Combustion theory ignition

The development of combustion theory has led to the appearance of several specialized asymptotic concepts and mathematical methods. An extremely strong temperature dependence for the reaction rate is typical of the theory. This makes direct numerical solution of the equations difficult but at the same time accurate. The basic concept of combustion theory, the idea of a flame moving at a constant velocity independent of the ignition conditions and determined solely by the properties and state of the fuel mixture, is the product of the asymptotic approach (18,19). Theoretical understanding of turbulent combustion involves combining the theory of turbulence and the kinetics of chemical reactions (19—23). 

From these many considerations, the propellant formulator is often faced with preparing a propellant with rather precise 7sp and burning-rate characteristics. As a result, there is considerable interest in understanding the basic propellant combustion and ignition processes and in developing the capability to prepare from theory propellants with the desired burning-rate and 7sp characteristics. 

J. Daou and A. Linan, The role of unequal diffusivities in ignition and extinction fronts in strained mixing layers. Combust. Theory Model. 2 449-477,1998. 

Luo, Z., Plomer, M., Lu, T.F., Som, S., Longman, D.E. A reduced mechanism for biodiesel surrogates with low temperature chemistry for compression ignition engine application. Combust. Theory Model. 16, 369-385 (2012a)... 

In the search for a better approach, investigators realized that the ignition of a combustible material requires the initiation of exothermic chemical reactions such that the rate of heat generation exceeds the rate of energy loss from the ignition reaction zone. Once this condition is achieved, the reaction rates will continue to accelerate because of the exponential dependence of reaction rate on temperature. The basic problem is then one of critical reaction rates which are determined by local reactant concentrations and local temperatures. This approach is essentially an outgrowth of the bulk thermal-explosion theory reported by Fra nk-Kamenetskii (F2). 

The subsection, theory, concentrates on the theory of the method(s) of relevance for this work, that is, the methods aiming at the ignition front rate, the conversion gas rate (by many authors referred to as burning rate or combustion rate), the conversion gas... 

Below are the theories behind the measurement methods of ignition front rate and combustion rate. 

A theory of the method to obtain the combustion rate and ignition rate was not described. Only results were presented. Limitations and assumptions of the method were not discussed. 

Nine studies regarding the thermochemical conversion of packed-beds of biomass have been reviewed. The review is summarized in Table 7 below. The focus of the survey has been on the theories of the methods applied to measure ignition front rate, conversion rate (combustion rate, burning rate), conversion gas stoichiometry, and air factors. 

Hermance, C. E., Solid Propellant Ignition Theories and Experiments, Eun-damentals of Solid-Propellant Combustion, Chapter 5, Vol. 90, Progress in Astronautics and Aeronautics, AlAA (Eds. Kuo, K. K., and Summerfield, M.), New York, 1984, pp. 239-304. 

Vieille, Kast and Schmidt (Refs 1, 2 3) presumed that in some cases the deton may be accompanied by a so-called explosive combustion (vzryvnoye goryeniye in Rus) during which the hot gaseous products of combstn penetrate into spaces between particles of expls and ignite their surfaces. This assumption was used in lp40 by Apin (Ref 4) who proposed the theory of deton called in Rus "struychato-proboynaya . 

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