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Research Papers

Numerical Investigation of the Unsteady Interaction Within a Close-Coupled Centrifugal Compressor Used in an Aero Engine

[+] Author and Article Information
Benjamin Wilkosz

e-mail: wilkosz@ist.rwth-aachen.de

Peter Jeschke

e-mail: jeschke@ist.rwth-aachen.de
Institute of Jet Propulsion and Turbomachinery,
RWTH Aachen University,
Templegraben 55,
Aachen 52062, Germany

Caitlin Smythe

GE Aviation,
1000 Western Avenue,
MD47410,
Lynn, MA 01910
e-mail: caitlin.smythe@ge.com

Not shown here due to lack of space.

Pressure gradient between the blade PS and SS.

The validation of the diffuser centerline static pressure recovery can be seen in the Appendix. A comparison of the velocity field with unsteady particle image velocimetry data is shown by Findeisen [15].

This quantity specifies the local irreversible specific entropy production due to friction and heat dissipation and is used here to identify dominant loss mechanisms, which is more difficult when using the entropy in the highly 3D flow due to the transport character of this quantity. In order to apply the transport equation for turbulent flow the Boussinesq-approximation proposed by Moore et al. [39] is used.

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the Journal of Turbomachinery. Manuscript received May 3, 2013; final manuscript received June 20, 2013; published online September 26, 2013. Editor: Ronald Bunker.

J. Turbomach 136(4), 041006 (Sep 26, 2013) (12 pages) Paper No: TURBO-13-1068; doi: 10.1115/1.4024892 History: Received May 03, 2013; Revised June 20, 2013

The present work forms part of a research project of the Institute of Jet Propulsion and Turbomachinery at the RWTH Aachen University in collaboration with GE Aviation. The subject is the detailed numerical analysis of the unsteady flow field, focusing on the interaction between the impeller and the passage diffuser of a close-coupled transonic centrifugal compressor used in an aero engine. The centrifugal compressor investigated is characterized by a close-coupled impeller and passage diffuser with a radial gap of only 3.6%. The close coupling tends to provide a high aerodynamic efficiency but simultaneously cause a high unsteady interaction between the impeller and the diffuser. These unsteady effects can have a significant impact on the performance of both components and present a challenge to state-of-the-art numerical methods. With increasing compressor efficiency, the more important it is to have an understanding of the detailed unsteady flow physics. Experimental data was obtained from a state-of-the art centrifugal compressor test rig located at the Institute of Jet Propulsion. Steady and unsteady pressure measurements within the impeller and diffuser are used to gain detailed information on the temporal, time-averaged, and spectral pressure distributions within the stage to validate the CFD. The work presented here shows the unsteady phenomena caused by the interaction and the location and propagation of these phenomena within the centrifugal stage. Within the impeller, the exducer is in first order excited by the blade passing frequency (BPF) of the diffuser, whereas in the diffuser both the BPF and the passage passing frequency (PPF), are present up until the end of the pipe-diffuser. Significant effects on the integral component performance could only be identified for the impeller. Special focus is paid to evaluate the diffuser upstream pressure field, since this is the major source of unsteadiness within the impeller. The performance of the rotor decreases due to the unsteady interaction. This effect is traced back to the unsteady tip-clearance flow, in which the time-averaged mass transport decreases, whereas the specific entropy production increases in a nonlinear way. Within the diffuser, local effects counteracting with respect to the integral performance are found. In front of the throat, there is less decay in the total pressure as a result of tangentially expanding pressure waves. Within the passage a decrease in flow uniformity in the unsteady flow is identified as the reason for the lower diffusion up until the throat and higher losses within the downstream diffuser passage.

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References

Hill, P., and Peterson, C., 1992, Mechanics and Thermodynamics of Propulsion, 2nd ed., Addison-Wesley, Reading, MA.
Wilfert, G., Sieber, J., Rolt, A., Baker, N., Touyeras, A., and Colantuoni, S., 2007, “New Environmental Friendly Aero Engine Core Concepts,” 18th International Symposium on Air Breathing Engines (ISABE), Beijing, September 2–7, Paper No. ISABE-2007-1120, pp. 11.
Dean, R. C. J., 1959, “On the Necessity of Unsteady Flow in Fluid Machines,” Trans. ASME, 81, pp. 24–28.
Ziegler, K. U., Gallus, H. E., and Niehuis, R., 2002, “A Study on Impeller-Diffuser Interaction—Part I: Influence on the Performance,” ASME Paper No. GT2002-30382. [CrossRef]
Kenny, D., 1969, “A Novel Low-Cost Diffuser for High-Performance Centrifugal Compressors,” ASME J. Eng. Power, 91(9), pp. 37–47.
Bourgeois, J. A., Martinuzzi, R. J., Savory, E., Zhang, C., and Roberts, D., 2011, “Assessment of Turbulence Model Predictions for an Aero-Engine Centrifugal Compressor,” ASME J. Turbomach., 133(1), p. 011025. [CrossRef]
Shum, Y., Tan, C., and Cumpsty, N., 2000, “Impeller-Diffuser Interaction in a Centrifugal Compressor,” ASME Paper No. 2000-GT-0428.
Dean, R. C. J. and Senoo, Y., 1960, “Rotating Wakes in Vaneless Diffusers,” ASME J. Basic Eng., 86, pp. 563–574. [CrossRef]
Abdelwahab, A., 2010, “Numerical Investigation of the Unsteady Flow Fields in Centrifugal Compressor Diffusers,” ASME Turbo Expo 2010: Power for Land, Sea and Air, Glasgow, UK, June 14–18, ASME Paper No. GT2010-22489. [CrossRef]
Grates, D. R., 2009, “Numerische simulation der instationaeren stroemung in einem radialverdichter mit pipe-diffusor,” Ph.D. thesis, RWTH Aachen, Aachen, Germany.
Hodson, H., and Dawes, W., 1998, “On the Interpretation of Measured Profile Losses in Unsteady Wake-Turbine Blade Interaction Studies,” ASME J. Turbomach.120(2), pp. 276–284. [CrossRef]
Ziegler, K., 2003, “Experimentelle untersuchung der laufrad-diffuror-interaktion in einem radialverdichter variabler geometrie,” Ph.D. thesis, RWTH Aachen, Aachen, Germany.
Denton, J., 1993, “Loss Mechanisms in Turbomachines,” ASME J Turbomach., 115(1993), pp. 621–656. [CrossRef]
Bryans, A., 1986, “Diffuser for a Centrifugal Compressor,” U.S. Patent No. 4,576,550, p. 8.
Findeisen, E., 2011, “Numerische pumpgrenzuntersuchung eines radialverdichters mittels stationaerer und instationaerer 3D-RANS-Simulation,” Master's thesis, IST, Fakultaet fuer Maschinenwesen Rheinisch-Westfaelische Technische Hochschule Aachen, Aachen, Germany.
Zachau, U., 2007, “Experimental Investigation on the Diffuser Flow of a Centrifugal Compressor Stage With Pipe Diffuser,” Ph.D. thesis, RWTH Aachen, Aachen, Germany.
Roe, P. L., 1981, “Approximate Riemann Solvers, Parameter Vectors, and Difference Schemes,” J. Comput. Phys., 43, pp. 357–372. [CrossRef]
Kuegeler, E., 2004, “Numerisches verfahren zur genauen analyse der kuehleffektivitaet filmgekuehlter turbinenschaufeln,” Ph.D. thesis, DLR, Ruhr Universitaet Bochum, Bochum, Germany.
Zachcial, A., 2006, Mischungsebenenmodellierung zur Analyse der raeumlichen Stroemung in mehrstufigen Turbomaschinenkomponenten, Shaker-Verlag, Aachen, Germany.
Giles, M., 1988, “Non-Reflecting Boundary Conditions for the Euler Equations,” Rolls Royce, Technical Report.
Schnell, R., 2004, “Numerische simulation des akustischen nahfeldes einer triebwerksgeblaesestufe,” DLR Institut fuerAntriebstechnik, Berlin, Technical Report.
Ashcroft, G., Heitkamp, K., and Kuegeler, E., 2010, “High-Order Accurate Implicit Runge-Kutta Schemes for the Simulation of Unsteady Flow Phenomena in Turbomachinery,” 5th European Conference on Computational Fluid Dynamics (ECCOMAS CFD 2010), Lisbon, Portugal, June 14.–17.
Wilcox, D. C., 1994, Turbulence Modeling for CFD, DCW Industries Inc., La Canada, CA.
Kozulovic, D., and Roeber, T., 2006, “Modelling the Streamline Curvature Effects in Turbomachinery Flows,” Proceedings of ASME Turbo Expo 2006: Power for Land, Sea and Air, Barcelona, Spain, May 8–11, ASME Paper No. GT2006-90265. [CrossRef]
Kozulovic, D., Roeber, T., Kuegeler, E., and Nuernberger, D., 2004, “Modifications of a Two-Equation Turbulence Model for Turbomachinery Fluid Flows,” DLR Institute of Propulsion Technology, Tecchnical Report.
Gaetani, P., Persico, G., Mora, A., Dossena, V., and Osnaghi, C., 2011, “Impeller-Vaned Diffuser Interaction in a Centrifugal Compressor at the Best Efficiency Point,” ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition, Vancouver, BC, Canada, June 6–10, ASME Paper No. GT2011-46223. [CrossRef]
Inoue, M., and Cumpsty, N., 1984, “Experimental Study of Centrifugal Impeller Discharge Flow in Vaneless and Vaned Diffusers,” ASME J. Eng. Gas Turbines Power, 106, pp. 455–467. [CrossRef]
Sato, K., and He, L., 1998, “Effect of Rotor-Stator Interaction on Impeller Performance in Centrifugal Compressors,” Proc. of ISROMAC-7, Honolulu, HI, February 22–26, Vol. C, A.Muszynska, J. A. Cox, and D. T. Nosenzo, eds., Bird Rock Pub. House, Honolulu, HI, pp. 1359–1368.
Fisher, E., and Inoue, M., 1981, “A Study of Diffuser/Rotor Interaction in a Centifugal Compressor,” J. Mech. Eng. Sci., 23(3), pp. 149–156. [CrossRef]
Gaetani, P., Persico, G., Mora, A., Dossena, V., and Osnaghi, C., 2011, “Impeller-Vaned Diffuser Interaction in a Centrifugal Compressor at Off Design Conditions,” ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition, Vancouver, BC, Canada, June 6–10, ASME Paper No. GT2011-46234. [CrossRef]
Braeunling, W. J. G., 2009, “Flugzeugtriebwerke: Grundlagen, Aero-Thermodynamik, ideale und reale Kreisprozesse,” Thermische Turbomaschinen, Komponenten, Emissionen und Systeme, Springer, Berlin, pp. 859–971.
Hoshide, R. K., and Nielsen, C. E., 1972, “Study of Blade Clearance Effects on Centrifugal Pumps, Final Report,” Rocketdyne-National Aeronautics and Space Administration.
Zimmermann, M., 2012, “Instationaere analyse eines radialverdichters mit pipe diffusor und eng gekoppeltem impellerdiffusor system,” Master's thesis, Institute of Jet Propulsion and Turbomachinery-Aachen University, Aachen, Germany.
Denton, J., 1994, “Loss Mechanisms in Turbomachines,” University of Cambridge, UK, June.
Wilkosz, B., Schwarz, P., Kunte, R., Jeschke, P., and Smythe, C., 2012, “Numerical and Experimental Investigation of an Impeller Tip Clearance Variation in a Centrifugal Compressor Stage With Pipe-Diffuser,” Proceedings of the DLRK 2012 Conference, Berlin, September 10–12, Paper No. DLRK-2012-281271, p. 13.
Connell, S., Braaten, M., Zori, L., Steed, R., Hutchinson, B., and Cox, G., 2011, “A Comparison of Advanced Numerical Techniques to Model Transient Flow in Turbomachinery Blade Rows,” ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition, Vancouver, BC, Canada, June 6–10, ASME Paper No. GT2011-45820. [CrossRef]
Kunte, R., 2011, “Experimentelle und numerische untersuchung eines radialverdichters mit pipe diffusor und umlenkbeschaufelung fuer eine triebwerksanwendung,” Ph.D. thesis, RWTH Aachen Institut fuer Strahlantriebe und Turboarbeitsmaschinen, Aachen, Germany.
Dawes, W., 1994, “A Simulation of the Unsteady Interaction of a Centrifugal Impeller With Its Vaned Diffuser: Flows Analysis,” ASME Paper No. 94-GT-105.
Adeyinka, O. B., and Naterer, G. F., 2004, “Modeling of Entropy Production in Turbulent Flows,” ASME J. Fluids Eng., 126, pp. 1–7. [CrossRef]
Schwarz, P., Wilkosz, B., Kunte, R., ▪J. S., and Jeschke, P., 2012, “Numerical Investigation Into the Ratio Between Passage Diffuser and Vaneless Diffuser in a Centrifugal Compressor Stage,” Deutscher Luft- und Raumfahrtkongress 2012, Berlin, September 10–12.
Giles, M., 1991, “UNSFLO: A Numerical Method for the Calculation of Unsteady Flow in Turbomachinery,” UNSFLO, Technical Report.
Wilkosz, B., Schwarz, P., Jeschke, P., Chen, N., and Smythe, C., 2012, “Numerical Investigation of the Steady Separation Including Mechanisms in a Passage Diffuser With Application of Two-Equation Turbulence Models,” Conference on Modelling Fluid (CMFF’12), Budapest, Hungary, September 4–7.
Runstadler, P. W., and Dolan, F. X., 1975, Diffuser Data Book, Creare Incorporated, Hanover, NH.
Kunte, R., Schwarz, P., Wilkosz, B., Jeschke, P., and Smythe, C., 2013, “Experimental and Numerical Investigation of Tip Clearance and Bleed Effects in a Centrifugal Compressor Stage With Pipe Diffuser,” ASME J. Turbomach., 135(1), p. 12. [CrossRef]

Figures

Grahic Jump Location
Fig. 5

Static pressure amplitude in the relative frame of the 1st BPF at 50% span

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Fig. 4

Comparison of the stage, impeller, and diffuser performance for the RANS-URANS(TA) with the experimental data

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Fig. 3

3D view of the CFD domain: complete GE centrifugal stage

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Fig. 2

Schematic view of the centrifugal stage

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Fig. 1

Cross-section of the GE test rig at the RWTH-Aachen

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Fig. 6

Diffuser upstream potential field from the diffuser in the circumferential direction

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Fig. 7

Impeller (a) shroud static pressure build-up, (b) blade loading, and (c) unsteady upstream diffuser potential field

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Fig. 9

Spectral analysis for the pipe-diffuser

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Fig. 13

Correlation between the throat blockage and secondary flow (left) and visualization of the change in the flow diffusion within the pipe (right)

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Fig. 10

Meridional development of the total pressure loss and pressure recovery within the diffuser

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Fig. 11

Visualization of the irreversible specific entropy production

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Fig. 12

Visualization of the pressure waves in the circumferential direction

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Fig. 8

Increase in specific entropy due to unsteadiness in the impeller

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Fig. 14

Diffuser centerline static pressure recovery at the ADP

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