Numerical simulation on inlet distortion of centrifugal compressor with 90° bent pipe

To understand the effects of centrifugal compressor inlet distortion caused by 90° bent pipe, two different axial position inlet bent pipes were numerically simulated with compressor and the influence on compressor performance was analyzed. The results show different performance deterioration between different bent pipes, the larger distance between bent pipe outlet and impeller inlet leads to more decrease. The bent pipe makes the flow field of impeller inlet strongly disorderly. The distortion causes a noticeable decline in compressor performance under large mass flow rate and a slight drop at low mass flow rate. The effect of inlet distortion amplifies and develops to the volute inlet while the mass flow rate increases, which functions together with circumferential distortion caused by volute tongue, resulting in decrease of the performance. When the mass flow rate is low, the inlet distortion reduces the flow loss in impeller passage, helping to maintain the performance of compressor at low mass flow rate.