Numerical Analysis of Transcritical Fluids Heating in Liquid Rocket Engine Cooling Channels

The modeling and the analysis of the coolant flow in rocket engine applications is a challenging task because of its particular features, such as the extremely high heat flux (up to 10 MW/m^2), the high Reynolds number (up to 10^7) and the three-dimensional geometry of the channel. A further complication that may arise is the transcritical operating condition of the fluid, which can greatly influence the coolant flow-field and the heat transfer. In the present work numerical simulations of supercritical nitrogen and transcritical hydrogen flow in heated circular channels are validated against experimental data. Also numerical simulations of transcritical-methane in circular straight channels are carried out to analyse the dependence of heat transfer deterioration on the assigned heat load. Results are discussed in detail and the transcritical-methane flow condition that exhibits the heat transfer deterioration is identified and emphasized. Finally a comparison with the empirical correlations known in literature is made to see if they can correctly predict the behaviour of transcritical methane.