平流层飞艇驻空过程热结构耦合特性

Thermal-structure coupling characteristics of flexible envelopes for stratospheric airships at float conditions

考虑太阳辐射、红外辐射、内外对流换热和太阳电池传热影响,建立了平流层飞艇驻空热模型,考虑薄膜褶皱和充气状态特征,建立了平流层飞艇囊体结构有限元模型。在模型验证基础上提出基于分区耦合策略的热结构耦合计算方法,对平流层飞艇昼夜驻空过程的热结构耦合特性进行仿真分析,得到典型飞行工况下囊体温度、变形和应力分布及随时间变化规律。计算结果表明:太阳辐射和太阳电池传热特性对囊体温度分布、变形和应力影响较大,在设计工况条件下,太阳电池铺设边界处最大温差达到60K,昼间囊体顶部最大径向位移达到1.5m,太阳电池铺设边界处最大轴向和环向应力分别约为82MPa和140MPa。在夜间囊体压差较小的情况下,囊体中部出现明显褶皱变形,囊体水平对称面以下部位褶皱幅值达到1.1m,对平流层飞艇结构性能有重要影响。

A three-dimensional transient thermal model for stratospheric airships during floating is developed,considering the effects of solar radiation,infrared radiation,internal and external convective heat transfer,and solar array heat transfer.The finite element model of the envelope structure for stratospheric airships is established,taking into account the characteristics of thin-film wrinkles and inflation status.Based on the model validations,the computational method of thermal-structure coupling is proposed according to the partitioned coupling strategy.The thermal-structure coupling characteristics of stratospheric airships at float conditions during day and night are simulated and analyzed to obtain the distributions of temperature,deformation and stress of envelopes and their temporal variation rules.The computational results show that solar radiation and solar array heat transfer characteristics have significant effects on the temperature distribution,deformation,and stress of envelopes.Under design conditions,the maximum temperature difference reaches 6o K at the layout boundary of the solar array,the maximum radial displacement at the top of envelopes during daytime reaches 1.5 m,and the maximum axial stress and the maximum circumferential stress at the layout boundary of the solar array are approximately 82 MPa and 140 MPa,respectively.There are obvious wrinkle deformations in the middle of envelopes with the wrinkle amplitude reaching 1.1 m below the horizontal symmetry plane at night under lower differential pressure conditions,which has important impacts on the structural performance of envelopes for stratospheric airships.