| Aim at the problem of big recoil and poor firing dispersion of weight-reducing grenade machine gun system(GMGS)mounted on light tripod when launching high muzzle velocity of projectiles,three low recoil technologies and firing dispersion are as research subjects.The key issues,such as the low recoil launch mechanism,dynamic characteristics of automation and the influence factors of recoil peak and firing dispersion are in-depth studied and explored based on multibody dynamics theory,gas dynamics theory and ballistics of gun.The main contents are as follows:(1)A low recoil technology of gas operated-floating barrel operated is proposed,based on external ballistic equations and gas dynamics of automatic weapons,gas dynamics equations that the heat dissipation and floating of barrel are both taken into consideration are derived in external ballistic period and after-effect period.Through the multibody dynamics theory,considering the elastoplastic of soil,the flexibility of barrel and three tripod,bullet-pull force,the multi-body model of GMGS is built.Based on the initial disturbances of muzzle obtained with the multi-body model,combined with the mathematical model of exterior ballistics,simulation analysis on the firing dispersion is carded out.(2)The dynamic characteristics of automation,change rules of recoil peak and vibration characteristics of muzzle are analyzed.The influences of firing boundary condition,structural parameters of barrel-recoil floating automation,structural parameters of gun,structural parameters of gas operated on dynamic characteristics of automation,change rules of recoil and firing dispersion are studied.The range of parameters adjustment is given to launch with low recoil and improve firing dispersion(3)Aim at the problem of the speedy attenuation of muzzle velocity and low reducing recoil efficiency,a low recoil scheme of reducing recoil by laval nozzle with double chamber is proposed.Based on external ballistic theory and supersonic aerodynamics theory,one dimensional unsteady jet gas mathematical model is established for solving coupling 4 calculation areas including after-chamber,anterior chamber,laval nozzle chamber and gas operated.(4)Change of gas pressure of 4 gas chambers is analyzed,the distribution of gas parameter in nozzle with time and position are selective discussed,reducing recoil mechanism of laval nozzle with double chamber is revealed.The influences of the position of laval nozzle with single chamber and structural parameters of laval nozzle with double chamber on the reducing recoil efficiency and the muzzle velocity are also studied.The launch dynamics model of GMGS using laval nozzle with double chamber is established,the influences of structural parameters on reverse thrust,dynamic characteristics of automation,change rules of recoil peak and firing dispersion are discussed.(5)Through balancing the advantages of against two low recoil technologies of gas operated-floating barrel operated and reducing recoil by laval nozzle with double chamber the disadvantages,both low recoil technologies are applied in GMGS.The launch dynamics model of GMGS using two low recoil technologies is built.The influences of key structural parameters of automation on dynamic characteristics of automation,change rules of recoil peak and firing dispersion are analyzed by simulation,the allowable ranges for structural parameters of automation are given to achieve launching high muzzle velocity of projectiles with low recoil.(6)Based on the study in this paper,the general testing scheme of GMGS is proposed,which includes the principle design and the layout design.The launching performances of GMGS including the muzzle velocity of projectiles,motion characteristics of automation,recoil,bore pressure,gas pressure of after-chamber and laval nozzle chamber and projectile dispersion are tested.The correctness of simulation results is verified by experiment,it also confirmes the validity of the interior ballistic model,firing dispersion model,mathematical model of laval nozzle with double chamber and the rigid-flexible coupling launch dynamics model of GMGS.By the above studies,a set of modeling theories and research mothod as technological support for development of new GMGS which has performance of high muzzle velocity,high firing accuracy,low recoil and light-weight are formed eventually. |
PDF Full Text Request