Enhancement heat transfer analysis of supercritical hydrogen fuel in small-scale channels with spherical concave

Abstract

Thermal protection is a key issue for rocket engines. To effectively protect the combustion chamber wall, this paper mainly proposes a novel enhancement heat transfer device of using a spherical concave surface in a small-scale cooling channel, and numerically analyzes the hydrogen flow and heat transfer characteristics under supercritical conditions. The spherical concaves with a depth-to-diameter ratio of 0.2 (D = 1 mm, H = 0.2 mm) are applied on the inner wall of the regenerative cooling channel. The numerical study results show that the spherical concave can significantly improve cooling capacity, increase convective heat transfer coefficient, and reduce the maximum heat wall temperature. The new structure will be conducive to reducing the influence of the non-uniform temperature distribution caused by single-side heating, resulting in the more uniform temperature distribution and the better enhancing heat transfer capacity. For Re = 42000, the average Nu of the spherical concave channel can be improved by 40%, but the pressure drop only increases 14% than the smooth channel.