Abstract:

Two Stage to Orbit （TSTO） vehicle may become an example of next-generation launch technology for its efficiency and reusability， but whether the two stages can be safely separated or not will directly determine the success or failure of the orbit mission. At present， parallel-staged TSTO vehicle mostly adopts a transverse stage separation scheme， in which strong aerodynamic interference is introduced between stages and directly increase the separation risk. Hence， it is necessary to explore a scheme to reduce or even avoid the strong aerodynamic interference during separation. In this study， a Longitudinal Stage Separation （LSS） scheme for the parallel-staged TSTO model， in which， the orbiter moves along the upper surface of the booster， is proposed and analyzed in detail by investigating the dynamic separation process numerically. A TSTO concept comprising a wide-speed waverider and a reusable space plane， as booster and orbiter respectively， was designed to investigate LSS by numerical simulation with the overset grid method. The flow mechanism， unsteady wall pressure distribution， as well as aerodynamic characteristics of LSS at different Angles of Attack （AOA） under hypersonic condition， are studied. The results show that the aerodynamic interference during LSS is simple and weak， which is only associated with type VI shock/shock interaction and the convergence of shock waves. No shock reflections or shock/boundary-layer interaction occurs between stages. The variations of pressure distribution show that the leading edge shock of the booster is the main factor affecting the aerodynamics of the orbiter. Moreover， the interference load on the booster is weaker than that of the orbiter. The interference flow structure of TSTO is similar among different AOA cases， and the appropriate AOA condition of safe LSS for the current TSTO model is presented.

Key words: TSTO, hypersonic, longitudinal stage separation, aerodynamic interference, unsteady flow