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Research Papers

On the Influence of a Hubside Exducer Cavity and Bleed Air in a Close-Coupled Centrifugal Compressor Stage

[+] Author and Article Information
Peter Kaluza

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

Christian Landgraf, Philipp Schwarz, Peter Jeschke

Institute of Jet Propulsion and Turbomachinery,
RWTH Aachen,
Templergraben 55,
Aachen 52062, Germany

Caitlin Smythe

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

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received September 8, 2016; final manuscript received December 7, 2016; published online March 7, 2017. Editor: Kenneth Hall.

J. Turbomach 139(7), 071011 (Mar 07, 2017) (9 pages) Paper No: TURBO-16-1232; doi: 10.1115/1.4035606 History: Received September 08, 2016; Revised December 07, 2016

In aero-engine applications, centrifugal compressors are often close-coupled with their respective diffusers to increase efficiency at the expense of a reduced operating range. The aim of this paper is to show that state-of-the art steady-state computational fluid dynamics (CFD) simulations can model a hubside cavity between an impeller and a close-coupled diffuser and to enhance the understanding of how the cavity affects performance. The investigated cavity is located at the impeller trailing edge, and bleed air is extracted through it. Due to geometrical limitations, the mixing plane is located in the cavity region. Therefore, the previous analyses used only a cut (“simple”) model of the cavity. With the new, “full” cavity model, the region inside the cavity right after the impeller trailing edge is not neglected anymore. The numerical setup is validated using the experimental data gathered on a state-of-the art centrifugal compressor test-rig. For the total pressure field in front of the diffuser throat, a clear improvement is achieved. The results presented reveal a drop in stage efficiency by 0.5%-points caused by a new loss mechanism at the impeller trailing edge. On the hubside, the fundamentally different interaction of the cavity with the coreflow increases the losses in the downstream components resulting in the mentioned stage efficiency drop. Finally, varying bleed air extraction is investigated with both cavity models. Only the full cavity (FC) model captures the changes measured in the experiment.

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References

Hunziker, R. , Dickmann, H. , and Emmrich, R. , 2001, “ Numerical and Experimental Investigation of a Centrifugal Compressor With an Inducer Casing Bleed System,” 4th European Conference on Turbomachinery, Paper No. ATI-CST-025/01.
Palmer, D. L. , and Waterman, W. F. , 1994, “ Design and Development of an Advanced Tow-Stage Centrifugal Compressor,” ASME Paper No. 94-GT-202.
Sun, Z. , Tan, C. , and Zhang, D. , 2009, “ Flow Field Structures of the Impeller Backside Cavity and Its Influences on the Centrifugal Compressor,” ASME Paper No. GT2009-59879.
Raetz, H. , Kammeyer, J. , Natkaniec, C. K. , and Seume, J. R. , 2011, “ Numerical Investigation of Aerodynamic Radial and Axial Impeller Forces in a Turbocharger,” ASME Paper No. GT2011-46360.
Guidotti, E. , Tapinassi, L. , Toni, L. , Bianchi, L. , Gaetani, P. , and Persico, G. , 2011, “ Experimental and Numerical Analysis of the Flow Field in the Impeller of a Centrifugal Compressor Stade at Design Point,” ASME Paper No. GT2011-45036.
Guidotti, E. , Naldi, G. , Libero, T. , and Chockalingam, V. , 2012, “ Cavity Flow Modeling in an Industrial Centrifugal Compressor Stage at Design and Off-Design Conditions,” ASME Paper No. GT2012-68288.
Satish, K. V. V. N. K. , Guidotti, E. , Rubino, D. T. , Tapinassi, L. , and Prasad, S. , 2013, “ Accuracy of Centrifugal Compressor Stages Performance Prediction by Means of High Fidelity CFD and Validation Using Advanced Aerodynamic Probe,” ASME Paper No. GT2013-95618.
Zeng, Y. , and Liu, J. , 2014, “ Investigations on Three-Dimensional Coupled Flow of Secondary Air System and Main Flow Passages in a Micro Gas Turbine,” ASME Paper No. GT2014-26582.
Ziegler, K. , Gallus, H. , and Niehuis, R. , 2003, “ A Study on Impeller–Diffuser Interaction—Part I: Influence on the Performance,” ASME J. Turbomach., 125(1), p. 173. [CrossRef]
Ziegler, K. , Gallus, H. , and Niehuis, R. , 2003, “ A Study on Impeller–Diffuser Interaction—Part II: Detailed Flow Analysis,” ASME J. Turbomach., 125(1), p. 183. [CrossRef]
Zachau, U. , Niehuis, R. , Hoenen, H. , and Wisler, D. C. , 2009, “ Experimental Investigation of the Flow in the Pipe Diffuser of a Centrifugal Compressor Stage Under Selected Parameter Variations,” ASME Paper No. GT2009-59320.
Kunte, R. , Schwarz, P. , Wilkosz, B. , Jeschke, P. , and Smythe, C. , 2012, “ Experimental and Numerical Investigation of Tip Clearance and Bleed Effects in a Centrifugal Compressor Stage With Pipe Diffuser,” ASME J. Turbomach., 135(1), p. 011005. [CrossRef]
Schwarz, P. , Wilkosz, B. , Kunte, R. , Schmidt, J. , Jeschke, P. , and Smythe, C. , 2012, “ Numerical Investigation Into the Ratio Between Passage Diffuser and Vaneless Diffuser in a Centrifugal Compressor Stage,” 61 Deutscher Luft- und Raumfahrtkongress, Paper No. DLRK-2012-281275.
Kunte, R. , Jeschke, P. , and Smythe, C. , 2012, “ Experimental Investigation of a Truncated Pipe Diffuser With a Tandem Deswirler in a Centrifugal Compressor Stage,” ASME Paper No. GT2012-68449.
Wilkosz, B. , Schmidt, J. , Guenther, C. , Schwarz, P. , Jeschke, P. , and Smythe, C. , 2014, “ Numerical and Experimental Comparison of a Tandem and Single Vane Deswirler Used in an Aero Engine Centrifugal Compressor,” ASME J. Turbomach., 136(4), p. 041005. [CrossRef]
Wilkosz, B. E. , 2015, “ Aerodynamic Losses in an Aero Engine Centrifugal Compressor With a Close-Coupled Pipe-Diffuser and a Radial-Axial Deswirler,” Ph.D. thesis, RWTH Aachen University, Aachen, Germany.
Zachau, U. , Buescher, C. , Niehuis, R. , Hoenen, H. , Wisler, D. , and Moussa, Z. M. , 2008, “ Experimental Investigation of a Centrifugal Compressor Stage With Focus on the Flow in the Pipe Diffuser Supported by Particle Image Velocimetry (PIV) Measurements,” ASME Paper No. GT2008-51538.
Zachau, U. , 2007, “ Experimental Investigation on the Diffuser Flow of a Centrifugal Compressor Stage With Pipe Diffuser,” Ph.D. thesis, RWTH Aachen University, Aachen, Germany.
Kuegeler, E. , 2004, “ Numerisches Verfahren zur Genauen Analyse der Kuehleffektivitaet Filmgekuehlter Turbinenschaufeln,” Ph.D. thesis, Ruhr Universitaet Bochum, Bochum, Germany.
Roe, P. L. , 1981, “ Approximate Riemann Solvers, Parameter Vectors, and Difference Schemes,” J. Comput. Phys., 43(3), pp. 357–372. [CrossRef]
Giles, M. , 1988, “ Non-Reflecting Boundary Conditions for the Euler Equations,” Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Technical Report No. CFDL-TR-88-1.
Zachcial, A. , 2006, “ Mischungsebenenmodellierung zur Analyse der Raeumlichen Stroemung in Mehrstufigen Turbomaschinenkomponenten,” Ph.D. thesis, DLR Cologne, Köln, Germany.
Wilcox, D. C. , 1994, Turbulence Modeling for CFD, 2nd ed., DCW Industries, La Canada, CA.
Wilkosz, B. , Zimmermann, M. , Schwarz, P. , Jeschke, P. , and Smythe, C. , 2014, “ Numerical Investigation of the Unsteady Interaction Within a Close-Coupled Centrifugal Compressor Used in an Aero Engine,” ASME J. Turbomach., 136(4), p. 041006. [CrossRef]
Giles, M. , 1991, “ Unsflo: A Numerical Method for the Calculation of Unsteady Flow in Turbomachinery,” Massachusetts Institute of Technology, Gas Turbine Laboratory, GTL Report, Technical Report No. 205.
Grates, D. R. , Jeschke, P. , and Niehuis, R. , 2014, “ Numerical Investigation of the Unsteady Flow Inside a Centrifugal Compressor Stage With Pipe Diffuser,” ASME J. Turbomach., 136(3), p. 031012. [CrossRef]
Dolan, F. X. , and Runstadler, P. W. , 1973, “ Pressure Recovery Performance of Conical Diffusers at High Subsonic Mach Numbers,” Creare Incorporated, Technical Report No. NASA CR-2299.

Figures

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Fig. 1

Test rig cross view with instrumentation

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Fig. 2

Schematic of the truncated diffuser

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Fig. 3

CFD domain with the full cavity model

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Fig. 4

Geometry of the aftbleed cavity: (a) overview, (b) detail: full cavity model, and (c) detail: simple cavity model

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Fig. 5

Circumferential averaged flow field for OP2 with nominal bleed extraction

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Fig. 6

Trailing edge flow visualization in the rotating frame: (a) simple cavity and (b) full cavity

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Fig. 7

Vortices and region of recirculation in the diffuser with nominal bleed extraction

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Fig. 8

Isentropic stage efficiency: comparison of both cavity models to experiment

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Fig. 9

Comparison of the total pressure contour on the pitot plane for OP2: (a) experiment, (b) CFD: FC, and (c) CFD: SC

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Fig. 10

Pressure rise at the diffuser shroud for OP2 with nominal bleed

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Fig. 11

Diffuser performance comparison

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Fig. 12

Differences between the simple and the full cavity model (Δ = SC − FC) in circumferential averaged flow profiles at the pipe inlet

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Fig. 13

Stage total pressure ratio with nominal and deactivated aftbleed extraction versus reduced diffuser inlet massflow

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Fig. 14

Circumferential averaged streamlines and entropy of the coreflow (cr ≥ 10 m/s) in the VS and PVS

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