# Launch Dynamic Simulation of a Compressed-Air Launcher for Fire Suppression
## 5 Conclusions  
To enhance the fire suppression performance through the utilization of compressed-air launching technology, a launch dynamics calculation model of a compressed-air launcher was developed using the VC++ program. This model was employed to simulate and analyze the effects of interior ballistics variations under different structural parameters and initial parameters.  
The results indicate that the developed calculation model and launch efficiency evaluation program, which are based on thermodynamics and kinetics theories, successfully simulate the launching process of a fire-extinguishing bomb propelled by compressed air. The bore pressure exhibited a similar pulsed trend to that observed in the traditional gunpowder launching process. This demonstrates the efficacy of the calculation model in accurately capturing the dynamics of the compressed-air launching system.  
The interior ballistics process was significantly influenced by the structural parameters. Specifically, as the nozzle diameter increased, the peak pressure rose and tended toward a maximum value when the nozzle diameter exceeded half of the launcher caliber. Moreover, the muzzle velocity, gas transfer efficiency, and launch efficiency exhibited the same trend as that of the peak pressure. Similarly, increasing the gas cylinder volume led to an increase in the peak pressure, which gradually approached a maximum value. The muzzle velocity followed a similar trend to that of the peak pressure. However, both the gas transfer efficiency and launch efficiency demonstrated an approximately linear decrease.  
As the initial pressure in the gas cylinder increased, both the peak pressure and muzzle velocity exhibited a linear increase. However, the gas transfer efficiency and launch efficiency decreased approximately linearly. Regarding the loading position, a slight decrease was observed in both the peak pressure and muzzle velocity. Conversely, the gas transfer efficiency and launch efficiency experienced a slight increase. Interestingly, the launch angle had a minimal influence on the interior ballistic process, indicating that it has little impact on the peak pressure, muzzle velocity, gas transfer efficiency, and launch efficiency.  
The lumped parameter model was established to describe the changes in macroscopic physical quantities in this paper. More accurate simulation models in the future will consider the actual flow of the high-pressure gas in the chamber and the heat loss distribution from the interaction between the projectile body and the barrel wall, which will show the details of the pressure and velocity distributions of the gas in the barrel.  
Conceptualization, Y.J. and Y.Z.; methodology, Y.G. and J.H.; software, Y.G. and J.Z.; validation, H.Z., J.H. and Y.J.; formal analysis, J.H. and C.J.; investigation, J.H. and C.J.; resources, Y.J.; data curation, H.Z., J.Z. and Y.Z.; writing--original draft preparation, Y.J. and J.H.; writing--review and editing, Y.J.; visualization, Y.Z.; supervision, J.Z.; project administration, J.Z.; funding acquisition, Y.J. and J.Z. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Youth Talent Cultivation Plan of Changzhou University (grant number ZMF2202006).  
Not applicable.  
The data are contained within this article. Further inquiries can be directed to the corresponding authors.  
The authors declare no conflict of interest.