Torque converter is an enclosed hydrodynamic turbomachine, used in vehicles for smooth transmission of power and speed change from the engine to the transmission and torque multiplication. Torque converter consists of three major components: a pump that is connected to the engine shaft, a turbine connected to the transmission shaft, and a stator connected to transmission housing through a one-way clutch. Stator blades provide a guiding for the fluid flow. Stator is a main factor in controlling the torque ratio, pressure distribution and coupling point speed ratio. In this paper, the effects of the stator blade shape on overall performance have been investigated numerically at different speed ratios, using commercial software, ANSYS-CFX. Two torque converters with two different stator blade shapes are used for this study. The first stator has a large round nose, while the second stator is a thinner blade stator. At high speed ratio there is more blockage to flow of large inlet radius stator. Results showed that torque converter with thin blade resulted in an increase of torque ratio at fixed turbine and maximum efficiency. The bending of the thin blade caused a blockage to fluid flow.

Number of blades of torque converter elements plays an important role in the design and performance of torque converters. In this paper, effects of the number of pump and turbine blades on the performance of torque converters are investigated numerically at different speed ratios, using a commercial software, ANSYS-CFX. Two torque converters, with the same outer diameter of 245 mm, were studied. Number of blades of the first torque converter is (32, 36 and 17) and for the second torque converter is (41, 37 and 17) for the pump, turbine and stator respectively. Blade shape and angles for the torque converter elements are the same. Numerical simulation results were compared and verified with the available literature and experimental results. A satisfactory agreement is presented between numerical and experimental results. Results showed that increasing the number of the blades of both of the pump and the turbine caused an increase of both of pump and turbine torque while the stall torque ratio is decreased and the coupling point occurred at lower speed ratio. Also, increasing the number of blades caused the maximum efficiency to be decreased. This may be explained by the change of slip factor of different number of blades as well as the effect of friction on shock losses. The study showed that there is an optimum number of blades required to improve the performance of torque converter.