筒形机翼升阻力特性的数值研究

Numerical research of lift and drag properties of ring-wing

采用有限体积方法,基于多块结构化的贴体网格,求解预处理形式的NS方程,数值模拟了筒形涵道机翼的气动特性。得到了筒形涵道机翼的升力系数、阻力系数和升阻比等气动力参数,通过改变机翼外形和来流参数获得了气动特性随涵道长径比、来流迎角等参数的变化关系。计算结果表明:采用S3021翼型的筒形涵道机翼的阻力系数和升力系数随长径比的增大而减小,升阻比特性随长径比和迎角的变化均不是单调的,在长径比0.75和迎角5°时可得到较大升阻比。

A duct, also known as a ring-wing or an annular airfoil, is the main lifting surface on a lift augmented ducted fan （LADF） UAV. The aerodynamic properties of such a ring-wing is a key factor in the design of a LADF UAV. To meet this engineering requirement, flows about a series of ring-wings with different length to diameter ratio are simulated. NS equations with time derivatives preconditioned are solved using finite volume method on a multi-block boundary-conforming grid system. Lift coefficients, drag coefficients and lift to drag ratios are calculated, upon that the variations of these aerodynamic forces versus length to diameter ratio and angle of attack are obtained. The results show that lift coefficient and drag coefficient of ring-wing with S3021 airfoil decrease as length to diameter ratio increases, the variation of lift to drag ratio is not monotonic as length to diameter ratio and angle of attack increase, the maximum value of lift to drag ratio appears approximately at length to diameter ratio is 0. 75 and angle of attack is 5°.