Experimental study on multi-method synchronous combustion diagnosis of aluminized solid propellants under 7.5-20 mpa

Improving the specific impulse of rocket motors has long been a challenge of great interest. One of the widely used methods is to increase the working pressure of combustion chamber. Despite their importance, the difficulty of capturing the combustion characteristics under high pressure has limited our knowledge of combustion stability and reliability of AP/HTPB aluminized propellants. To overcome these limitations, we developed a multi-method combustion diagnostic system built based on a window bomb combustor with 4 optical paths. The maximum working pressure is ~30 MPa. Utilizing high-speed photography, shadowgraph and emission spectroscopy simultaneously to diagnose the combustion of aluminized AP/HTPB composite propellants under high pressure (7.5-20 MPa). This system is suitable for obtaining multiple typical characteristic parameters at the same time, including burning rate, emission spectrum and pressure curve of propellants under different pressures. The results show that, with the increase of pressure, the burning rate and chemiluminescence of propellants increases significantly, and the soot generated by combustion become denser, increasing the difficulty of optical diagnosis. This study lays the groundwork for future research into synchronous combustion diagnostic of composite propellants under ultrahigh pressure (≥ 20 MPa).