An Experimental Study on Combustion in Mesoscale Coaxial Swirling Burner Arrays

Abstract

ABSTRACT An experimental study of combustion in diffusion and coaxial mesoscale burner arrays was conducted. To that end, different linear and planar arrangements were tested, and blow-off limits, flame geometry, and oscillations parameters were determined. The new results of the experiments showed that the coaxial burner arrays, in general, are characterized by leaner values of the blow-off limit compared to premixed flames. Moreover, the large planar arrangement (square 5 × 5) provides the global blow-off equivalence ratio value of about 0.1 at low thermal power operating modes (less than 2 kW). All arrays of coaxial jets feature flame separation into small coaxial flamelets. However, linear coaxial arrangements provide complete flame separation, whereas jets of a planar array are not fully separated and merged in pairs. At the equivalence ratio value less than 0.45, separated flames start oscillating strongly until the blow-off occurs, that is unacceptable in terms of combustion efficiency, pollutant emission, and related parameters. Therefore, the most favorable operating modes correspond to the equivalence ratio ranging from 0.45 to 0.6.