Multi-Point Optimization of a Centrifugal Compressor Stage

Abstract

Turbocharger has a paramount influence on the performance of an internal combustion. Improved emission requirements have led to complex after treatment systems, which add pressure drop to the air management system. One of the ways to mitigate negative effects of pressure drop is to improve turbocharger efficiency. The scope of performance improvement for a typical turbocharger majorly lies on the modification of compressor wheel, turbine wheel, volutes etc. The major challenges in compressor wheel modification include setting the right major geometrical dimensions, considering compressor operability at different application requirements, design cycle time and the cost of computation. Present study is about evolving an effective optimization methodology, which comprises of parametrization of compressor stage at preliminary design stage and optimization of the chosen parameters through coupling one dimensional flow analysis tool with a robust optimization tool. The parameters were chosen based on their influence on overall efficiency and pressure ratio at different mass flows and varying engine rotational speeds. Surrogate models have been used to choose the optimal designs from the preliminary design space as per requirement and optimized designs were analyzed further for verification. Final validation has been carried out using a 3D RANS code.