不同边界扰动形式对充气天线反射面形面精度的影响

充气天线的性能主要取决于其形面几何精度。该文以几何非线性有限元法为基础,对不同焦径比和口径的天线反射面进行分析,探讨了三种具有代表性的边界扰动分布形式(均匀扰动、局部扰动及波形扰动)对天线反射面几何形状及应力的影响特性及原因,并分别获得了形面精度对这三种扰动的敏感度。研究从影响区域、影响值大小、影响敏感度及褶皱分布等几个方面对三种扰动形式进行了定性和定量的比较,得到如下主要结论:均匀扰动及波形扰动对整个曲面形状均有影响,在边界影响区曲面会同时产生平移和曲率变化,中间区域则主要发生曲面平移。局部扰动则只对局部区域有影响;三种扰动形式中,在扰动值相同的情况下,均匀扰动引起的误差值最大,但形面误差值对局部扰动和波形扰动更敏感;除施加向外均匀扰动时无褶皱以外,其他扰动形式均会导致在影响区域内出现褶皱。此外,研究还探讨了天线焦径比和口径的影响。最后,在上述研究成果的基础上给出了反射面形面精度被动控制和主动控制的合理建议。

STABILITY OF 3-D DISTURBANCE WAVES ON BOUNDARY LAYER WITH DISTRIBUTED LOCAL ROUGHNESS

The numerical solution of the stable basic flow on a 3-D boundary layer is obtained by using local ejection, local suction, and combination of local ejection and suction to simulate the local rough wall. The evolution of 3-D disturbance T-S wave is studied in the spatial processes, and the effects of form and distribution structure of local roughness on the growth rate of the 3-D disturbance wave and the flow stability are discussed. Numerical results show that the growth of the disturbance wave and the form of vortices are accelerated by the 3-D local roughness. The modification of basic flow owing to the evolvement of the finite amplitude disturbance wave and the existence of spanwise velocity induced by the 3-D local roughness affects the stability of boundary layer. Propagation direction and phase of the disturbance wave shift obviously for the 3-D local roughness of the wall. The flow stability characteristics change if the form of the 2-D local roughness varies.