Design And Research Of Double Medium Hydrodynamic Force Check Valve

With the development of deep mining in China,underground drainage technology of coal mine is becoming increasingly mature.Check valve has become an indispensable equipment in coal mine drainage system.Check valve can prevent the backflow of mine water caused by the emergency matters such as the sudden loss of power damage to the water pump and the lines near water hammer,and ensure the personal safety of the operators.The general check valve closed quickly,the equipment such as pump can be damaged by the water hammer caused by the large pressure fluctuation;and micro-resistance slow closing check valves due to the slow speed can lose efficacy caused by impurity of the mine water accumulate in the damping device.In this paper,the working principle and problems of the micro-resistance slow closing check valve in the market are analyzed and studied.According to the actual operating conditions,the design objective new type of check valve was proposed.Through lot of design schemes,the design scheme of double medium fluid power check valve was determined.Finally,the improved design structure is put forward.The check valve can be slowly closed to avoid water hammer,when the pump fluid backflow caused by power suddenly stop.The key mechanism--buffer device of check valve was carried out dynamic simulation by using dynamic mesh technology.According to the characteristic of the valve core has different equivalent aperture in two stages of the movement,and obtaining the relationship between the dynamic resistance and velocity under the two equivalent apertures using curve fitting of discrete data,which provide the basis for studying the performance of buffer device.The results show that the dynamic resistance is proportional to the square of velocity.Damping hole makes the valve core under a great resistance in movement.And the buffer device has a good buffer effect.Performing steady state numerical simulation of flow field in check valve using FLUENT software,respectively analyzing the flow field distribution of normal operation of centrifugal pump fluid forward flow to check valve and sudden power reverse flow the check valve these two conditions and calculating the the characteristics of fluid power and resistance of check valve.Through the internal flow field and hydrodynamic condition,the opening point of the two stages of the spool can be determined.Simulation results show that when the opening ratio is less than 40%,the change of the flow field is complex and the hydrodynamic force is large.The opening can be regarded as the dividing point of the two stages.When spool less than the range of the opening,it needs slow motion.And the smaller of the opening cause the larger of flow resistance coefficient and the smaller of the flow coefficient.Performing the fluid-structure interaction numerical simulation of liquid force,the position and value of stress and strain of the valve plug can be got.According to the simulation results,the purpose of improving the deformation resistance of the valve core can be achieved.The simulation results show that the maximum total deformation of the spool occurs on the valve clack and excessive deformation will affect the seal of check valve.Biggish equivalent stress occurs in valve stem,valve body and the contact site of valve stem and valve body.Excessive equivalent stress will damage and squash the component.The structure of the valve clack is changed into the upper and lower surfaces,and not only improves the deformation resistance of the valve core,but also makes the flow field more stable for arc surface.A check valve simulate rig is designed and stimulating large lift,large inertia effect of mine drainage system by utilizing the combined action of gear pump and displacement pump.The system can be used to simulate the working performance of the check valve under two conditions that are the flow field distribution of check valve' s normal operation of centrifugal pump fluid forward flow to check valve and sudden power reverse flow the check valve.And multiway valve can be used to quickly switch the two conditions.The test environment is more in line with the actual situation of mine drainage and is of great help for the study of check valve performance.Testing the check valve under free mode through LMS Test Lab,so as to obtain the structural frequency distribution,through the test can provides a range for determining the disturbance frequency of the check valve.