Development and validation of a CFD based optimization procedure for the design of torque converter cascade

Traditional one-dimensional (1D) design theory no longer satisfies modern torque converter design requirements due to the lack of accuracy and long trial-and-error process. A computational fluid dynamics (CFD) based optimization approach was brought forward. This study is devoted to two key processes in bringing CFD into torque converter design–blade parameterization/evaluation and optimization. A six-parameter blade camber line design method was employed to represent the blade shape. The blade profile was evaluated based on manufacturability considerations. A low-fidelity CFD model was developed for parameter study and optimization, and a high-fidelity CFD model considering the transient and cavitation effects was employed to evaluate the optimization outcome. The parameter sensitivity study was performed using design of experiment (DOE) technique and the variables were categorized into primary design variable, effective design variable and insignificant design variable groups. Optimization on the primary variables was carried out using the genetic algorithm. Two optimum solutions were evaluated with the transient full 3D CFD model and then tested. The optimum torque converters’ test results indicated significant performance improvement. The proposed design procedure can improve the design efficiency & accuracy and shorten the design cycle by the application of different CFD models in conjunction with an optimization algorithm.