Research On Improving The Performance Of Dual-Turbine Hydrodynamic Torque Converter Under Low Speed Ratio Condition

The engineering machinery needs to have a large driving force and working efficiency under the condition of low speed and heavy load,this performance has important influence on the mobility and economy,therefore,the research has important theoretical guiding significance and practical value.In the hydrodynamic drive device,the two-turbine hydraulic torque converter is characterized by high starting torque coefficient,wide range of adjustment and wide range of high efficiency,therefore,it has good development prospect and high research value.Based on one dimensional beam theory and computational fluid dynamics(CFD),a YJSW315 dual turbine torque converter is taken as the research object,In order to improve the performance of the torque converter with low speed ratio(i=0~0.376),the number of blades and the blade angle of the torque converter is optimized.Finally,an optimized scheme for improving the working condition of low speed ratio is obtained.The relevant conclusions are as follows:(1)A series of studies are conducted on the inlet and outer packing angle of two stage turbine and guide vane.The general influence rule of the inner and outer ring on the performance of the torque converter is obtained: When the angle of the inner ring is constant,the decrease of the angle of the outer ring improved the efficiency of the low speed ratio,so that the middle and high speed is lower than the working condition;When the angle of the outer ring is fixed,the increases or decreases of angle can decrease the efficiency of the low speed ratio and increases the efficiency of the medium and high speed.(2)The optimization of the first stage turbine is studied.Finally,the scheme of optimizing the number of first turbine blades to 36 blades is determined,and the blade is rotating 5°in the direction of reducing the positive impact angle of the liquid flow.Now,the angle of the blade inlet is 64.5°,the outlet angle is 25.9°,the blade inlet flow angle is 3.7°,and the outlet liquid flow angle is 2.4°.(3)The optimization of inlet angle and inlet and outlet angle of two stage turbine blades is studied.The secondary stage turbine turned to 5°in the direction of decreasing the positive impact angle of the liquid flow,the angle of the outer ring inlet angle of the blade is reduced 12°,the angle of the inner ring is reduced 5°.Now,the angle of the blade inlet is 136.4°,the outlet angle is 39°,the outer ring and inner circle angle are 78°.The start moment ratio of the secondary stage turbine is from 3.91 to 4.23 after two optimization schemes,the optimal efficiency is increased from 82.7% to 86.5%,and the efficiency of the low speed ratio is obviously improved.(4)The number of guide vane and the angle of inlet and outer ring were optimized,the number of blades is 24,the angle of the inner ring of the blade inlet was reduced 0°,the angle of the outer ring of the blade inlet was reduced 3°.Now,the angle of the outer ring angle is 89°,and the angle of the inner ring angle is invariable.After optimization,the torque ratio of torque converter is increased from 4.23 to 4.36,and the efficiency of low speed ratio is increased by 0.6%~3.3%.The optimal working condition and the middle and high speed are lower than that of the secondary turbine,but the decrease range is smaller,and the optimization goal is satisfied in the whole.