Flow Field in the Turbine Rotor Passage in an Automotive Torque Converter Based on the High Frequency Response Rotating Five-hole Probe Measurement Part II: Flow Field at the Off-design Condition and Effects of Speed Ratio

The flow field at the design condition was presented and interpreted in Part I. The flow field at one off-design condition (Speed Ratio 0.065) is presented and interpreted in this part. In addition, the hydraulic performance is analyzed by using flow measurement results both upstream and downstream of the turbine and inside the turbine rotor passage. It is found that at the off-design conditions, especially the near stall condition (Speed Ratio 0.065), most of the pressure drop occurs in the first half of turbine passage. About 82% of the total torque is extracted between the turbine inlet and the middle plane. In addition, the shell develops torque at nearly five times the rate of core. Furthermore, the higher the speed ratio, the higher the total pressure drop. Loss is maximum at the near stall condition and varies almost linearly with the speed ratios. A compromise has to be made between the design and the off-design performance in order to improve the overall performance and fuel economy of torque converters.