Thermal Analysis of Cooling Channels on Electromechanical Actuator During Actual Flight

Abstract

Liquid methane is regarded as a potential cryogenic propellant that can be used as coolant for regenerative cooling channels of high-power electrical devices, in addition to the oxygen/methane thrust chamber, owing to its moderate working temperature. This study examines the thermal performance of supercritical methane in cooling channels of the electromechanical actuator of a flight vehicle at varying angles of inclination and flight acceleration overloads. The main effects of overload and attitude at various angles of inclination on heat transfer are shown as variation in buoyancy force, which can be classified into gravitational and centrifugal buoyancy forces. Both forces can disturb the turbulent structure and complicate heat transfer under the influence of the drastically variable properties of the supercritical fluid. The authors also discuss conjugate impacts of the two kinds of buoyancy forces on the thermal performance of the cooling channel at various angles of inclination and flight acceleration overloads. The physical model was constructed as a helically coiled tube with angles of inclination varying from 0 to 90 deg, and flight overload was implemented as and (where is the gravitational acceleration). The analysis shows that both the flight attitude and overload played an essential part in the thermal performance of supercritical methane in the cooling channel. Some novel findings were obtained; an enhancement and a deterioration in local heat transfer could occur at large overloads with inclined orientations. The gravitational buoyancy force leading to secondary flow was an essential factor in the deterioration of local heat transfer but was inconspicuous under the gravity of Earth. Moreover, the trends of development of and were consistent, implying that the buoyancy force generated by gravity and centrifugal forces was not isolated.