EVALUATION OF EXISTING EQUATIONS OF STATE FOR THE MODELLING OF PROPELLANT COMBUSTION IN INTERIOR BALLISTICS

Increasing performance of an armament system often leads to increasing the maximal pressure inside the chamber or increasing the compacity of the system. Telescoped ammunition and the associated weapon (40 CTAS) developed by CTA International is a solution that combines both improvements. With the increase of maximal pressure, the equations of interior ballistics might not be appropriate anymore since the models were established when the pressure was moderated. The aim of this paper is to compare the potential candidates for the equation of state of the combustion gases in a high-pressure system, such as telescoped ammunition. Within this study, the following equations of state are studied: ideal gas equation, Noble-Abel equation, Van der Waals equation and virial equation. The study is divided in two: a first study for air as the coefficients needed are easily accessible in the literature and a second study for combustion products stemming from propellant combustion.