Abstract
The purpose of this study is to develop an ultra-micro annular type combustor that uses two types of coaxial cylindrical flames, rich premixed flame and diffusion flame. The combustor consists of inner and outer porous tubes, and rich C_3H_8-air mixture and air issued, respectively, through the inner tube outwardly and through the outer tube inwardly, forming a cylindrical stagnation plane sandwiched by the inner rich premixed flame and the outer diffusion flame. Petal type flame was also observed in the downstream of the cylindrical flames. Keeping the equivalence ratio φ_i and flow rate q_i of the rich mixture constant, an overall equivalence ratio φ_<all> is controlled by varying the air flow rate q_a of the outer tube. As a result, the minimum values of exergy loss and heat loss rates were found to be 0.57 and 0.31 respectively.
