An experimental investigation of liquid methane convection and boiling in rocket engine cooling channels

The steady-state heat transfer characteristics under internal forced convection of liquid methane were experimentally investigated using a rectangular channel with a cross section of 1.8×4.1  mm and square channels with a cross section of 3.2×3.2  mm; three square channels had surface finishes typical of milled channels and another three square channels had internal longitudinal fins. A high heat flux test facility capable of handling cryogenic temperatures, which was developed at the Center for Space Exploration Technology Research for the purpose of simulating the high heat load conditions, representative of regeneratively cooled rocket engines, was used in this study. Subcooled film-boiling phenomena were discovered for all the channels presented in this study. Film-boiling onset at critical heat flux was correlated to the boiling number Bo∼0.1. The convective Nusselt number follows predicted trends for Reynolds number with a wall temperature correction for both the boiling and nonboiling regimes.