Basic Experiments on a Cryogenic Wind Tunnel of Flashing-Blowdown Type

Abstract

This paper deals with the experimental approach to a new concept of cryogenic wind tunnel of short duration. In the last two decades various closed-cycle and continuous operation (CCCO) cryogenic wind tunnels have been developed and they have shown many advantages for high Reynolds number experiments. These cryogenic wind tunnels, however, suffer from problems of purging and cooldown required before their operations and warming up too. And it is also rather difficult to perform mixing jet experiments by different gases. Therefore, the development of intermittent cryogenic wind tunnels seems to be necessary in the same way that many short duration wind tunnels have been developed for atmospheric temperatures. In this paper we report a flashing blowdown cryogenic wind tunnel developed at the Muroran Institute of Technology [MH(Maeno-Hanaoka)-Cryo.Flash.W.Tunnel]. This cryogenic wind tunnel utilize the rapid flashing phenomenon of pressurized liquid nitrogen under rapid depressurization by a quick opening valve. The operating principal and details of the insturmentation for the pressure and temperature measurement are given. Test results and flow visualization results are presented. The usefulness of this small-scale pilot wind tunnel for large scale apparatus is discussed.