A post test analysis of a high-speed two-stage axial flow compressor

In 1991 under a Space Act Agreement between then Allison Gas Turbine Division (Rolls-Royce), NASA Lewis (NASA Glenn), and the Army Propulsion Directorate, a combined experimental and analytical research program was initiated to assess the capability of advanced computational fluid dynamics (CFD) codes to predict the aerodynamic performance of high-speed, high-aerodynamic- loaded axial flow compressors. Both two-stage compressors that were designed, fabricated, and tested in this study and reported upon in this paper had a design pressure ratio of 5:1. In addition, several tests were run of the first stage of each of these two-stage machines in isolation. Extensive use was made of CFD codes to support the aero-design process. The objective of this paper is to report upon what was learned from this aero- design exercise. Both experimental and post-test CFD simulation results are presented. The original build of the two stage compressor fell short of meeting the targeted aero-performance goals. The shortcomings of this design are attributed to the failure of the CFD simulations conducted in support of the design to capture key phenomena which limited the aero-performance of the compressor. This failure is not due to the inability of the CFD code to account for these key phenomena. Rather the fault lies in not accounting for them in the simulations that were conducted in support of the aerodynamic design. Finally the paper outlines the steps taken in the aerodynamic design of the second build to overcome the shortcomings of the first build.