| With the rapid development of coal industry and fully mechanized mining technology,coal mining efficiency has been rapidly improved.So there are higher requirements for the performance of mine transport equipment.As an important transmission equipment,valve-controlled liquid-filled c coupling is widely used in the soft start of heavy scraper conveyor.In this thesis,a high power valvecontrolled hydraulic coupling is the research subject,the change rule of the circulation characteristics and the torque transfer characteristics of the flow field in the impeller under various working conditions,the cavitation characteristics under the condition of full liquid filling and the strength of the impeller under the limit torque are analyzed and studied.The aim is to provide a reliable method for predicting the characteristics of turbine-machinery,improve the controllability of the soft start of the hydraulic coupling,and improve the theory of optimization of the cascade system.In impeller full liquid transmission phase,the ratio of the flow field characteristic analysis was completed.Analysis model of flow field characteristics based on high precision hexahedron structured grid was built.Based on the numerical results of the flow field,the distribution law of internal and external flow field characteristics under the condition of full liquid filling is analyzed.Thus,the distribution law of velocity and pressure in the flow field with different speed ratio is obtained.In the coupling valve control filling phase,hydraulic coupling part liquid circulation characteristics calculation model was established.Different two-phase flow prediction precision of the model was compared.The circulation characteristics of the internal flow field at 0 to 0.99 velocity ratios at 0 to 90% filling rates and corresponding different filling rates was numerically analyzed.Prediction results of flow field circulation characteristics in multiple working conditions were analyzed.Thus,the flow characteristics and torque transfer characteristics of the effluent at different charging rates were obtained,and the turbulence characteristics of the baffle were further analyzed.Aiming at the influence of cavitation phenomenon on the flow field characteristics under full liquid filling condition,a flow field cavitation calculation model based on Rayleigh-Plesset model and homogenization model was built.The steady state cavitation and transient cavitation processes of different velocity ratio flow fields are obtained,the distribution characteristics and evolution laws of cavitation are analyzed,and the influence laws of cavitation on torque transfer characteristics are further compared and analyzed.The influence law of cavitation on the characteristics of the flow field is obtained.The results showed that the cavitation model can improve the accuracy of torque prediction by about 13%.According to the analysis of impeller strength,the strength analysis model was established by FSI unidirectional fluid-solid coupling analysis technology,based on the calculation results of pressure distribution under the condition of full liquid filling.The stress and strain distribution characteristics of single blade under the condition of ultimate torque were obtained.The results showed that the stress of the impeller is concentrated near the outside of the circular circle,and the strain is concentrated near the center of the circular circle.After calculation and checking,it is found that the impeller strength meets the use requirements.The external characteristic test bed of the hydraulic coupling was built.The torque transfer characteristic data of the coupling under full charge condition were measured.The experimental data were compared with the numerical results,and showed that the numerical analysis of the flow field with cavitation could predict the working characteristics of the hydraulic coupling well,and the prediction error of the torque transfer characteristic was less than 6%.This thesis provides a high precision prediction method for the working principle and torque characteristics of the hydraulic coupling based on CFD technology,which provides a reliable theoretical basis for the design of the cascade structure and the design of the liquid-filled speed regulation strategy of the hydraulic coupling. |
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