Integration bionic design of cavitation flow control for a hydrodynamic torque converter: CFD simulation and multiobjective optimization strategy

The pursuit of high-power density has emerged as a prominent objective in the design of turbine machinery. Investigating the unsteady cavitation characteristics due to the complex rotor–stator interaction resulting from the high rotating speed within the working chamber is challenging but often overlooked. This study aims to provide numerical approaches for evaluating cavitating performance and exploring potential suppression methods. Therefore, a full wheel transient cavitation model is established to accurately capture the dynamic evolution law of the vortex morphology inside the torque converter by integrating experimental data on hydraulic performance under different operating conditions. The findings indicate that the development of cavitation is observed to primarily align with variations in the incident angle. Under the stall condition, the stator blade experiencing the greatest incident angle and flow rate is affected by the oil, leading to the worst-case scenario for cavitation. However, when operating under high-speed ratio settings, the discrepancy in rotating speed between the pump and the turbine is diminished, resulting in an increase in pressure throughout the fluid channel without the occurrence of cavitation. This ensures the maintenance of maximum efficiency. By employing the Latin hypercube experimental design method in conjunction with the multiobjective optimization algorithm, the study investigates the effects of bionic tubercles on both hydrodynamic characteristics and cavitation performance. It is confirmed that the amplitude has a more significant control influence on cavitation control. The optimized model has the capability to mitigate the formation of cavitation, inhibit the occurrence of separation vortex, and minimize flow losses.