Applications of Sodium/GH4099 Heat Pipes for Nose Cap Cooling

In this study, sodium/GH4099 heat pipes are proposed for nose cap cooling. X-51 nose cap-like sodium/GH4099 heat pipe spreaders were designed and prepared in China Academy of Aerospace Aerodynamics (CAAA). And their startup properties were tested at a 500 kW quartz lamp calorifier. The experimental results indicated that the sodium/GH4099 heat pipes startup successfully at heat flow of about 75 kW/m(2), displaying a uniform temperature of about 800 degrees C. On the other hand, startup failures were also found. Working fluid of sodium leaked out of the GH4099 shell, resulting in temperature distributions of 684-946 degrees C. The frozen startup limit of sodium is 2.4, satisfying the criterion for frozen startup. At simulated aerothermal conditions of Ma 5-7, the heat pipe can decrease the stagnation temperature effectively to be lower than end-use temperature of GH4099. Thus, it is concluded that sodium/GH4099 heat pipes are feasible for nose cap cooling.