Study On Energy Loss And Efficiency Prediction Of Internal Flow Field In Hydrodynamic Torque Converter

Hydrodynamic torque converters have been used in vehicle transmission system widely due to its good characteristics,such as changing torque and revolving speed steplessly,vibration reduction,buffer and so on.The low efficiency is the main factor to limit its further application and development.So it is necessary to study the energy loss mechanism of internal flow field to improve its efficiency.In this paper,the energy loss mechanism in one type of comprehensive hydrodynamic torque converter is studied to analyze the reason for energy loss from microscopic view.First of all,the single flow channel of hydrodynamic torque converter is established,and then the flow field was also simulated and studied by the method of Computational Fluid Dynamics(CFD).Combined with the theory of Proper Orthogonal Decomposition(POD),the velocity vector field and pressure distribution of internal flow field were analyzed at different ratios from 0 to 0.8.So the feasibility and accuracy of the POD method which is used to reduce the internal flow field can be certified.What's more,where there is a higher energy percentage of the first mode,the stable vertex structures become clearer.Then,the comparative analysis of velocity vector field,pressure distribution field and vorticity distribution field was done around the speed ratio of 0.7.So the method to describe the flexible and turbulent flow field clearly in hydrodynamic torque converter was obtained.The main pattern of internal energy loss was also confirmed,which is that the main reason for internal energy loss is the stable vertex structures.On the foundation of that,combined the method of POD with interpolation method,the internal flow pattern and transmission efficiency can be predicted accurately by this agent model.Finally,the whole channel model with leakage areas was built to calculate and analyze the volume loss and internal flow pattern in leakage areas in hydrodynamic torque converter.From the analysis result,we can see that leakage areas have a great influence on the characteristics of hydrodynamic torque converter.After the leakage areas were considered,the torque ratio at the speed ratio of 0 reduced by 4.37%,and the maximum efficiency also decrease by 3.84%.But for torque coefficient of pump,it increase by 7.36% at the speed ratio of 0.On the foundation of that,the volume loss coefficient was gained to modify the loss calculation by the mathematics fitting method.The volume loss coefficient can be described as a linear equations system.