Explosions- und Verbrennungsvorgänge in Gasen

Hydrocarbon oxidation high-temperature chemistry

“…It is well known for many decades, that combustion chemistry is a rather complex phenomenon [1,2], and realistic reaction mechanisms for simple hydrocarbons have been published in the last decade [3][4][5]. Nevertheless, for 2D or 3D applications in combustion science and technology, one-step approaches are used nearly exclusively at the present to make solutions possible within realistic computing times or to avoid principal physical problems (e.g., closure problems in modeling turbulent combustion).…”

“…According to the pioneering of Guldberg and Waage [6], the reaction rate R i of species i in eq. 1 often is proportional to powers of molar concentrations c i , if the variation of experimental conditions is sufficiently small: (2) The advantage of this approach, of course, is its short, simple formulation. However, this is paid for with a huge disadvantage: No extrapolation is possible to other experimental conditions, and even interpolation is dangerous due to the fact that the parameters κ (rate coefficient) and α i (reaction order with respect to c i ) in general are empirical parameters dependent on the experimental conditions, and cannot be given a physical meaning in a simple way (which means that no values can be estimated): …”

Oscillating flames: multiple-scale analysis

“…As in Jost (1939), on the time scale of acoustics, the front is moving very slowly, so that the acoustics can be solved by assuming a frozen front location. Indeed, motion is triggered by combustion, so that all velocities scale with the propagation speed, typically of the order of 1 m s…”

“…This impulsive start will initially be described by an acoustic model. Furthermore, since there is no dissipation mechanism in the physical model, the acoustics will not disappear (Jost 1939). As a result, a complete description of the motion requires accounting for both the fast acoustic scale and the slow incompressible time scale.…”

“…In addition to the spectrum, the amplitudes are determined, thus completing the solution to the problem studied by Jost and Guénoche. According to Guénoche (1964), Jost (1939) only considered the case of ignition near an open end. Among the four possible combinations between closed and open tube ends, Guénoche (1949) himself considered three cases, including ignition near a closed end, but he did not analyse the fourth, current case.…”