Numerical Investigation of Compressor Blades Deformation During Stall Development into Surge

Abstract

The present paper focuses on the simulations of the flow behavior and the structural analysis for a high-speed compressor at the transition time between stall and surge. Two cases are presented; the first case is for the compressor with its original design unchanged, and the other case is for the compressor controlled with air injection at the vaneless area. The case of the compressor with air injection was studied aerodynamically and discussed in detail in a previously published paper done by the authors of the current presented work. Results showed that the stall effect is relatively higher at the impeller exit near the shroud surface due to the interaction between the main flow and the secondary flow, which causes strong pressure and velocity fluctuations at this area. Results also indicated that the forces and moments for the case of the controlled compressor are lower than those for the uncontrolled compressor during stall and surge. The blades tip surface deflection is maximized at the moment of the maximum pressure in the surge cycle, and the most dangerous region at the deformed blades tip surface is located at the transition area between the axial and radial blade profile. Results also showed that the deformation of the blades at the tip region can be limited by changing the shaft bearing stiffness.