Optimization of the Internal Ballistic Performance of Supercritical Nitrogen Ejection

This paper investigates a scheme of introducing TNT into a high-pressure chamber containing supercritical nitrogen as the working substance to enhance the utilization of the working substance and the mass of the ejection missile. Based on the S-R-K real gas state equation and the quasi-static pressure and temperature prediction model of TNT, the internal ballistic equations for supercritical nitrogen are established for a missile of 30000 kg, so as to demonstrate the scheme for ejecting a large mass missile and analyze its optimization. Meanwhile, the influence of the high-pressure chamber volume and TNT initiating time on internal ballistic performances is studied, respectively. Simulation results indicate that when the capacity of the high-pressure chamber decreases and the initiating time is delayed, the peak acceleration of the missile and its ejection velocity could be steadily lowered, but the utilization of nitrogen working substance increases. Moreover, the duration of high temperatures in the low-pressure chamber increases as the delay of the initiating time grows. These conclusions could be utilized as a reference for optimizing the design of ejectors.