Loading Characteristics Of Internal And Partially Confined Explosions

Currently anti-ship missiles can penetrate the side shells of surface combatant ships and explode inside the compartment,which may cause serious damage to ship structures and equipments.In order to reduce the damage caused by the explosion,it is usually to set up vented holes on the bulkhead to guide the energy of the explosion shock wave to other places.Therefore,it is of importance to research the loading characteristics of internal explosions and partial confined explosions.In this thesis,the theoretical analysis,numerical simulation and experiment methods are adopted to investigate the loading characteristics of the internal explosions and partially confined explosions.The detailed research contents are as follows:(1)The empirical formulas of the peak overpressure of explosive shock wave in free air are analyzed and compared.The FCT solver and the Grodnov solver in Autodyn code are employed to calculate the pressure of shock wave in free air,respectively.The results obtained by the numerical simulation are compared with those obtained by the empirical formulas.It is found that the results obtained by the FCT solver are more accurate.The effects of mesh size on the results of numerical simulation are discussed.It is shown that the smaller the mesh size is,the larger the results of the numerical simulation are.However,the mesh size that yields the results with the highest accuracy is not a constant for the different scaled distances.(2)The experiment studies on explosions inside a two-space model are performed.The effect of charge on the pressure of the detonation space is studied.The explosions inside a two-space model are numerically simulated using the code Autodyn.The comparison between the experimental results and the numerical simulation results validates the effectiveness of the numerical simulation method.It is found that the shape of charge has little influence on the quasi-static pressure by comparing the numerical simulation results obtained by cylindrical charge and spherical charge.(3)The loading characteristics of the detonation space and the venting space are studied by the numerical simulation method.The effect of charge on the pressure of the different spaces is researched.The internal explosions are numerically simulated for the different space models.The effect of vented hole on the pressure of the detonation space and the venting space is discussed.It is found that the vented hole is an effective way to reduce the load inside the detonation space.(4)Through the comparison of the pressure-time curves obtained by the equivalent high pressure gas model,the venting explosion model,and the experiment,it is found that the equivalent high pressure gas model can calculate the quasi-static pressure of the venting explosion.Based on the equivalent high pressure gas model and the available simplified algorithm in literature three improved analytical methods is proposed to determine the quasi-static pressure of the single space during the venting explosion.The influences of the volume of the space,the charge and the area of the vented hole on the pressure in the space are studied,and the validity of the improved analytical method is verified.(5)Based on the venting explosion model and equivalent high pressure gas model the loading characteristics in the two spaces during the venting explosion are investigated by the numerical simulation method.On the basis of above,a simplified analytical method is established in order to calculate the quasi-static pressure of the two spaces during the venting explosion.The quasi-static pressures of the two spaces are calculated by the simplified analytical method and the numerical simulation method.The effectiveness of the simplified analytical method is demonstrated.