Ignition of composite propellants in a stagnation region under rapid pressure loading

Ignition of AP-based composite solid propellants located at the tip of an inert crack wasinvestigated both experimentally and theoretically. The ignition process was observed by simultaneously using a high-speed (≈40,000 pictures/s) camera and a fast-response photodiode system. Heat flux to the propellant surface was measured with a thin-film heat-flux gage. Effects of pressurization rate, crack-gap width, and igniter flame temperature on the ignition process were studied experimentally. Experimental results indicate that the ignition-delay time decreases and the heat flux to the propellant surface increases as the pressurization rate is increased. Results of the theoretical analysis which employed separate solid-phase energy equations for fuel and oxidizer and the measured heat flux to the propellant surface are in good agreement with experimental data. The decrease in ignition delay with increasing pressurization rate is caused by enhanced heat feedback to the propellant surface at higher pressurization rates. This augmentation in heat feedback to the propellant at higher pressurization is believed to be a result of a combination of the following mechanisms: heating due to compression-wave reflection at the closed end; heat release due to burning of unreacted igniter species near the tip, behind the compression wave; and enhanced heat transfer due to recirculating hot gases near the tip.

[1]  H. Wise,et al.  Thermal Diffusivity of Ammonium Perchlorate , 1966 .

[2]  F. Williams,et al.  A model of ammonium perchlorate deflagration between 20 and 100 atm , 1971 .

[3]  C. F. Price,et al.  A model of composite solid-propellant combustion based on multiple flames , 1970 .

[4]  R. Kumar,et al.  Gas Phase Ignition Theory of a Heterogeneous Solid Propellant Exposed to a Hot Oxidizing Gas , 1971 .

[5]  T. Ohlemiller,et al.  A Critical Analysis of Arc Image Ignition of Solid Propellants , 1968 .

[6]  K. Kuo,et al.  A model for AP-based composite propellant ignition including gas-phase and subsurface reactions , 1982 .

[7]  Martin Summerfield,et al.  THE BURNING MECHANISM OF AMMONIUM PERCHLORATE-BASED COMPOSITE SOLID PROPELLANTS , 1968 .

[8]  K. Kuo,et al.  Ignition of Composite Propellants under Rapid Pressure Loading , 1981 .

[9]  M. M. Ibiricu,et al.  Theory of ignition of solid propellants. , 1966 .

[10]  Kenneth K. Kuo,et al.  Review of Solid-Propellant Ignition Studies , 1982 .

[11]  W. Strahle,et al.  Thermal decomposition studies of some solid propellant binders , 1971 .

[12]  F. Williams,et al.  Gas-Phase Ignition of a Solid with In-Depth Absorption of Radiation , 1977 .

[13]  C. Reinsch.  Smoothing by spline functions , 1967 .

[14]  K. Kuo,et al.  Convective Burning in Isolated Solid Propellant Cracks , 1979 .

[15]  Kenneth K. Kuo,et al.  Ignition of Solid Propellant Crack Tip under Rapid Pressurization , 1980 .

[16]  T. Kashiwagi.  A Radiative Ignition Model of a Solid Fuel , 1973 .

[17]  R. Kumar,et al.  Role of Gasphase Reactions During Radiant Ignition of Solid Propellants , 1976 .