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Research Papers: Flows in Complex Systems

Torque Converter Capacity Improvement Through Cavitation Control by Design

[+] Author and Article Information
Cheng Liu

Rotating Machinery and Controls Laboratory,
Mechanical and Aerospace Engineering Department,
University of Virginia,
122 Engineer's Way,
Charlottesville, VA 22904-4746
e-mail: cl3hx@virginia.edu

Wei Wei

National Key Laboratory for Vehicular Transmission,
School of Mechanical Engineering,
Beijing Institute of Technology,
Beijing 100081, China
e-mail: weiweibit@bit.edu.cn

Qingdong Yan

National Key Laboratory for Vehicular Transmission,
School of Mechanical Engineering,
Beijing Institute of Technology,
Beijing 100081, China
e-mail: yanqd@bit.edu.cn

Brian K. Weaver

Rotating Machinery and Controls Laboratory,
Mechanical and Aerospace Engineering Department,
University of Virginia,
122 Engineer's Way,
Charlottesville, VA 22904-4746
e-mail: bkw3q@virginia.edu

1The authors contributed equally to this work.

2Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received July 11, 2016; final manuscript received November 1, 2016; published online February 16, 2017. Assoc. Editor: Kwang-Yong Kim.

J. Fluids Eng 139(4), 041103 (Feb 16, 2017) (8 pages) Paper No: FE-16-1436; doi: 10.1115/1.4035299 History: Received July 11, 2016; Revised November 01, 2016

Heavy cavitation in torque converters can have a significant effect on hydrodynamic performance, particularly with regards to the torque capacity. The objective of this study is to therefore investigate the effects of pump and turbine blade geometries on cavitation in a torque converter and improve the torque capacity without increasing the torus dimension. A steady-state homogeneous computational fluid dynamics (CFD) model was developed and validated against test data at stall operating condition. A full flow passage with a fixed turbine-stator domain was used to improve the convergence and accuracy of the cavitation model. Cavitation analysis was carried out with various pump and turbine blade geometries. It was found that there is a threshold point for pump blade exit angle in terms of its effect on torque capacity due to heavy cavitation. Further increasing the pump blade exit angle past this point will worsen cavitation condition and decrease torque capacity. The study also shows that a higher turbine blade exit angle, i.e., lower stator incidence angle, could reduce flow separation at the stator suction surface and consequently abate cavitation. A base high-capacity torque converter was upgraded utilizing the cavitation model, and the resulting design exhibited a 20.7% improvement in capacity constant without sacrificing other performance metrics.

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References

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Figures

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Fig. 1

Torque converter blade angle system

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Fig. 2

Torque converter entrance bias

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Fig. 3

Three-domain torque converter CFD model without cavitation

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Fig. 5

Comparison of three-domain CFD results without cavitation and test performance characteristics for the base torque converter design under various operating conditions

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Fig. 6

Various blade geometries considered in the analysis

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Fig. 7

Turbine flow passage area ratio distribution

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Fig. 8

Absolute pressure distribution on the midspan stator blade with different pump blades

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Fig. 9

Flow rate and capacity constant as a function of pump exit angle with base turbine and base stator

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Fig. 10

Flow velocity distributions under various turbine blade exit angles

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Fig. 11

Velocity distribution at the turbine outlet

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Fig. 12

Isosurface of 10% vapor fraction in the stator under various turbine exit angles: (a) base model (incidence angle = 42 deg) and (b) T1 model (incidence angle = 32 deg)

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