Effects of Air Cooling-Cavity Structure on the Flow Field Characteristics and Wall Temperature Distribution of Integrated Flameholders

Abstract This study investigates integrated flameholders with distributed air-cooling-cavities and film holes under cold-state thermal environment in a wide-range afterburner. Wall temperature and total pressure recovery coefficient were measured in a non-afterburning condition using a test system that combined a main combustor and an afterburner with an integrated flameholder. The effects of geometric parameters on flow characteristics and wall temperature distribution of flameholder were investigated by using the experimentally verified CFD method. The results show that the flow-field is primarily influenced by blockage ratio and outer/inner ring width ratio (WR), while the wall temperature distribution is mainly affected by the arrangement of air-cooling-cavities, the WR, and the tail structure. Compared to the baseline scheme with an integrated cooling-cavity, the overall cooling effectiveness of other five schemes using front-rear distributed cooling-cavities are higher. Smooth tail wall design can inhibit hotspot formation, rather than V-groove configuration. At inlet Mach numbers of 0.1-0.3, the cold-state total pressure recovery coefficient exceeds 0.98 for all schemes. When the mainstream temperature is in range of 1100-1600 K, cooling effectiveness is improved by increasing the width ratio within a certain range. Due to reasonable cooling airflow distribution of impingement-cavity/cooling-cavity, the scheme with a width ratio at 1.2857 exhibits best cooling performance. Additionally, the recirculation zone downstream of this flameholder is wider and longer, with smaller variations at different heights, which is beneficial for flame stabilization.