Characterizing the Effect of Automotive Torque Converter Design Parameters on the Onset of Cavitation at Stall

Robinette, Darrell; Anderson, C. L.; Blough, Jason R.; Johnson, M. A.; Maddock, D. G.; Schweitzer, Jean

doi:10.4271/2007-01-2231

Cited by 13 publications

(19 citation statements)

References 16 publications

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“…It is clear from Fig.7 that diameter and average pressure significantly influence the onset of cavitation. The stator torque threshold at cavitation was found to be 95 to 118 Nm greater than the smaller diameter with 95% confidence, as reported by [10]. These observations lead to the development of a dimensionless quantity by [11] incorporating stator torque at the onset of cavitation, Ts,i, diameter, D and average pressure, pave as given by Eq.…”

Section: Non-dimensionalizing Onset Of Cavitationmentioning

confidence: 68%

“…The pressures imposed upon the torque converter are included in the list of variables for the dimensional analysis. As found by [10], increasing charging pressure can alter the stator torque cavitation threshold at stall by as much as 150 Nm for a particular design. Secondary variables that affect the cavitation threshold are those describing the thermal conditions of the toroidal flow, namely cooling flow rate, Q, and the automatic transmission fluid properties of density, ρ, viscosity, μ, specific heat, Cp, and thermal conductivity, k. Rather than using charge and back pressures, average pressure, pave, and pressure drop, Δp, will be used as they implicitly comprehend the cooling flow rate through the toroidal flow.…”

Section: Pi Group Formulationmentioning

confidence: 97%

“…Element blade design manifests itself as the integrated quantities of K-factor and TR. Both of these quantities correlate to cavitation behaviour at stall, see [10], and their simplicity is favored over a lengthy list of individual blade design parameters. The number of stator blades as well as their shape can strongly influence performance and therefore the onset of cavitation.…”

Section: Pi Group Formulationmentioning

confidence: 99%

“…This value was found to give an accuracy of +/-40 rpm with 95% confidence across the broad range of converter designs and operating points tested. The details regarding the experimental setup, post processing and identifying the exact pump speed at onset of cavitation can be found in [10]. …”

Section: Acoustical Detection Of Incipient Of Cavitationmentioning

confidence: 99%

“…The number of stator blades as well as their shape can strongly influence performance and therefore the onset of cavitation. The airfoil shape of the stator blade is described by the ratio of blade maximum thickness, tmax, and chord length, lc, and has been shown to have a statistically significant effect on the stator torque cavitation threshold, see [10]. The pressures imposed upon the torque converter are included in the list of variables for the dimensional analysis.…”

Section: Pi Group Formulationmentioning

confidence: 99%

See 4 more Smart Citations

Development of a Dimensionless Model for Predicting the Onset of Cavitation in Torque Converters

Robinette¹,

Anderson²,

Blough³

2012

New Advances in Vehicular Technology and Automotive Engineering

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Section: Non-dimensionalizing Onset Of Cavitationmentioning

confidence: 68%

Section: Pi Group Formulationmentioning

confidence: 97%

Section: Pi Group Formulationmentioning

confidence: 99%

Section: Acoustical Detection Of Incipient Of Cavitationmentioning

confidence: 99%

Section: Pi Group Formulationmentioning

confidence: 99%

See 3 more Smart Citations

Development of a Dimensionless Model for Predicting the Onset of Cavitation in Torque Converters

Robinette¹,

Anderson²,

Blough³

2012

New Advances in Vehicular Technology and Automotive Engineering

Self Cite

View full text Add to dashboard Cite

Torque Converter Capacity Improvement Through Cavitation Control by Design

Liu

Wei

Yan

et al. 2017

Journal of Fluids Engineering

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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.

show abstract

Influence of Stator Blade Geometry on Torque Converter Cavitation

Liu

Wei

Yan

et al. 2017

Journal of Fluids Engineering

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Cavitation in torque converters may cause degradation in hydrodynamic performance, severe noise, or even blade damage. Researches have highlighted that the stator is most susceptible to the occurrence of cavitation due to the combination of high flow velocities and high incidence angles. The objective of this study is to therefore investigate the effects of cavitation on hydrodynamic performance as well as the influence of stator blade geometry on cavitation. A steady-state homogeneous computational fluid dynamics (CFD) model was developed and validated against test data. It was found that cavitation brought severe capacity constant degradation under low-speed ratio (SR) operating conditions and vanished in high-speed ratio operating conditions. A design of experiments (DOE) study was performed to investigate the influence of stator design variables on cavitation over various operating conditions, and it was found that stator blade geometry had a significant effect on cavitation behavior. The results show that stator blade count and leaning angle are important variables in terms of capacity constant loss, torque ratio (TR) variance, and duration of cavitation. Large leaning angles are recommended due to their ability to increase the cavitation number in torque converters over a wide range of SRs, leading to less stall capacity loss as well as a shorter duration of cavitation. A reduced stator blade count is also suggested due to a reduced TR loss and capacity loss at stall.

show abstract

Characterizing the Effect of Automotive Torque Converter Design Parameters on the Onset of Cavitation at Stall

Cited by 13 publications

References 16 publications

Development of a Dimensionless Model for Predicting the Onset of Cavitation in Torque Converters

Development of a Dimensionless Model for Predicting the Onset of Cavitation in Torque Converters

Torque Converter Capacity Improvement Through Cavitation Control by Design

Influence of Stator Blade Geometry on Torque Converter Cavitation

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