Numerical investigations on the launch process of a gun-launched missile from the muz- zle of a cannon to the free-flight stage have been performed in this paper. The dynamic overlapped grids approach are applied to d...Numerical investigations on the launch process of a gun-launched missile from the muz- zle of a cannon to the free-flight stage have been performed in this paper. The dynamic overlapped grids approach are applied to dealing with the problems of a moving gun-launched missile. The high-resolution upwind scheme （AUSMPW ＋） and the detailed reaction kinetics model are adopted to solve the chemical non-equilibrium Euler equations for dynamic grids. The development process and flow field structure of muzzle flows including a gun-launched missile are discussed in detail. This present numerical study confirms that complicated transient phenomena exist in the shortly launching stages when the gun-launched missile moves from the muzzle of a cannon to the free- flight stage. The propellant gas flows, the initial environmental ambient air flows and the moving missile mutually couple and interact. A complete structure of flow field is formed at the launching stages, including the blast wave, base shock, reflected shock, incident shock, shear layer, primary vortex ring and triple point.展开更多
The simulation of the artillery interior and intermediate ballistics problem is performed to investigate the influence of a gas dynamics device,muzzle brake,on the muzzle hazard phenomena,such as flash and blast waves...The simulation of the artillery interior and intermediate ballistics problem is performed to investigate the influence of a gas dynamics device,muzzle brake,on the muzzle hazard phenomena,such as flash and blast waves.The correlation of the chemical reactions with the characteristics of the muzzle flow field is analyzed by the simulation for a further understanding of the secondary combustion phenomenon of the muzzle flow.The novel structure of muzzle flow caused by the muzzle brake is presented by the simultaneous solution of the interior ballistics model and multi-species Navier-Stokes equations in order to analyze the influence of the muzzle brake structure on the chemical reactions.The secondary combustion of the muzzle flow due to the oxygen-supplement chemical reactions is obtained by the chemical reaction kinetic model.The interaction of the blast waves released from the muzzle brake is illustrated in detail and the mechanism of the formation of muzzle flash is analyzed.This research provides a reference for the studies on the suppression of the muzzle flash.展开更多
Artificial intelligence technology is introduced into the simulation of muzzle flow field to improve its simulation efficiency in this paper.A data-physical fusion driven framework is proposed.First,the known flow fie...Artificial intelligence technology is introduced into the simulation of muzzle flow field to improve its simulation efficiency in this paper.A data-physical fusion driven framework is proposed.First,the known flow field data is used to initialize the model parameters,so that the parameters to be trained are close to the optimal value.Then physical prior knowledge is introduced into the training process so that the prediction results not only meet the known flow field information but also meet the physical conservation laws.Through two examples,it is proved that the model under the fusion driven framework can solve the strongly nonlinear flow field problems,and has stronger generalization and expansion.The proposed model is used to solve a muzzle flow field,and the safety clearance behind the barrel side is divided.It is pointed out that the shape of the safety clearance under different launch speeds is roughly the same,and the pressure disturbance in the area within 9.2 m behind the muzzle section exceeds the safety threshold,which is a dangerous area.Comparison with the CFD results shows that the calculation efficiency of the proposed model is greatly improved under the condition of the same calculation accuracy.The proposed model can quickly and accurately simulate the muzzle flow field under various launch conditions.展开更多
A two?dimensional axisymmetric numerical simulation was successfully carried out on the muzzle flow field of a 300 mm?caliber counter?mass propelling gun. Based on the FLUENT software,using the finite volume method(FV...A two?dimensional axisymmetric numerical simulation was successfully carried out on the muzzle flow field of a 300 mm?caliber counter?mass propelling gun. Based on the FLUENT software,using the finite volume method(FVM)and the realizable k?ε turbulence model,we adopted the holistic movement of a partitioned mesh processing method coupled with the intermediate ballistic model and the six degree?of?freedom model(6?DOF). We compared the flow field characteristics at the velocity of 1 730.4,978.3,and 323.4 m/s. The results indicate that the pressure of the hypersonic initial flow field is much higher than that of the subsonic and supersonic initial flow fields. In the case of the subsonic(323.4 m/s)flow field,the tiny disturbance spreads throughout the whole domain. But in the cases of the supersonic(978.3 m/s) and the hypersonic(1 730.4 m/s) flow fields,it cannot spread to the upstream disturbance source,and the disturbance domain of the supersonic flow field is wider than that of the hypersonic. It is noted that the subsonic flow field has a rounded shock wave before the projectile. However,in the supersonic and hypersonic flow fields,a shear layer is formed which begins from the head of the projectile and extends outward from the side of the projectile. Then a multi?layer shock wave is formed composed of coronal shock waves,bottom shock waves,reflected shock waves,and Mach disk.展开更多
The integrative process of a quiescent projectile accelerated by high-pressure gas to shoot out at a supersonic speed and beyond the range of a precursor flow field was simulated numerically. The calculation was based...The integrative process of a quiescent projectile accelerated by high-pressure gas to shoot out at a supersonic speed and beyond the range of a precursor flow field was simulated numerically. The calculation was based on ALE equations and a second-order precision Roe method that adopted chimera grids and a dynamic mesh. From the predicted results, the coupling and interaction among the precursor flow field, propellant gas flow field and high-speed projectile were discussed in detail. The shock-vortex interaction, shockwave reflection, shock-projectile interaction with shock diffraction, and shock focus were clearly demonstrated to explain the effect on the acceleration of the projectile.展开更多
To improve the accuracy of numerical simulation of muzzle chemical flow field,and study the gunpowder combustion productions, the muzzle flow field is simulated coupled with the calculation of combustion productions i...To improve the accuracy of numerical simulation of muzzle chemical flow field,and study the gunpowder combustion productions, the muzzle flow field is simulated coupled with the calculation of combustion productions in bore. The calculation in bore uses the gibbs free-energy minimization method and the classical interior ballistics model. The simulation of the muzzle flow field employs the multi-component ALE( Arbitrary Lagrange-Euler) equations. Computations are performed for a 12. 7 mm gun. From 2. 48 ms to3. 14 ms,the projectile moves in the gun barrel. CO and H2 O masses decrease by 3. 37% and 6. 51%,and H2 and CO2masses increase by 11. 11% and 10. 58%. The changes conform to the fact that the water-gas equilibrium reaction of all reactions plays a dominant role in this phase. After the projectile leaves the barrel,the masses of H2 and CO decrease,and the masses of H2 O and CO2 increase. When it moves to 80 d away from the muzzle,the decreases are 12. 75% and 8. 05%,and the increases are 12. 76% and 36. 26%,which tallies with the existence of muzzle flame. Further,CO and H2 burn more and more fiercely with the muzzle pressure pg increasing,and burn more and more weakly with the altitude rising. When two projectiles launch in series,the combustion of the second projectile muzzle flow field is fiercer than the first projectile. Analysis results have shown that the proposed method is effective for simulating the muzzle flow filed.展开更多
A two-dimensional axisymmetric model, employing a dynamic mesh and user-defined functions, is used to numerically simulate the transient multiphase flow field produced by an underwater gun. Furthermore, a visualized s...A two-dimensional axisymmetric model, employing a dynamic mesh and user-defined functions, is used to numerically simulate the transient multiphase flow field produced by an underwater gun. Furthermore, a visualized shooting experiment platform with a high-speed camera is built to observe the evolution process of such a multiphase flow field. The simulated phase distribution diagram is agreed well with the shadow photo of the experiment, indicating that the numerical model is reasonable. Further examinations of the multiphase flow fields by using the submerged and sealed launch methods show that use of the sealed launch can significantly improve the interior ballistic performance of an underwater gun. In the cases by using these two types of underwater launch methods, the displacement of the projectile within the range of the muzzle flow field meets the exponential law over time. Moreover, a not fully developed bottle-shaped shock wave is formed when t = 0.4 ms, but this bottle-shaped shock wave expands more rapidly for the sealed launch. In addition, the amplitude of pressure oscillation for the sealed launch is larger than that of the submerged launch, but the pressure oscillation of the sealed launch lasts shorter.展开更多
A two-dimensional model,employing a dynamic mesh technology,is used to simulate numerically the transient multiphaseflowfield produced by two submerged parallel guns.After a grid refinement study ensuring grid inde-pende...A two-dimensional model,employing a dynamic mesh technology,is used to simulate numerically the transient multiphaseflowfield produced by two submerged parallel guns.After a grid refinement study ensuring grid inde-pendence,five different conditions are considered to assess the evolution of cavitation occurring in proximity to the gun muzzle.The simulation results show thatflow interference is enabled when the distance between the par-allel barrels is relatively small;accordingly,the generation and evolution of the vapor cavity becomes more com-plex.By means of the Q criterion for vorticity detection,it is shown that cavitation causes the generation of vorticity and the evolution of the vapor cavity can result in an asymmetric distribution of vorticity for a certain distance of the barrels.In particular,the evolution of the vapor cavity can hinder the expansion of the gas and force it toflow outward,while an asymmetric distribution of vorticity can lead to a gas jetflowing outward and rotating simultaneously.展开更多
基金financially supported by the National Natural Science Foundation of China (No. 11402119)the National Defence Pre-research Foundation of China (No. 404040302)
文摘Numerical investigations on the launch process of a gun-launched missile from the muz- zle of a cannon to the free-flight stage have been performed in this paper. The dynamic overlapped grids approach are applied to dealing with the problems of a moving gun-launched missile. The high-resolution upwind scheme （AUSMPW ＋） and the detailed reaction kinetics model are adopted to solve the chemical non-equilibrium Euler equations for dynamic grids. The development process and flow field structure of muzzle flows including a gun-launched missile are discussed in detail. This present numerical study confirms that complicated transient phenomena exist in the shortly launching stages when the gun-launched missile moves from the muzzle of a cannon to the free- flight stage. The propellant gas flows, the initial environmental ambient air flows and the moving missile mutually couple and interact. A complete structure of flow field is formed at the launching stages, including the blast wave, base shock, reflected shock, incident shock, shear layer, primary vortex ring and triple point.
文摘The simulation of the artillery interior and intermediate ballistics problem is performed to investigate the influence of a gas dynamics device,muzzle brake,on the muzzle hazard phenomena,such as flash and blast waves.The correlation of the chemical reactions with the characteristics of the muzzle flow field is analyzed by the simulation for a further understanding of the secondary combustion phenomenon of the muzzle flow.The novel structure of muzzle flow caused by the muzzle brake is presented by the simultaneous solution of the interior ballistics model and multi-species Navier-Stokes equations in order to analyze the influence of the muzzle brake structure on the chemical reactions.The secondary combustion of the muzzle flow due to the oxygen-supplement chemical reactions is obtained by the chemical reaction kinetic model.The interaction of the blast waves released from the muzzle brake is illustrated in detail and the mechanism of the formation of muzzle flash is analyzed.This research provides a reference for the studies on the suppression of the muzzle flash.
基金Supported by the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20210347)Supported by the National Natural Science Foundation of China(Grant No.U2141246).
文摘Artificial intelligence technology is introduced into the simulation of muzzle flow field to improve its simulation efficiency in this paper.A data-physical fusion driven framework is proposed.First,the known flow field data is used to initialize the model parameters,so that the parameters to be trained are close to the optimal value.Then physical prior knowledge is introduced into the training process so that the prediction results not only meet the known flow field information but also meet the physical conservation laws.Through two examples,it is proved that the model under the fusion driven framework can solve the strongly nonlinear flow field problems,and has stronger generalization and expansion.The proposed model is used to solve a muzzle flow field,and the safety clearance behind the barrel side is divided.It is pointed out that the shape of the safety clearance under different launch speeds is roughly the same,and the pressure disturbance in the area within 9.2 m behind the muzzle section exceeds the safety threshold,which is a dangerous area.Comparison with the CFD results shows that the calculation efficiency of the proposed model is greatly improved under the condition of the same calculation accuracy.The proposed model can quickly and accurately simulate the muzzle flow field under various launch conditions.
基金supported in part by the National Natural Science Foundation of China (No. 51305204)
文摘A two?dimensional axisymmetric numerical simulation was successfully carried out on the muzzle flow field of a 300 mm?caliber counter?mass propelling gun. Based on the FLUENT software,using the finite volume method(FVM)and the realizable k?ε turbulence model,we adopted the holistic movement of a partitioned mesh processing method coupled with the intermediate ballistic model and the six degree?of?freedom model(6?DOF). We compared the flow field characteristics at the velocity of 1 730.4,978.3,and 323.4 m/s. The results indicate that the pressure of the hypersonic initial flow field is much higher than that of the subsonic and supersonic initial flow fields. In the case of the subsonic(323.4 m/s)flow field,the tiny disturbance spreads throughout the whole domain. But in the cases of the supersonic(978.3 m/s) and the hypersonic(1 730.4 m/s) flow fields,it cannot spread to the upstream disturbance source,and the disturbance domain of the supersonic flow field is wider than that of the hypersonic. It is noted that the subsonic flow field has a rounded shock wave before the projectile. However,in the supersonic and hypersonic flow fields,a shear layer is formed which begins from the head of the projectile and extends outward from the side of the projectile. Then a multi?layer shock wave is formed composed of coronal shock waves,bottom shock waves,reflected shock waves,and Mach disk.
基金the National Key Laboratory of Transient Physics of China
文摘The integrative process of a quiescent projectile accelerated by high-pressure gas to shoot out at a supersonic speed and beyond the range of a precursor flow field was simulated numerically. The calculation was based on ALE equations and a second-order precision Roe method that adopted chimera grids and a dynamic mesh. From the predicted results, the coupling and interaction among the precursor flow field, propellant gas flow field and high-speed projectile were discussed in detail. The shock-vortex interaction, shockwave reflection, shock-projectile interaction with shock diffraction, and shock focus were clearly demonstrated to explain the effect on the acceleration of the projectile.
文摘To improve the accuracy of numerical simulation of muzzle chemical flow field,and study the gunpowder combustion productions, the muzzle flow field is simulated coupled with the calculation of combustion productions in bore. The calculation in bore uses the gibbs free-energy minimization method and the classical interior ballistics model. The simulation of the muzzle flow field employs the multi-component ALE( Arbitrary Lagrange-Euler) equations. Computations are performed for a 12. 7 mm gun. From 2. 48 ms to3. 14 ms,the projectile moves in the gun barrel. CO and H2 O masses decrease by 3. 37% and 6. 51%,and H2 and CO2masses increase by 11. 11% and 10. 58%. The changes conform to the fact that the water-gas equilibrium reaction of all reactions plays a dominant role in this phase. After the projectile leaves the barrel,the masses of H2 and CO decrease,and the masses of H2 O and CO2 increase. When it moves to 80 d away from the muzzle,the decreases are 12. 75% and 8. 05%,and the increases are 12. 76% and 36. 26%,which tallies with the existence of muzzle flame. Further,CO and H2 burn more and more fiercely with the muzzle pressure pg increasing,and burn more and more weakly with the altitude rising. When two projectiles launch in series,the combustion of the second projectile muzzle flow field is fiercer than the first projectile. Analysis results have shown that the proposed method is effective for simulating the muzzle flow filed.
基金This work was supported by the National Natural Science Foundation of China(No.11372139)the China Postdoctoral Science Foundation(2020M681596).
文摘A two-dimensional axisymmetric model, employing a dynamic mesh and user-defined functions, is used to numerically simulate the transient multiphase flow field produced by an underwater gun. Furthermore, a visualized shooting experiment platform with a high-speed camera is built to observe the evolution process of such a multiphase flow field. The simulated phase distribution diagram is agreed well with the shadow photo of the experiment, indicating that the numerical model is reasonable. Further examinations of the multiphase flow fields by using the submerged and sealed launch methods show that use of the sealed launch can significantly improve the interior ballistic performance of an underwater gun. In the cases by using these two types of underwater launch methods, the displacement of the projectile within the range of the muzzle flow field meets the exponential law over time. Moreover, a not fully developed bottle-shaped shock wave is formed when t = 0.4 ms, but this bottle-shaped shock wave expands more rapidly for the sealed launch. In addition, the amplitude of pressure oscillation for the sealed launch is larger than that of the submerged launch, but the pressure oscillation of the sealed launch lasts shorter.
基金This work is supported by the National Natural Science Foundation of China(Grant No.52201385)the Natural Science Foundation of Shanxi Province(Grant No.20210302123023)the Shanxi Scholarship Council of China(Grant No.2020-106).
文摘A two-dimensional model,employing a dynamic mesh technology,is used to simulate numerically the transient multiphaseflowfield produced by two submerged parallel guns.After a grid refinement study ensuring grid inde-pendence,five different conditions are considered to assess the evolution of cavitation occurring in proximity to the gun muzzle.The simulation results show thatflow interference is enabled when the distance between the par-allel barrels is relatively small;accordingly,the generation and evolution of the vapor cavity becomes more com-plex.By means of the Q criterion for vorticity detection,it is shown that cavitation causes the generation of vorticity and the evolution of the vapor cavity can result in an asymmetric distribution of vorticity for a certain distance of the barrels.In particular,the evolution of the vapor cavity can hinder the expansion of the gas and force it toflow outward,while an asymmetric distribution of vorticity can lead to a gas jetflowing outward and rotating simultaneously.
