Numerical Analysis of Blade Platform Leakage in Axial Compressors

This paper deals with the complex interacting flow between the main flow in the gas path of compressors and the hub gap leakage in the rotor blade row when considering the real geometry of the platform. The results of the present investigation agreed well with previous findings while complementing the overall compressor model. Significant local differences of the flow field between simplified endwalls and a real geometry case were detected when both circumferential and streamwise platform gaps were taken into account. At design conditions, rotor hub leakage caused by inter-platform gaps of 2.6% passage pitch reduced polytropic rotor efficiency and total pressure ratio by as much as 3.2% and 2.3%, respectively, relative to the smooth endwall setup. Front circumferential leakage was found to intensify with the presence of inter-platform leakage. The latter contributed to the formation of a large recirculation region and increased secondary flow close to the blade’s trailing edge on its suction side. A steep deterioration of the row performance from zero to non-zero midpassage massflow was observed, implying that emphasis should be placed on the avoidance of any inter-platform leakage. Flow vectors, surface streamlines, and schematic leakage paths illustrate the aerodynamic conditions under the influence of endwall leakage.     «

This paper deals with the complex interacting flow between the main flow in the gas path of compressors and the hub gap leakage in the rotor blade row when considering the real geometry of the platform. The results of the present investigation agreed well with previous findings while complementing the overall compressor model. Significant local differences of the flow field between simplified endwalls and a real geometry case were detected when both circumferential and streamwise platform gaps w...     »