Investigation of transcritical methane flow and heat transfer in curved cooling channels

Flow modeling in regeneratively cooled rocket engines is a challenging task because of the high wall temperature gradient, the high Reynolds number, the high aspect ratio of the channel cross section and the curved geometry. If coolant is methane, a further complication is its near-critical operating condition. In this thermodynamic regime large changes of the fluid properties can greatly influence the coolant flow field and the heat transfer. In the present study numerical simulations of transcritical methane flow field in asymmetrically heated rectangular channel with high aspect ratio and strong wall temperature differences are carried out for both straight and curved channels (heated both on the convex and concave side) by means of a validated Reynolds Averaged Navier-Stokes solver for real fluids. Results are discussed in detail by comparison of transcritical and supercritical flow field, and comparison of a "full-scale" high-Reynolds number channel flow representative of the actual cooling channel geometry versus a scaled channel, low-Reynolds solution. Emphasis is given to the most critical case in terms of cooling performance, that is the curved channel heated on the convex side.