Characteristics of supersonic combustion of unmixed gases in channels

Abstract

6. P. N. Rowe, K. T. Claxton, and J. B. Lewis, Trans. Inst. Chem. Eng., 43, TI4-T31 (1963). S. V. Bukhman and E. Nurekenov, Problems in Thermal Power Generation and Applied Thermophysics [in Russian], No. 2, Nauka, Alma-Ata (1965). CHARACTERISTICS OF SUPERSONIC COMBUSTION OF UNMIXED GASES IN CHANNELS V. L. Zimont, V. M. Levin, E. A. Meshcheryakov, and V. A. Sabel'nikov UDC 536.46:533.6 Supersonic combustion of unmixed gases in channels is determined by the interaction of turbulent diffusion, chemical kinetics, and gasdynamic effects accompanying the liberation of heat. Under certain conditions, the influence of each of the factors listed can become critical for the combustion process. In this paper we present the results of measurements and of calculations in order to clarify the role of these factors in the formation of the physical picture of the flow. Primary attention is devoted to the analysis of the influence of deceleration of the supersonic flow to subsonic velocities, pulsations in the concentra- tion, and finite rates of chemical reactions on the combustion. i. Two regimes, which are analogs of undercompressed (combustion products have super- sonic velocity, M > i) and overcompressed (M i. With combustion in a pseudojump, a broad subsonic region occurs at the center of the channel. This is what distinguishes the pattern of the flow in the second case (with the flow of fuel examined) from the flow in the pseudojump without combustion, where the sub- sonic zone is situated near the wall [2]. This circumstance must be taken into account in developing models of such flows. Apparently, a correct calculation of such flows is possible only based on the solution of the complete elliptical system of transport equations. 2. At the present time, numerical investigations of combustion in channels are per- formed primarily in the boundary layer approximation. The influence of concentration pulsa- tions on the process of diffusion combustion with subsonic flow velocities in channels was analyzed in [5]. Here the analysis is generalized to the combustion of a supersonic hydrogen jet. In contrast to subsonic combustion, in the case examined, the kinetic energy in the expression for the total energy (enthalpy) cannot be neglected. For this reason, the unaver- aged density and temperature depend on the concentration of the inert admixture Z and the velocity u. To determine the average values of the density $ and the temperature T, the joint probability density P(Z, u) was approximated by the following expression (if this ex- pression is integrated over u, then we obtain the approximation of the probability density P(Z) used in [5]): p (z, u) = (1 - v) 6 (u - u~) 8 (z) + v8 (u - ut) 6 (z - zt),