| The obturator ring is an important part of the wedge-breechblock of large caliber gun,which is closely related to the reliability,safety,service life and serviceability of gun.The working environment of the obturator ring is very complex.On the one hand,the obturator ring will be deformed under the pressure load of gunpowder gas.On the other hand,the deformation also will affect the contact and fit between the obturator ring of the wedge-breechblock,the obturator ring of the barrel,and bore.The leakage of gunpowder gas will occur for the bad status of the contact and fit,which will affect the law of gunpowder gas pressure.Therefore,there is interaction between the gas flow and the deformation of the obturator ring.However,the existing design method generally splits the solid domain structure analysis and the hydrodynamics calculation for the obturator ring,which is difficult to characterize the actual physical process.Therefore it is urgent to carry out the research of the fluid-solid coupling numerical simulation.Based on this background,this paper attempts to study the fluid structure coupling analysis method of the performance of the obturator ring for the large caliber gun.(1)The force environment,structure composition and working principle of wedge-breechblock and obturation structure were analyzed.And the structural characteristics and obturation principle of three types of obturator were introduced,including the single cone structure in barrel bore,the double cones structure,the mixed structure for obturation along radial direction of in-bore and the end surface of outside bore.According to the requirements of the obturator of a large caliber gun,the type of obturation will be determined,and based on such structure the comprehensive analysis will be conducted.In view of the requirements of the obturator,the necessity of the fluid structure coupling analysis method for the obturation performance of the obturator ring was investigated.The basic principle of fluid structure coupling analysis and the contact mechanics algorithm in structure domain were introduced,and the sub program of structure coupling interface contact in analysis of obturation ring was developed.(2)The nonlinear finite element method was used to calculate the solid domain of the obturator ring,and the Lattice Boltzmann method has been used to calculate the coupling calculation method of gunpowder gas fluid domain.The finite elements meshing model of obturator was established,including the grid model of partial chamber,obturator ring and wedge-breechblock,as well as the regional modeling and design encryption criteria of propellant gas.The contact surface between gas domain and the solid domain of obturator ring was defined,as well as initial load of the physical field.The file subroutine was used for the data exchange and load transfer of the contact surface to cause the deformation or sliding of the fluid structure domain contact surface.At the same time,displacement,pressure,speed and other physical data by two-way exchange can be realized.Based on the analysis of the calculation results,the results of the stiffness and strength characteristics,the pressure distribution,the vector velocity distribution and the leakage of propellant gas were obtained,and then the comprehensive analysis of the obturation performance was carried out.(3)Taking the results of fluid structure coupling calculation as the initial boundary condition and pressure load,the structural optimization design of the obturator ring was carried out by combining the finite element method with approximate model and genetic algorithm.By constructing the optimization objective function and using the genetic algorithm to solve the problem,the Pareto optimal solution set of the obturation performance was examined for the obturator ring,and the optimized obturation structure was retrieved,which will provide theoretical guide for effectively reducing the leakage of gunpowder gas and improving the service life of the obturator ring. |
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