Automated aerodynamic optimization of a return channel vane of a multistage radial compressor

This paper presents the design process of a new return channel system for a single shaft centrifugal compressors comprising multiple stages. The first part of the paper gives an overview on aerodynamic features of common return channel systems used in process industry relevant radial turbomachinery. The problem of vortex free outlet flow downstream the return channel is discussed in detail. The main part focuses on the design process and development of a new return channel system and presents the methodology of optimization. The optimization procedure includes the geometry generation of the return channel vanes, meshing, CFD-calculations (Computational Fluid Dynamics) and automated evaluation. A genetic algorithm is used to control the optimization process and to generate progress. The optimization goals are both the enhancement of design point efficiency and minimization of the deviation of averaged outflow angle. In order to preserve the compressor operating range, two additional operating points (towards choke line and surge line) are considered for optimization. Calculation results of optimization show that the new return channel vane provides a higher stage efficiency and a reduced outlet flow angle distortion.