Research on the heat transfer characteristics of through-hole transpiration cooling based on ceramic matrix composites

Abstract

Ceramic matrix composites (CMCs) are one of the primary materials used for transpiration cooling in aircraft due to their lightweight and high-temperature durability characteristics. However, there is relatively little research on the transpiration cooling of through-holes in CMCs at high temperatures. This paper establishes a numerical model for flow and heat transfer of through-holes transpiration cooling in the combustion chamber environment of a scramjet engine, analyzing the effects of blowing ratio, hole arrangement, hole size, and material thermal conductivity on the effectiveness of transpiration cooling, revealing potential strategies for optimizing hole arrangement using Response Surface Methodology (RSM). The calculation results show that increasing the blowing ratio can effectively enhance transpiration cooling performance. However, a higher blowing ratio increases the pressure gradient within the through-holes, leading to non-uniform coolant distribution and an increased temperature gradient. The plum hole arrangement provides better cooling performance than the parallel hole arrangement. Under the same blowing ratio, cooling efficiency improves by 8%, and uniformity increases by 50%. Increasing the size of the leading-edge holes can effectively reduce the pressure gradient within the through-holes. After optimization, the temperature gradient and average temperature improve by 8.824% and 4.290%, respectively. Additionally, enhancing the thermal conductivity in the direction of heat flow increases cooling efficiency more significantly compared to other directions.