Three-dimensional Flow Field Numerical Simulation And Analysis For High-power Hydrodynamic Torque Converter

Hydrodynamic planetary gear variable-speed transmission device has manyadvantages such as high transmission power, high efficiency, wide variable-speedrang compared with variable speed hydrodynamic couplings, etc. Large amounts ofenergy can be saved if using this device as the transmission device of larg eequipment needing to be adjusted flow such as high-power centrifugal pumps, fans,etc. Therefore, it is widely used in power stations, petroleum and chemicalindustries. However, much of the technology relating to the device remains todevelop in our country, resulting in the situation that lots of companies in chinahave to import this kind of device. Adjustable guide vane hydrodynamic torqueconverter is the key hydrodynamic control component in hydrodynamic planetarygear variable-speed transmission device, the power of which in hydrodynamicplanetary gear variable-speed transmission device for high-power equipment isrelatively large, generally more than one thousand kilowatts. And this high-powerhydrodynamic torque converter is rarely applied in China. This paper uses LB46hydrodynamic torque converter once applied in dredger as the model and designsthe high-power hydrodynamic torque converter based on the principle of similardesign. Then the numerical simulation method is put into use to predict itsperformance and calculate the axial force of its impellers, making some correlationanalysis in the meantime. Some research and analysis on high-power hydrodynamictorque converter in the paper can provide relevant reference for the research anddevelopment of hydrodynamic planetary gear variable-speed transmission device, aswell as the design and development of high-power hydrodynamic torque convertersin future.This paper firstly introduces the basic equations of fluid mechanics applied inthe numerical simulation of flow field and discrete methods widely used innumerical calculation. What’s more, transport equations of several two-equationturbulence models currently widely used are given, and the application scope ofthese turbulence models is discussed. Then the paper outlines and sums up somenumerical methods for researching the flow field of hydrodynamic torque converterat home and abroad. Afterwards, taking LB46hydrodynamic torque converter for anexample, the process and methods of the flow field numerical simulation forcentrifugal turbine hydrodynamic torque converter are described in detail.In this paper, standard k-ε model and SST model are separately chosen tosimulate the flow field of LB46hydrodynamic torque converter. By comparing the numerical simulation of the two turbulence models, the turbulence model that isappropriate for numerical simulation of centrifugal turbine hydrodynamic torqueconverter flow field is determined. Meanwhile, the paper analyzed the source of theerror between characteristic curves of numerical simulation and the experimentalcharacteristic curves. The characteristic of the high-power hydrodynamic torqueconverter LB830is predicted and analyzed, with the same numerical simulationmethod with LB46and choosing SST model as the calculation model of the flowfield.The paper describes the traditional calculation method and numericalsimulation method for the axial force of hydrodynamic torque converterrespectively. In the meantime, taking high-power hydrodynamic torque converterLB830for an example, the axial force of pump wheel and turbine is calculated withthe above two methods, and analysis and comparison of two results are made. Itillustrates that the reason why there is a large error between the traditionalcalculation result and numerical simulation result is that the traditional calculationmethod can only calculate a part of the axial force of hydrodynamic torqueconverter and makes a lot of assumptions in the calculation process. By numericalsimulation of the impeller flow field inside and outside, the trend that the axial forceof pump wheel and turbine varied with the change of working condition is workedout, the main influence factor on which is analyzed. The axial force of pump wheeland turbine at different adjustable guide vane position is calculated, and then it isfound that the change of circulation flow had some effects on the axial force ofpump wheel and turbine in the same working conditions.