there was no measurable change in the corrected fan thrust and a 1.8% loss in corrected 

stator vane thrust, which resulted in a total net thrust loss of approximately 0.5% compared with the baseline 

reference stator vane set. 

I. Introduction 

The NASA Fundamental Aeronautics Program Subsonic Fixed Wing Project (SFW) has set an aggressive noise 

reduction goal for the next generation (N+1) subsonic commercial aircraft of 32 dB cumulative below the current 

Stage 4 noise regulation. To meet this goal, a high fidelity wind tunnel experiment was conducted as part of the 

SFW Project to investigate and determine the noise reduction potential of two advanced noise reduction 

technologies for the Ultra High Bypass (UHB) engine cycle. These two technologies, Over-the-Rotor (OTR) metal 

foam acoustic liner treatment and acoustically treated Soft Vanes (SV), were tested using the NASA Glenn Research 

Center turbofan acoustic test bed propulsion simulator in the Glenn anechoic 9- x 15-Foot Low Speed Wind Tunnel 

(9’x15’) at velocities simulating aircraft takeoff and landing speeds. 

The objective of these technologies was to reduce the noise generated by the fan tip vortex/fan case interaction 

and the rotor wake/stator interaction. They were designed to modify the local unsteady pressure response to the 

flow and reduce the noise by redirecting and absorbing the acoustic energy. Acoustic results show that the OTR 

acoustic treatment configurations had a minimal impact on the fan model noise, while the SV configuration did 

produce significant noise reduction benefits. The acoustic results from this experiment are more fully described by 

Elliot and Woodward (Ref. 1). The effect of these technologies on the fan and stator aerodynamic performance was 

considered in the design process in an effort to minimize their impact. This paper presents the results obtained to 

measure their effect on the UHB model fan and stator aerodynamic performance. 

 

NASA/TM—2013-216073 1
II. Research Hardware

The experiment used fan model hardware developed for the NASA/Pratt & Whitney Advanced Ducted 

Propulsor (Ref. 2) and the NASA Fan Trailing Edge Blowing (Ref. 3) experiments, both being 18-bladed, 1.3 fan 

pressure ratio UHB fan models, and both previously tested at NASA Glenn. Whenever possible, as much legacy 

model hardware was used and as much of the original internal flowpath in the model was maintained. Fig. 1 shows 

photos of the fan model hardware installed on the Glenn drive rig in the 9x15 wind tunnel and a close-up of the fan 

disk. Fig. 2 is an illustration of the fan model showing the re-used hardware in silver and the new hardware pieces 

in color (except for the fan and spinner, which were existing hardware but colored for contrast). 

The two noise reduction technologies investigated were designed to reduce the noise by manipulating the noise 

source mechanisms, the unsteady pressures generated when the local flow interacts with the physical model 

hardware. In Fig. 2 the locations of the two technologies in the fan model are shown. One of the noise reduction 

technologies, called Over-the-Rotor (OTR) treatment, was designed to address the noise generating mechanisms at 

the fan tip. The intent was to modify the interaction between the fan tip flow and the fan case. This was 

accomplished by incorporating a 1.5 inch thick layer of high porosity (80 to 100 pores per inch), low density (6% to 

8%, or 92% to 94% open area), metallic foam (described in Refs. 4 and 5) into the fan case above the fan tip. The 

metallic foam resembled a sponge material with a very large number of very small cavities. A portion of the sound 

pressure fluctuations would propagate into the foam instead of propagating into the free field, and would then be 

trapped or absorbed in the foam material. 

Two different OTR design configurations were tested. The design rationale of the acoustically-treated rubstrips 

is described by Jones, et al. (Ref. 4). Sutliff, et al. (Ref. 5) has documented the noise reduction potential of this 

metal foam liner in experiments in the NASA Glenn Aeroacoustics Propulsion Laboratory (AAPL) using the 

Advanced Noise Control Fan, a very low pressure ratio device, as well as with a metal foam backed perforated 

rubstrip in a high speed turbofan application using a Williams International engine (Ref. 6). One design (FOAM) 

had the metal foam exposed on the flow surface, substituting for the normal rub material surface used at the fan tip. 

Pictures of the FOAM rubstrip are shown in Fig. 3. The other design (PERF) had a wearable, rigid plastic resin rub 

material shaped to duplicate the normal rubstrip flow surface backed by the metal foam. This configuration was 

intended to more realistically approach a conventional design fan case rubstrip flow surface. The plastic material 

was perforated with uniformly spaced holes 0.035” in diameter, producing an open area that was 20% of the total 

flow surface area of the rub surface. The hole-diameter-to-length ratio was close to 1:3. The design intent was to 

allow the sound pressure fluctuations to pass unimpeded through the holes in the rub material and into the foam 

behind without significantly impacting the flow at the fan tip because of the small diameter of the holes in the rub 

material. Ideally, the flow would treat the rubstrip surface as a solid. Fig. 4 are pictures of the PERF rubstrip. In 

order to provide a baseline for comparison for the OTR designs, a conventional, solid hardwall (HW) rubstrip was 

also tested. A picture of the baseline rubstrip is shown in Fig. 5. A nominal gap of 0.030” between the fan blade tip 

and the fan case rub surface was designed for all three rubstrip configurations tested, the two OTR and the baseline. 

For all three rubstrips, the tip gap was reduced to nominally 0.017” at the maximum fan speed due to fan blade 

growth produced by the aerodynamic and centrifugal forces. 

The second of the technologies, called Soft Vanes (SV), was designed to minimize the rotor-stator interaction 

noise generated as the fan wake impinges on the stator vanes. The design rationale behind the SV is discussed in 

Ref. 4. Again, the intent was to modify the noise generating mechanism by changing the unsteady pressure 

fluctuation response on the suction surface of the vanes. In this case, the stator vanes were hollow and divided into 

four separate internal chambers of varying length and internal volume. Each chamber was designed to act upon a 

certain frequency range of the interaction noise spectrum. Access to these internal chambers was provided by holes 

in the vane surface from 10% to 40% of the chord. This was determined analytically to be the location of maximum 

pressure response on the vanes where the fan wake impinges on the vane suction surface. The holes were then 

covered by a high impedance screen material to minimize the disturbances produced by airflow over the holes, and 

so minimize performance losses. The high impedance screen material provides a smooth aerodynamic surface, 

supporting steady pressures, but allows for the unsteady pressure perturbations to pass through in to the treatment 

Then, pressure waves in the designated specific frequencies propagated into the internal chambers and were 

dissipated, or canceled, preventing them from propagating into the farfield. There were a total of 25 vanes in the 

stator vane assembly. Fig. 6 is photos of the SV assembly and individual stator vane. Fig. 7 shows the acoustic 

treatment design and photos of internal vane structure. A set of solid metal stator vanes (HV) with the same 

aerodynamic design as the SV was also tested, in order to establish a baseline for comparison with the SV acoustic 

results. Fig. 8 is a picture of the HV stator assembly and an individual stator vane. 

The fan aerodynamic performance was determined by measuring the pressure and temperature rise across the 

fan with four fixed, 10-element rakes located behind the fan between the fan and stators. Each rake element 

NASA/TM—2013-216073 2
consisted of instrumentation to measure local total pressure and total temperature. A description of the 

instrumentation can be found in Ref. 2. Stator losses were determined by measuring the thrust produced using a sixcomponent static force balance, since there was no allowance made in the fan model for measuring pressure losses 

across the stators. Since the stators were an integral part of the nacelle system, including inlet, fan duct, cowl and 

bypass nozzle, the static balance measurements included force contributions from those elements as well. A twocomponent rotating force balance was used to measure the fan thrust and torque produced at the same time. By 

combining the two force balance measurements and correcting to standard day conditions, the total net thrust of the 

fan model system was determined. In this way, the impact of the SV on the complete fan model was measured. 

These measurements were made in conjunction with farfield acoustic testing, since the model was in the flight 

configuration with the complete nacelle installed and all pressure and temperature instrumentation was removed. A 

description of the force balance systems and their capabilities can be found in Ref. 7. Total weight flow into the 

model was determined from a previously defined curve fit of static pressure measurements in the model inlet with 

fan speed for the model hardware used. 

III. Test Plan 

The fan and stator aerodynamic performance was measured along a fixed operating line with a nozzle area sized 

to optimize fan performance at takeoff conditions for the baseline rubstrip configuration without treatments. The fan 

pressure and temperature rise and adiabatic efficiency were measured at several fan speeds along the operating line 

with each of the three OTR configurations installed – HW, PERF and FOAM – to determine their effect on the fan. 

Finally, the fan and stator thrust with the HV and SV configurations installed was measured using the rotating and 

static force balances at the same fan speed points while acoustic testing was conducted. The model is in the cleanest 

aerodynamically and is the closest simulation to the engine configuration during acoustic testing. 

IV. Test Results 

In the succeeding sections, the effect of the two noise reduction technologies on the fan and stage aerodynamic 

performance is shown. The data displayed in Figures 9 through 24 have been tabularized and can be found in 

Appendix A. 

A. Comparison of Hardwall and Perforated OTR Rubstrips 

Figs. 9 to 11 illustrate the difference in aerodynamic performance between the hardwall (HW) baseline fan case 

rubstrip and the OTR perforated (PERF) rubstrip. The results show the fan performance drops with the PERF 

rubstrip installed compared with the hardwall. Fig. 9 shows that there is a loss in fan total pressure ratio with a 

corresponding loss in corrected total weight at all fan speeds. The loss in total pressure was from 0.1% to 0.5% with 

a drop in total weight flow from 0.6% to 1.3% as the fan speed increased from 55% to 100% of the fan design speed. 

The associated change in total temperature ratio is shown in Fig. 10. Here, the change in fan performance is shown 

as an increase in the total temperature, indicating a drop in performance produced as the fan tries to increase the 

energy in the flow. The resultant energy imparted to the flow is in the form of heat rather than an increase in 

pressure. The increase in temperature was from 0.1% to 0.2% compared to the HW rubstrip at the same fan speeds 

described above. In Fig. 11, the resultant drop in fan adiabatic performance is shown, illustrating the significant 

impact the PERF rubstrip has on the fan efficiency compared with the HW rubstrip. Loss in adiabatic efficiency 

ranges from 2.7% to 4.0% as the fan speed increases. 

To better illustrate the effect of the PERF rubstrip on fan blade loading, Figs. 12 to 14 show the various 

parameter radial profiles produced from the fan exit performance rake data. Results are shown at three fan speeds; 

62%, 86% and 100% of the fan design speed. These three speeds represent the aircraft acoustic rating point speeds 

of approach, cutback and takeoff for this engine cycle. They can also be used as reference speeds for illustrating 

detailed fan performance results since the speeds also span the fan operating line. In Fig. 12, the total pressure ratio 

profiles are shown for the PERF and HW rubstrips. As can be seen, the PERF rubstrip does have an impact on the 

local fan pressure loading. The fan loading is reduced along nearly the entire span of the blade, but is most 

significant in the outer half of the fan blade, especially near the fan tip, or the last roughly 20% of blade span. The 

difference in pressure rise ranges from 0.07% to .43% as radius increases on the blade to sensor 8, then jumps to a 

1.40% drop at the last sensor near the fan tip at 100% fan speed. In Fig. 13, the total temperature ratio profiles are 

shown. Interestingly, the change in fan loading seems have a slightly positive effect on the total temperature rise 

since there is a slight decrease in total temperature inboard in the fan wake. At 100% fan speed, the total 

temperature decreases compared to the HW baseline by 0.03% to 0.08% from sensor locations 1 to 8, then 

NASA/TM—2013-216073 3
significantly increases by 1.48% at the fan tip as the PERF rubstrip disrupts the flow there. In Fig. 14, the 

distribution of adiabatic efficiency along the fan blade is shown. Again, the dramatic change in fan performance 

produced by the PERF rubstrip is illustrated at the fan tip with the large loss in efficiency. At 100% fan speed, peak 

adiabatic efficiency losses are 0.60% at 80% span, increasing to an 18.61% loss at 100% span. At other inboard 

radial locations on the fan blade, efficiency losses were much less, +/- 0.4% or less. This agrees with the slightly 

improved total temperature results inboard on the fan blade in Fig. 13, where the fan is better at doing work on the 

flow. 

B. Comparison of Hardwall and Exposed Metal Foam OTR Rubstrips 

In this section, the difference in fan performance with the hardwall (HW) baseline rubstrip and the exposed 

metal foam OTR acoustic treatment (FOAM) rubstrip will be discussed. Performance comparison plots are shown 

in Figs. 15 to 17. Fig. 15 shows the fan total pressure ratio and weight flow with fan speed along the fixed operating 

line for both rubstrip configurations. The loss in total pressure and weight flow follows the same trend as shown in 

Fig. 9, but the losses are significantly larger with the FOAM rubstrip; the losses in pressure and weight flow are 

almost double the losses with the PERF rubstrip in Fig. 9. Compared with the HW baseline rubstrip performance, 

the loss in total pressure is between 0.2% and 1.2% as the fan speed increases between 55% and 100%, with a 

corresponding decrease in weight flow between 1.6% and 2.9% over the same speed range. In Fig. 16, the change in 

total temperature ratio shows the same trend as shown in Fig. 10, but also significantly larger. The increase in total 

temperature ranges between 0.1% and 0.4% as fan speed increases from 55% to 100%, almost double the 

temperature increase seen with the PERF rubstrip in Fig. 10. Finally in Fig. 17, the loss in adiabatic efficiency is 

shown and is from 6.8% at 55% speed to as much as 9.3% at 100% speed. This figure clearly demonstrates that this 

OTR configuration is unacceptable due to the large losses in performance. 

To better visualize the impact the FOAM rubstrip has on the fan blade loading, radial parameter profiles are 

shown in Figs. 18 to 20 comparing the FOAM and HW rubstrips. The huge impact on the blade flow can easily be 

seen in Figs. 18 and 19 by the dramatic pressure losses and temperature increases in the last roughly 40% of the fan 

blade span. The last four outboard radial measurement locations show losses in efficiency from 13.3% to 28.3% at 

100% speed. Interestingly, a secondary flow phenomenon may be partially the cause of these large losses. Both 

pressure and temperature profiles show a large jump in losses and efficiency at the next to last radial measurement 

station on the rake, followed by a slight reversal in losses at the furthest outboard rake radial measurement location. 

It appears that the flow could be separating then reattaching, or that an external influence has caused unfavorable 

changes to the incoming flow incidence angle to the fan blade locally. Hot wire turbulence results presented in 

Ref. 1 indicate that the leading blade tip vortex looks to be significantly migrating toward the following blade. If 

this vortex flow is influencing the incoming flow of the following blade, the local fan blade performance could be 

significantly affected. In any case, the tip vortex flow phenomenon is occurring as a result of the open FOAM 

rubstrip as the fan flow is unimpeded by the rubstrip and reacts as if there is much more open gap at the fan tip. 

C. Comparison of Hard and Soft Stator Vanes 

In this section, the effect of the Soft Vanes (SV) on the fan and stator aerodynamic performance will be 

discussed. Thrust and torque produced by the fan and stators are used as the aerodynamic performance metric since 

there was no instrumentation located behind the stator vanes to make total pressure measurements. The SV 

performance is compared to a conventional, solid metal, baseline stator vane set (HV) designed to have similar 

aerodynamic of the SV. The corrected thrust and corrected torque of the fan, corrected thrust of the stator vanes, 

and the corrected total thrust of the fan and stators together are shown in Figs. 21 to 24. Since a measurement of the 

total weight flow was not available during this part of the test, the force numbers are plotted as a function of the 

percent corrected fan speed. Fig. 21 shows the corrected fan thrust produced as fan speed increases. Clearly, the 

differences in fan performance between the two different rubstrip configurations are very small, within the 

measurement accuracy of the force balance thrust which is +/- 5 lbs. Fig. 22 shows the corrected fan torque 

produced as fan speed increases. This is a measure of the amount of work needed to drive the fan to produce thrust 

at the given fan speed. Again, the differences between the two rubstrips is small, however the SV do require slightly 

more power starting at fan speeds of 65% and above. The differences are small but measureable since accuracy of 

the force balance torque is +/- 3.5 ft-lbs. The indication here is that there is a small increase in flow blockage with 

the SV that cause a minor backpressure on the fan that requires more power to achieve the same fan speed as the HV 

baseline. The blockage is most likely caused by the disturbed flow over the mesh screen covering the inlet hole 

interface to the SV chambers. If the screen is not perfectly aligned with the vane surface at the leading edge of the 

screen, the screen can trip the flow resulting in higher flow losses and turbulence. Fig. 23 bears this out, which 

NASA/TM—2013-216073 4
shows the corrected stator thrust produced by the two stator vane assemblies. Here, the slightly reduced thrust 

produced by the SV compared to the HV can be seen at fan speeds beyond 85%. The data shows the loss in thrust 

increasing as the fan speed increases. Still, the losses are small compared to the total stator thrust produced, shown 

in Fig. 24. The maximum loss is only 8 lbs. at 100% speed, which is 1.9% of the stator vane total thrust. Overall, 

the loss in corrected total thrust, the combination of fan and stator thrust, of the SV compared to the HV is no more 

than 7 lbs., or 0.5% of the corrected total thrust of 1,277 lbs. at 100% speed. 

V. Summary and Conclusion 

A test was conducted in the NASA Glenn 9’x15’ Low Speed Wind Tunnel as part of the Fundamental 

Aeronautics Program Subsonic Fixed Wing Project to investigate the potential benefit of two advanced noise 

reduction technologies and their impact on the aerodynamic performance of an Ultra High Bypass turbofan model. 

The two technologies were called Over-the-Rotor (OTR) metal foam acoustic treatment and Soft Vanes (SV). Each 

technology was aimed at reducing the noise produced when flow from the fan interacts with hardware located in the 

flow path. In the case of OTR treatment, the acoustic pressure waves produced at the fan tip as part of the tip vortex 

flow were attenuated in the tortuous path in the very small cell, highly porous, metal foam located above the fan tip. 

Two OTR treatment designs were tested: one had the metal foam exposed to the flow and acted as the fan case 

rubstrip; and the other had the metal foam located behind a plastic resin material which had holes accounting for 

20% of the total fan rubstrip area to allow the noise access to the foam behind the plastic rubstrip. In the case of the 

SV, the pressure waves generated as the fan wake interacts with the downstream stator vanes were allowed to pass 

through a holes in the suction surface of the stator vanes and into tuned cavities within the hollow stator vane and 

dissipate in the cavities. In addition, the entry holes in the vanes were covered with a high impedance mesh 

prevented reflection of the pressure waves. This report addressed the effect these technologies had on the fan and 

stator aerodynamic performance. 

The test results show that both of the OTR treatment designs had a significant impact on the fan performance 

compared with a hardwall, conventional rubstrip. The perforated OTR rubstrip has the least impact, but still reduced 

the total weight flow as much as 1.3% at 100% fan speed, with accompanying losses in total pressure of 0.5% and 

adiabatic efficiency by 4.0% compared with the solid hardwall baseline rubstrip. The exposed foam OTR rubstrip 

showed a very large impact on the performance, with losses slightly more than double those shown for the 

perforated OTR rubstrip. At 100% fan speed, the losses with the foam OTR rubstrip were 2.9% in weight flow, 

1.2% in total pressure and 9.3% in adiabatic efficiency. 

Fan and stator performance with the SV installed showed very small to negligible changes in fan and stator 

forces compared with the solid set of stator vanes used as a baseline reference. Forces measured from rotating and 

static force balances measured thrust and torque forces on the fan and stators. Combined fan and stator corrected 

total thrust results showed using the SV produced losses in total thrust of only 0.5% at 100% fan speed compared to 

the solid baseline stator vanes. 

In conclusion, the performance test results presented in this paper show the effect of two advanced noise 

reduction technologies, Over-the-Rotor acoustic treatment and Soft Vanes, on the aerodynamic performance of the 

fan and stators. The results indicate that both Over-the-Rotor acoustic treatment designs produce large, 

unacceptable losses in fan aerodynamic performance compared to the performance using a conventional, solid 

hardwall rubstrip. Acoustic test results presented in Ref. 1 indicate the OTR rubstrips did have an impact on the fan 

model noise, but only in the middle of the range of fan speeds tested. Further research is required to reduce the fan 

losses to more acceptable levels (1% or less in fan adiabatic efficiency) and increase the noise reduction benefit at 

the lower and higher fan speeds. A modified rubstrip design that reduces the impact of the OTR acoustic treatment 

on the fan blade loading and fan tip flow needs to be investigated. Performance results with the Soft Vanes, 

however, show small losses in the thrust produced by the fan and stators compared with conventional, solid metal 

stator vanes. The performance losses are within the acceptable range (less than 1% of total system thrust). Based on 

the acoustic test results shown in Ref. 1, the SV also produce a significant benefit in reducing the fan model noise, 

thus making the SV noise reduction technology an attractive technology for further development into larger scale 

demonstration. 

References 

1. Elliot, D.E.; Woodward, R.P.; Podboy, G.P.; “Acoustic Performance of Unique Liner Locations for a High 

Bypass Model Turbofan at Simulated Flight Conditions,” AIAA-2009-3140.

2. Jeracki, R.J.; “Comprehensive Report of Fan Performance from Duct Rake Instrumentation on 1.294 Pressure 

Ratio, 806 ft/sec Tip Speed Turbofan Simulator Models,” NASA/TM-2006-213863, 2006. 

NASA/TM—2013-216073 5
3. Fite, E.B.; Woodward, R.P.; Podboy, G.G.; “Effect of Trailing Edge Flow Injection on Fan Noise and 

Aerodynamic Performance,” AIAA 2006-2844.

4. Jones, M.G.; Parrott, T.L.; Sutliff, D.L.; Hughes, C.E.; “Assessment of Soft Vane and Metal Foam Engine 

Noise Reduction Concepts,” AIAA-2009-3142.

5. Sutliff, D.L.; Jones, M.G.; “Foam-Metal Liner Attenuation of Low-Speed Fan Noise,” AIAA–2008-2897.

6. Sutliff, D.L.; Elliot, D.E.; Jones, M.G.; Hartley, T.C.; “Attenuation of FJ44 Turbofan Engine Noise with a 

Foam-Metal Liner Installed Over-The-Rotor,” AIAA-2009-3141. 

7. Jeracki, R.J.; “Model Engine Performance Measurement From Force Balance Instrumentation,” NASA/TM1998-208486. 

 

NASA/TM—2013-216073 6
Figure 1. Ultra High Bypass fan model hardware installed in the NASA Glenn 9’x15’ LSWT. 

Figure 2. Illustration of the UHB fan model indicating existing hardware in silver and new hardware in 

color, and locations of noise reduction technologies. 

Over-the-Rotor fan case with

metal foam acoustic treatment

Acoustically treated

Soft Vanes

NASA/TM—2013-216073 7
Figure 3. Fan case with exposed metal foam (FOAM) rubstrip. 

Figure 4. Fan case with perforated (PERF) rubstrip. 

Metal Foam Treatment behind perforated rubstrip material

NASA/TM—2013-216073 8
Figure 5. Baseline hardwall (HW) fan case rubstrip. 

Figure 6. Acoustically treated Soft Vanes (SV), forward looking aft. 

Figure 7. Details of Soft Vane acoustic treatment design; leading edge of vane is on the left. 

View of internal chambers

and porous suction surface

CAD model

NASA/TM—2013-216073 9
Figure 8. Solid Hard Vane (HV) baseline stator vanes. 

Figure 9. Comparison of fan pressure rise between HW and PERF rubstrips. 

1.05

1.10

1.15

1.20

1.25

1.30

1.35

40 45 50 55 60 65 70 75 80 85

Fan Total Pressure Ratio, P/Pt

Total Corrected Weight Flow, lbm/sec

HW

PERF

NASA/TM—2013-216073 10
Figure 10. Comparison of fan temperature rise between HW and PERF rubstrips. 

Figure 11. Comparison of fan adiabatic efficiency between HW and PERF rubstrips. 

Figure 12. Comparison of radial fan pressure profiles between HW and PERF rubstrips. 

1.01

1.02

1.03

1.04

1.05

1.06

1.07

1.08

1.09

40 45 50 55 60 65 70 75 80 85

Fan Total Temperature Ratio, T/Tt

Total Corrected Weight Flow, lbm/sec

HW

PERF

0.80

0.82

0.84

0.86

0.88

0.90

0.92

0.94

0.96

0.98

1.00

40 45 50 55 60 65 70 75 80 85

Fan Adiabatic Efficiency

Total Corrected Weight Flow, lbm/sec

HW

PERF

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

1.05 1.10 1.15 1.20 1.25 1.30 1.35 1.40

Rake Sensor Radial Position (hub to tip), in.

Fan Total Pressure Ratio, P/Pt

HW

PERF

ap (62%)

cb (86%)

to (100%)

NASA/TM—2013-216073 11
Figure 13. Comparison of radial fan temperature profiles between HW and PERF rubstrips. 

Figure 14. Comparison of radial fan adiabatic efficiency profiles between HW and PERF rubstrips. 

Figure 15. Comparison of fan pressure rise between HW and FOAM rubstrips. 

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

1.01 1.03 1.05 1.07 1.09 1.11 1.13

Rake Sensor Radial Position (hub to tip), in.

Fan Total Temperature Ratio, T/Tt

HW

PERF

ap (62%)

cb (86%)

to (100%)

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

0.56 0.60 0.64 0.68 0.72 0.76 0.80 0.84 0.88 0.92 0.96 1.00

Rake Sensor Radial Position (hub to tip), in.

Fan Adiabatic Efficiency

HW

PERF

ap (62%)

cb (86%)

to (100%)

1.05

1.10

1.15

1.20

1.25

1.30

1.35

40 45 50 55 60 65 70 75 80 85

Fan Total Pressure Ratio, P/Pt

Total Corrected Weight Flow, lbm/sec

HW

FOAM

NASA/TM—2013-216073 12
Figure 16. Comparison of fan temperature rise between HW and FOAM rubstrips. 

Figure 17. Comparison of fan adiabatic efficiency between HW and FOAM rubstrips. 

Figure 18. Comparison of fan pressure profiles between HW and FOAM rubstrips. 

1.01

1.02

1.03

1.04

1.05

1.06

1.07

1.08

1.09

1.10

40 45 50 55 60 65 70 75 80 85

Fan Total Temperature Ratio, T/Tt

Total Corrected Weight Flow, lbm/sec

HW

FOAM

0.80

0.82

0.84

0.86

0.88

0.90

0.92

0.94

0.96

0.98

1.00

40 45 50 55 60 65 70 75 80 85

Fan Adiabatic Efficiency

Total Corrected Weight Flow, lbm/sec

HW

FOAM

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

1.00 1.05 1.10 1.15 1.20 1.25 1.30 1.35 1.40

Rake Sensor Radial Position (hub to tip), in.

Fan Total Pressure Ratio, P/Pt

HW

FOAM

ap (62%)

cb (86%)

to (100%)

NASA/TM—2013-216073 13
Figure 19. Comparison of fan temperature profiles between HW and FOAM rubstrips. 

Figure 20. Comparison of fan adiabatic efficiency profiles between HW and FOAM rubstrips. 

Figure 21. Comparison of fan thrust between HV and SV stators. 

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

1.01 1.03 1.05 1.07 1.09 1.11 1.13

Rake Sensor Radial Position (hub to tip), in.

Fan Total Temperature Ratio, T/Tt

HW

FOAM

ap (62%)

cb (86%)

to (100%)

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

0.50 0.54 0.58 0.62 0.66 0.70 0.74 0.78 0.82 0.86 0.90 0.94 0.98 1.02

Rake Sensor Radial Position (hub to tip), in.

Fan Adiabatic Efficiency

HW

FOAM

ap (62%)

cb (86%)

to (100%)

200

300

400

500

600

700

800

900

1000

50 55 60 65 70 75 80 85 90 95 100 105

Corrected Fan Thrust, lbf

Percent Corrected Fan Speed

HV

SV

NASA/TM—2013-216073 14
Figure 22. Comparison of fan torque between HV and SV stators. 

Figure 23. Comparison of stator thrust between HV and SV stators. 

Figure 24. Comparison of total thrust between HV and SV stators. 

100

200

300

400

500

600

700

50 55 60 65 70 75 80 85 90 95 100 105

Corrected Fan Torque, ft-lbs

Percent Corrected Fan Speed

HV

SV

0

100

200

300

400

500

50 55 60 65 70 75 80 85 90 95 100 105

Corrected Stator Thrust, lbf

Percent Corrected Fan Speed

HV

SV

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

50 55 60 65 70 75 80 85 90 95 100 105

Corrected Total Thrust, lbf

Percent Corrected Fan Speed

HV

SV

NASA/TM—2013-216073 15
Appendix A—Aerodynamic Performance Data 

Table 1A. Performance data taken with Hardwall (HW) Rubstrip installed during HW-PERF comparison 

test 

 

Percent Corrected Fan Fan Fan 

Corrected Weight Total Total Adiabatic 

Fan Flow, Pressure Temperature Efficiency 

Speed lbm/sec Ratio Ratio 

 

54.99 44.88 1.0794 1.0236 0.9339 

61.97 50.15 1.1021 1.0301 0.9368 

64.99 52.44 1.1124 1.0330 0.9364 

70.05 56.28 1.1322 1.0386 0.9353 

76.63 61.35 1.1602 1.0464 0.9352 

80.04 63.93 1.1762 1.0507 0.9355 

86.08 68.59 1.2068 1.0590 0.9347 

90.01 71.67 1.2288 1.0647 0.9367 

95.44 75.96 1.2623 1.0732 0.9399 

100.02 79.54 1.2930 1.0809 0.9417 

 

Table 1B. Performance data taken with Perforated (PERF) Rubstrip installed during HW-PERF comparison 

test

 

Percent Corrected Fan Fan Fan 

Corrected Weight Pressure Temperature Adiabatic 

Fan Flow, Ratio Ratio Efficiency 

Speed lbm/sec 

 

55.03 44.61 1.0787 1.0241 0.9088 

61.98 49.78 1.1010 1.0306 0.9097 

64.99 52.08 1.1112 1.0336 0.9097 

70.01 55.86 1.1304 1.0393 0.9067 

76.63 60.86 1.1582 1.0474 0.9050 

80.01 63.41 1.1737 1.0518 0.9045 

85.99 67.92 1.2035 1.0602 0.9033 

90.02 70.98 1.2256 1.0662 0.9035 

95.42 75.08 1.2571 1.0749 0.9020 

100.04 78.54 1.2872 1.0827 0.9048 

 

 

NASA/TM—2013-216073 16
Table 2A. Performance data taken with Hardwall (HW) Rubstrip installed during HW-FOAM comparison 

test 

 

Percent Corrected Fan Fan Fan 

Corrected Weight Total Total Adiabatic 

Fan Flow, Pressure Temperature Efficiency 

Speed lbm/sec Ratio Ratio 

 

55.01 44.87 1.0792 1.0231 0.9526 

61.99 50.17 1.1016 1.0296 0.9491 

65.03 52.45 1.1121 1.0326 0.9468 

70.04 56.29 1.1315 1.0381 0.9438 

76.58 61.31 1.1591 1.0458 0.9413 

80.02 63.97 1.1751 1.0501 0.9420 

86.04 68.65 1.2054 1.0583 0.9405 

95.44 76.08 1.2606 1.0723 0.9459 

100.07 79.69 1.2909 1.0801 0.9450 

 

Table 2B. Performance data taken with Exposed Metal Foam (FOAM) Rubstrip installed during HWFOAM comparison test 

Percent Corrected Fan Fan Fan 

Corrected Weight Total Total Adiabatic 

Fan Flow, Pressure Temperature Efficiency 

Speed lbm/sec Ratio Ratio 

55.02 44.16 1.0771 1.0241 0.8881 

61.97 49.32 1.0986 1.0308 0.8839 

65.01 51.48 1.1088 1.0340 0.8814 

70.00 55.32 1.1275 1.0398 0.8776 

76.63 60.24 1.1551 1.0480 0.8757 

80.04 62.78 1.1701 1.0527 0.8720 

86.07 67.25 1.1991 1.0612 0.8695 

91.54 71.27 1.2276 1.0698 0.8647 

95.45 74.13 1.2492 1.0759 0.8646 

100.11 77.42 1.2753 1.0839 0.8574 

 

NASA/TM—2013-216073 17
Table 3A. Performance profile data taken with Hardwall (HW) Rubstrip installed during HW-PERF 

comparison test 

 

Percent Corrected Fan Speed 54.99 61.97 64.99 70.05 76.63 80.04 86.08 90.01 95.44 100.02

Corrected Weight Flow, lbm/sec 44.88 50.15 52.44 56.28 61.35 63.93 68.59 71.67 75.96 79.54

Radial

Pos, in. Fan Total Pressure Ratio

6.204 1.0576 1.0736 1.0812 1.0947 1.1129 1.1228 1.1411 1.1534 1.1709 1.1858

6.924 1.0674 1.0859 1.0947 1.1105 1.1332 1.1457 1.1694 1.1859 1.2093 1.2299

7.577 1.0755 1.0965 1.1066 1.1248 1.1509 1.1657 1.1934 1.2130 1.2421 1.2672

8.177 1.0807 1.1036 1.1143 1.1344 1.1631 1.1791 1.2100 1.2316 1.2639 1.2931

8.737 1.0852 1.1095 1.1209 1.1424 1.1727 1.1902 1.2234 1.2466 1.2827 1.3139

9.263 1.0877 1.1130 1.1243 1.1468 1.1787 1.1966 1.2316 1.2569 1.2938 1.3297

9.760 1.0891 1.1152 1.1266 1.1494 1.1818 1.2003 1.2371 1.2618 1.3025 1.3392

10.233 1.0895 1.1155 1.1275 1.1501 1.1822 1.2018 1.2372 1.2650 1.3052 1.3444

10.685 1.0889 1.1143 1.1253 1.1476 1.1784 1.1965 1.2320 1.2583 1.2999 1.3385

11.119 1.0724 1.0935 1.1026 1.1214 1.1477 1.1632 1.1931 1.2157 1.2527 1.2882

Fan Total Temperature Ratio 

6.204 1.0166 1.0210 1.0231 1.0268 1.0320 1.0347 1.0399 1.0433 1.0481 1.0525

6.924 1.0191 1.0241 1.0265 1.0308 1.0368 1.0401 1.0465 1.0507 1.0570 1.0623

7.577 1.0213 1.0270 1.0296 1.0345 1.0413 1.0452 1.0524 1.0574 1.0646 1.0708

8.177 1.0230 1.0291 1.0320 1.0374 1.0448 1.0490 1.0569 1.0624 1.0704 1.0773

8.737 1.0241 1.0308 1.0338 1.0395 1.0475 1.0520 1.0604 1.0663 1.0748 1.0827

9.263 1.0250 1.0319 1.0349 1.0409 1.0493 1.0540 1.0631 1.0690 1.0783 1.0862

9.760 1.0255 1.0325 1.0358 1.0417 1.0502 1.0553 1.0642 1.0708 1.0801 1.0891

10.233 1.0260 1.0330 1.0361 1.0423 1.0508 1.0556 1.0650 1.0716 1.0816 1.0906

10.685 1.0270 1.0344 1.0378 1.0443 1.0533 1.0581 1.0680 1.0746 1.0849 1.0944

11.119 1.0287 1.0368 1.0406 1.0478 1.0577 1.0633 1.0740 1.0813 1.0924 1.1030

Fan Adiabatic Efficiency

6.204 0.9733 0.9778 0.9775 0.9763 0.9699 0.9684 0.9625 0.9608 0.9594 0.9510

6.924 0.9823 0.9874 0.9897 0.9880 0.9891 0.9873 0.9840 0.9842 0.9791 0.9779

7.577 0.9866 0.9894 0.9918 0.9898 0.9912 0.9902 0.9884 0.9887 0.9897 0.9881

8.177 0.9748 0.9817 0.9824 0.9805 0.9838 0.9833 0.9831 0.9835 0.9828 0.9860

8.737 0.9801 0.9782 0.9819 0.9812 0.9810 0.9812 0.9813 0.9806 0.9858 0.9808

9.263 0.9741 0.9732 0.9752 0.9750 0.9753 0.9750 0.9715 0.9783 0.9748 0.9836

9.760 0.9683 0.9753 0.9681 0.9724 0.9747 0.9681 0.9769 0.9698 0.9788 0.9772

10.233 0.9544 0.9609 0.9666 0.9630 0.9645 0.9707 0.9650 0.9698 0.9693 0.9738

10.685 0.9125 0.9128 0.9075 0.9058 0.9014 0.9056 0.9035 0.9099 0.9167 0.9200

11.119 0.7016 0.7026 0.6977 0.6964 0.6958 0.6973 0.6996 0.7059 0.7194 0.7284

NASA/TM—2013-216073 18
Table 3B. Performance profile data taken with Perforated (PERF) Rubstrip installed during HW-PERF 

comparison test 

 

Percent Corrected Fan Speed 55.03 61.98 64.99 70.01 76.63 80.01 85.99 90.02 95.42 100.04

Corrected Weight Flow, lbm/sec 44.61 49.78 52.08 55.86 60.86 63.41 67.92 70.98 75.08 78.54

Radial

Pos, in. Fan Total Pressure Ratio

6.204 1.0574 1.0732 1.0806 1.0937 1.1123 1.1221 1.1401 1.1528 1.1697 1.1850

6.924 1.0671 1.0854 1.0941 1.1096 1.1322 1.1444 1.1677 1.1845 1.2080 1.2287

7.577 1.0752 1.0961 1.1060 1.1239 1.1499 1.1644 1.1914 1.2117 1.2399 1.2654

8.177 1.0804 1.1030 1.1137 1.1333 1.1619 1.1775 1.2079 1.2297 1.2622 1.2907

8.737 1.0847 1.1088 1.1200 1.1409 1.1712 1.1883 1.2207 1.2446 1.2789 1.3113

9.263 1.0872 1.1122 1.1234 1.1453 1.1770 1.1945 1.2290 1.2542 1.2907 1.3250

9.760 1.0884 1.1141 1.1257 1.1478 1.1801 1.1984 1.2335 1.2592 1.2975 1.3339

10.233 1.0890 1.1147 1.1263 1.1486 1.1806 1.1990 1.2340 1.2618 1.3006 1.3385

10.685 1.0882 1.1130 1.1238 1.1451 1.1752 1.1921 1.2257 1.2513 1.2869 1.3234

11.119 1.0701 1.0898 1.0985 1.1159 1.1416 1.1565 1.1847 1.2063 1.2371 1.2702

Fan Total Temperature Ratio 

6.204 1.0166 1.0210 1.0230 1.0268 1.0320 1.0347 1.0397 1.0432 1.0479 1.0522

6.924 1.0192 1.0241 1.0264 1.0307 1.0367 1.0400 1.0460 1.0505 1.0566 1.0619

7.577 1.0213 1.0269 1.0295 1.0344 1.0413 1.0450 1.0520 1.0570 1.0643 1.0704

8.177 1.0230 1.0291 1.0318 1.0372 1.0446 1.0487 1.0563 1.0619 1.0697 1.0767

8.737 1.0242 1.0307 1.0336 1.0393 1.0472 1.0516 1.0599 1.0658 1.0742 1.0817

9.263 1.0249 1.0317 1.0348 1.0407 1.0490 1.0537 1.0624 1.0684 1.0775 1.0854

9.760 1.0255 1.0324 1.0355 1.0415 1.0499 1.0547 1.0634 1.0703 1.0791 1.0880

10.233 1.0259 1.0329 1.0360 1.0422 1.0507 1.0553 1.0648 1.0711 1.0812 1.0898

10.685 1.0283 1.0364 1.0400 1.0470 1.0569 1.0623 1.0729 1.0806 1.0916 1.1013

11.119 1.0321 1.0413 1.0456 1.0536 1.0652 1.0718 1.0842 1.0935 1.1071 1.1193

Fan Adiabatic Efficiency

6.204 0.9665 0.9693 0.9749 0.9685 0.9645 0.9647 0.9615 0.9597 0.9570 0.9524

6.924 0.9773 0.9832 0.9864 0.9829 0.9837 0.9827 0.9837 0.9824 0.9802 0.9797

7.577 0.9808 0.9863 0.9892 0.9868 0.9867 0.9880 0.9863 0.9890 0.9861 0.9877

8.177 0.9723 0.9777 0.9810 0.9788 0.9813 0.9807 0.9841 0.9825 0.9874 0.9860

8.737 0.9732 0.9754 0.9796 0.9773 0.9782 0.9797 0.9790 0.9802 0.9810 0.9852

9.263 0.9725 0.9729 0.9713 0.9716 0.9720 0.9701 0.9729 0.9767 0.9763 0.9800

9.760 0.9608 0.9681 0.9695 0.9686 0.9717 0.9704 0.9755 0.9680 0.9762 0.9752

10.233 0.9522 0.9566 0.9610 0.9576 0.9573 0.9621 0.9554 0.9661 0.9598 0.9676

10.685 0.8628 0.8539 0.8469 0.8406 0.8297 0.8267 0.8216 0.8210 0.8161 0.8225

11.119 0.6082 0.6027 0.5965 0.5945 0.5921 0.5909 0.5892 0.5890 0.5852 0.5928

NASA/TM—2013-216073 19
Table 4A. Performance profile data taken with Hardwall (HW) Rubstrip installed during HW-FOAM 

comparison test 

 

Percent Corrected Fan Speed 55.01 61.99 65.03 70.04 76.58 80.02 86.04 95.44 100.07

Corrected Weight Flow, lbm/sec 44.87 50.17 52.45 56.29 61.31 63.97 68.65 76.08 79.69

Radial

Pos, in.

6.204 1.0575 1.0733 1.0810 1.0941 1.1123 1.1221 1.1401 1.1691 1.1841

6.924 1.0672 1.0855 1.0945 1.1099 1.1324 1.1448 1.1683 1.2081 1.2285

7.577 1.0754 1.0963 1.1064 1.1242 1.1500 1.1647 1.1921 1.2408 1.2660

8.177 1.0806 1.1034 1.1142 1.1339 1.1622 1.1781 1.2086 1.2628 1.2917

8.737 1.0850 1.1092 1.1208 1.1418 1.1717 1.1892 1.2221 1.2809 1.3123

9.263 1.0875 1.1127 1.1242 1.1462 1.1777 1.1956 1.2301 1.2925 1.3279

9.760 1.0891 1.1149 1.1265 1.1488 1.1809 1.1996 1.2361 1.3009 1.3372

10.233 1.0895 1.1153 1.1274 1.1497 1.1814 1.2009 1.2358 1.3040 1.3431

10.685 1.0885 1.1136 1.1246 1.1466 1.1768 1.1947 1.2300 1.2977 1.3353

11.119 1.0715 1.0922 1.1016 1.1200 1.1459 1.1612 1.1909 1.2497 1.2830

6.204 1.0160 1.0204 1.0226 1.0263 1.0315 1.0341 1.0393 1.0470 1.0517

6.924 1.0185 1.0235 1.0259 1.0302 1.0362 1.0395 1.0457 1.0560 1.0616

7.577 1.0207 1.0264 1.0291 1.0339 1.0407 1.0445 1.0516 1.0636 1.0702

8.177 1.0224 1.0286 1.0315 1.0369 1.0441 1.0483 1.0561 1.0694 1.0765

8.737 1.0236 1.0303 1.0333 1.0389 1.0469 1.0513 1.0596 1.0739 1.0818

9.263 1.0244 1.0314 1.0345 1.0404 1.0487 1.0533 1.0624 1.0774 1.0855

9.760 1.0250 1.0320 1.0353 1.0412 1.0496 1.0546 1.0633 1.0792 1.0883

10.233 1.0256 1.0326 1.0357 1.0419 1.0503 1.0549 1.0643 1.0810 1.0898

10.685 1.0268 1.0343 1.0378 1.0441 1.0531 1.0579 1.0677 1.0845 1.0939

11.119 1.0281 1.0362 1.0400 1.0470 1.0568 1.0623 1.0729 1.0913 1.1017

6.204 1.0080 1.0012 0.9964 0.9895 0.9806 0.9798 0.9719 0.9707 0.9571

6.924 1.0137 1.0096 1.0070 1.0016 0.9993 0.9973 0.9938 0.9910 0.9835

7.577 1.0133 1.0085 1.0059 1.0026 1.0007 1.0003 0.9971 0.9999 0.9936

8.177 0.9998 0.9978 0.9971 0.9919 0.9940 0.9920 0.9915 0.9937 0.9922

8.737 0.9997 0.9933 0.9957 0.9924 0.9888 0.9895 0.9892 0.9913 0.9867

9.263 0.9926 0.9880 0.9869 0.9848 0.9836 0.9825 0.9767 0.9832 0.9874

9.760 0.9869 0.9875 0.9799 0.9815 0.9808 0.9772 0.9861 0.9859 0.9806

10.233 0.9702 0.9709 0.9764 0.9714 0.9705 0.9785 0.9694 0.9725 0.9791

10.685 0.9159 0.9112 0.9040 0.9038 0.8959 0.8998 0.9006 0.9150 0.9170

11.119 0.7093 0.7055 0.7014 0.7000 0.6986 0.7001 0.7021 0.7199 0.7256

Fan Total Pressure Ratio

Fan Adiabatic Efficiency

Fan Total Temperature Ratio 

NASA/TM—2013-216073 20
Table 4B. Performance profile data taken with Exposed Metal Foam (FOAM) Rubstrip installed during 

HW-FOAM comparison test 

 

Percent Corrected Fan Speed 55.02 61.97 65.01 70.00 76.63 80.04 86.07 91.54 95.45 100.11

Corrected Weight Flow, lbm/sec 44.16 49.32 51.48 55.32 60.24 62.78 67.25 71.27 74.13 77.42

Radial

Pos, in.

6.204 1.0573 1.0730 1.0807 1.0935 1.1121 1.1220 1.1401 1.1570 1.1690 1.1847

6.924 1.0671 1.0853 1.0941 1.1093 1.1319 1.1441 1.1677 1.1909 1.2079 1.2288

7.577 1.0753 1.0960 1.1060 1.1236 1.1495 1.1638 1.1912 1.2186 1.2392 1.2646

8.177 1.0805 1.1030 1.1137 1.1329 1.1613 1.1770 1.2071 1.2368 1.2599 1.2886

8.737 1.0847 1.1085 1.1197 1.1403 1.1703 1.1869 1.2198 1.2520 1.2759 1.3072

9.263 1.0870 1.1118 1.1231 1.1445 1.1761 1.1935 1.2273 1.2611 1.2871 1.3191

9.760 1.0885 1.1137 1.1254 1.1471 1.1788 1.1966 1.2312 1.2658 1.2922 1.3261

10.233 1.0888 1.1142 1.1256 1.1475 1.1793 1.1969 1.2315 1.2657 1.2899 1.3141

10.685 1.0826 1.1048 1.1148 1.1353 1.1652 1.1810 1.2100 1.2343 1.2524 1.2722

11.119 1.0588 1.0758 1.0848 1.1015 1.1265 1.1396 1.1650 1.1935 1.2181 1.2478

6.204 1.0162 1.0206 1.0227 1.0264 1.0316 1.0345 1.0395 1.0443 1.0474 1.0519

6.924 1.0187 1.0237 1.0261 1.0303 1.0363 1.0397 1.0458 1.0519 1.0562 1.0617

7.577 1.0210 1.0266 1.0293 1.0341 1.0409 1.0447 1.0517 1.0586 1.0637 1.0701

8.177 1.0226 1.0287 1.0316 1.0369 1.0442 1.0483 1.0560 1.0637 1.0690 1.0762

8.737 1.0237 1.0303 1.0333 1.0389 1.0468 1.0512 1.0595 1.0674 1.0734 1.0807

9.263 1.0246 1.0313 1.0345 1.0403 1.0485 1.0532 1.0618 1.0703 1.0762 1.0843

9.760 1.0252 1.0321 1.0353 1.0413 1.0496 1.0542 1.0631 1.0718 1.0786 1.0866

10.233 1.0268 1.0344 1.0379 1.0443 1.0534 1.0585 1.0677 1.0772 1.0850 1.0956

10.685 1.0316 1.0406 1.0448 1.0525 1.0636 1.0699 1.0812 1.0918 1.0982 1.1082

11.119 1.0310 1.0398 1.0444 1.0527 1.0653 1.0724 1.0861 1.1008 1.1114 1.1240

6.204 0.9893 0.9870 0.9894 0.9780 0.9740 0.9701 0.9655 0.9613 0.9623 0.9560

6.924 1.0000 0.9987 0.9970 0.9910 0.9923 0.9885 0.9892 0.9865 0.9870 0.9829

7.577 0.9998 0.9980 0.9981 0.9940 0.9939 0.9908 0.9916 0.9913 0.9923 0.9904

8.177 0.9905 0.9887 0.9876 0.9838 0.9876 0.9859 0.9862 0.9823 0.9889 0.9864

8.737 0.9905 0.9861 0.9865 0.9839 0.9817 0.9799 0.9821 0.9833 0.9816 0.9852

9.263 0.9809 0.9813 0.9786 0.9754 0.9780 0.9754 0.9758 0.9754 0.9814 0.9772

9.760 0.9746 0.9733 0.9724 0.9695 0.9701 0.9703 0.9698 0.9699 0.9669 0.9701

10.233 0.9175 0.9131 0.9073 0.9047 0.9033 0.9008 0.9061 0.9022 0.8879 0.8487

10.685 0.7255 0.7114 0.7041 0.7040 0.7021 0.6966 0.6893 0.6756 0.6763 0.6577

11.119 0.5316 0.5298 0.5304 0.5314 0.5300 0.5254 0.5181 0.5146 0.5205 0.5268

 Fan Total Pressure Ratio

Fan Total Temperature Ratio 

Fan Adiabatic Efficiency

NASA/TM—2013-216073 21
Table 5A. Force balance performance data taken with Hardwall Vanes (HV) installed during HV-SV 

comparison test 

Table 5B. Force balance performance data taken with Soft Vanes (SV) installed during HV-SV 

comparison test 

Percent Corrected Corrected Corrected Corrected

Corrected Fan Fan Stage Total

Fan Thrust, Torque, Thrust, Thrust,

Speed lbf ft-lbs lbf lbf

54.99 254.98 180.06 80.54 335.52

62.01 327.91 230.83 111.23 439.14

65.08 361.16 255.08 129.43 490.59

70.00 421.42 296.23 154.61 576.03

76.58 510.54 359.14 203.41 713.95

80.03 557.56 394.34 231.46 789.02

86.00 651.60 458.37 278.28 929.88

95.38 803.76 566.72 362.02 1165.78

100.04 875.53 620.23 401.36 1276.89

Percent Corrected Corrected Corrected Corrected

Corrected Fan Fan Stage Total

Fan Thrust, Torque, Thrust, Thrust,

Speed lbf ft-lbs lbf lbf

54.99 255.49 181.61 79.35 334.84

62.02 326.08 231.19 112.00 438.08

65.07 357.46 255.14 125.17 482.63

70.01 419.31 297.68 158.67 577.98

76.63 511.65 362.01 200.48 712.13

80.01 560.32 397.28 227.67 787.99

86.02 649.78 461.97 276.35 926.13

95.40 803.77 571.51 355.66 1159.43

100.02 877.07 704.70 393.81 1270.88

NASA/TM—2013-216073 22

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4. TITLE AND SUBTITLE

Effect of Two Advanced Noise Reduction Technologies on the Aerodynamic Performance of 

an Ultra High Bypass Ratio Fan 

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6. AUTHOR(S)

Hughes, Christopher, E.; Gazzaniga, John, A. 

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WBS 561581.02.08.03.18.04 

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National Aeronautics and Space Administration 

John H. Glenn Research Center at Lewis Field 

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13. SUPPLEMENTARY NOTES

Portions of this material were presented at the 15th AIAA/CEAS Aeroacoustics Conference (30th AIAA Aeroacoustics Conference) 

cosponsored by AIAA and CEAS, Miami, Florida, May 11-13, 2009. 

14. ABSTRACT

A wind tunnel experiment was conducted in the NASA Glenn Research Center anechoic 9- by 15-Foot Low-Speed Wind Tunnel to 

investigate two new advanced noise reduction technologies in support of the NASA Fundamental Aeronautics Program Subsonic Fixed

Wing Project. The goal of the experiment was to demonstrate the noise reduction potential and effect on fan model performance of the two 

noise reduction technologies in a scale model Ultra-High Bypass turbofan at simulated takeoff and approach aircraft flight speeds. The two 

novel noise reduction technologies are called Over-the-Rotor acoustic treatment and Soft Vanes. Both technologies were aimed at modifying 

the local noise source mechanisms of the fan tip vortex/fan case interaction and the rotor wake-stator interaction. For the Over-the-Rotor 

acoustic treatment, two noise reduction configurations were investigated. The results showed that the two noise reduction technologies, 

Over-the-Rotor and Soft Vanes, were able to reduce the noise level of the fan model, but the Over-the-Rotor configurations had a significant 

negative impact on the fan aerodynamic performance; the loss in fan aerodynamic efficiency was between 2.75 to 8.75 percent, depending 

on configuration, compared to the conventional solid baseline fan case rubstrip also tested. Performance results with the Soft Vanes showed 

that there was no measurable change in the corrected fan thrust and a 1.8 percent loss in corrected stator vane thrust, which resulted in a total 

net thrust loss of approximately 0.5 percent compared with the baseline reference stator vane set.

15. SUBJECT TERMS

Noise reduction; Vanes; Stators; High bypass; Turbofan; Wind tunnel; Scale model; Acoustics; Acoustic properties; Noise treatment; 

Rotor; Noise (sound); Fan blades; Thrust; Aerodynamic characteristics; Fan adiabatic efficiency 

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