Numerical Investigation Of Supercritical Tur-bulent Heat Transfer Of Cryogenic-propellant Methane In A Horizontal Tube

A numerical module, containing an accurate estimation of the thermodynamic and transport properties of methane, was systematically developed based on the user-coding capability of a com-mercial CFD code, Fluent. It had been applied for elucidating turbulent convective heat transfer phenomena of cryogenic-propellant methane at supercritical conditions, which played a signifi-cant role in the regenerative cooling system in LOX/methane rocket engines. The effects of inlet pressure, heat flux, inlet velocity, inlet temperature on the convective heat transfer were exam-ined, along with the Nusselt number variation. Numerical results indicate that under supercritical pressures, the variations of thermophysical properties produce significant effects on turbulent heat transfer. Particularly in the critical region of methane, drastic property variations result in heat transfer deterioration. Under supercritical conditions, the heat transfer coefficient is improved with increasing pressure (especially at a high wall heat flux, i.e.7MW/m2) and velocity, but it decreases with increasing inlet temperature. The conventional heat transfer formula such as Sieder & Tate and Gnielinski correlations, although considering property variations, cannot be applied directly for calculating turbulent heat transfer coefficient of cryogenic-propellant methane under supercritical pressures. A new correlation, modified from Jackson & Hall correlation, is devel-oped and it corresponds well with numerical results except when inlet pressure is below 8 MPa and heat flux above 7 MW/m2.