地面颤振模拟试验中的非定常气动力模拟

 地面颤振模拟试验作为一种颤振研究的新方法,可以有效地弥补传统气动弹性试验的不足。对地面颤振模拟试验的主要难点,即非定常分布式气动力集成减缩加载的方法开展研究:基于亚声速偶极子格网法和活塞理论建立了亚声速以及超声速翼面的非定常气动力模型,通过曲面样条插值以及有理函数拟合获得了试验时域减缩气动力;提出以颤振关键模态的振型为优化目标,使用遗传算法搜寻气动力最优减缩位置的优化方法;建立了闭环系统的时域状态空间模型,使用颤振时域仿真结果与频域理论结果进行对比,对比发现二者误差可控制在3%以内。研究结果表明,该文提出的非定常气动力模拟方法可以很好地表征翼面非定常气动力分布特性,可以作为地面颤振模拟试验研究可靠的理论基础。

Simulation of the Unsteady Aerodynamic Forces for Ground Flutter Simulation Test

A novel method to determine the flutter speed and frequency i.e., the ground flutter simulation test, is proposed as a complementary method for traditional aeroelasticity tests. The key challenge of this new technique is the method to reduce the unsteady distributed aerodynamic forces to a few concentrated loads, and this is studied in this paper. The unsteady aerodynamic forces at the subsonic and supersonic Mach numbers of the wings are generated by using the subsonic doublet lattice method and piston theory. Subsequently the time-domain concentrated loads for testing are achieved by the use of the infinite plate spline method and the rational function approximation method. A genetic optimization is carried out to determine the best locations for the reduction of the unsteady aerodynamic forces, which takes the flutter related modes as the optimization objective. State-space modeling of the closed loop system is derived to observe the time-domain flutter results. The time-domain simulation flutter speeds have a very good agreement with the frequency-domain analysis results with an error which can be controlled to within 3%. The study demonstrates that the unsteady aerodynamic simulation method proposed in this paper can represent unsteady distributed aerodynamic forces for the wings and provid ecertain guidance for further ground flutter simulation studies.