In Situ Monitoring of Phase Transitions During Combustion of Solid Composite Propellants Using Optical Fiber Sensors

Solid composite propellant, as the energy source of solid rocket motors, is widely used in tactical rockets and missile weapons. Accurate characterization of solid composite propellant during the combustion process is critical to the revelation of the combustion mechanism and ensuring safe and stable operation of solid rocket motor. However, it has been a challenge to explicitly disclose the interphase conversion mechanism during the combustion process of propellants. Herein, we demonstrate an optical fiber-based approach to continuously monitoring the temperature distribution of propellant and understanding the phase transition during combustion by embedding a couple of optical fiber sensors in the propellant. With the aid of optical fiber sensors, a stable and reproducible correlation between the temperature evolution and the optical response is constructed, and the experiment results show the two step phase transition regions and the key condensed phase to gas phase transition, and obtain the burning surface temperature of 578.2 °C ~ 640.2 °C. The proposed method provides an effective tool for revealing the combustion mechanisms, which has great guidance for the optimization of propellant formulation design and enhancement of propellant combustion performances.