Using the results of previous experimental research by means of high-speed video recording, a mathematical model of ignition was developed for a typical gel fuel particle, based on an organic polymer thickener, in a high-temperature motionless air medium. The structure of such fuel is a rather dense polymer matrix with fine droplets of combustible liquid in the cells. The advantages of gel fuels over liquid rocket propellants dictate their prospects as an energy resource in aerospace industry. The mathematical model of the process under study was developed using the mathematical tools of continuum mechanics and chemical kinetics. It is represented by a system of time-dependent nonlinear partial differential equations with the corresponding initial and boundary conditions. The developed mathematical model describes the process in terms of a limiting mode: the rate of heat supply from the source to the fuel and combustible gas-vapor mixture is limited. This implies that the typical heating time is much longer than the time of chemical reactions. In this case, the factors limiting the process intensity are heat supply and diffusion. Exothermic reactions can be assumed to develop in equilibrium with due consideration of corresponding conditions in the gas medium around the fuel particle. Satisfactory verification results for the mathematical model and numerical algorithm made is possible to conclude that this approach can be used to reliably predict the ignition characteristics of such kind of gel fuels. Gel particles 0.25–2.00 mm in size were considered. They were heated in an air medium at 750–1473 K. The ignition delay times under such conditions ranged from 0.3 to 10.0 s.
ASJC Scopus subject areas
- Aerospace Engineering