刚度构型对飞艇定常流固耦合特性的影响研究

飞艇作为临近空间高分辨率观测的重要平台,力学性能研究非常重要。飞艇的主体材料一般由柔性蒙皮构成,容易在气动作用下产生较大的变形,存在较强的流固耦合效应,是其力学性能研究的关键。该文采用松耦合方法形成了定常流固耦合计算方法,并且针对流场与结构的模型展开了详细的计算,和实验结果进行了验证。针对不同刚度构型飞艇模型的计算结果显示:硬式飞艇不需考虑流场和结构的耦合效应,半硬式和软式飞艇的耦合效应较明显。其中半硬式飞艇,耦合效应主要影响区域为柔性最大的橡胶部分,考虑耦合效应后,飞艇位移变形量增加约5%。软式飞艇,变形最为明显的是飞艇的尾部和头部,在来流作用下会出现明显的抬头位移,最大位移增量为225%。此外还采用量纲分析方法,得到了艇体变形与膜材料弹性模量、内压、来流的变化规律。当模型与实物满足几何相似、材料相似和动力学相似的条件下,变形将满足几何相似律。

EFFECTS OF STIFFNESS ON THE CHARACTERISTICS OF STEADY FLUID-STRUCTURE INTERACTIONS OF AN AIRSHIP

An airship is used for high resolution earth observations in near space. The study of mechanical properties is important. An airship is made of flexible material, and it is prone to large deformation under the aerodynamic forces. The fluid-structure interaction effects should be considered. Loosely coupled method is adopted. An airship model was calculated to obtain the flow field and the structure distribution characteristics. The simulation results are verified by the experimental data. Results show that: the effect of fluid-structure interactions is not needed to consider for a rigid airship. For a semi-rigid airship, the rubber part is the main region affected by the coupling. The displacement is enlarged 5%. For a soft airship, the tail and head of the airship have the most obvious deformation. The maximum displacement increment is 225%. Moreover,the control parameters of airship deformation are attained by the dimensional analysis. The influences of the elasticity modulus, internal pressure, and flow condition are discussed. The deformation will satisfy the geometrical similarity law when the model meet the geometric, material, and dynamic similarity with the test model.