Dirichlet边界条件低阶面无法的改进

 对基于内部Ｄｉｒｉｃｈｌｅｔ边界条件的低阶面元法的速度分布提出一个改进算法。由极限过程结合高阶奇异积分的解析计算直接计算物面速度分布取代传统的偶强梯度法,以避免偶极强度边缘外推的困难。改进算法改善了ＶＳＡＥＲＯ分析中诱导阻力系数估值过低的问题。对后掠翼、前掠翼和翼身组合体等算例的计算表明,计算结果的准确度与高阶面元法相近。此外,直接积分法还可正确地计算外部流场速度分布。这是偶强梯度法不能完成的。

AN IMPROVEMENT FOR LOWER-ORDER PANEL METHOD BASED ON THE DIRICHLET BOUNDARY CONDITION

An improved algorithm for velocity field of general configurations is presented for low-order panel method based oD the internal Dirichlet boundary condition,A direct calculating method for the velocity distribution by means of a limit process combining with analytic evaluation of high-order singular integrals instead of the conventional method of doublet strength gradient is devised in order to avoid the difficulty of edge extrapolation of doublet strength.The problem that the in-duced drag coefficient obtained from the VSAERO analysis is substantially underpredicted has dis-appeared for the present improved algorithm. Illustrative calculations for several test cases such as swept back wing,swept forward wing and wing-body combination show that the accuracy of re-sults may be improved and is competitive with high-order panel method.In addition,the present direct integral method can be used to evaluate the velocity distribution for external flow field cor-rectly where the method of gradient cannot be used at all.