Numerical Analysis of a Centrifugal Compressor Including a Vaneless Diffuser and a Volute

Within the scope of this paper, a centrifugal compressor including a volute and a vaneless diffuser from the company Liebherr Aerospace is analyzed. The main aim of this paper is to get findings, which help to plan experimental measurements and choose meaningful positions for measurement probes. Furthermore, the flow inside the volute shall be analyzed. The focus for the investigations lies at operation point near the surge line. For the first analysis, only the impeller with a vaneless diffuser is simulated. Afterwards, the volute is taken into account and gets simulated with the impeller and the diffuser. The main findings of the study are that the instrumentation of the impeller should be focused on the leading and trailing edge of the blade. At the surge line it can be seen that the tip vortex and a region at the suction side of the blade, which is endangered of flow separation, have the biggest influence. Furthermore a region, which is endangered of flow separation, evolves at the trailing edge. The flow inside the volute is mainly dependent on the inflow angle at the inlet of the volute. The pressure distribution around the tongue of the volute could have impact on the surge and rotating stall phenomena, thus there should be measurements too