Matching of an Overhung Volute to a Centrifugal Compressor at Varied Operating Conditions

Abstract Centrifugal compressors are widely used in turbocharged powertrains for Heavy-Duty applications. The volute of the centrifugal compressors is generally of the overhung type. The design of volutes is often neglected, and the shape of the volute is dictated by the packaging requirements of the engine. However, with the advent of Hydrogen-based propulsion systems, the efficiency of all the components of the centrifugal compressor stage is important in order to achieve a higher efficiency at the stage level and also to understand the contribution of the volute towards stage performance. Measuring static pressure and total pressure inside and at the exit of the volute is a challenging task due to the complex nature of the flow inside an overhung volute. This study involves an experimental campaign to quantify the volute performance using static and total pressure measurements at different locations on the volute. The total pressure measurements were carried out using calibrated rotating Kiel probes to quantify the flow angles and the corresponding total pressure values. This enabled the measurement of the maximum total pressure value at a location for a given operating condition. These total pressures and static pressures were measured for a variety of operating conditions across the entire compressor map at the inlet and exit of the volute. In addition, two new parameters were introduced, a fictive area ratio and uniformity index that could be used to quantify volute performance and also help match the volute to a given diffuser and impeller configuration.