Study of Influence of Diffuser Meridian Channel Shape on Performance of Micro-Gas Turbine Centrifugal Compressor

Three-dimensional viscous flow numerical simulation was conducted to study influence of diffuser meridional-section shape with different width ratio on micro-gas turbine centrifugal compressor. Then, the curves of efficiency, total pressure recovery coefficient, total pressure ratio and static pressure ratio were compared under different width ratio. Moreover, the velocity vector in diffuser flow channels, the magnitude distribution of absolute velocity near vane´s endwall and the secondary flow in the across-section near outlet of diffuser were analyzed in detail under width ratio of 0.6, 0.8 and 1.1. The results show: When the width ratio is around 0.6, the flow in diffuser flow channels tends to be uniformity. The backflow and vortex near the pressure surface disappear, and the vortex and detachment near the suction surface decrease. Therefore, the total pressure recovery coefficient is enhanced, the flow losses are reduced and the efficiency is increased. Both the total pressure ratio and the static pressure ratio approximate the maximum value.