Research on head cooling of high-speed aircraft by liquid nitrogen

Abstract

In the development process of high-speed aircraft, the head of the aircraft is subject to high temperatures and high speed flows, supporting the maximum heat flow and thus requiring a reliable cooling system. A new type of head cooling system is proposed herein. An internal flow channel model of the heat transfer in a ball head made from high-temperature alloy steel is constructed, then an experimental platform is built to carry out relevant experiments on the performance of this cooling system. Firstly, the influence of different experimental conditions on the cooling efficiency of the ball head is studied. For given liquid-nitrogen supply pressure, a higher heating heat flux density on the outer surface of the ball head corresponds to higher cooling efficiency. Then, the vaporisation effect under different experimental conditions is evaluated using temperature sensors at the inlet and outlet of the ball head heat exchange channel in combination with images of the visualised glass tube. It is found that liquid nitrogen can vaporise completely when flowing through the heat exchange channel. The characteristics of the heating effect and liquid nitrogen injection for the ball head were evaluated using an infrared camera. Finally, under different experimental conditions of liquid-nitrogen supply pressure, it is found that liquid nitrogen can vaporise completely in each case, and the total temperature of the vaporised nitrogen is about 300K. It can thus be collected as a secondary gas source.