THE EFFECT OF EXCESS AIR ON THE CHARACTERISTICS OF THE NON-ISOTHERMAL FLOW OF MICROJET STABILIZER-TYPE BURNERS

The results of studies of the structure of non-isothermal flow in microjet burner devices with asymmetric fuel gas supply, intended for operation in conditions of increased values of the coefficient of excess air α. It is indicated that these conditions take place in industrial furnaces for various purposes, dryers, etc. A schematic diagram of this device is described. The system of fuel supply and supply of primary and secondary air is considered. The features of mathematical modeling of the analyzed physical situation are analyzed. It is noted that the solution to this problem was obtained using the DES method (Detached Eddy Simulation — a method for modeling detached eddies). The data of mathematical modeling that relate to the identification of the effects of the coefficient of excess air (α = 2.0 … 4.0) on the flow characteristics in the considered burner device are presented. It is indicated that the change in the total air flow rate was simulated by changing the fuel gas flow rate at a constant air flow rate. The main differences of the velocity fields are analyzed for different values of the coefficient of excess air. In particular, it is noted that large values of the coefficient α correspond generally to lower values of the flow rate of the combustion products. Particular attention is paid to the study of the laws of the influence of the coefficient of excess air on the characteristics of the circulation zone in the astern area of the flame stabilizer. It is indicated, in particular, that the length of the reverse current zone in this region decreases significantly with increasing value of α. The features of the vortex structures in the near wake of the flame stabilizer are analyzed for different values of the coefficient of excess air. The results of studies on the spatial distribution of the RMS velocity pulsations with varying air excess coefficients are presented. It is noted that with an increase in the value of α, a zone of increased velocity pulsations is removed from the end of the stabilizer.