Transition from the regime of low rates of filtration combustion of gases to the regime of high rates with a pressure increase

Regularities of the transition from the regime of low rates (RLR) of filtration combustion (FC) of gases to the regime of high rates (RHR) with a pressure increase are investigated. It is shown that allowance for gas-phase transfer is important for description of FC, at least when the size of the skeleton pores d>1.5–2.0 mm and the calorific power of the fuel exceeds the limit of propagation of the flame. With an increase of 1–2 atm in the working pressure as compared to atmospheric pressure the critical pore size decreases by a factor of 2.0–2.5. A theoretical model that makes it possible to evaluate the velocities and temperatures of FC stationary waves under conditions of the transition from RLR to RHR and to establish realization limits for these regimes is proposed. It is shown that a more adequate description of the transient regime and the regime of high rates is achieved when the turbulent character of the combustion is allowed for.