THE STEADY STATE BURNING MECHANISM OF COMPOSITE SOLID PROPELLANTS INCLUDING THOSE WITH NEGTIVE PRESSURE EXPONENTS
Xu Wengan Li Baoxuan Wang Kexiu
To study the steady state burning mechanism of AP-based composite solid propellants including those with negtive pressure exponents, the scanning electron microscope was used to examine the extinguished combustion strands and single-frame microphotography of self-illumination or laser-shadow was used to observe the burning samples. It has been found that the covering of the melten binder over the oxidizer surface is not a particular phenomenon of PU propellant in the mesa burning region, but a general phenomenon taken place in extensive region. It was indicated that the local cover may not result in local extinction. Further, a new theoretical model is developed. The existence of cover of melten binder over the oxidizer surface and the condensed phase reaction and opposed gasification of covered AP are considered in the analysis. The model is developed for AP-based composite solid propellants can be used to explain plateau, mesa and normal burning behavior and to analyse the effect of initial temprature and AP particle size on burning behavior. Furthermore, the model will also be able to provide a basis for studying the erosive combustion and nonsteady combustion of composite solid propellants including mesa propellants.