Numerical Investigations on Inuence of Volute Non-Axisymmetry on Unsteady Flow in Centrifugal Compressor

The influence of volute non-axisymmetry on the unsteady flow in a centrifugal compressor is investigated by the unsteady numerical simulation. The results indicate that, the flow unsteady uctuation in the centrifugal compressor is dominated by the impeller. The inuence of volute non-axisymmetry can be propagated to the leading edge of impeller when the volute is operated away from its design condition. The influence of the non-axisymmetric structure of volute on the instantaneous pressure at the pressure surface of diffuser vane is mainly on the main and splitter blades passing frequency at the low and design flow rates, while the impeller shaft rotating frequency also plays an important role under the large flow rate condition. The pressure uctuation on the pressure surface of impeller main blade is mainly affected by the impeller shaft rotation frequency, the diffuser blade passing frequency and their multiple frequencies.