Influence of Blowing Ratio on Double-Wall Cooling Characteristics under the Condition of High-temperature Flue Gas

Abstract

Double-wall cooling structure has been widely studied due to its excellent cooling performance. Most of the previous studies on the cooling characteristics of double-wall have been carried out in the non-reacting conditions without considering the influence of high-temperature flue gas radiation. In this paper, an experiment was carried out to assess the effect of blowing ratio M on cooling characteristics of effusion/impingement cooling at reacting flow conditions. The experiment was performed at atmospheric pressure with adiabatic flame temperature of the flue gas reaching 1800 K. The flue gas temperature was measured by S type thermocouples. The temperature distribution on the wall was measured by an infrared camera and N type thermocouples. The results show that the laterally averaged cooling effectiveness of effusion/impingement cooling system increases with the increase of M. After M>3, the effect on cooling effectiveness is no longer obvious. The laterally averaged cooling effectiveness gradually increases along the flow direction, while its growth rate slows down. Meanwhile, the cooling effectiveness remains basically unchanged after X/D>50.