Experimental study of high-pressure turbulent premixed flames

Recent experimental studies of high-pressure combustion using burner-stabilized turbulent premixed flames conducted at the Institute of Fluid Science, Tohoku University are presented. Bunsen flames with and without turbulence were stabilized in a high- pressure chamber with the chamber pressure being kept constant up to 3.0 MPa. This method enables long-duration measurements of the flame under steady conditions of pressure, temperature, and turbulence. Flame visualization was performed using the instantaneous Schlieren method, laser tomography, and OH-PLIF, and the effects of pressure on turbulent burning velocity, flame structure, and wrinkling scales of the flame front were investigated. Results showed that the increase in pressure caused a finer and more convoluted structure of the flame and that the effects of pressure on turbulent burning velocity were extensive. It was implied that the intrinsic instability of the flame front at high pressure was the major mechanism involved. The findings of these experiments should prove useful for exploring the turbulent combustion characteristics in a high-pressure environment and also for the prediction and modeling of premixed-type gas-turbine combustors.