Parametric investigation on a transonic axial compressor stage using CFD techniques

Abstract

Tip clearance and secondary flow are regarded as important parameters resulting in degradation of compressor performance as a result of the stall-inception, total loss of pressure and end-wall blockage. To investigate the effect of rotor tip clearance and rotor blade solidity on fluid dynamic interaction of tip leakage flow and secondary flow an numerical investigation was conducted on stage NASA-37 with zero rotor tip clearance, nominal and twice the nominal rotor tip clearance and also with (1.4276, 1.3574, 1.2873, 1.2145, 1.1437) rotor blade solidity. NASA-37 stage was discreatized and analysed using ANSYS-Turbogrid and CFX 15.0 software. The tip clearance flow arising from the leading edge of rotor blade flows across the passage shock and on impinging on the pressure surface of the adjacent blade interacts with vortices of secondary flow. The compressor stage performance is affected by decrease in peak stage pressure ratio by 3.6% and 2% in peak isentropic efficiency with increase in rotor tip clearance due to the strong interaction of fluid flow as a result of the retarded momentum of fluid zone. Also Low fluid flow interaction is noticed as the rotor blade solidity is increased from 1.1437 to 1.4276. Hence, reducing the losses in compressor stage at higher solidity for three tip clearances.