Abstract
In order to get high Reynolds number flows in a wind tunnel, it is the best way to use a gas of small kinematic viscosity by making temperature lower and pressure higher in the closed wind tunnel. About 20 of cryogenic wind tunnels are being used in the world. In this report, at first, its principle, structure and characteristics are described. Then a look of several representative ones in the world are given. The status of researches using cryogenic wind tunnels are also described.
