Hydrogen flow and heat transfer characteristic analysis in cooling channel wall with the spherical convexity structure

Abstract

In the thermal protection design for rocket engines chamber, the internal wall always suffers from high combustion temperature and small cooling channel size, thus an efficient method by changing inner wall structure in cooling channel is investigated. This paper proposed a structure with spherical convexity on the inner wall for improving the entire cooling performance, weakening thermal stratification phenomenon, and protecting the overheated structure. Optimized spacing is obtained through comparison to achieve better cooling effect and smaller flow pressure drop. An enhanced disturbance, which stems from the newly introduced spherical convexity surface to control coolant flow, finally improves the convective heat transfer efficiency. The results show that the spherical convexity structure of a depth 0.2 mm and spacing 2.5 mm is proper for enhancing heat transfer and weakening thermal stratification phenomenon in the channel with cross-section 2 mm*2 mm. Compared to the smooth channel, the (Nu/Nu0)/(f/f0)1/3 is increased by 55%, and the maximum temperature is decreased by 10% but the pressure drop is only increased by a maximum 14.5%.