Study On Vibration And Flow Pressure Drop Characteristics Of Liquid Hydrogen Transport Pipeline

Liquid hydrogen is the fuel that is launched by aviation rockets,but it is usually transported to the refueling equipment rocket through low-temperature transmission pipelines.In the process of transmission,the vibration of the piping system and the pressure fluctuation of the liquid hydrogen flow will have a serious impact on the conveying process,which is not conducive to the success of the filling process.In view of this situation,the aim is to study the relationship between the flow state in the liquid hydrogen pipe and the vibration of the conveying pipe,thereby improving the stability of the conveying system.By analyzing the mathematical model of boiling flow in the liquid hydrogen pipe and the vibration equation of pipe,a three-dimensional model of the liquid hydrogen transfer pipe was established by using liquid hydrogen as the cryogenic medium.The numerical simulation of the fluid-structure interaction vibration characteristics and boiling pressure drop characteristics of liquid hydrogen transport pipeline was performed.The modal analysis and harmonic response analysis were used to calculate the variation of natural frequency of liquid hydrogen transport pipeline under the influence of different factors.According to the vibration equation of pipeline compiled by UDF,the pressure drop of different boundary conditions(inlet velocity,wall temperature),pipeline vibration conditions(vibration frequency,vibration amplitude)and pipe diameters was simulated,and the frequency spectrum analysis method was used to calculate the frequency and amplitude of pressure drop fluctuations.The results show that the established numerical model is verified on the basis of the existing related experimental data and the calculated correlation,and the relative error is within 10%.When the external vibration source is not considered,the length of the pipe obtained has the greatest influence on the natural frequency of the pipe.When the pipe length increases to twice the original,the natural frequency of the pipe is reduced to 0.36 times the original value.Harmonic response analysis shows that the first three-stage frequency of the pipeline(200Hz~350Hz)has a great influence on the vibration intensity of the pipeline.The displacement response of the pipeline in the x and y directions is 12-13 times larger than that of the z-direction displacement response.Considering the external vibration source,the frequency and amplitude of the liquid hydrogen pressure drop fluctuations with the boundary conditions,the vibration conditions of the pipeline,and the diameter of the pipe are obtained.When the velocity changes from 2m/s to 4m/s,the pressure drop fluctuates,which is about 3 times to the original;when the pipe diameter is changed from 0.1m to 0.2m,the pressure drop fluctuation ranges from-1000~2400Pa to-600~1200Pa..Through the numerical calculation and analysis of the fluid-solid interaction vibration characteristics and flow pressure drop characteristics of the liquid hydrogen transmission pipeline,it is shown that controlling the flow velocity in the liquid hydrogen tube and properly increasing the wall thickness and diameter of the delivery pipeline can reduce the degree of fluctuation of the flow pressure drop in application,thereby the stability of the delivery system is improved effectively,and the possibility of system resonance is reduced.