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- Englisch (6)
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- Detonation (2)
- Surface detonation (2)
- Bubbles (1)
- Chemically equilibrium gas (1)
- Condensation (1)
- Convection (1)
- Initiation (1)
- Periodicity (1)
- Quasi-periodicity (1)
- Rayleigh-Benard convection (1)
Modelling of detonation wave parameters, initiation and hazard of chemically active bubble systems
(2002)
The detonation processes in chemically active bubble systems at high initial pressures are calculated numerically. The dependences of detonation wave velocity at sub- and supersonic regimes of propagation on molar fraction of gas in the mixture and on initial pressure have been calculated for the first time. The Chapman-Jouguet condition for supersonic bubble detonation wave is obtained. The principal possibility for a different detonation wave structure in the case of propagation in the mixture with high initial pressure and longitudinal gradient of bubble volume fraction is predicted.
The dynamics and ignition of a chemically active bubble in a field of external pressure is analyzed. It is shown, that an inert diluent addition can increase the explosion hazard of heterogeneous gas - liquid systems. Calculations demonstrate the possibility of chemically active bubble ignition on the second pulsation. It is shown, that single chemically active bubble ignition is possible also owing to a decompression impulse.
An algorithm for the calculation of thermodynamic parameters of chemically equilibrium hydrocarbon gas with soot particles has been suggested. It is shown, that soot formation can have an essential influence on the dynamics of single bubble in chemically active hydrocarbon-oxygen (organic solvent (liquid) - oxidizer (gas)) heterogeneous systems.
The problem of the RayleighBenard convection for a chemical equilibrium gas is solved numerically. The gas is assumed to be incompressible, and the layer boundaries are assumed to be flat, isothermal, and free from shear stress. The Boussinesq model with the coefficient at the buoyancy term depending on the transverse coordinate is used. The resultant nonlinear system of equations is solved by a previously developed numerical method based on the spectral representation of vorticity and temperature fields. According to the idea of splitting, analytical formulas are first used to take into account the linear increase in disturbances, and then the nonlinear convective transfer is calculated by the finite-difference method. Various convection modes are obtained: stationary, periodic, quasi-periodic, and stochastic convection.
The model of convection of a chemical equilibrium gas, presented here, can be useful for the understanding of the transition of a cellular combustion of surface systems into an explosion (initiation of surface detonation) and for the calculation of operating regimes of chemical reactors.