Laser Velocimeter Measurements in the Pump of an Automotive Torque Converter: Part II — Unsteady Measurements

Abstract

The unsteady velocity field found in the pump of an automotive torque converter was measured using laser velocimetry. Velocities in the inlet, mid-, and exit planes of the pump were investigated at two significantly different operating conditions: turbine/pump rotational speed ratios of 0.065, and 0.800. A data organization method was developed to visualize the three dimensional, periodic unsteady velocity field in the rotating frame. For this method, the acquired data is assumed to be periodic at synchronous and blade interaction frequencies. Two shaft encoders were employed to obtain the instantaneous angular position of the torque converter pump and turbine at the instant of laser velocimeter data acquisition. By proper “registration” of the data visualizing the transient interaction effects between the stator and the pump, and the pump and the turbine was possible. Results showed strong cyclic velocity fluctuations in the pump inlet plane as a function of the relative stator-pump position. Typical percent periodic fluctuations in the through flow velocity were 70% of the average through flow velocity. The upstream propagation influence of the turbine on the pump exit plane flow field was seen to he smaller. Percent periodic fluctuations of the through flow velocity were typically 30%. The effect of the stator and turbine on the mid-plane flow field was seen to be negligible. The incidence angle at the pump inlet fluctuated by 27° and 14° for the 0.065 and 0.800 speed ratios, respectively. Typical slip factors at the exit were 0.965 and fluctuated by less than 1%.