Structure Design And Aerodynamic Characteristic Analysis Of Multi-nozzle Rocket-assisted Mortar Projectile

The range is an important tactical technical indicator of the weapon system.With the development of precision guidance technology,the firing accuracy of mortar projectile has been greatly enhanced,therefore,improving its range is of great importance.The improvement of firing range can have an emphatic defeat to the enemy's effective strength either in the attack or in the defense.Therefore,this paper designs the rocket-assisted mortar projectile with four-nozzle solid rocket engine and analyzes its aerodynamic characteristic.The main research contents are the followings:First,the overall structural configuration of the rocket-assisted mortar projectile with four-nozzle solid rocket engine on its shape,payload,engine system and stabilizing device is designed..Secondly,the projectile's quality change model,engine thrust model and particle ballistic trajectory model are build up.By using ISIGHT optimization design software,it analyzes the influence of the angle of firing,the ignition timing of the engine,the operating pressure and propellant mass to the range and obtains the optimum operating parameters of the engine.Then,basing on the above parameters,the engine charge is specially designed.The UG surface offset function is used to obtain the change rule of the combustion area with the burned thickness,and then the intra-ballistic equations of the rocket engine are established.Finally,the pressure-time curve is obtained by resolving and contrastive analysis with the optimized results is conducted.Considering the viscoelasticity of the propellant material,the ABAQUS finite element simulation software is used to simulate the motion of the projectile,and the stress distribution of the propellant grains and other main parts is obtained.At the same time,adding gaskets solves the problem of excessive stress caused by stress imbalance at the bottom of the grain.Finally,by using Fluent computational fluid mechanics,the contrastive analysis of aerodynamic characteristics of the rocket-assisted mortar projectile under two state conditions-with jet stream and with no jet stream.The analysis result shows that the jet stream increases the resistance and with the increase of mach number and attack angle,the influence of jet stream on the resistance is in a decreasing tendency,the influence of jet stream on the lift force and the force of moment is not obvious.The computed result of stable reserve shows that the stable reserves with jet stream and with no jet stream are above 12%,which meet stability requirements.