Fuel-air mixing under simulated high pressure and high temperature conditions

Abstract

A method to characterize and understand the fuel/air mixing under simulated high temperature and high pressure conditions is presented. These conditions were simulated using an isothermal liquid flow facility and model co-annular swirl burner. At increased pressures and temperatures the thermophysical properties (e.g. viscosity, vapor density) change which subsequently provides an influence on the fuel-air mixing, combustion efficiency, flame stability and generation of unwanted emissions. The results provide the effect of different flowrates and burner exit geometry (burner quads made of quartz glass) on the mixing behavior in the turbulent swirling flames. Planar laser-induced fluorescence (PLIF) diagnostics have been used to analyze the fuel-air mixing behavior under various conditions. A series of photographs of the flow field for twelve different cases have been examined. These photographs provide information on the evolutionary behavior of local and global flow structures in the flow field. Time averaged information on the flow field was obtained by averaging the desired number of photographs using an image processing software. Statistical evaluation on the scale and intensity of segregation has been determined for all cases using PLIF photographs of both the individual and time averaged results. These results provide the important role of burner geometry and flow parameters on mixing and its subsequent effect on combustion characteristics in advanced gas turbine combustors. These results provide inexpensive means of determining unmixedness and methods to improve mixedness under high pressure and high temperature gas turbine combustion conditions.