Investigation of churning torque for hydraulic torque converter based on CFD

The CFD (Computational Fluid Dynamics) method is used to calculate the external churning torque of the hydraulic torque converter, and an experiment system is developed to validate. The influence of oil level and viscosity and rotation speed is analysed. The boundary layer thickness is calculated. A method of adding fairing to reduce churning torque is proposed. The results show that the churning torque increases with increasing rotation speed, oil level and viscosity. For three sets of curves, the errors are respectively 5.83%, 10.99% and 11.8%. Oil level affects the churning more than oil viscosity and rotation speed. Its increment dimensionless number is 1.17. Adding fairing reduces the churning torque by up to 80.45%. The streamlines become more orderly and regular, and wall shear reduces much. There is a large resistance torque of the pump when it starts. And the resistance torque decreases with the reduction of oil.