Experimental Investigations on the Spray Combustion Produced by Effervescent Atomizers

This paper designed an effervescent atomizer to investigate spray flow characteristics, spray flame and elements of exhaust gases. The spray characteristics including mean drop size distributions and droplets velocity profiles were measured by Particle Dynamics Analysis. The velocity profiles of spray are similarly in all experimental conditions. The spray cone angle decreases slightly at higher liquid mass flow rate and lower air/liquid mass flow rate ratio. With the increasing of air/liquid mass flow rate ratio, Sauter mean drop size reduces gradually at the same liquid mass flow rate. A cylindrical laboratory furnace was devised to investigate diesel oil spray flame systematically. In swirling air flow, the spray flame is turbulent. Heat transfer and mass transfer processes among vortexes induce flame propagation. Temperature profile near burner was dominated by inner recirculation zone and lateral recirculation zone. The volume fractions of carbon monoxide, hydric and hydrocarbon in exhaust gases decrease gradually with the increasing of excess air and air/liquid mass flow rate ratio. The exhaust gas recirculation reduces the nitrogen oxides by 30%. The air swirl intensity has distinct effects on spray flame structure. In different swirl numbers of the guide vane airs wirler, combustion performances are different. Experimental results show that the optimal swirl number is 1.2.