Design and debugging of the liquid nitrogen storage device in continuous transonic wind tunnel cooling system

The low temperature operation is an effective way to improve the Reynolds number in wind tunnel experiments. By means of liquid nitrogen injection, the first cooling system for the NF-6 continuous transonic wind tunnel has been built in China. The overall scheme and main technical indicators of the liquid nitrogen injection cooling system in NF-6 wind tunnel are introduced. The structure and technical principles of the liquid nitrogen storage device of the cooling system are expounded and the static and dynamic debugging results are presented. Test results indicate that our calculation method of the liquid nitrogen consumption is correct and it provides theoretical references for volume estimation of the liquid nitrogen tank. The scheme design of the liquid nitrogen storage device is reasonable and the liquid nitrogen injecting process is smooth and unimpeded. Meanwhile, the self-pressurized system of the liquid nitrogen storage device is working well and the heat-insulating properties of the liquid nitrogen tank can meet the requirements of the cryogenic liquid nitrogen storage.The daily evaporation rate of the liquid nitrogen in the tank is 0.044%, far lower than the designed index.The liquid nitrogen storage device has a good match with the whole cooling system. Throughout the debugging process, the key indicators such as the total temperature, total pressure, Mach number and running time have reached design requirements and excellent performance was achieved.