Implications Concerning General Ignition Processes from the Analysis of Homogeneous, Thermal Explosions

Abstract

Two recent approximate analyses of ignition in homogeneous, adiabatic systems with fuel consumption specifically included are discussed and compared with the derived exact solution of the problem. The singularity present in both approximate solutions is shown to be the same as that found in the exact solution, and is characteristic of the time required to establish nearly complete chemical reaction. A similar situation is shown to exist for i~ition in non-adiabatic, homogeneous systems-the classical Semenov problem--causing the proposal and discussion of a thesis that a correct description of any ignition event must always include the transient behavior as quasisteady combustion is approached. Intuitively satisfying, the theoretical and experimental implications of this thesis are discussed.

Numerical Solution of the Two-Dimensional Premixed Laminar Flame Equations

“…Furthermore, it does not have any direct relation to the high temperature characterizing the ignition delay in the theory of homogeneous explosions. 22 As a result it is looked upon simply as a necessary mathematical artifice to remedy the cold boundary difficuty. However, it is believed that this temperature possesses some physical significance because it expresses a physically satisfying, real limit for the vanishingly small, but finite, Arrhenius reaction rate at temperatures near the cold boundary temperature.…”

“…Ill B cm 3 = flame speed in Eq. (22), cm/s = velocity of the mixture at the downstream boundary (_L toS out ),cm/s = rate of consumption of fuel per unit volume and time, g/cm 3 s = mass of reactant (fuel) per unit mass of mixture -mass of reactant (fuel) in unburned mixture per unit mass of that mixture = Y/Y O A = thermal conductivity of the mixture cal/cm s K p = local mixture density, g/cm P 0 = density of unburned mixture, g/cm 3 Pom = density of the mixture at the downstream boundary, Sec. Ill B Subscript 0 = upstream boundary (reactants or cold)…”

Droplet Combustion in a Reactive Environment

“…The ambient temperature now is the adiabatic flame temperature and is therefore much hotter. Homogeneous ignition theory can be used to assess the reactivity of the ambiance (Hermance, 1975;Kassoy and Poland, 1975).…”

Thermal Decomposition, Ignition Process and Combustion Behavior of Nitrate Ester Plasticized Polyether Propellant at 0.1–3.0 MPa

“…As an attractive heating source, a laser has high output energy and controllable loading time, which allows noninvasive, remote, and direct ignition of solid propellants. In the 20th century, Baer and Ryan [8], Hermance et al [9,10], Kashiwagi [11], Niioka et al [12], and Kulkarni et al [13] began research into the ignition performance of solid propellants, including ignition theory, test methods, and performance. Based on the earliest solid-phase ignition model, gas-phase ignition and heterogeneous ignition models have been established.…”