Flow analysis of transcritical methane in rectangular cooling channels

The knowledge of the flow behavior inside cooling channels is of great importance to improve design and performance of regeneratively cooled rocket engines. The modeling of the coolant flow is a challenging task because of its particular features, such as the high wall temperature gradient, the high Reynolds number and the 3D-geometry of the passages. In case of methane as coolant, a further complication is the transcritical operating condition of the fluid. In this thermodynamic regime large changes of the fluid properties can greatly influence the coolant flow field and the heat transfer. Numerical simulations of transcritical methane flow field in asymmetrically heated rectangular channel with high aspect ratio and strong wall temperature differences are carried out by a suitable Navier-Stokes solver. Results are discussed in detail and compared with a supercritical flow field. Finally the aspect ratio effect on transcritical methane flows is analyzed by comparison of four different rectangular cooling channels geometries. Emphasis is given to the comparison of wall heat flux distribution and fluid cooling performance.