An automotive torque converter was tested in order to determine the effect of converter operating condition and turbine blade design on turbine blade strain in the region of the inlet core tab restraint. The converter was operated over a wide range of speed ratios (0 to 0.95) at constant input torque and a stall condition for two input torques. Foiltype strain gages in combination with wireless microwave telemetry were used to measure surface strain on the turbine blade. Strain measurements were made on two turbine blade designs.The steady component of strain over the range of speed ratios suggests the effect of both torque loading and centrifugal loading on the turbine blade tip. The unsteady strain was greatest at stall condition and diminished as speed ratio increased. Greater input torque at stall condition resulted in both greater steady strain and greater unsteady strain. The spectral distribution of strain over the range of tested speed ratios displayed an increase in low-frequency broadband fluctuations near stall condition. A blade-periodic event is observed which correlates to the pump-blade passingfrequency relative to the turbine rotating frame. Reducing the blade-tip surface area and increasing the inlet-tab root radius reduced the range of steady strain and magnitude of unsteady strain imposed near the inlet core tab restraint over the range of operating conditions.The automotive torque converter transfers rotational energy from an engine to a transmission through a viscous and incompressible working fluid. The three primary elements of a converter are the pump, turbine and stator. Each element is composed of a number of blades shaped such that they redirect the flow of oil passing though them, resulting in a change in angular momentum of the working fluid. While the converter is designed to perform optimally at a particular condition, it must function satisfactorily over a diverse range of conditions including idle, stall, near couple, and overspeed.Several previous studies have been conducted to better understand the nature of oil flow within the torque converter, with the primary concern being converter efficiency and performance. Dong et al. (1998) used a miniature high-frequency-response five-hole probe to find that the flow pattern at the pump exit is complex. The flow structure was described as having four main regions: the free-steam, the pump blade wake, the core-suction corner separation, and the intense mixing region. Additionally, a strong secondary flow was observed along with unsteadiness dominated by the pump blade passing frequency. Brun and Flack (1997a) used laser velocimetry to demonstrate a strong jet-wake region which propagates across the turbine inlet plane at the pump-turbine interaction frequency. Throughflow velocity unsteadiness and incidence angle unsteadiness, due to pumpturbine blade interaction, was found to be greater at a high speedratio (SR = 0.8) compared to near-stall (SR = 0.065). This is possible when the flow enters the turbine at approximately 45 • from the no...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.