Numerical Simulation And Experimental Research On Explosion Process Of Pressure Vessel Based On FLUENTD

Natural gas,as a clean energy source,it continues to take up the bigger proportion of my country’s energy structure.Natural gas has the characteristics of high heating value and low pollution,but if the Natural gas storage not well,it can bring great potential dangers to human society.Once the combustible gas is exploding in the sealed container,the explosion shock wave and the fragment will cause huge economic losses and casualties;therefore,it is very necessary to research the explosion process of combustible gas in the closed container and explore the effect of the flow field parameters on the explosion in the process of a combustible gas explosion.Not only the experimental results can provide a real data source for designing the safety pressure vessel,but also improve the safety margin for pressure container.At the same time,it also further provide a real theoretical basis for making the effective measures of flammable gas explosion suppression and explosion protection.However,due to the limitations of experimental sites,experimental funds,and experimental safety,it is difficult to develop the theories of the process of the combustible gas bursting in sealed container.Nowadays with the development of computer hardware,computing performance and computational fluid dynamics,which make the numerical simulation becoming the main method for exploring the law of combustible gas explosion in closed containers.Based on a 20L combustible gas explosion testing device,this paper studied the explosion pressure of methane-air premixed gas and the explosion rise rate under the different concentration of methane in a closed container,and finds the best mixing ratio of methane and air.Using the Fluent software to explore the best mixing ratio when the explosion characteristic curve get max values.Using the experimental data to verify the accuracy of the simulations results which was obtained under the same conditions.And explore the Spatial distribution characteristics of various flow field parameters（explosion pressure,detonation temperature,turbulent kinetic energy,velocity,density,the component concentration of reactants and products）.find the relationship between of the radius of the gas cloud,reaction time and pressure during the process of the methane explosion.The specific conclusions are stated as follows:1.The experimental results show that when the ratio of concentration of methane and air is equal to 10%,the explosion pressure reaches the peak value P_max=653100Pa,the explosion pressure rise rate reaches the peak value（dp/dt）_max=20.5208Mpa/s,and the characteristic time t=0.24s when the explosion pressure get the peak value.In this paper,the explosion characteristic value K_G=55 is obtained by calculation,and it satisfies the"cubic law"of a spherical sealed container;2.Numerical simulation results show that when V_CH4/V_air+CH4=10%,the peak explosion pressure is 779000Pa,the characteristic time for the peak explosion pressure t=0.25s.the error of the peak explosion pressure is less than 18%,and the peak explosion pressure of the simulation curve appears The characteristic time is very close to the experimental value;3.From the results of numerical simulation,it can be seen that in the initial stage of the explosion,due to the ignition of the central pulse,the methane-air premixed air mass in the center of the reactor is quickly consumed,resulting in a sudden decrease in the density at the center.At the same time,with the rapid occurrence of chemical reactions,the flame on The front surface begins to diffuse from the center to the spherical wall.The precursor shock wave at the front of the flame front continuously compresses the premixed gas in the unburned area,resulting in a continuous increase in density.At the same time,due to the impact and disturbing effect of the precursor shock wave on the premixed gas in the reactor,the inside of the reactor is caused When t<0.01s,the turbulent kinetic energy gradually increases and t=0.01s reaches the peak K_max=2.25m²/s²,and then the turbulent kinetic energy gradually weakens;as the flame front continues to move to the spherical wall,there is continuous heat from The burned area is injected into the unburned area,causing the methane-air premix in the reaction field to burn rapidly;when t=0.20s,the flame front velocity reaches the maximum value U_max=0.40m/s.When t=0.25s,the methane in the reactor is completely burned at this time,causing the temperature to reach the peak value T_max=2500k and the density to reach the peak value ρ_max=5.0kg/m³.