Flow and Heat Transfer in Hydraulic Reservoir of Thrust Vector Control System

Launch vehicle thrust vector control provides vehicle steering functions during powered flight starting from liftoff until engine cutoff. The thrust vector control on the first stage of Ares 1 provides steering during the first 133 s of ascent, while the thrust vector control on the upper stage provides steering for the next 465 s. Heat absorption by the hydraulic reservoir is a key factor in the performance of the upper stage thrust vector control system. A computational fluid dynamics simulation of the fluid flow and heat transfer in the hydraulic reservoir in the Ares 1 upper stage thrust vector control has been performed with the corresponding operating conditions and environmental conditions. The reservoir was set at 75% full of working fluid. Two steady-state cases, for fluid inlet temperatures of 294.3 and 394.3 K, and one transient case for the fluid inlet temperature ramping from 294.3 to 352.2 K over a 4.63 min period were simulated. The temperature, velocity, and pressure fields, as well as the absorbed heat for each case, were obtained, which have improved the understanding of the thermal dynamics of the thrust vector control subsystem.