Analysis of energy loss mechanism at the speed ratio of design operating condition in hydrodynamic torque converters

Low transmission efficiency of hydrodynamic torque converters limits their wider application, so it is necessary to observe the microstructures of internal flow in depth and to analyze the mechanism of energy loss for reducing the energy loss in flow field. Computational Fluid Dynamics (CFD) is a common way to model and simulate the flow field and Proper Orthogonal Decomposition (POD) is also a good method to do some simplified calculation. Combined CFD and POD, internal flow field in a hydrodynamic torque converter was analyzed to study the relationships among energy percentage of the first mode, vortex structure and the mechanism of energy loss on design operating condition (speed ratio of 0.7). Compared with the energy percentage amount of the first mode, the phenomenon was found that the vortex structure of the internal flow field became clearer with larger percentage amount. Therefore, the existence of regular vortex structure is the major reason for energy loss inside hydrodynamic torque converters. The position of vortex core went hand in hand with internal structures not only with the existence of low pressure area, but also the different locations with various features, which should be adopted to improve the performance in hydrodynamic torque converters.