Ablation model of thermal insulator in oxygen-rich condition
- Paper number
IAC-06-C4.P.2.04
- Author
Mr. Yu Xiao-Jing, Northwestern Polytechnical University, China
- Coauthor
Prof. Guoqiang He, Northwestern Polytechnical University, China
- Coauthor
Prof. Jiang Li, Northwestern Polytechnical University, China
- Year
2006
- Abstract
This paper investigated ablation mechanism of thermal insulator in oxygen-rich condition of secondary combustor of SRR (Solid Rocket Ramjet) from experimental and theoretical aspects. An experiment system simulated secondary combustor oxygen-rich condition was established. The system was composed of ablation test motor, gas supply sub-system and measurement and control subsystem. Ablation experiments were carried out using this system to study main factors that influenced ablation. The experiment results showed that such parameters as oxygen percentage and pressure would affect ablation greatly. The ablation process in oxygen-rich condition was explored and a physical model was established. Electron Microscope scanning showed that thermal insulation would form three layers during ablation, namely, primitive material layer, pyrolytic layer and charred layer. Because thermal insulator was in oxygen-rich condition of secondary combustor and charred layer was porous, oxygenous gas in mixture would penetrate into charred layer and chemical reaction would take place in whole charred layer, which intensified the ablation process. According to the physical model, a mathematical model and computational method were proposed. An axially symmetric transient thermal conduction equation was put forward, which included material pyrolysis, pyrolysis gas flow and chemical reaction in charred layer. Chemical reaction was controlled by chemical dynamics, and the reaction rate was computed using Arrhenious Equation. The discrete equation was deduced by control volume integral method, and realized by numerical method. The calculation results were consistent with test data. Finally, the numerical technique was used to investigate influence that different parameters on ablation rate. The relationship between oxygen percentage, pressure, depth of charred layer and ablation rate were obtained.
- Abstract document