Design Work of a Compressor Stage Through High-to-Low Speed Compressor Transformation

Low-speed model testing has advantages such as great accuracy, low cost and risk, so it’s widely used in the design procedure of HPC exit stage. The low-speed model testing project is conducted in Nanjing University of Aeronautics and Astronautics, to represent aerodynamic load and flow field structure of the seventh stage of a high-performance 10-stage high-pressure compressor. This paper outlines the design work of the low speed four-repeating-stage axial compressor, the third stage of which is the testing stage. The first two stages and the last stage provide the compressor with entrance and exit conditions respectively. The high-to-low speed transformation process involves both geometric and aerodynamic considerations. Accurate similarities demand the same Mach number and Reynolds number, which will not be maintained due to motor power/size and its low-speed feature. Compromises of constraints are obvious. Modeling principles are presented in high-to-low speed transformation. Design work is carried out based on these principles. Four main procedures are proceeded subsequently in the general design, including establishment of low-speed modeling target, global parameter design of modeling stage, throughflow aerodynamic design and blading design. In global parameter design procedure, rotational speed, shroud diameter, hub-tip ratio, mid-span chord and axial spacing between stages are determined by geometrical modeling principles. During throughflow design process, radial distributions of aerodynamic parameters such as D-Factor, pressure-rise coefficient, loss coefficients, stage reaction and other parameters are obtained by determined aerodynamic modeling principles. Finally, rotor and stator blade profiles of LSRC at seven span locations are adjusted, to make sure that blade surface pressure coefficients agree well with that of the HPC. 3D flow calculations are performed on low-speed four-stage axial compressor, and the resultant flow field structures agree well with that of the HPC. It’s worth noting that a large separation zone appears in both suction surfaces of LSRC and HPC. How to diminish it through 3D blading design in LSRC test rig is our further work.