The Research On Resonance Failure Of Check Valve In Power System Under Ship Induced By Water Hammer Wave

It is well known that the water hammer can cause the failure of check valves and pipelines,but how the water hammer can cause the failure of valves and pipelines remains to be further studied.According to the traditional concept,the strength of valve and pipeline is greater than the maximum water hammer pressure to effectively avoid the occurrence of water hammer accidents,but engineering practice shows that the smaller water hammer pressure can also cause serious valve damage accidents.Aiming at this kind of problem,this paper puts forward the prediction of resonance failure of check valve under water hammer wave excitation,which is verified by experimental research and numerical simulation.On this basis,the numerical simulation of water hammer for a shipborne pump dynamic system is carried out.The main research work is as follows:(1)In this study,a small scale pipeline water hammer test bench was built,and the influence parameters of the water hammer process were analyzed.The results show that a series of water hammer waves with different phases are superimposed in the pipeline during the process of check valve closing,and the phase state of liquid is converted when the water hammer is negative,finally forming a complex but regular curve of water hammer waves.(2)On the basis of the experiment,Matlab/Simulink and Pipe Surge software were used to simulate the water hammer test bench.The results show that the water hammer curve simulated by Simulink is highly consistent with the experiment,the calculated maximum and minimum water hammer pressure and the error of the experimental data are respectively 18% and 5%,and the wave velocity error of the water hammer is 9%.The Pipe Surge has some errors in the curve line and the experimental curve,but the maximum and minimum simulated water hammer pressure errors are only 3.4% and 9.5%.(3)Modal analysis was carried out on the experimental model,and the modal frequencies under five sets of different constraint conditions were analyzed and compared.The results show that the constraint conditions have a certain influence on the piping modes.Under specific working conditions,the first-order natural frequency of the valve is 4.16 Hz,while the water hammer frequency is 4.149 Hz,which is only0.26% different in value.It is concluded that the water hammer wave and check valve will produce resonance phenomenon when the valve is closed in the pipe valve system,which is also confirmed by the experimental observation.(4)On the basis of previous research,Matlab/Simulink and Pipe Surge software were used to simulate and analyze the water hammer process that might occur in the operation of a typical shipborne pump dynamic double circuit system.Simulink simulates the water hammer pressure of a two-loop pump and valve system,it is found that the extreme value of water hammer pressure of the main valve and the bypass valve is basically the same under the two working conditions,but the water hammer pressure curves under the two working conditions are quite different.Pipe Surge simulates the two-loop pump and valve system,and it is found that the water hammer pressure values and pressure curves are quite different in both steady and transient states.