SOME KEY PROBLEMS IN THE STUDY OF AERODYNAMIC CHARACTERISTICS OF NEAR-SPACE HYPERSONIC VEHICLES

The advantages of the hypersonic vehicle in maneuverable flight in 30\sim70km airspace are that it can carry out long-distance maneuverable gliding flight by coupling the lift generated by the air in the airspace and the centrifugal force of high-speed flight, which has important practical value. Although significant progress has been made in the past decades in the study of hypersonic flows, there are still many challenges in the design and research of hypersonic vehicles for near-space long-range gliding, especially the unclear understanding of the flow mechanism under specific flight conditions. This paper introduces the progress of the author's research team in the development of key aerodynamic problems related to hypersonic vehicles in near space, mainly including: the flow model of hypersonic flight in near space is established, and the relative computational aerodynamics method of the system is developed, a suitable sliding boundary condition is studied for the coupling effect of rarefied gas effect and real gas effect under high altitude and high speed flight conditions, the slippage effect including velocity slip condition, temperature slip condition and pressure slip condition in high-temperature chemically reacting flows are considered. A dynamic optimization method for the aerodynamic shape of the aircraft was proposed, and the aerodynamic shape of the aircraft with high lift-drag ratio, which can be used in engineering, was obtained. The dynamic stability theory of high speed aircraft has been established, and great progress has been made in realizing the dynamic stability of hypersonic vehicles. In the end, some key technical and scientific problems that should be paid more attention to in the design of hypersonic vehicles are discussed, and the possible solutions to these problems are discussed.