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

Abstract

The unsteady velocity field found in the turbine of an automotive torque converter was measured using laser velocimetry. Velocities in the inlet, quarter, mid, and exit planes of the turbine 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 velocity data, visualizing the transient interaction effects between the turbine, pump, and stator was possible. Results showed strong cyclic velocity fluctuations in the turbine inlet plane as a function of the relative turbine-pump position. These fluctuations are due to the passing of upstream pump blades by the slower rotating turbine blades. Typical fluctuations in the through flow velocity were 3.6 m/s. Quarter and mid plane velocity fluctuations were seen to be lower; typical values were 1.5 m/s and 0.8 m/s, respectively. The flow field in the turbine exit plane was seen to be relatively steady with negligible fluctuations of less than 0.03 m/s. From the velocity data, the fluctuations of turbine performance parameters such as flow inlet angles, root-mean-square unsteadiness, and output torque per blade passage were calculated. Incidence angles were seen to vary by 3° and 6° for the 0.800 and 0.065 speed ratios, respectively, while the exit angles remained steady. The turbine output torque per blade passage fluctuated by 0.05 Nm for the 0.800 speed ratio and 0.13 Nm for the 0.065 speed ratio.

Numerical investigations of the flow induced oscillation of a torque converter

“…It was observed that the turbine inlet flow is significantly periodic and the pump exit flow shows independence of the turbine blades passing, similar to the results obtained by Browarzik (1994). Brun and Flack (1997) measured the unsteady velocity field in the turbine through laser velocimetry at two typical speed ratios: 0.065 and 0.800. In their research, the speed ratio had a significant impact on the pressure pulsation in the stator.…”

Internal Flow Structure of Torque Converter Analyzed with Dynamic Mode Decomposition under Steady Driving Condition

“…An experimental study using laser Doppler velocimetry showed that the flow field changes at the relative position of the cascades with respect to each other. (6) Another case study reported that the phase-averaged velocity maps according to the relative angles of the dynamic to the static cascades were reconstructed to visualize characteristics of this unsteady flow field. (7) There has also been a report on the effect of the stator on the frequency characteristics by applying a wavelet transform to the flow field around the stator.…”

Effects of blade lean angle on a hydraulic retarder

“…Because fluid transport in the blade passage is highly three-dimensional and unsteadily turbulent, with large regions of separated flows and intense secondary flows, 2,3 it is quite difficult to design the optimal geometrical dimensions of the rotating components. For many years, steady-state one-dimensional performance models have been employed to analyze fluid couplings and torque converters.…”