bluuebunny/crossref_metadata_2025 huggingface dataset:
An Experimental Investigation of Transpiration Cooling. Part I: Application of an Infrared Measurement Technique
Authors: Wang J. H. , Messner J. , Stetter H.
Published: March 2007

This study was an investigation into the application of the infrared thermal imaging technique (IRTIT) to evaluate transpiration cooling performance through a porous wall. Two typical infrared thermograph systems, the AGA 782 short‐wavelength system and the VARIOSCAN 3021 long‐wavelength system, were employed to demonstrate the availability of the IRTIT measurement. In comparison with general infrared apparent temperature measurement, several factors that influence measurement accuracy need to be addressed in the application of the IRTIT in the region of transpiration cooling on the porous surfaces of turbine components. In this article, the influence of these factors on measurement accuracy is discussed, the corresponding calibration methods of the two infrared systems are described, and the ambient conditions and stability of the measurement are analyzed. Aporous circular tube was used as a specimen. The tube consisted of sintered chromium‐nickel steel with a porosity of 21%. The experiment was carried out in the hotgas wind tunnel at the Institute of Thermal Turbomachinery at the University of Stuttgart, Stuttgart, Germany.
Deflections and Strains in Cracked Shafts Due to Rotating Loads: A Numerical and Experimental Analysis
Authors: Bachschmid Nicolò , Tanzi Ezio
Published: March 2007

In this article the deflections of a circular cross‐section beam presenting a transverse crack of varying depths caused by various loads (bending, torsion, shear, and axial loads) are analyzed with the aid of a rather refined three‐dimensional model that takes into account the nonlinear contact forces in the cracked area. The bending and shear loads are applied in several different angular positions in order to simulate a rotating load on a fixed beam or, by changing the reference system, a fixed load on a rotating beam. Torsion and axial loads are fixed with respect to the beam.

Results obtained for the rotating beam can then be used for the analysis of cracked horizontal‐axis heavy rotors in which the torsion is combined with the bending load. The effect of friction is also considered in the cracked area. The characteristic “breathing” behavior of the cracked area was analyzed and compared to that obtained with a rather simple one‐dimensional model. The differences in results with respect to those based on fracture mechanics are emphasized. In order to highlight the effect of the presence of the crack, the deflections of the uncracked beam loaded with the same loads were subtracted from the deflections of the cracked beam.

Finally, a cracked specimen was extensively analyzed by means of several strain gauges to study the strain distribution on the outer surface around the crack in various loading conditions. Consistent pre‐stresses were found, and they influence the breathing behavior. The experimental results were compared with those obtained using the onedimensional linear model.
Weibull‐Based Design Methodology for Rotating Structures in Aircraft Engines
Authors: Zaretsky Erwin V. , Hendricks Robert C. , Soditus Sherry
Published: March 2007

The NASA Energy‐Efficient Engine (E3‐Engine) is used as the basis of a Weibull‐based life and reliability analysis. Each component′s life, and thus the engine′s life, is defined by high‐cycle fatigue or low‐cycle fatigue. Knowing the cumulative life distribution of each of the components making up the engine as represented by a Weibull slope is a prerequisite to predicting the life and reliability of the entire engine. As the engine′s Weibull slope increases, the predicted life decreases. The predicted engine lives L5 (95% probability of survival) of approximately 17,000 and 32,000 hr do correlate with current engine‐maintenance practices without and with refurbishment, respectively. The individual high‐pressure turbine (HPT) blade lives necessary to obtain a blade system life L0.1 (99.9% probability of survival) of 9000 hr for Weibull slopes of 3, 6, and 9 are 47,391; 20,652; and 15,658 hr, respectively. For a design life of the HPT disks having probable points of failure equal to or greater than 36,000 hr at a probability of survival of 99.9%, the predicted disk system life L0.1 can vary from 9408 to 24,911 hr.
Steady and Unsteady Casingwall Flow Phenomena in a Single‐Stage Low‐Speed Compressor at Part‐Load Conditions
Authors: Saathoff H. , Deppe A. , Stark U. , Rohdenburg M. , Rohkamm H. , Wulff D. , Kosyna G.
Published: March 2007

This article describes an investigation of the casingwall flow phenomena in a single‐stage, axial‐flow, low‐speed compressor at part‐load conditions, utilizing an oil‐flow technique to visualize the boundary layer development and highfrequency sensors to measure ensemble‐averaged velocity and flow‐angle distributions as well as unsteady total pressure distributions. Representative results are shown and discussed. The results enable different sources of endwall blockage to be identified and changes with flow rate to be determined.
Rotor Cascade Shape Optimization with Unsteady Passing Wakes Using Implicit Dual‐Time Stepping and a Genetic Algorithm
Authors: Lee Eun Seok , Dulikravich George S. , Dennis Brian H.
Published: March 2007

An axial turbine rotor cascade‐shape optimization with unsteady passing wakes was performed to obtain an improved aerodynamic performance using an unsteady flow, Reynolds‐averaged Navier‐Stokes equations solver that was based on explicit, finite difference; Runge‐Kutta multistage time marching; and the diagonalized alternating direction implicit scheme. The code utilized Baldwin‐Lomax algebraic and k‐ε turbulence modeling. The full approximation storage multigrid method and preconditioning were implemented as iterative convergence‐acceleration techniques. An implicit dual‐time stepping method was incorporated in order to simulate the unsteady flow fields. The objective function was defined as minimization of total pressure loss and maximization of lift, while the mass flow rate was fixed during the optimization. The design variables were several geometric parameters characterizing airfoil leading edge, camber, stagger angle, and inter‐row spacing. The genetic algorithm was used as an optimizer, and the penalty method was introduced for combining the constraints with the objective function. Each individual′s objective function was computed simultaneously by using a 32‐processor distributedmemory computer. The optimization results indicated that only minor improvements are possible in unsteady rotor/stator aerodynamics by varying these geometric parameters.
Darmstadt Rotor No. 2, II: Design of Leaning Rotor Blades
Authors: Bergner Jörg , Hennecke Dietmar K. , Hoeger Martin , Engel Karl
Published: March 2007

For Darmstadt University of Technology′s axial singlestage transonic compressor rig, a new three‐dimensional aft‐swept rotor was designed and manufactured at MTU Aero Engines in Munich, Germany. The application of carbon fiber–reinforced plastic made it possible to overcome structural constraints and therefore to further increase the amount of lean and sweep of the blade. The aim of the design was to improve the mechanical stability at operation that is close to stall.

To avoid the hazard of rubbing at the blade tip, which is found especially at off‐design operating conditions close to the stability limit of the compression system, aft‐sweep was introduced together with excessive backward lean.

This article reports an investigation of the impact of various amounts of lean on the aerodynamic behavior of the compressor stage on the basis of steady‐state Navier‐Stokes simulations. The results indicate that high backward lean promotes an undesirable redistribution of mass flow and gives rise to a basic change in the shock pattern, whereas a forward‐leaning geometry results in the development of a highly back‐swept shock front. However, the disadvantage is a decrease in shock strength and efficiency.
Computational Fluid Dynamics in Torque Converters: Validation and Application
Authors: Schweitzer Jean , Gandham Jeya
Published: March 2007

This article describes some of the computational fluid dynamics (CFD) work being done on three‐element torque converters using a commercially available package CFX TASCflow. The article details some of the work done to validate CFD results and gives examples of ways in which CFD is used in the torque‐converter design process. Based on the validation study, it is shown that CFD can be used as a design and analysis tool to make decisions about design direction. Use of CFD in torque converters is a developing field. Thus, more work needs to be done before the requirement of hardware to validate designs can be fully eliminated. This article demonstrates the confidence level in torque converter CFD and demonstrates how it can be used to assist torqueconverter design today.
Aerodynamic and Performance Behavior of a Three‐Stage High Efficiency Turbine at Design and Off‐Design Operating Points
Authors: Schobeiri M. T. , Gilarranz J. L. , Johansen E. S.
Published: March 2007

This article deals with the aerodynamic and performance behavior of a three‐stage high pressure research turbine with 3‐D curved blades at its design and off‐design operating points. The research turbine configuration incorporates six rows beginning with a stator row. Interstage aerodynamic measurements were performed at three stations, namely downstream of the first rotor row, the second stator row, and the second rotor row. Interstage radial and circumferential traversing presented a detailed flow picture of the middle stage. Performance measurements were carried out within a rotational speed range of 75% to 116% of the design speed. The experimental investigations have been carried out on the recently established multi‐stage turbine research facility at the Turbomachinery Performance and Flow Research Laboratory, TPFL, of Texas A&M University.
Multi‐Control‐Volume Analysis of the Compression Process in a High‐Temperature Root′s Type Compressor
Authors: Blekhman David I. , Mollendorf Joseph C. , Felske James D. , Lordi John A.
Published: March 2007

In this study we have modeled a high‐temperature Root′s type compressor and compared predicted results with measurements. Compression process is modeled using multiple control volumes. Initially, there are two control volumes connected
by an “expansion nozzle” naturally formed by the rotor tip and the blower casing. The “nozzle” has time‐varying geometry and is modeled to allow transition from choked to non‐choked flow. The well‐filling process is modeled via expansion
of the compressed gas from the high‐pressure reservoir into the well through this “nozzle.” When the pressures in the well and reservoir equalize, the “passive” part of the compression process is taken to be complete. At this point, the gas in the well is assumed to be fully‐mixed and the two control volumes are subsequently considered as one. Then the “active” part of compression takes place. Numerical computations are shown to agree well with the experimental data.
Discharge Coefficient Measurements for Flow Through Compound‐Angle Conical Holes with Cross‐Flow
Authors: Taslim M. E. , Ugarte S.
Published: March 2007

Diffusion‐shaped film holes with compound angles are currently being investigated for high temperature gas turbine airfoil film cooling. An accurate prediction of the coolant blowing rate through these film holes is essential in determining the film effectiveness. Therefore, the discharge coefficients associated with these film holes for a range of hole pressure ratios is essential in designing airfoil cooling circuits. Most of the available discharge coefficient data in open literature has been for cylindrical holes. The main objective of this experimental investigation was to measure the discharge coefficients for subsonic as well as supersonic pressure ratios through a single conical‐diffusion hole. The conical hole has an exit‐to‐inlet area ratio of 4, a nominal flow length‐to‐inlet diameter ratio of 4, and an angle with respect to the exit plane (inclination angle) of 0°, 30°, 45°, and 60°. Measurements were performed with and without a cross‐flow. For the cases with a cross‐flow, discharge coefficients were measured for each of the hole geometries and 5 angles between the projected conical hole axis and the cross‐flow direction of 0°, 45°, 90°, 135°, and 180°. Results are compared with available data in open literature for cylindrical film holes as well as limited data for conical film holes.
Partial Compensation of Unbalance by Oneand Two‐Plane Automatic Balancing Devices
Authors: Ryzhik Boris , Duckstein Henner , Sperling Lutz
Published: March 2007

This article presents an analysis of several aspects of one‐ and two‐plane automatic balancing devices of rigid rotors. The effect of partial compensation of unbalance and the decreasing of vibrations in the region beyond the first critical
speed is studied analytically and confirmed by the results of computer simulations. The possibility of partial unbalance compensation is very important considering application of
autobalancing devices to rotors with a large polar moment of inertia.

Among the most important practical applications of devices are centrifuges, hand power tools, washing machines, and optical disk drives.
Identification of Rub and Unbalance in 320‐MW Turbogenerators
Authors: Bachschmid N. , Pennacchi P. , Vania A. , Zanetta G. A. , Gregori L.
Published: March 2007

This article presents two experiences of application of a model‐based fault identification method on real machines. The first case presented is an unbalance identification on a 320‐MW turbogenerator unit operating in a fossil power plant. In the second case, concerning a machine of the same size but of a different manufacturer, the Low Pressure (LP) turbine was affected by a rub in the sealings and this time, the fault was modeled by local bows. The identification of the faults is performed by means of a model‐based identification technique in frequency domain, suitably modified in order to take into account simultaneous faults. The theoretical background of the applied method is briefly illustrated and some considerations also are presented about the best choice of the rotating speed set of the run‐down transient to be used for an effective identification and about the appropriate weighting of vibration measurements at the machine bearings.
Identification of a Generator Fault by Model‐Based Diagnostic Techniques
Authors: Pennacchi P. , Vania A.
Published: March 2007

Model‐based diagnostic techniques can be used successfully in the health analysis of rotormachinery. Unfortunately, a poor accuracy of the model of the fully assembled machine, as well as noise in the signals and errors in the evaluation of the experimental vibrations that are caused only by the impending fault, can affect the accuracy of the fault identifications. This can make it difficult to identify the type of actual fault as well as to evaluate with care its severity and position. This article shows some techniques that have been developed by the authors to measure the accuracy of the results obtained with model‐based identification methods aimed to diagnose faults in rotating machines. In this article, the results obtained by means of the analysis of experimental data collected in a power plant are described. Finally, the capabilities of the developed methods are shown and discussed.
Design Optimization of Tilting‐Pad Journal Bearing Using a Genetic Algorithm
Authors: Saruhan Hamit , Rouch Keith E. , Roso Carlo A.
Published: March 2007

This article focuses on the use of genetic algorithms in developing an efficient optimum design method for tilting pad bearings. The approach optimizes based on minimum film thickness, power loss, maximum film temperature, and a global objective. Results for a five tilting‐pad preloaded bearing are presented to provide a comparison with more traditional optimum design methods such as the gradient‐based global criterion method, and also to provide insight into the potential of genetic algorithms in the design of rotor bearings. Genetic algorithms are efficient search techniques based on the idea of natural selection and genetics. These robust methods have gained recognition as general problem solving techniques in many applications.
Development of a Three‐Dimensional Geometry Optimization Method for Turbomachinery Applications
Authors: Kämmerer Steffen , Mayer Jürgen F. , Stetter Heinz , Paffrath Meinhard , Wever Utz , Jung Alexander R.
Published: March 2007

This article describes the development of a method for optimization of the geometry of three‐dimensional turbine blades within a stage configuration. The method is based on flow simulations and gradient‐based optimization techniques.
This approach uses the fully parameterized blade geometry as variables for the optimization problem. Physical parameters such as stagger angle, stacking line, and
chord length are part of the model. Constraints guarantee the requirements for cooling, casting, and machining of the blades.

The fluid physics of the turbomachine and hence the objective function of the optimization problem are calculated by means of a three‐dimensional Navier‐Stokes solver especially designed for turbomachinery applications. The gradients required for the optimization algorithm are computed by numerically solving the sensitivity equations. Therefore, the explicitly differentiated Navier‐Stokes equations are incorporated
into the numerical method of the flow solver, enabling the computation of the sensitivity equations with the same numerical scheme as used for the flow field solution.

This article introduces the components of the fully automated optimization loop and their interactions. Furthermore, the sensitivity equation method is discussed and several
aspects of the implementation into a flow solver are presented. Flow simulations and sensitivity calculations are presented for different test cases and parameters. The validation
of the computed sensitivities is performed by means of finite differences.
The Pre‐Stall Behavior of a 4‐Stage Transonic Compressor and Stall Monitoring Based on Artificial Neural Networks
Authors: Methling Frank-Oliver , Stoff Horst , Grauer Frank
Published: March 2007

Current research concerned with the aerodynamic instability
of compressors aims at an extension of the operating
range of the compressor towards decreased massflow. In
practice, a safety margin is maintained between operating
point and stability limit to prevent the compressor from going
into stall and surge. In this article, we analyze the behavior
of a 4‐stage transonic axial compressor before entering
the unstable range and present an approach to identifying incipient
surge and stall using artificial neural networks. This
method is based on measurements of the unsteady static wall
pressure in front of the first rotor.

Analyzing the static pressure signals by using the Fast
Fourier Transform shows that peripheral disturbances
(modal waves) can only be identified in a small range close
to nominal speed (at 95%). At lower speeds (60 to 80% of
nominal speed), the investigated compressor flow enters instability
by spike‐type stall.

Monitoring stability over the entire speed range of the compressor relies on artificial neural networks using the unsteady wall pressure signal. In the present case, artificial neural networks show to be the most useful tool to indicate approaching instability. The method works reliably for both types of instabilities, spike‐type stall as well as modal waves.
Transient Vibration Prediction for Rotors on Ball Bearings Using Load‐Dependent Nonlinear Bearing Stiffness
Authors: Fleming David P. , Poplawski J. V.
Published: March 2007

Rolling‐element bearing forces vary nonlinearly with
bearing deflection. Thus an accurate rotordynamic transient
analysis requires bearing forces to be determined at each
step of the transient solution. Analyses have been carried
out to show the effect of accurate bearing transient forces
(accounting for nonlinear speed and load‐dependent bearing
stiffness) as compared to conventional use of average rolling‐element
bearing stiffness. Bearing forces were calculated by
COBRA‐AHS (Computer Optimized Ball and Roller Bearing
Analysis—Advanced High Speed) and supplied to the
rotordynamics code ARDS (Analysis of Rotor Dynamic Systems)
for accurate simulation of rotor transient behavior.
COBRA‐AHS is a fast‐running five degree‐of‐freedom computer
code able to calculate high speed rolling‐element bearing
load‐displacement data for radial and angular contact
ball bearings and also for cylindrical and tapered roller bearings.
Results show that use of nonlinear bearing characteristics
is essential for accurate prediction of rotordynamic
behavior.
Aspect Ratio Effect on Convective Heat Transfer of Radially Outward Flow in Rotating Rectangular Ducts
Authors: Kuo C. R. , Hwang G. J.
Published: March 2007

Experiments were conducted to investigate the effects of rotation and aspect ratio on the convective heat transfer of radially
outward air flows in rotating rectangular ducts with a uniform wall heat flux by using fiberglass duct walls lined with
separated film heaters. The duct hydraulic diameter, heater active length, and mean rotation radius were 4, 120, and 180 mm,
respectively. Ranges of parameters were through‐flow Reynolds number, 1,000–15,000; rotation number, 0–0.32; rotational
buoyancy parameter, 0–1.2; and cross‐sectional aspect ratio, 0.5, 1.0, and 2.0. The results showed that the higher the rotation
number, the greater the enhancement ofthe heat transfer rate especially at the pressure side. The rotational buoyancy parameter
decreases the heat transfer for low Re but enhances the heat transfer for high Re. The largest heat transfer enhancement is
seen for AR = 1.0, and the enhancement for AR = 0.5 is greater than that for AR = 2.0.
Case Study of Pump Failure Due to Rotor‐Stator Interaction
Authors: Ohashi Hideo
Published: March 2007

Fluiddynamic interaction between rotor and stator generates local pressure fluctuation and can be a cause ofstructural vibration
of turbomachines. The interaction produces a spatial distribution of pressure fluctuation with a certain diametrical mode and
propagating speed, known as rotating pressure field. When the frequency and mode of a rotating pressure field coincide
with those of the structural vibration, a fluid‐excited resonance takes place, leading to eventual severe structural damage. An
example of such damage is described in detail using the case of PLR pump failure of a BWR plant.
The Effect of Surface Roughness of a Body in the HighReynolds Number Flow
Authors: Adachi Tsutomu
Published: March 2007

In this paper, first, the principle, structures, operations, and performances of the cryogenic wind tunnel are described. By
changing the pressure, temperature and velocity of gas a high Reynolds number flow (5 × 104 < Re < 107) can be obtained.
From the research results, a high Reynolds number flow with comparatively low power, LN2 consumptions was attained. It was with Mach number independent of each other.To show some examples of high Reynolds number flow, the effects of surface roughness and grooves on the surface
of a cylinder on the flow are measured using models with various values of roughness and size. A model test of an airship
was also conducted. With the high Reynolds number flow, the thickness of the boundary layer becomes thinner. Then the
surface conditions of a body have great effect on the flow phenomena and on the drag of the body. Some attempts to reduce
the drag of the body were shown.
Laser Velocimetry Measurements in a Double Volute Centrifugal Pump
Authors: De Ojeda William , Flack Ronald D. , Miner Steven M.
Published: March 2007

Laser velocimetry measurements were taken in a double volute/single discharge centrifugal pump (0.60 specific speed, 1583
US units) with symmetrical volute halves. Blade‐to‐blade radial and tangential velocity profiles at the impeller exit are
presented and compared to data for a similar single volute pump. Flow rates ranged from 40% of design flow to the design
point. The blade‐to‐blade profiles were more uniform than for the single volute pump. Also, the average circumferential
variations for the double volute pump were more symmetric than for the single volute pump. For the double volute geometry
measurements indicate that radial inward flow (recirculation) was only present for flow rates below 60% of design flow,
compared to 80% of design flow for the single volute pump. Velocity data was also used to determine volute losses, slip
factor, and momentum contributions to the impeller radial forces. Volute losses were quantified and shown to increase for
flow rates below 80% of design flow and were approximately 10% of the developed head at 40% flow. The efficiency in
the double volute compared to the single volute shows decreased performance for flows above 55% of design flow, which
is attributed to increased boundary layer friction; at low flow rates increased performance is ascribed to better control over
the recirculation regions. Slip factors were symmetric around the volute but were lower than for a single volute pump.
Finally, momentum contributions to the total impeller radial load were shown to be maximum at the design point,
contributing 40% of the force developed by the pressure distribution; the significance diminished at lower flow rates and
the contribution was negligible at 40% of the design flow.
Convex Curvature Effect on the WakeIncluding Recovery from the Curvature
Authors: You S. M.
Published: March 2007

Streamwise convex‐curvature effect including recovery process is discussed. Previous studies have demonstrated that even
mild streamwise curvature has a marked effect on turbulence structure, heat transfer and skin friction coefficient. This effect
is further investigated in the present study with Coles wake law. Coles previously reported that flows in or near equilibrium
have a constant wake parameter depending on the strength of streamwise pressure gradient. Turbulent boundary layers on
the curved and following recovery wall may not be in or near equilibrium and the wake parameter may depend upon the
strength of curvature, δ/R. Different streamwise curvature strength, ranging 0.01–0.1, is tested to confirm the validity of the
wake law. The ratio of wake parameter between the curved and flat wall is found to be proportional to that of skin friction
coefficient for the flows in both convexly curved and recovery sections. This relationship describes the deviation of wake
behavior from the flat‐plate turbulent boundary layer due to convex curvature.
Effects of Nonuniform Blade Pitch on the FlowThrough an Annular Turbine Nozzle
Authors: Kurz Rainer
Published: March 2007

This paper discusses flow measurement results both upstream and downstream of a transonic annular gas turbine nozzle with a nonuniform pitch. The downstream measurements are performed in the plane where the leading edge of the rotor blade
is located in the gas turbine. The experiments were performed using total pressure probes and wall static pressure taps. The pitch variation modifies the flow field both upstream and downstream of the nozzle, although the experiments show that the effect is localized to the immediate neighborhood of the involved blades. The effects on the wakes and on the inviscid flow are discussed separately. The mean velocities show a strong sensitivity to the changes of the pitch, which is due to a potential flow effect rather than a viscous effect.
Ekman Boundary Layers and Energy Dissipation inRotating Drums During Spin‐Down Process
Authors: Ohue Hiroshi , Kawashima Genshi , Yang Wen-Jei
Published: March 2007

The Laser Doppler Velocimetry (LDV) is employed to investigate energy dissipation during a spin‐down process inside a rotating drum. The tracer/light sheet method is applied to observe flow patterns in the entire flow field from which the
instantaneous, two‐dimensional velocity distribution and the formation and subsequent time wise variation of the Ekman boundary layer are determined. Results are synthesized to find the relationship between the Ekman boundary layer and the redistribution of secondary‐flow induced angular momentum. The fluid viscosity, drum size and speed of rotation are varied to determine their effects on both the Ekman boundary layer and energy dissipation during spin‐down process. The role of Ekman boundary layer in the reduction of rotating fluid motion is determined. Results from the study may be used to
develop a method to achieve uniform mixing in an enclosed vessel.
An Integrated Flow Analysis System for theRecalculation of Hydraulic Machinery Bladings
Authors: Haas H. , Riedel N. , Watzelt Ch. , Fernandez A. , Schilling R.
Published: March 2007

The present paper deals with the recalculation of hydraulic machinery bladings. By combining numerical tools for the geometrical description of the bladings, mesh generation, different CFD flow models (Q3D Euler, 3D Euler, Navier‐Stokes)
and post‐processing a highly efficient integrated flow analysis system is obtained.

The capability of the developed software package is shown by recalculating water turbine runners of different specific speeds, a semi‐axial and a radial centrifugal impeller. The results of the flow computations are compared to each other and to existing measurements.
A Small Perturbation CFD Method for Calculation ofSeal Rotordynamic Coefficients
Authors: Athavale M. M. , Hendricks R. C.
Published: March 2007

Seal rotordynamic coefficients link the fluid reaction forces to the rotor motion, and hence are needed in the stability calculations for the overall rotating systems. Presented in this paper is a numerical method for calculations of rotordynamic
coefficients of turbomachinery seals with rotors nominally at centered, eccentric and/or misaligned position. The rotor of the seal is assumed to undergo a prescribed small whirling motion about its nominal position. The resulting flow variable perturbations are expressed as Fourier functions in time. The N‐S equations are used to generate the governing equations for the perturbation variables. Use of complex variables for the perturbations renders the problem quasi‐steady. The fluid reaction forces are integrated on the rotor surface to obtain the fluid reaction forces at several different whirl frequencies.
The rotordynamic coefficients are calculated using appropriate curve fitting. Details of the model are presented, and sample results for concentric and eccentric annular incompressible flow seals are included to demonstrate the capability and accuracy of the proposed method.
Identification of the Quadrature Resonances UsingModal Nonsynchronous Perturbation Testing andDynamic Stiffness Approach for an Anisotropic RotorSystem with Fluid Interaction
Authors: Jang Eungu , Muszynska Agnes , Park Young-Pil , Kim Chang-Ho
Published: March 2007

The paper presents the dynamic analysis of an anisotropic rotor system with fluid interaction by using modal nonsynchronous perturbation testing and dynamic stiffness approaches. The anisotropic rotor system produces more complex rotor behavior than an isotropic system. In particular, the existence of the quadrature resonance phenomenon for
backward precession is demonstrated. A symmetric rotor supported anisotropically by one fluid lubricated bearing and one rolling element bearing simulates rotating machinery behavior. A dynamic stiffness anisotropy algorithm which includes fluid terms is used to process experimental data in order to identify lightly loaded journal fluid film force parameters. The existence of the quadrature resonance for backward precession obtained from the experiment is compared with the analytical model. The results from modeling show strong agreement with experimental results.
Mass Transfer over a Film‐Cooled Turbine Blade
Authors: Chen Ping-Hei , Miao Jr-Ming
Published: March 2007

A naphthalene sublimation technique was employed to study the mass transfer distributions over a turbine blade surface with secondary flows ejected in the spanwise direction through three rows of equally‐spaced injection holes located in the leading
edge region. The mass transfer measurements were conducted in a range of blowing ratios from 0.6 to 1.2 at two different mainstream turbulence levels (0.4% and 6.0%) while keeping the exit Reynolds number, Re⁡2, at a constant value of 397,000.
An Aerodynamic Method for the Analysis of IsolatedHorizontal‐Axis Wind Turbines
Authors: Masson Christian , Ammara Idriss , Paraschivoiu Ion
Published: March 2007

The aerodynamic analysis of a wind turbine represents a very complex task since it involves
an unsteady three‐dimensional viscous flow. In most existing performance‐analysis methods,
wind turbines are considered isolated so that interference effects caused by other rotors or by
the site topology are neglected. Studying these effects in order to optimize the arrangement
and the positioning of Horizontal‐Axis Wind Turbines (HAWTs) on a wind farm is one of the
research activities of the Bombardier Aeronautical Chair. As a preliminary step in the
progress of this project, a method that includes some of the essential ingredients for the
analysis of wind farms has been developed and is presented in the paper. In this proposed
method, the flow field around isolated HAWTs is predicted by solving the steady‐state,
incompressible, two‐dimensional axisymmetric Navier‐Stokes equations. The turbine is represented
by a distribution of momentum sources. The resulting governing equations are
solved using a Control‐Volume Finite Element Method (CVFEM). This axisymmetric implementation
efficiently illustrates the applicability and viability of the proposed methodology,
by using a formulation that necessitates a minimum of computer resources. The axisymmetric
method produces performance predictions for isolated machines with the same
level of accuracy than the well‐known momentum‐strip theory. It can therefore be considered
to be a useful tool for the design of HAWTs. Its main advantage, however, is its capacity to
predict the flow in the wake which constitutes one of the essential features needed for the
performance predictions of wind farms of dense cluster arrangements.
Dynamic Stability of an Elastic Rotating System:Shell‐Disc‐Shaft
Authors: Ruge P. , Senker P.
Published: March 2007

This paper presents a methodology and some results on the dynamic stability of an elastic
rotating system consisting of one‐ and twodimensional members. These parts may contain
different kinds of unsymmetries: either from mass‐ or stiffness imperfections or from anisotropic
especially hydrodynamic bearings. The equations of motion are formulated using
virtual work and an Finite Element approach. Special attention is paid to a kinematically
consistent coupling of the elastic shell and disc. The eigenvalue extraction is based upon the
method of Lanczos including a modal reduction and a correction process in order to ensure
true diagonal system matrices. Some typical results for a shaft‐disc‐shell system with different
bearings and imperfections are presented in detail.
Interaction of Parametric and Forced Vibrations in HighSpeed Rotor‐Bearing‐Systems
Authors: Weyh Bernhardt
Published: March 2007

In this paper the interaction of periodic parameter excitation with forced excitations of in
general non commensurable basic frequencies is under consideration. The method of enlarged
systems serves as a toolbox, where the central idea of the method and the structure of
the enlarged system are in the same way derived as the complete homogeneous and the
manifold of inhomogeneous solutions are discussed. The application to a realisation of a
high speed twin‐disc rotor‐bearing‐system of a textile spinning turbine illustrates the resonance
effects that haven’t been characterized before.
Flow Measurements and Flow Analysis in the ExitRegion of a Radial Turbine
Authors: Murugan D. M. , Tabakoff W. , Hamed A.
Published: March 2007

Three‐dimensional flow measurements using LDV system were obtained in the exit region of
a radial inflow turbine at an off‐design operating condition. The measurements reveal a
complex flow pattern near the tip region at the rotor exit due to the interaction of the tip
clearance flow. The effect of the rotor on the exit flow field is observed in the proximity of
the rotor exit. Steady axisymmetric, compressible, turbulent flow computations with a two
equation turbulence model were performed using the PARC code for the meridional flow in
the radial turbine exit region. The computational results obtained in the meridional plane are
compared with the experimental results, which are correlated to the rotor blade rotation in
the exit region of the radial turbine.

A version of this paper was presented at the 30th AIAA/ASME/SAE/ASEE Joint Propulsion
Conference, Indianapolis, Indiana, Paper no. AIAA‐94‐3075.
Flow Studies using Laser Anemometry Technique in aSmall Power Unit Radial Inflow Turbine
Authors: Zaidi Sohail H. , Elder Robin L.
Published: March 2007

T‐100 is a multipurpose small power unit developed by Sundstrand Power Systems (USA).
An extensive research programme was launched for the detailed tests of the rig components
including inlet protection system, Compressor stage, Combustor and the Turbine stage. Turbomachinery
Group at Cranfield was involved in the study of the Turbine unit used in this
programme. From the design point of view, detailed aerodynamics in these small units are of
great interest especially where high velocities and narrow passages are involved. Experimental
study was carried out to investigate the flow in the region between the nozzle guide vanes
and the turbine rotor entry. The main concern was to find out how the nozzle guide vane flow
was modified by the rotor and how the rotor flow was affected by the nozzle guide vanes.
Laser measurements were taken at these positions for various flow conditions. An other area
which needs considerable attention is downstream of the turbine rotor where the turning of
flow and mixing process make the situation very complicated. Laser studies were undertaken
in that region and to gain more confidence on laser results, a Cobra pressure probe was
traversed at these stations. This paper describes various steps undertaken to obtain laser
results within the machine. At the end typical laser results have been presented and discussed.
Measurements of the Influence of Integral Length Scale on Stagnation Region Heat Transfer
Authors: Van Fossen G. James , Ching Chan Y.
Published: March 2007

The purpose of the present work was twofold: first, to determine if a length scale existed that
would cause the greatest augmentation in stagnation region heat transfer for a given turbulence
intensity and second, to develop a prediction tool for stagnation heat transfer in the
presence of free stream turbulence. Toward this end, a model with a circular leading edge
was fabricated with heat transfer gages in the stagnation region. The model was qualified in
a low turbulence wind tunnel by comparing measurements with Frossling′s solution for
stagnation region heat transfer in a laminar free stream. Five turbulence generating grids
were fabricated; four were square mesh, biplane grids made from square bars. Each had
identical mesh to bar width ratio but different bar widths. The fifth grid was an array of fine
parallel wires that were perpendicular to the axis of the cylindrical leading edge. Turbulence
intensity and integral length scale were measured as a function of distance from the grids.
Stagnation region heat transfer was measured at various distances downstream of each grid.
Data were taken at cylinder Reynolds numbers ranging from 42,000 to 193,000. Turbulence
intensities were in the range 1.1 to 15.9 percent while the ratio of integral length scale to
cylinder diameter ranged from 0.05 to 0.30. Stagnation region heat transfer augmentation
increased with decreasing length scale. An optimum scale was not found. A correlation was
developed that fit heat transfer data for the square bar grids to within ±4%. The data from
the array of wires were not predicted by the correlation; augmentation was higher for this
case indicating that the degree of isotropy in the turbulent flow field has a large effect on
stagnation heat transfer. The data of other researchers are also compared with the correlation.
Dynamics of Anisotropically Supported Rotors
Authors: Muszynska Agnes , Hatch Charles T. , Bently Donald E.
Published: March 2007

The paper discusses dynamic effects occurring in machinery rotors supported in bearings and
pedestals with laterally different characteristics. In the considered rotor model the anisotropy
of radial stiffness and tangential (“cross”) stiffness components are included. Within certain
ranges of the rotative speed the support anisotropy leads to the specific, excited‐by‐unbalance
rotor lateral synchronous vibrations in a form of backward (reverse) precession. In
addition, one section of the rotor may precess backward, while the other section simultaneously
precesses forward. Experimental results illustrate this phenomenon. The analytical
model of the system is based on multimode modal approach. It is also shown in this paper
that greatly enhanced information for machine malfunction diagnostics can be obtained by
simulated rotation of the XY transducer system observing rotor lateral vibration. This simulated
rotation can be accomplished by the machine diagnostic data acquistion and processing
system. The data processing also includes extraction of forward and backward components
of elliptical orbits filtered to one frequency, and the filtered orbit major axis magnitude and
its angular orientation.

Numerical examples, field data, and experimental results performed on a rotor rig illustrate
applications.
Advanced Compressor Loss Correlations, Part II:Experimental Verifications
Authors: Schobeiri M. T.
Published: March 2007

Reliable efficiency calculation of high‐subsonic and transonic compressor stages requires a
detailed and accurate prediction of the flow field within these stages. Despite the tremendous
progress in turbomachinery computational fluid mechanics, the compressor designer still
uses different loss correlations to estimate the total pressure losses and thus the efficiency of
the compressor stage. The new shock loss model and the modified diffusion factor, developed
in Part I, were implemented into a loss calculation procedure. In this part, correlations
for total pressure loss, profile loss, and secondary loss coefficients are presented, using the
available experimental data. Based on the profile loss coefficients, correlations were also
established for boundary layer momentum thickness. These correlations allow the compressor
designer to accurately estimate the blade losses and therefore the stage efficiency.
Instability Threshold of a Rigid Rotor‐Tilting PadJournal Bearings System
Authors: Pagano Stefano , Rocca Ernesto , Russo Michele , Russo Riccardo
Published: March 2007

The stability of a rigid rotor supported on radial tilting pad journal bearings is analysed. This
study has been tackled both for small unbalance values by linearising the equations of
motion, and also in the case where, because of the high unbalance value, the rotor axis
describes orbits with an amplitude such that the system′s non‐linearity cannot be ignored. In
both cases the system′s stable operation maps have been obtained and verified through
numerical integration of the differential equations of motion.
Visualization of Flows in Curved Channels with aModerate or High Rotation Speed
Authors: Wang Liqiu , Cheng K. C.
Published: March 2007

Flows in channels with streamwise curvature and spanwise rotation are visualized in terms
of end‐view near the exit of the test sections through injecting smoke into the flows. Two test
sections are used, i.e. the rectangular channels with the aspect ratio of and 10, respectively.
The work focuses on visualization of Dean and Coriolis vortices under the effects of secondary
instabilities and flows in the region with a relatively high rotation speed. The results
show that the secondary instabilities cause the Dean and Coriolis vortices oscillating in
various forms and the flows at high rotation speeds are controlled by the secondary instabilities
rather than the primary instability. In particular, the secondary instabilities lead the
flows to be unsteady and turbulent somewhat like the bursting flow in the turbulent boundary
layers.
Effects of Operating Conditions on the Flow in theMoving Blade Passage of a Single Stage Axial‐Flow Fan
Authors: Adachi Tsutomu , Yamashita Yutaka , Yasuhara Kennichiro , Kawai Tatsuo
Published: March 2007

Three dimensional steady and unsteady velocity distributions in the axial flow fan were
measured using a hot wire probe for various operational conditions, various rotational
speeds and various measuring positions. For measuring the velocity distributions in the blade
passage, a specially designed and manufactured hot wire traversing apparatus was used.
Steady velocity distributions, turning angles, effects of incident to the cascade, flow leakage
through the tip clearance and effects of the flow separation show the flow phenomena
through the blade passages. Unsteady velocity distributions show time dependent procedures
of the wake flowing through the moving blade passage. Considering these results of
measurements, the effects of the upstream stationary blade and the effects of Reynolds
number on the flow were considered.
Heat (Mass) Transfer in a Rotating Two‐Pass Square Channel — Part II:Local Transfer Coefficient, Smooth Channel
Authors: Kukreja R. T. , Park C. W. , Lau S. C.
Published: March 2007

Naphthalene sublimation technique and the heat/mass transfer analogy are used to determine the detailed local heat/mass transfer distributions on the leading and trailing walls of a twopass square channel with smooth walls that rotates about a perpendicular axis. Since the variation of density is small in the flow through the channel, buoyancy effect is negligible. Results show that, in both the stationary and rotating channel cases, very large spanwise variations of the mass transfer exist in he turn and in the region immediately downstream of the turn in the second straight pass. In the first straight pass, the rotation‐induced Coriolis forces reduce the mass transfer on the leading wall and increase the mass transfer on the trailing wall. In the turn, rotation significantly increases the mass transfer on the leading wall, especially in the upstream half of the turn. Rotation also increases the mass transfer on the trailing wall, more in the downstream half of the turn than in the upstream half of the turn. Immediately downstream of the turn, rotation causes the mass transfer to be much higher on the trailing wall near the downstream corner of the tip of the inner wall than on the opposite leading wall. The mass transfer in the second pass is higher on the leading wall than on the trailing wall. A slower flow causes higher mass transfer enhancement in the turn on both the leading and trailing walls.