Effect of Coolant Passage Configuration on the Film Cooling Performance of Aero-Optic Infra-Real Window with CFD Approach

• Main Authors: Tzu-Yi Lo, 羅子益
• Other Authors: Jr-Ming Miao
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/55205518479555994614

碩士 === 國防大學理工學院 === 機械工程碩士班 === 97 === The aim of this thesis is to investigate the thermal protection performance of cooled slot flow over an IR optical window equipped in the head of a hypersonic flight missile with CFD method. The seeker in the IR window is used to track the target then to guide the missile to the modified trajectory in high flight speed. As the anti-missile vehicle flight in the high attitude atmosphere layer, most of the kinetic energy will be transformed into the thermal energy over the surfaces of missile body due to the thin shock layer characteristics. Therefore, the flow field nearby the IR window is influenced by the interaction of shock wave and developing boundary layer flow. The variations in density, pressure and species concentration result in high temperature gradient over the IR window. Not only the structure strength of IR window but also the aero-optic performance in such a severe environment must be considered in the design stage. To reduce the heat load on the IR window, the external film cooling method from a slot with various mass flow rates is used in present work. The numerical code is validated with similar cases in literatures before conducting runs. Three different types of cooled flow passage configuration were tested when the flight Mach number is 6. Results indicate that the optimum configuration is the forward inclined angle of 225 degree cavity model over tested ranges of mass flow rate of coolant. Comparison of .area-averaged film cooling performance among tested cases shows that the mass flow rate of 0.125 kg/s is suitable for cooling down the surface temperature of IR window below 500K. There is a minor influence of attack angle on the film cooling performance of slot flow over present IR window.