Hi, I need to calculate the pressure of the gases generated when a mass of a specific explosive compound is detonated inside a confined space, for which I know: The density of the explosive (1980 kilograms per cubic metre) Detonation Velocity of explosive (10,100 metres per second) Volume of said confined space ( a small cylinder, with volume 1.900153047e^-6 metres cubed) Relative Effectiveness Factor (2.38) The explosive is octanitrocubane. 20% to 30% more powerful than RDX. One molecule of Octanitrocubane decomposes into 8 molecules of CO2 and 4 molecules of N2 (nitrogen), so it has a pretty large volume of expanding gases. I do not know the enthalpy change of this reaction and thus I don't know the heat released but it shouldn't be too difficult to figure out. In other words I am looking These expanding gases will be pushing a bullet which I require to reach 900 metres per second so I do know the total thrust that must be exerted on this bullet by the pressures generated by the explosive. You may assume that all the materials will be able to withstand the pressures and temperatures generated. The thrust I calculated is 103.3210964 Kilo Newtons. Using F=ma (and a bullet that weights 0.045359237 kilograms) acceleration is equal to 2277840.264 m/s. However acceleration isn’t constant due to the increasing volume between the back of the bullet and the back of the propellant casing as the bullet travels down the barrel. Perhaps you guys could clarify how to approach calculating the summation of the effect of these constantly decreasing thrust forces on the bullet (but for that I assume we need the maximum chamber pressure generated by the propellant. I know this may be a weird question but thanks for any help you guys can give me.
