Study On The Factors For The Efficiency Of Adjustable Hydraulic Torque Converter At Low Speed Ratio Condition

With the development of China's economy and society,the demand for energy keep increasing.As a large energy importer,the energy conservation is related with national strategic issue and sustainable development.Rotating machinery such as pumps,fans and compressors consume more than 800 billion KW of electricity,which accounting for more than 40% electricity generation in China.Variable speed regulation is an effective measure for such equipment to save energy.Hydrodynamic planetary gear variable-speed system is very suitable for high-power pump to save energy,there is few research on its core element guide vane adjustable hydraulic torque converter in China,which restricted the development of this excellent high-power variable-speed equipment.This paper based on EL9 hydraulic torque converter research the factors affecting low speed efficiency,combined with one beam theory and CFD,designed the method for low speed efficiency optimization,and illustrates the inner mechanism of the efficiency change.Including:(1)Based on one beam theory,building the mathematical model of the adjustable hydraulic torque converter.Add the vortex loss to fix the deviation caused by turbine blade curvature increasing during the optimization process in the model.With the model being the core of calculation,use AMGA to optimize the low speed efficiency.After optimization,the low speed efficiency and pump impeller torque coefficient are improved.(2)Based on the result of one beam theory optimization,building a three-dimensional model of the torque converter.The numerical simulation results show that the efficiency improve when speed ratio is lower than 0.7.The average efficiency increased by 3.53% in the area that speed ratio between 0.1 ~ 0.5.The maximum increasing is 4.36% which appears at 0.2 speed ratio.The pump impeller torque coefficient are small rise in all conditions.The results of total pressure loss and entropy generation rate analysis of flow field show that the main reason for the low speed efficiency rise lies in the energy loss in turbine and adjustable guide vane decrease.(3)As the inlet shape of the pump blade can not be considered by the one beam theory,the numerical simulation is carried out for the columnar pump blade and the equal velocity inlet pump blade.Base on the result analysis the internal mechanism how blade inlet shape influencing the torque converter efficiency.After change pump blade into columnar blade and equal velocity inlet blade,the energy loss increase at impeller inlet area and decrease at impeller outlet area.The equal velocity inlet blade performs better overall.