The equations of interior ballistics

Aberdeen Proving Ground, Maryland: Ballistic Research Laboratories. 1942.In establishing the the thermodynamic foundations of interior ballistics we begin for simplicity by assuming for the powder gas an equation of state of the со-volume type. Such an equation is a van der Waals equation containing the "b" terra but not the "a" term. Possible modification of the equation of state and the effect on the equations of interior ballistics will be mentioned later. For a gas obeying such an equation of state the specific internal energy depends only on the temperature and not on the density. Even if such an equation holds for each component gas, however, it can hold for the mixture only if all chemical reactions that occur are equivoluminar and if gas imperfection has no appreciable effect oh the chemical equilibrium constants. This statement follows from the facts that an equilibrium constant is independent of density only if the latter two assumptions hold and that dependence' of equilibrium constants on- density would mean dependence of relative concentrations on density as well as temperature, with a resulting dependence of specific internal energy on density as well as temperature.