Structural Design And Numerical Simulation Of The Super Caliber Extinguishing Ammunition

In order to solve the problems such as forests,ports,warehouses,high-rise buildings and other places can not be fast,safe and efficient fire extinguishing.Aiming at the present situation that the new type of Mortar Extinguishing Ammunition developed by our school has less fire extinguishing agent charge and structural failure,the fire extinguishing effect is not good,the center of mass and ballistic instability.This thesis combined the"military and civilian general fire extinguishing products mobilization center"intelligent Mortar Extinguishing Ammunition project,Based on the study of the factors affecting the fire extinguishing effect of the Extinguishing Ammunition,the influence of the structure of the fire extinguishing charge on the throwing distance of the fire extinguishing agent and the stability of the projectile centroid for the flight stability of the projectile,a Super Caliber(120mm)Mortar Extinguishing Ammunition projectile based on the 60mm caliber mortar platform was designed(The following is referred to as Mortar Extinguishing Ammunition).CoMPared with the 60mm caliber mortar,the charge quality of the Super Caliber(120mm)Mortar Extinguishing Ammunition was increased,and the fire extinguishing effect was stronger.CoMPared with ordinary 120mm caliber bombs,The Super Caliber Extinguishing Ammunition was lighter in weight,more convenient to carry,and had quicker response and maneuverability due to the smaller diameter of the emitting part.The total length of the Super Caliber Mortar Extinguishing Ammunition is 738cm.The shape of the Super Caliber Mortar Extinguishing Ammunition warhead was based on the characteristics of the long-elastic,and the launching part draws on the stability device of the conventional60mm mortar,the cylindrical part and air-closing devices was added.The specific research content can be studied as the following aspects:(1)ABS plastic was selected as the shell of the warhead.Warhead has a diameter of120mm,a length of 200mm and a wall thickness of 3mm.The central burst tube was set inside.The center burst tube has a diameter of 20mm and a length of 180mm.The internal charge is TNT/RDX casting explosive(TNT/RDX=50/50).The charge density is 1.66g/cm~3and the charge quantity is 52.12g.The central burst shell was made of kraft paper with a thickness of 0.08mm.ABC dry powder fire extinguishing agent was selected as fire extinguishing agent,and pressing method is adopted for charging,the density is 1.80g/cm~3,and the loading amount is 3.67kg,which is 1.71kg more than bulk charge.Press-fitted fire extinguishing agent stabilizes the center of mass and increases the flight stability of the Mortar Extinguishing Ammunition.The setting of the central squib increases the throwing distance of the fire extinguishing agent and the fire extinguishing effect is stronger.(2)The cylinder of the Mortar Extinguishing Ammunition was made of 50 gauge steel,with a diameter of 40mm,a length of 350mm,and a wall thickness of 6.75mm.In order to reduce the leakage of gunpowder gas,there is a gas-closing device at the junction with the tail pipe,and the gas-closing device was composed of an annular groove made of a car,and there are 8 annular grooves,each groove having a depth of 1.5 mm and a width of 1 mm;.The tail pipe was made of 50 gauge steel,with a diameter of 30mm,a length of 150mm,a wall thickness of 6.75mm,and a tail fin at the bottom.There are 16 fire holes above the tail,each diameter of the fire hole is 6mm.(3)The basic medicine tube was placed in the tailpipe,The double base propellant was selected.and the auxiliary charge selected 0~2 charge.The rear wing has 8 pieces,made of aluminum alloy.The length of each piece is 30mm,the width is 13mm and the thickness is1.5mm.The interface between the warhead and the fuze is available,using intelligent fuze to initiate Mortar Extinguishing Ammunition.(4)The three-dimensional model of the Mortar Extinguishing Ammunition was established by SolidWorks.On this basis,the loading condition of the Mortar Extinguishing Ammunition projectile was studied,and the emission intensity of the Mortar Extinguishing Ammunition projectile was checked by ANSYS/WorkBench.Under the maximum chamber pressure of 29.4MPa,the maximum stress of the Mortar Extinguishing Ammunition shell is87MPa,less than the intensity limit 120MPa,and the maximum stress of the fuze is 211MPa,less than the limit of strength 450MPa,and the extinguishing agent.The stress of the central tube is 17MPa and 3.7MPa respectively,much less than the 100MPa of the strength limit.The stress of the cylinder and the tail is 198MPa and 45MPa respectively,less than the limit of strength 380MPa.The maximum strain part is at the tail part,0.39mm,and all parts meet the lunch requirements.(5)Analysis of the external ballistics of the Mortar Extinguishing Ammunition.Analyzed various factors affecting the trajectory,conducted preliminary analysis on the error caused by the design,built a simulation model based on the external trajectory,and simulate the external trajectory of the Mortar Extinguishing Ammunition with MATLAB.The maximum range of the Mortar Extinguishing Ammunition is 1000m,the shooting height is 300m,and the flight time is 8~11s.(6)The explosion and dispersal process of the Mortar Extinguishing Ammunition was studied,and the Mortar Extinguishing Ammunition model was established by TrueGrid.Selected SPH algorithm,ANSYS/LS-DYNA software was used to simulated the explosion throwing process.By coMParing the simulation results of different specific doses,the diameter of the central squib was chosen to be 20mm.under this condition,The maximum throwing radius of the fire extinguishing agent is 3.47m,and the fire extinguishing area is37.8m~2,which has guiding significance for its practical application.