Unsteady separation mechanism of ground horizontal-sliding takeoff system

Complex aerodynamic interference has long posed challenges to the safe separation of multi-body systems. Based on a new conceptual ground horizontal-sliding takeoff approach, the rocket sled system, computational fluid dynamics (CFD) simulations are conducted to study the separation between the payload and the rocket booster, with the Advisory Group for Aerospace Research and Development Model B representing the payload. The motion trajectory of the payload and the unsteady interaction flow mechanisms during separation are analyzed by altering the payload's layout, center of gravity (CoG), and sliding Mach number. The results show that positioning the payload closer to the front along the axis increases the likelihood of collisions after separation. At a sliding velocity of Ma = 3 , the payload tends to exhibit a nose-down attitude when l_c/l_p < 0.64 . Conversely, when l_c/l_p > 0.64 , the pitching angle becomes excessively large, which increases the risk of stalling or somersaulting. Furthermore, the CoG needs to move forward to reduce the growth rate of the pitching angle when the separation Mach number is increased. These studies can provide valuable references for the development of separation technology for the rocket sled system.