Gasdynamic effects

We have so far treated the quasi-one-dimensional flame as a constant pressure system with an interaction solely between chemical events and diffusion of matter and energy. Provided that the flame Mach number is low, this is a perfectly legitimate means of investigating the interaction per se, and it leads to a solution which includes the steady state, one-dimensional, laminar burning velocity. As an eigenvalue of the steady-state differential equations, the laminar burning velocity is a fundamental property which depends on the 

For slow flames, Eq. (4.79) may be uncoupled from the remainder of the calculation (as has been done so far), and Eq. (2.7b) may be used to determine the steady-state pressure profile at the end of the integration. For much faster flames where there are appreciable gasdynamic effects and associated density changes, the momentum equation must be coupled directly into the system, and the energy equations (2.19), (2.20) or (2.20q) must be used in place of Eq. (2.20b). In the finite-difference formulation discussed in Section 4.2, it then also becomes necessary to modify Eq. (4.44) to include the effect of variable pressure on the density and to introduce the condition 

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The theoretical questions which are posed and solved in these papers by Ya.B. and by Ya.B. with Yu. A. Zysin (articles 17 and 17a) have developed into an extensive separate branch of science—the theory of chemical reactors. Combustion in a reactor with ideal mixing is an example of the simplest thermal and gasdynamic situation, when the analysis requires only algebraic relations. This allows explicit demonstration of the basic features of exothermic chemical reactions in a flow which are also present in more complicated form in other combustion regimes—a laminar flame, diffusive combustion, detonation wave and others. Critical conditions of ignition and extinction and the existence of several regimes whose occurrence depends on the initial conditions—these are the most remarkable effects of combustion which attract the attention even of laymen. The relative ease of recording them makes them a convenient tool for physico-chemical research. 

P. A. Urtiew and C. M. Tarver, Effects of Cellular Structure on the Behavior of Gaseous Detonation Waves under Transient Conditions, in Gasdynamics of Detonations and Explosions, vol. 75 of Progress in Astronautics and Aeronautics, J. R. Bowen, N. Manson, A. K. Oppenheim, and R, I. Soloukhin, eds.. New York American Institute of Aeronautics and Astronautics, 1981, 370-384. 

Numerical simulations of the detonation reflection and shock propagation process were performed. These simulations were of the inviscid gasdynamic processes of unsteady fluid motion and shock wave propagation. The effect of turbulent dissipation mechanisms was examined... 

Alexeenko et al. [9, 10] have performed non-continuum Direct Simulation Monte Carlo (DSMC) analyses of milli-/micro-nozzle flows in order to examine the influence of rarefaction effects on performance. The DSMC method is a statistical approach to the solution of the Boltzmann equation, the governing equation for rarefied gasdynam-ics. Their work has found that for Knudsen numbers of Kn 0.1, gas-surface interactions have a strong influence on the flow in both the converging and diverging sections... 

Figure 6 —Velocity distribution (peak normalized) for A1 (AI2O3) at 15 J cm X=I064 nm. Solid curve is based on a plasma gasdynamic model [3,4] using the parameters shown in the figure, where y is an effective heat capacity ratio used to model the expansion process subscript s refers to target surface condition, p the plasma, and b the molecular beam. Measurement uncertainties are v 1000 cm s" at 10 cm s" based on 5 ps channel time resolution at 47 9 cm density distribution < 0.05 arb. units.

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