Effects of step height on wall temperature of a microcombustor

We investigate the effects of step height of a cylindrical microcombustor on the premixed flame and external wall temperature. A simulation study is carried out employing a hydrogen-air fuel mixture and the detailed reaction mechanism. The external wall temperature increases drastically with decreasing step height, while the flame temperature is nearly independent of step height. Experimental investigations have been conducted on microcombustor tubes to explore the effects of step height and compare the results with those obtained by simulation. A stable flame is obtained in microcombustors having step heights of 1 mm, 2 mm and 3 mm. Good agreement between the simulated and measured external wall temperature has been achieved. When the inlet velocity and fuel-air ratio are constant, the emissive power of the microcombustor wall increases with decreasing step height.