临近空间飞艇内部自然对流的流场特征仿真研究

针对临近空间飞艇，对其内部氦气的自然对流特征进行了数值模拟。首先采用计算流体力学方法，并利用自编的用户自定义函数将外部的温度边界条件导入壁面网格。进而，在不同的稳态条件下，通过对内部氦气压力、温度、速度的分布等流场特征参数的研究，分析了临近空间飞艇内部气体自然对流的运动特性及其影响规律，并对自然对流非稳态变化过程进行了初步的探索。仿真结果表明，在临近空间环境下，飞艇内部氦气的自然对流，对于内部氦气自身的热交换具有一定程度的促进作用，而对蒙皮受力和结构安全性影响很小。

Simulation Research on Natural Convection Characteristics inside Near Space Airship

Aiming at the near space airship, the natural convection characteristics of the helium inside an airship are simulated numerically. First, based on the computational fluid dynamics method and User-Defined function, external temperature boundary condition is led into the wall grids for the simulation. Then, under conditions of different steady states, the motion characteristics and influence regulation of natural convection inside the airship are analyzed by the characteristic parameters of flow field such as distribution of pressure, temperature, speed. Besides, the process of an unstable state is also studied preliminarily. The simulation results show that under environment of the near space, natural convection inside an airship has some active influence on heat exchange for helium; but the influence is very weak on stress of skin and structural safety.