The experimental and theoretical investigation of the micro combustor that will be part of micro engine was conducted. In order to know the combustion features in micro combustor, several micro combustors whose heights are 1mm, 2mm, and 3mm for diameter of 15mm was made. Also to study the effect of diameter, the combustors whose diameter are 7.5mm and 15mm for height of 2mm was made. The fuels used in this experiment were $φ=1 H_2$ & Air, $φ=2 H_2$ & Air, and $φ=1 CH_4$ & Air.
The Pressure transition was obtained for various initial pressure and fuels. The initial pressure was varied from 1bar to 4bar (absolute) to examine the effect of initial pressure on combustion feature. The maximum pressure was increased as increasing the initial pressure. Also as the height of combustor increases, the maximum pressure of combustor was increase. For $φ =1 CH_4$ and Air, and $φ =2 H_2$ & Air, the flame propagation was occurred for specific conditions because of quenching distance. The optimal mixture to obtain maximum pressure was $φ =1 H_2$ & Air premixed mixture, because the burning velocity of $φ =1 H_2$ & Air is the fastest. Schlieren photography was carried out to observe the flame propagation with high speed CCD camera.
The theoretical research on micro combustor was carried out simultaneously. The numerical algorithm that can simulate combustion phenomena in spherical constant volume combustor was modified by adding heat loss effect in order to adopt cylindrical micro combustor. The heat loss coefficient was determined to give good agreement with experimental pressure transition. Using this heat loss coefficient, properties such as temperature, density, and composition distribution could be predicted.
