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Combustion, Explosion and Shock Waves

2017 year, number 6

Determination of the Transfer Coefficient of Natural Turbulence Occurring Near the Solid-Propellant Gasification Zone. II. Hydrodynamic Instability in Blowing

K.O. Sabdenov1, M. Erzada2
1Kozybayev North-Kazakhstan State University, Petropavlovsk, 150000, Kazakhstan
2Gumilev Eurasian National University, Astana, 010008 Kazakhstan
Keywords: эрозионный эффект, "собственная" турбулентность, гидродинамическая неустойчивость, erosion effect, natural turbulence, hydrodynamic instability

Abstract

Solution is obtained to the problem of determining the conditions of hydrodynamic stability in the presence of flow of gaseous combustion products blowing over the propellant gasification surface. The blowing flow has a low gradient along the direction of motion. Analysis of the obtained dispersion equation shows the development of hydrodynamic instability with fluctuations. The transport coefficients of natural turbulence are presented in the form of the sum of two terms: the first of these is responsible for the transfer in the absence of blowing, and the second takes into account the enhancement of transport processes in blowing. Their dependence on the initial temperature of solid propellant combustion predicts a reduction in the negative erosion effect in accordance with experimental data. Accounting for the relaxation time of the evaporation process has a stabilizing effect. In the limit of strong relaxation, this leads to oscillatory stability (in the absence of blowing), the perturbations do not grow and do not decay. However, arbitrarily weak blowing leads to instability.