Studies on performance evaluation method of a wing in surface effect

WIG(地效机翼)或WISE S(地效机翼)有望成为未来海上高速航行器之一。本文从3个角度对假体的性能评价方法进行了研究：1.假体绕流场的表述及近似求解方法从摄动法的角度出发，研究了三维假肢的三维效应。由于升力线理论中尾涡的下洗效应可以忽略，因此构造了考虑翼尖效应的环流分布的局部解，并在跨中区域应用了二维解。改进了二维假肢在规则海面上的非定常运动近似解方法，解决了二维假肢的辐射和绕射问题。基于入射波的船舶运动相位延迟不仅取决于基于假肢总长度的普通频率，而且还取决于新定义的基于出现不足长度的频率参数。二维假肢的形状优化利用非线性规划方法，得到具有最大升力系数的二维假肢截面。在一定的约束条件下，得到了波浪形的截面。应用格林函数对假发周围的流场进行了二维WIGA数值分析的兴波效应。用线性涡流格子单元来表示厚厚的假发，效果很好。

WIG( Wing In Ground effect) or WISE S (Wing in Surface Effect Ship) is expected in future as one of high speed vehicles on seaway. Wing section with flat characteristics in motion has to be developed to avoid unexpected ship motion in sea due to nonlinearity of surface effect.From 3 points of view, studies on performance evaluation method of WIG are made as followings :1. Formulation and approximate solution method of flow field around a WIG(l)High aspect ratio approximation of 3D WIGFrom the view point of perturbation method, a study is made to clear 3D effects of WIG.Since the downwash effect due to the trailing vortex seen in the lifting line theory is negligible, local solutions of circulation distribution with wing tip effect are constructed and 2D solution is applied in the mid span area. Composite solution of both areas shows good agreement in whole area with a computational solution.(2) Unsteady motion of 2D WIG in regular seaApproximate solution method is enhanced to solve a radiation and diffraction problem of 2D WIG.Phase late of ship motion based on incident wave is dependent not only on the ordinary frequency rate based on whole WIG length but also on the newly defined frequency parameter based on a deficient length in appearance.2. Shape optimization of 2D WIGIt is intended to obtain a 2D WIG section with maximum Lift coefficient by using a nonlinear programming method. Under some restricted condition a wavy cross section is obtained.3. Wave generation effect of 2D WIGA numerical analysis of flow field around a WIG is made applying Green's function with the effect of wave generation. Linear vortex lattice element to represent a thick WIG gives good results.