DIGITAL SIMULATION METHOD BASED ON FINITE-VOLUME METHOD FOR SOLVING THE DIRECT PROBLEM OF INTERNAL BALLISTICS FOR THE BALLISTIC SYSTEMS, CAL. 40X46 MM WITH TWO PRESSURE CHAMBERS

摘要

The invention relates to a method for pointing out the phenomena which occur and are carried on in a barrel of a firearm or in a combustion chamber of a rocket engine. According to the invention, the method carries out a digital simulation by means of which there is analyzed the evolution of the thermodynamic parameters of gases and combustion products in order to obtain the variation of the pressure in high and low pressure chambers and the variation of the speed of a grenade in the barrel of a thrower, depending on space and time and it is based on the following reasons: the base powder is considered being spherical, highly digressive and, consequently, it does not have a constant combustion surface; the exponential law is adopted as law of the combustion speed; the base powder burns in a high pressure chamber (CIP) reaching a value at which the nozzles are opened and continues the burning in this chamber (CIP), the resulting gases passing into a low pressure chamber (CJP), where the pressure starts to increase, and in the high pressure chamber (CIP) the maximal pressure is reached, when the combustion of the powder is finished the discharge of gases in the low pressure chamber (CJP) is continued, the pressure in the high pressure chamber (CIP) decreases, while the pressure in the low pressure chamber (CJP) increases, reaching, at a certain moment, an equilibrium by equalizing the pressures; the heat transfer from the powder gases to the separator, cartridge walls and barrel is taken into consideration by diminishing the powder force; the transformations are considered isothermal just to the moment when the combustion of the base powder is finished, then following the adiabatic expansion of gases.