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Abstract. The problem of the Rayleigh-Benard convection in a gas in a state of chemical equilibrium is considered in the frames of Boussinesq approximation. The method of linear analysis is used. Horizontal boundaries are assumed to be isothermal and free from shearing stresses. Thermodynamic parameters of a gas are described by the model of chemical equilibrium. Stoichiometric hydrogen-oxygen mixture is considered. It is shown that owing to recombination and dissociation processes the Rayleigh number in the gas under consideration equals to the corresponding number in chemically inert gas, multiplied with some additional factor. The critical Rayleigh number weakly depends on the pressure. Another and more effective way to control of the convection is to change temperature. The minimal value of the convection intensity is realized at very low and very high temperatures. At such temperatures the mixture under consideration can be considered as inert gas. An increase of temperature between its minimal and maximal values led to a shift of chemical equilibrium. As the result, the convection intensity pass through a local maximum.

The characteristics of an ascending heated plume in a compressible, viscous and heat-conducting gas are studied by numerical simulation. It is known that at the subcritical height of the region, the isobaric convection regime is realized, and at the supercritical one, adiabatic and superadiabatic. It is shown that adiabatic processes play a decisive role at the supercritical height of the region, and diffusion processes at the subcritical height.