Aerodynamic Performance and Stability of a Transonic Axial Compressor Stage with an Airfoil Vortex Generator

Abstract

Performance of a NASA 37 transonic compressor stage with a symmetric Airfoil Vortex Generator (AVG) positioned in the upstream of rotor is investigated through a numerical simulation. Steady state flow simulations were performed with k-ω SST turbulence model in ANSYS CFX flow solver. Grid independence study for the baseline compressor was performed besides CFD predicted performance characteristics were validated against available experimental data. The results of parametric study shows that AVG is able to improve compressor stall margin with a penalty on the stage efficiency. Incorporation of an AVG on the casing surface upstream of rotor reduces its specific work capacity, incurs flow losses and decreases stage peak efficiency by 3.34%. However few AVG configurations have negligible reduction, nearly 0.27-0.4%, in stage efficiency compared to baseline case. At near stall operating point, an AVG affects both rotor and stator flow field. An AVG under loads rotor tip region and decreases tip leakage mass flow rate, leading to the reduction of flow blockage. The flow swallowing capacity of the stator passage increases by diffusing the flow considerably to a low velocity. Consequently, AVG is able to increase the compressor stage stall margin by 8.06%.