Investigation of Blade Tip Interaction With Casing Treatment in a Transonic Compressor—Part II: Numerical Results

A single stage transonic axial compressor was equipped with a casing treatment consisting of 3.5 axial slots per rotor pitch in order to investigate its influence on stall margin characteristics, as well as on the rotor near tip flow field, both numerically and experimentally. Contrary to most other studies, a generic casing treatment (CT) was designed to provide optimal optical access in the immediate vicinity of the CT, rather than for maximum benefit in terms of stall margin extension. The second part of this two-part paper deals with the numerical developments and their validation, carried out in order to efficiently perform time-accurate casing treatment simulations. The numerical developments focus on the extension of an existing coupling algorithm in order to carry out unsteady calculations with any exterior geometry coupled to the main flow passage (in this case a single slot), having an arbitrary pitch. This extension is done by incorporating frequency domain, phase-lagged boundary conditions into this coupling procedure. Whereas the phase lag approach itself is well established and validated for standard rotor-stator calculations, its application to casing treatment simulations is new Its capabilities and validation will be demonstrated on the given compressor configuration, making extensive use of the detailed particle image velocimetry flow field measurements near the rotor tip. Instantaneous data at all measurement planes will be compared for different rotor positions with respect to the stationary slots in order to evaluate the time-dependent interaction between the rotor and the casing treatment.

[1]  Xingen Lu,et al.  Experimental and Numerical Investigation of a Subsonic Compressor With Bend Skewed Slot Casing Treatment , 2006 .

[2]  Michael Lötzerich,et al.  Breakdown of Tip Leakage Vortices in Compressors at Flow Conditions Close to Stall , 1997 .

[3]  N. A. Cumpsty,et al.  Flow Phenomena in Compressor Casing Treatment , 1984 .

[4]  H. Takata,et al.  Stall Margin Improvement by Casing Treatment—Its Mechanism and Effectiveness , 1977 .

[5]  Michael D. Hathaway,et al.  Self-Recirculating Casing Treatment Concept for Enhanced Compressor Performance , 2002 .

[6]  C. Hah,et al.  Application of Casing Circumferential Grooves for Improved Stall Margin in a Transonic Axial Compressor , 2002 .

[7]  Lakshmi N. Sankar,et al.  Assessment of the Self-Recirculating Casing Treatment Concept Applied to Axial Compressors , 2005 .

[8]  Hong Yang,et al.  Numerical Investigation of Casing Treatment Mechanisms With a Conservative Mixed-Cell Approach , 2003 .

[9]  Heinz-Peter Schiffer,et al.  Effect of Circumferential Grooves on the Aerodynamic Performance of an Axial Single-Stage Transonic Compressor , 2007 .

[10]  H.-P. Kau,et al.  A Numerical Investigation of the Flow Mechanisms in a HPC Front Stage With Axial Slots , 2003 .

[11]  Dirk Nürnberger,et al.  Appropriate Turbulence Modelling for Turbomachinery Flows using a Two-Equation Turbulence Model , 2006 .

[12]  Hans-Peter Kersken,et al.  Toward Excellence in Turbomachinery Computational Fluid Dynamics: A Hybrid Structured-Unstructured Reynolds-Averaged Navier-Stokes Solver , 2006 .

[13]  Michael B. Giles,et al.  Nonreflecting boundary conditions for Euler equation calculations , 1990 .

[14]  W Chu,et al.  Experimental and numerical investigation of a subsonic compressor with bend-skewed slot-casing treatment , 2006 .

[15]  Rainer Schnell.  Investigation of the Tonal Acoustic Field of a Transonic Fanstage by Time-Domain CFD-Calculations With Arbitrary Blade Counts , 2004 .

[16]  H. D. Joslyn,et al.  A Fundamental Criterion for the Application of Rotor Casing Treatment , 1979 .

[17]  L. He,et al.  Method of Simulating Unsteady Turbomachinery Flows with Multiple Perturbations , 1992 .

[18]  Jinhee Jeong,et al.  On the identification of a vortex , 1995, Journal of Fluid Mechanics.

[19]  Wuli Chu,et al.  The Effects of Bend Skewed Groove Casing Treatment on Performance and Flow Field Near Endwall of an Axial Compressor , 2005 .

[20]  Qiushi Li,et al.  An Experimental Investigation on the Unsteady Excitation Effect of Casing Treatment on a Low Speed Axial Compressor , 2007 .

[21]  P. Roe.  Approximate Riemann Solvers, Parameter Vectors, and Difference Schemes , 1997 .

[22]  Vincent Chapin,et al.  Generalized Expression of Chorochronic Periodicity in Turbomachinery Blade-Row Interaction , 1991 .