Journal of Jilin University(Engineering and Technology Edition) ›› 2023, Vol. 53 ›› Issue (8): 2236-2244.doi: 10.13229/j.cnki.jdxbgxb.20211113

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Numerical simulation of cavitation in torque converter and analysis of its influence on performance

Bo-sen CHAI1,2,3(),Guang-yi WANG1,Dong YAN2,Guo-ren ZHU1(),Jin ZHANG1,Heng-sheng LYU1   

  1. 1.School of Mechanical and Aerospace Engineering,Jilin University,Changchun 130022,China
    2.State Key Laboratory of Automobile Simulation and Control,Jilin University,Changchun 130022,China
    3.Sinotest Equipment Co. ,Ltd. ,Changchun 130103,China
  • Received:2021-10-28 Online:2023-08-01 Published:2023-08-21
  • Contact: Guo-ren ZHU E-mail:chaibs2012@jlu.edu.cn;zhugr@jlu.edu.cn

Abstract:

The flow field in torque converter is numerically simulated based on computational fluid dynamics, and the external characteristic curves are drawn from the two perspectives of whether cavitation is considered or not. The accuracy of simulation results is verified by experiment. In order to deeply analyze the cavitation of torque converter for the influence law of internal and external characteristic, Q criterion of vortex identification method is used to extract the internal three-dimensional vortex structure characteristic. The dynamic evolution law of cavitation characteristic on each blade surface under low-speed ratio conditions is analyzed and clarified, and the cavitation phenomenon on stator blade is mainly studied, and the influence mechanism of cavitation phenomenon on spatiotemporal structure distribution of flow field and energy loss is analyzed and revealed. The results show that: ① The numerical simulation considering cavitation is in good agreement with the experimental results, and the prediction error of external characteristics is less than 3%; ② There is a large error between the torque coefficient of the pump and the test data in the numerical simulation results without considering cavitation, and the error is more than 20% on the braking condition, simulation results are seriously distorted; ③ When pump speed is 2000 r/min, the condition of 0.4 speed ratio is the critical point of cavitation disappearance, with the reduction of the speed ratio, cavitation phenomenon and its influence become more obvious. The research results can provide theoretical guidance for high precision numerical simulation of torque converter.

Key words: mechanical engineering, torque converter, cavitation, computational fluid dynamics, three-dimensional vortex, external characteristic test

CLC Number: 

  • TH137.332

Fig.1

Calculation model"

Fig.2

Grid model of torque converter"

Table 1

Siulation setting"

参数无空化瞬态模型空化稳态模型空化瞬态模型
仿真类型瞬态计算稳态计算瞬态计算
液体密度/(kg·m-3860860860
液体黏度/(Pa·s)0.02580.02580.0258
气体密度/(kg·m-32.12.1
气体黏度/(Pa·s)1.2×10-51.2×10-5
饱和蒸汽压/Pa110110
湍流模型SBESSBESSBES
收敛条件1×10-51×10-41×10-4
交界面模型瞬态转静子法冻结转子法瞬态转静子法
时间步长1×10-31×10-3
步数5001000500
壁面边界无滑移光滑壁面无滑移光滑壁面无滑移光滑壁面

Fig.3

External characteristic test bench of torque converter"

Table 2

External characteristics test data"

转速比i变矩比K效率η泵轮转矩系数λP (10-6 min2·r-2·m-1
0.01.820.005.67
0.11.730.175.83
0.21.630.336.00
0.31.540.456.08
0.41.430.576.16
0.51.330.676.32
0.61.230.736.16
0.71.120.795.43
0.81.030.834.54

Fig.4

Comparison of hydraulic characteristics with or without cavitation model"

Fig.5

Three dimensional vortex structure with or without cavitation model"

Fig.6

Stator vortex structure with or without cavitation model"

Fig.7

10% bubble volume distribution equipotential surface under braking condition"

Fig.8

Cavitation evolution process with speed ratio"

Fig.9

Velocity distribution under different conditions"

Fig.10

Pressure distribution under different conditions"

Fig.11

Bubble distribution under different conditions"

Fig.12

Turbulent kinetic energy distribution under different conditions"

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