Under Special Conditions, The Mechanism Of The Combustion Process Research

The diffusion flame in microgravity has different features from the counterparts in normal gravity and the diffusion principles of in microgravity and weak buoyancy environment are obviously different from the ones in normal gravity. It is of importance to study these features for the understanding of fundamental combustion processes and verifying the existing combustion theories and developing new ones. Taking the candle flame and the flame spread over thermally thin fuel as example, This paper has investigated the diffusion flame features experimentally and numerically and has got some results.In the first part the paper introduces the significance and the development of microgravity science and microgravity combustion science. At last the paper introduces the research content.In the second part this paper introduces the ways for numerical combustion calculation in microgravity and the combustion research apparatus in microgravity. This part mainly introduces the dispersant for the differential equation.In the third part the paper numerically investigates the flame spread in microgravity and establishes the heat falling theory model of solid fibrin and the theory model of the flame spread along thin solid fibrin surface. Firstly in this part the paper establishes three fibrin heat falling models: fibrin decalescence decomposition model; fibrin heat release decomposition model and burnt carbon heat release model. The paper also shows their reaction velocity in this part. In the third chapter of this part, numerical simulations are presented to analyze the mechanism of flame spread over solid thermal thin fuel in the quiescent microgravity environment. Effects of solid surface radiation heat losses on the flame spread characteristics are studied at different ambient oxygen concentrations and ambient pressures. The results show that surface radiation heat losses can considerably affect the flame structure and the spread rate. By radiating heat to the environment, the surface acts as a heat sink for flame. The flame cools, becomes smaller, and moves closer to the surface to supply additional heat to compensate for the radioactive loss. When considering surface radiation heat loss, the rate of spread increases with the increase of pressure, which agrees with the experimentalresults in microgravity. With the increase of surface radioactive emission coefficient, the peak values of the flame temperature decrease. A radiation or conduction parameter is identified that adequately describes the importance of the surface radiation.In the forth chapter the paper investigates the features of the candle flame and temperature in microgravity and establishes candle flame mathematics model in Simple method. In this chapter the candle flame structure and temperature are discussed. The diminishing of natural convection in microgravity is responsible for the hemispherical shape of candle flame. The lower candle flame temperature accounts for the non-sooty and dim blue color of candle flame in microgravity. And also the radiative heat loss, air current and oxygen thickness effects on flame.In the fifth chapter the paper analyzes and discusses experimental data. Steady solid fibrin temperature and the experiment result of the solid diffusion flame spread have been analyzed in this chapter. And also the candle flame shape flying parabola line has been analyzed. The paper applies error theory and neural network theory to get a smooth and continuous flame temperature value curve in different gravity and analyzes it.