Non-axisymmetric flow characteristics in centrifugal compressor

To investigate the non-axisymmetric flow in centrifugal compressor internal caused by the asymmetric structure of the volute, the combined experimental and numerical methods(Turbulence model choosing S-A model) are used. The results show that the perturbing pressure wave caused by the high static pressure zone of the volute propagates to the upstream in off-design conditions, which brings the non-axisymmetric flow in the compressor. The non-uniform degrees of the static pressure distribution of the volute in the large flow conditions(0.40kg/s) are more obvious than those of the small flow conditions(0.26kg/s). The strong disturbance pressure wave of the impeller outlet can be transmitted to the circumferential position of the impeller inlet about 180°. In the small flow conditions, the circumferential non-uniform degrees of the radial and tangential velocity of the gas flow through the diffuser are more significant. In the large flow conditions, the air flow fluctuations at volute inlet are more obvious. The blade loading distribution and its fluctuations are also affected by the the non-axisymmetric flow. The loading fluctuations of the main blades in the large flow conditions are mainly affected by the blade pass frequency, but in the small flow condition, they are mainly influenced by the two times of the blade pass frequency.