Structure optimization and performance analysis of interstage elbow of air compressor

In order to study the influence of the change of parameters of the interstage elbow on the aerodynamic performance of the high pressure stage air compressor, a centrifugal two-stage series air compressor is optimized as the research object, and the numerical simulation method is used to calculate and analyze the three typical working conditions and internal flow of the air compressor. The results show that the optimized design scheme can improve the performance of the air compressor, and the improvement is most obvious by maintaining the same diameter of the inlet and outlet of the interstage elbow. At the design condition, the pressure ratio and efficiency are increased by 1.2% and 6.1%, respectively. At surge conditions, the pressure ratio and efficiency are increased by 3.4% and 2.8%, respectively, and the stall margin is increased by 3.8%. At the design condition, the swirl intensity, referred to as SI, decreased by 21.6% at the outlet of the elbow. The total pressure distortion index DC60 showed a downward trend at all operating conditions. The distribution of total pressure and axial velocity at the inlet of the high pressure stage impeller is similar and regular under different radius ratios at the blockage condition and the design condition, while the surge condition fluctuates violently and unevenly at 0.9R near the tip clearance. The total pressure and axial velocity at 0.5R–0.7R in the middle of the flow channel of the above scheme are larger than those of other models and are the most stable.