Influence of Axial Velocity Density Ratio in Cascade Testing of Supercritical Compressor Blades

Abstract

An experimental and numerical study of the influence of axial velocity density ratio (AVDR) in cascade testing of two high-turning compressor blades at supercritical flow conditions was conducted. Both solid and slotted sidewalls were used in the experiments such that the cascade performances were evaluated with the variation of AVDR at the same flow condition. In addition, the cascade flow was computed by solving 2- D and 3-D steady Navier-Stokes equations. 2-D CFD computation provided the ideal 2-D flow results (AVDR = 1.0) while 3-D CFD characterized the 3-D cascade flow in the test section with solid sidewalls. Thus, the sidewall secondary flow and the flow contraction across the blade passage were simulated (AVDR > 1.0). Detailed analysis of the AVDR influence on the flow was performed through the comparison of experimental and numerical results, including losses, blade surface Mach number, blade surface flow visualization and shadowgraph. Different AVDR influences were found on the two blades and also at different flow conditions. Nonetheless, solid sidewall cascade testing was found to be acceptable to evaluate the relative blade performances, in spite of the AVDR influence.