附加质量及惯性矩对于大型飞艇气动性能和开环控制响应的影响

Influence of Added Mass and Moment on Aerodynamic Performance and Open-loop Response of Large Airship

在临近空间飞行的飞艇体积庞大以保持自身浮力克服重力,排挤的大量空气在黏性效应下对飞艇的反作用力可形成附加在飞艇表面的附加质量或者附加力矩,在工程上通常忽略或简单估算,显著影响大型飞艇的飞行稳定性。该文基于数值模拟和飞行仿真的手段,考察了附加质量和力矩对于大型飞艇气动性能和操纵性的影响。针对倒Y型尾翼布局的大型飞艇,采用六自由度非定常匀加速和重叠网格的CFD技术,得到了飞艇平动和转动的附加质量和力矩;基于计算结果,分析了布局形式对于沿y轴、z轴平动的附加质量、转动的附加力矩的影响差异;通过飞行动力学仿真手段,考察了附加质量和力矩对于飞艇开环控制的响应影响。CFD计算结果表明,布局形式使得飞艇沿y轴和z轴平动的附加质量、绕y轴和z轴转动的附加惯性矩近似相等;飞行仿真结果表明,考虑附加质量和力矩情况,飞艇对于开环控制的响应速度更慢,由此引起的响应迟滞可降低操控性,不可忽略。

The airship flying in the near space is bulky to maintain its own buoyancy and overcome the gravity.The reaction force of the large amount of displaced air on the airship under the viscous effect can form added mass or moment attached to the surface of airship,which is usually ignored or simply estimated in the engineering,which significantly affects the flight stability of large airship.Based on numerical simulation and flight simulation,the influence of added mass and moment on aerodynamic performance and manipulation of large airship was studied.The added mass and moment of the translation and rotation of a large airship with Y-type empennage were obtained by using the CFD technique of unsteady uniform acceleration with six degrees of freedom and overset mesh.Based on the results,the influence of the layout on the added mass of translation and moment of rotation along the y-axis and z-axis were analyzed.The influence of added mass and moment on the open-loop response was investigated by method of flight dynamics simulation.The results show that the added mass of the airship for translation along the y and z axes and the added moment for rotation around the y and z axes are approximately equal because of the layout of large airship.Otherwise,considering the added mass and moment,the speed of response of the airship is more slowly to open-loop control,which reduces manipulation.