Abstract:
The development of high enthalpy wind tunnel and its test technology are the cornerstone to help mankind enter the hypersonic era, and the great progress has been achieved in recent years. High enthalpy wind tunnels with four typical driving modes are introduced. Those are the air-directly-heated hypersonic wind tunnel, the light-gas-heated shock tunnel, the free-piston-driven shock tunnel, and the detonation-driven shock tunnel. Theories and critical techniques for developing these wind tunnels are introduced, and their merits and weakness are discussed based on tunnel performance evaluation. The measurement techniques are usually included into wind tunnel techniques because that the hypersonic and high-enthalpy flow is a chemically-reacting gas motion and its diagnose needs specially-designed instruments. Three measuring techniques are introduced here, including aerodynamic heat flux sensors, aerodynamic balances, and optical diagnose techniques. These techniques were usually developed for conventional hypersonic wind tunnels and combustion research, and are further improved to measure the hypersonic and high-enthalpy flows. The prospect for developing the experimental techniques of hypersonic and high-enthalpy wind tunnels is presented from author's point view.