| The liquid suspension passive shutdown technology mainly uses the fluid flow power inside the system to ensure that the mobile body is suspended in the normal working position.When an unprotected transient loss-of-flow accident occurs in the system,the jacking force received by the moving body from the fluid gradually decreases.When the gravity of the moving body is greater than the hydraulic thrust,it automatically starts and falls to a rigid position to complete the shutdown operation.Therefore,the liquid suspension type passive shutdown component needs to meet: under normal working conditions,the mobile body should be suspended in the working position,and the unreliable transient flow loss accident takes a short time for the mobile body to fall,the fall is stable,and the buffer throttle The buffer effect is good.In this paper,the numerical simulation is used to analyze the falling characteristics of the moving body of the liquid suspension passive shutdown module and the suspension state of the abnormal station.The specific research content and research results mainly include:1.Design the test piece by analyzing the structure and working principle of the liquid suspension passive shutdown component,and use the test piece for physical test and numerical simulation.The critical flow required by the mobile body in the suspended state of the normal working position and the moving elements of the mobile body falling process are compared with the numerical simulation calculation results to verify the rationality of the calculation grid size used in the numerical simulation and the selection of related parameters.2.Through the numerical simulation of the unprotected transient loss-of-flow drop process of the mobile body in the upper working position and the 70 mm coaxial non-rotating working condition,the time-consuming,falling displacement,velocity,Time-dependent changes in the force of the moving body and the total pressure drop of the system.The results show that the bottoming speed of the moving body is high and the final force is small,it can be seen that the buffering effect of the buffer throttle is obviously insufficient.3.In view of the unsatisfactory buffering effect of the buffer throttle in the liquid suspension passive shutdown assembly,it is proposed to increase the length of the buffer throttle and increase the gap size between the buffer throttle and the moving body from 5mm by gradual change.The optimization and improvement program as small as 2mm and verify its buffer and throttling effect.The results show that the critical flow of the optimized scheme is reduced by 1.65% compared with the original scheme,the total time for the moving body to fall is increased by 1.8%,and finally the force of the moving body is increased by 123%,and the bottoming speed of the moving body is reduced by 35%.It can be seen that the optimization effect of the buffer and throttling parts of the optimization scheme is significantly improved compared with the original scheme.4.Through the study of the constant flow field in the working condition of the liquid suspended passive shutdown component,the moving body is in the suspended state and is located in the "abnormal working position",the detailed flow field information and movement within the different working conditions are obtained.The state of body stress,the flow distribution of the inner flow channel and the critical flow of the corresponding working conditions.The numerical simulation results are used to analyze the influence of the moving body in different positions,different misalignment sizes and different rotation angles on the force state of the moving body,the flow distribution of the internal flow channel of the model,and the critical flow in the corresponding working conditions. |
PDF Full Text Request