Research On Coupling Flow Field Characteristics Of Multi-flow Domains In A Torque Limited Hydraulic Coupling

The hydrodynamic coupling has excellent functions such as light-load starting,preventing overload,reducing vibration and shock during starting,and multi-machine driving,and its structure is simple,reliable,and no special maintenance is required.Therefore,it is widely used in mechanical equipment with large inertia,difficult to start,and overload protection.With the gradual development of industrial machinery and equipment in the direction of high power,large inertia,and high speed,the performance requirements for torque limited hydrodynamic couplings are gradually increasing,and the research and development of torque limited hydrodynamic couplings in my country is mainly improvements are made on the basis of imported products from abroad,and there is less accumulation of the internal flow mechanism of the hydrodynamic coupling.This thesis mainly takes the YOX500 type dynamic pressure relief torque limited hydrodynamic coupling with a circulation circle diameter of 500mm as the research object.The dynamic pressure relief torque limited hydrodynamic coupling has been studied comprehensively from the aspects of numerical simulation method,internal flow mechanism,torque characteristic prediction,bench experiments and so on.The main research work and conclusions are as follows:1.Numerical simulation of flow field in working cavity of torque limited hydrodynamic couplingThe dynamic pressure relief type torque limited hydrodynamic coupling is simplified,the complicated structure of the rear auxiliary cavity is removed,and the high-quality hexahedral mesh is used to divide it.VOF model and Mixture model are used to simulate it respectively,and its gas-liquid two-phase distribution,pressure distribution,and velocity distribution are obtained.By monitoring the torque of the pump wheel,the characteristic curve of the pump wheel torque is obtained.The results show that the VOF model can better reflect the gas-liquid two-phase distribution inside the coupling,and the torque characteristic curve reflects the torque drop caused by the transition of the circulation pattern.The Mixture model can better reflect the changes in the internal circulation of the coupling.These provide the basis for subsequent full-flow simulation calculations.2.Numerical simulation of coupled flow field in multi-flow domains of torque limited hydrodynamic couplingThe flow channel of the YOX500 type torque limited hydrodynamic coupling is a multiflow domain flow channel composed of a working cavity,a front auxiliary cavity,and a rear auxiliary cavity.The working cavity,the front auxiliary cavity and the rear auxiliary cavity are connected by a flow hole.Due to the complexity of the structure,a tetrahedral mesh with better adaptability is used to mesh it.The VOF model is used to track the gas-liquid two-phase interface,and analyze the gas-liquid two-phase distribution under different filling rates and different working conditions in the hydrodynamic coupling.Comparing the liquid phase distribution of the suction surface and pressure surface of the impeller blade with the experimental data of the liquid phase distribution of the same cavity type hydrodynamic coupling,the liquid phase distribution trend is basically consistent with the experiment,which proves the effectiveness of the method and applicability.The Mixture model is used to obtain the velocity distribution and pressure distribution inside the entire flow channel,and further reveal the complex coupling flow mechanism inside the torque limited hydrodynamic coupling.3.Experimental research on the external characteristics of torque limited hydrodynamic couplingThe torque limited hydrodynamic coupling was tested on the pump wheel torque experiment on the hydrodynamic coupling test bench.The torque values of different working conditions(i=0-0.97)under three typical filling rates(q=50%,q=62.5%,q=80%)are measured.The measured values are fitted to form the external characteristic curve of the torque limited hydrodynamic coupling,and compared with the simulation results of the VOF model and the Mixture model to prove the applicability and feasibility of the two simulation methods.