Abstract The thermal behavior of cryogenic propellant tanks is crucial issue in the operation of cryogenic propulsion systems. Herein, ground experiments were conducted in a 600-mm-diameter cryogenic tank filled with liquid nitrogen. As pre-pressurants, gaseous helium and gaseous nitrogen (of the same species as the liquid), were used to investigate its effect in accordance with actual propulsion systems. The tank was sealed after pre-pressurization to observe the self-pressurization. The evaporation rate and heat flow in the tank were estimated based on pressure and temperature measurements. In addition, the axial liquid temperature distribution was obtained through the liquid draining from the tank bottom, and a thermal stratification model was developed. These results demonstrated that the type of pre-pressurant significantly affected the thermal behavior in the tank. A higher evaporation rate and higher liquid internal energy rise rate with a thicker thermal layer were observed in the helium pre-pressurization case. The lower nitrogen partial pressure in the helium case enhanced the vaporization and growth of the thermal layer. Estimation of the power balance in the tank demonstrated that not only the ullage but also the heat mass of the tank provided heat for the evaporation and thermal layer. The evaporation occurs mainly at the contact point between the tank skin and liquid surface. The nitrogen vapor rises in a thin layer along the tank skin because of buoyancy under nitrogen pre-pressurization; however, buoyancy is lower under helium pre-pressurization, and a radial vapor flow is probably produced from the contact point instead, leading to a higher heat flux to the liquid.

中文翻译：

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不同压力下低温推进剂罐内热行为的实验分析

摘要 低温推进剂罐的热行为是低温推进系统运行中的关键问题。在这里，地面实验是在一个充满液氮的 600 毫米直径的低温罐中进行的。使用气态氦气和气态氮（与液体同种）作为预加压剂，根据实际推进系统研究其效果。罐体预加压后密封，观察自加压情况。罐中的蒸发率和热流是根据压力和温度测量值估算的。此外，通过罐底排液得到轴向液体温度分布，建立了热分层模型。这些结果表明，预加压剂的类型显着影响了罐中的热行为。在氦预加压的情况下，观察到更高的蒸发率和更高的液体内能上升率以及更厚的热层。在氦气情况下较低的氮分压增强了热层的蒸发和生长。罐内功率平衡的估计表明，不仅是空量，而且是罐的热质量为蒸发和热层提供热量。蒸发主要发生在罐皮和液面之间的接触点。由于氮气预加压下的浮力作用，氮蒸气沿罐皮呈薄层上升；然而，在氦气预加压下浮力较低，