Research on effect of working oil temperature for hydraulic torque converter performance using CFD and test

Using computational fluid dynamics (CFD) and test methods, the influence of the working oil temperature on the original characteristic parameters of torque converter (torque ratio k, capacity coefficient λ, and efficiency η), pump torque T_p and turbine torque T_t. Since working oil temperature mainly influences the density and viscosity of the oil, using CFD simulation analysis methods, investigate the influence of the single variable of density or viscosity on the performance of torque converter. The results show that the working oil temperature influence on torque converter performance is the result of oil density and viscosity changing, and viscosity influence plays a leading role; As working oil density decreasing, λ, k and η are not affected, T_p and T_t are decreasing. As working oil viscosity decreasing, T_p, T_t, λ, k and η are all increasing; As temperature increasing, viscosity and density of working oil are all decreasing, T_p and λ are decreasing, T_t is barely changed, but k and η are increasing. Therefore, under the requirement of the sealing and working oil life time, torque converter working temperature should increasing as high as possible to improve its performance.