Effect of valve on ballistic performance in supercritical CO2 pneumatic launch

To investigate the impact of the launch valve on the performance of the supercritical CO2 pneumatic launch, a numerical model was developed based on the principles of mass and energy conservation. Specifically, the thermos-physical properties of real gas were used to describe CO2 during the launch process. Expansion experiments were conducted to validate the numerical model's accuracy. The study also examined the effects of the valve's opening mode, full opening time, and full opening area on launch performance. The findings indicate that when using the same launch valve, a decrease in the full opening time of the valve leads to an increase in the average temperature of the low-pressure chamber. Additionally, injecting the medium into the low-pressure chamber at a faster rate results in improved working responsiveness and energy conversion efficiency. Once the valve reaches a certain size, further increases offer little benefit. The parabolic valve is the optimal choice for both overload and final velocity. However, if the aircraft can handle it, a quick-opening valve will result in a shorter launch time and higher final velocity. This study offers theoretical guidance to improve the precision of aircraft cold launches.