A periodic-average flow measurement technique involving a hot-wire sensor was used to measure the periodically unsteady velocity field in the first stage of a low-speed, multistage, axial-flow research compressor. In portions of the compressor annulus, the periodic-average velocity patterns for imbedded rotor and stator exit flows showed appreciable sequential variation with the systematically changed data sampling position of the rotor blades. Representative examples of periodic-average flow field variation with rotor blade sampling position in stop-action sequence are shown for various locations in the compressor. A simple, first-order approximation physical description of blade wake flow transport and interaction based on experimental data interpretation is proposed to organize and thus help understand the data obtained.

This paper summarizes the results of evaluating and validating three 3D viscous “RANS” Reynolds-Averaged Navier-Stokes codes for a Honeywell modern design of axial-centrifugal compressor test case with high quality test data. The compressor consists of a single stage axial followed by a single stage centrifugal designs. The axial stage consists of a transonic axial rotor and stator. The centrifugal stage consists of a centrifugal impeller, a vane-island radial diffuser, a 90-degrees bend and tandem deswirl vanes. The compressor was designed and rig tested by Honeywell in the early ‘00s. Detailed measurements of total pressure and total temperature were made at the compressor inlet, exit, and between the stages, including an X-Y survey at the axial stage exit, with sufficient resolution to provide a good estimate of the performance of each stage of this compressor. The validation and calibration was performed by running simulations for the entire compressor as tested in the rig. The RANS CFD programs used in this study are the NASA Glenn Research Center’s average-passage program APNASA, the Numeca’s Fine Turbo program and the ANSYS/CFX. The APNASA program employs only the standard K-ε turbulence model while the Numeca’s Fine Turbo and ANSYS/CFX employ various turbulence closures that are based on the standard two-equation K-ε turbulence model and the Wilcox K-ω model. The paper presents a comparison between the three CFD codes’ predictions and the measured test data for the overall compressor performance and the performance of the different compressor stages. These results shed some light on the ability of these codes to predict the overall compressor performance and the performance of the individual components. Sensitivity of the two codes predictability for mesh resolution and turbulence modeling variations are also presented.

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