Effect of Deflector on the Combustion Characteristics of a Micro-Combustor With a Controlled Centrally Slotted Bluff Body

Abstract Flame tip-opening in a micro-combustor with a controlled centrally slotted bluff body adversely affects the combustion characteristics, leading to reduced average combustion efficiency and exhaust gas temperature. To minimize the adverse effects of the flame tip-opening, a deflector is introduced in the micro-combustor, downstream to the bluff body, and its effect on various combustion parameters is studied. The insertion of a deflector significantly increases the exhaust gas temperatures in the central region by establishing a secondary flame root. However, sudden changes in the flow direction caused by the insertion of deflector induce a sudden expansion-compression strain on the flame front, thereby slightly reducing the temperature of the flame zones on either side of the central region. A downstream shift in the position of the deflector marginally mitigates the adverse effects of sudden expansion-compression strain on the exhaust gas temperature, as they are induced within the secondary reaction flame zones. On the other hand, the downstream shift of the deflector negatively impacts the exhaust gas temperature in the central region due to the reduced length available for near-complete combustion downstream of the secondary flame root. In conclusion, the deflector positioned farther from the outlet is found to result in better overall combustion characteristics at higher controllable flow ratios.