Development of a High Performance Centrifugal Compressor Using a 3D Inverse Design Technique

Diesel engines developed to meet future US and European emissions regulations place an unprecedented demand on compressor performance in terms of pressure ratio and flow range capability. Additionally the direct impact compressor efficiency has on engine fuel consumption means that the new generation of centrifugal compressors designed for Turbochargers will have to meet very demanding efficiency targets. Cummins Turbo Technologies have been exploring the application of inverse design techniques for improved compressor efficiency and pressure ratio. This paper describes the application of 3D inverse design method TURBOdesign-1 to a centrifugal compressor wheel. The baseline compressor is a production impeller with straight filament blades. In this paper the main features of the inverse design method and its design parameters are described. The impeller computed by the inverse design method has 3D geometry and has a pitchwise splitter location that is automatically optimized across the span. The structural and vibration characteristic of the new impeller are computed and compared with the conventional impeller by using 3D Finite Element Analysis. The flow through the inverse designed and conventional impellers are analysed by using a 3D CFD code both for impeller only and whole stage configurations. Furthermore comparison of the measured performance map of the inverse designed and conventional stages are presented. The results confirm that the inverse designed impeller results in improved stage efficiency of up to 3 points and improvements in pressure ratio of up to 4.5% while maintaining or slightly improving the compressor’s stable operating range.

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