Study On Heat Transfer Characteristics Of Small Caliber Gun Barrel

When small-caliber guns fired continuously at high speed,high-temperature powder gas of up to 3000 K is generated,which continuously thermal shocks the surface of the bore and causes the temperature of the barrel to rise sharply,even reaching the melting point of the material,resulting in the barrel thermal ablation,and excessive chamber temperature may cause accidental spontaneous combustion of the chamber charge,bringing serious thermal safety issues.Aiming at the above problems of smallcaliber high-rate artillery,this paper analyzes the temperature distribution characteristics of the barrel during continuous high-frequency firing,and explores the change law and influencing factors of the barrel temperature field.Taking a 30 mm small-caliber gun as an example,the LS-DYNA finite element software is used to analyze and discuss the transient heat transfer and temperature field distribution characteristics of the local barrel during the internal ballistic process of the gun.Firstly,according to the principle of heat transfer and combined with classical internal ballistic,the model of heat transfer in the barrel is established.From the classical internal ballistic theory,the calculation program is written,and the projectile velocity and bore pressure curve are obtained.Based on the research method of inverse heat conduction problems,the heat flux load distribution characteristics during internal ballistic launch are obtained.On this basis,it is used as the initial boundary condition of the barrel heat transfer simulation.The effects of flame temperature of different charge,different barrel thickness,different firing frequency,different ambient temperature,different inner chamber chromium layer thickness and firing mode on the temperature field of barrel during firing are studied.The peak temperature of the inner wall of the barrel is approximately linearly increasing with the flame temperature,shooting frequency and ambient temperature.The increase of chromium layer thickness decreases the peak temperature of the surface of the barrel matrix.Within a certain thickness of the barrel,the temperature of the inner wall decreases with the increase of the thickness of the barrel during each round.Under the condition of interval firing,the radial high temperature area of the barrel will be transferred from the inner surface of the barrel to the outer surface,and the temperature of the inner and outer walls will gradually tend to be the same.The calculation results show that when the flame temperature is 3000 K,during continuous firing,the temperature of the surface of the inner wall of the barrel is a power function of the number of shots when each round is loaded.The sensitivity of the peak temperature of the bore surface to the flame temperature,barrel thickness,shooting frequency and ambient temperature was calculated and analyzed by orthogonal experimental method,and the results show that when firing one shot,the increase of flame temperature will significantly increase the peak temperature of the inner bore surface,while the increase of the thickness of the barrel only slightly reduced the peak temperature of the bore surface.