Controlling Plane Jet Flame by a Fluidic Oscillation Technique

Abstract

A planejet flame was manipulated by passing the fuel jet through a jetimpingement fluidic oscillator. The plane fuel jet bifurcated into two streams of selfsustained pulsating jets in the cavity of the fluidic oscillator and issued out of two slits on the exit plane of the fluidic oscillator. The oscillation of the bifurcated plane fuel jets caused the flame behavior and combustion characteristics to change significantly compared with the corresponding behavior and characteristics of a nonoscillating planejet flame. The oscillation frequency, flame behavior, thermal structure, and combustionproduct distributions of the fluidicoscillator flame were experimentally examined and compared with the nonoscillating planejet flame. The flame behavior was studied with instantaneous and longexposure photography. The temperature distributions were measured with a finewire thermocouple. The combustionproduct concentrations were detected with a gas analyzer. The results showed that the length and width of the fluidicoscillator flame were reduced by approximately 45% and enlarged by approximately 40%, respectively, compared with the length and width of the nonoscillating planejet flame. The transverse temperature profiles of the fluidicoscillator flame presented a wider spread than did the planejet flame. The fluidicoscillator flame’s maximum temperature was approximately 100 آ°C higher than that of the planejet flame. The fluidicoscillator flame presented a larger CO2 concentration and a smaller unburned C3H8 concentration than did the planejet flame. The experimental results indicated that the combustion in the fluidicoscillator flame was more complete than that in the planejet flame.