Non-axisymmetric phenomenon of shroud pressure and tip leakage in the centrifugal compressor

Volutes are usually designed to be the spiral configuration.The circumferential distortion induced by the circumferential non-uniform geometric structure of volute has significant influence on compressor internal flow field.Experimental and numerical approaches were used to study the non-axisymmetric flow characteristics in a compressor under two mass flow conditions.Results show that the compressor shroud static pressure distributions in the circumferential direction maintain the same characteristics of axisymmetric distortion form in volute.In the process of reverse transmission of downstream flow field distortion to the upstream,its impact on the upstream is gradually weakening.When shroud circumferential high pressure zone of the impeller outlet spreads to the impeller inlet,it appears phase difference to that of the impeller outlet high circumferential position.Under different mass flow conditions, the static pressure's non-uniform distribution leads to the differences of the circumferential distribution of the blade tip leakage flow.Under small mass flow condition,the leakage flow shows a decreasing,and then increasing and late decreasing.Under large mass flow condition,the leakage flow shows an increasing and then keeps the continuous decreasing.