CFD Calculation And Investigation On Axial Force In A Torque Converter

Hydraulic torque converter one of the important hydraulic components of the hydraulic transmission which uses liquid as the working medium can transfer powers. Torque converter has many excellent driving characteristics such as high power / mass ratio, overload protection, automatic adaptability, etc. This is not an alternative to other traditional transmission components. But a hydraulic torque converter in the work cannot be avoided to produce a large axial force which will affect the working performance, reliability and sustainability of a hydraulic torque converter. At present, the research of hydraulic torque converter in China is mainly concentrated in radial turbine torque converter which is widely used in engineering machinery and automotive automatic transmission. In recent years, however, the research on the centrifugal turbine torque converter which has been applied to the start and operation of the diesel engine is very little. In foreign countries, the gas turbine starting and turning gear, high speed and high power variable speed planetary gear with the superposition of the planetary gear system, large wind power system adapt to the wind wheel speed change to achieve constant generator input speed and other industrial applications and adjustable centrifugal turbine hydraulic torque converter as the core element occupies an important position. This paper takes the EL9 adjustable guide vane centrifugal turbine hydrodynamic torque converter as the research object and calculates the axial force of the torque converter through numerical simulation of three dimensional flow field in the working chamber of the converter and the gap between work wheel and body. It provides an important basis for the overall design of the transmission system.In this paper, the general method of calculating the axial force of the torque converter is introduced which involves some basic theories, including basic hypothesis, control equation, turbulence model and numerical calculation method.The whole process of numerical simulation of the flow field in the adjustable hydraulic torque converter with the purpose of calculating the axial force is introduced. And during the process describes how to change the actual structure of the converter is simplified in order to achieve in the calculation results under the premise of the minimum possible large decrease in grid division and solution calculation workload in the process. This paper analysis of the flow field calculation results of the EL9 adjustable guide vane centrifugal turbine hydrodynamic torque converter, finds out the physical cause of this phenomenon through the analysis of the flow phenomena. It provides effective help for the further analysis of various factors affecting the axial force of the hydr aulic torque converter and the method of balancing axial force.According to the numerical calculation results of the three-dimensional flow field of the adjustable hydraulic torque converter, the axial force of the fluid in the different basin of the EL9 model is calculated. In each component of the axial force of the torque converter, the axial force generated by the working fluid in the gap is the largest in the total axial force and its value is often greater than the axial force of the working wheel. The axial force of the turbine is always pushes the turbine away from the pump wheel, and decreases gradually with the increase of the turbine speed. In the braking mode(i=0), the axial force of the pump wheel pushes the pump wheel away from the turbine, and gradually reduced with the increase of the speed ratio. The axial force of the pump wheel changed its direction at high rotation speed ratio. The pressure in the two sides of the turbine disk can be effectively balanced by the method of opening the unlo ading hole. The axial force of the turbine is greatly reduced, but the axial force of the pump is increased. The maximum axial force of the turbine is reduced by 10242 N, and the maximum axial force of the pump wheel is increased by 4912 N. The method of opening unloading hole can achieve the purpose of reducing the axial force.