后缘发散翼型在宽体客机机翼设计中的应用

Applications of divergent trailing edge airfoil in wide-body airliner wing design

用计算流体力学手段,研究了在宽体客机机翼剖面上施加后缘发散修形设计可获得的收益。提出了一种使用幂函数表达扰动量的后缘发散修形设计方法,使用该方法研究了扰动幂次和后缘厚度对超临界翼型气动性能的影响规律,并对比了雷诺数4×10^(6)和2×10^(7)下后缘厚度对翼型阻力、力矩影响的差异。研究结果表明,后缘厚度是后缘发散翼型的关键参数,相同后缘厚度下雷诺数2×10^(7)的减阻效果不及雷诺数4×10^(6)。雷诺数2×10^(7)下,考虑跨声速减阻、亚声速增阻和低头力矩等因素后,后缘厚度取3‰c左右较为有利。尝试了后缘发散设计的两种应用思路,一是用来换取翼型厚度增加,二是用来调整机翼载荷分布。在翼型设计应用中,发现后缘厚度增加2‰c的修形量可使得最大相对厚度10.2%的超临界翼型在厚度放大到11.5%后仍具有不低于初始的升阻性能。在某宽体客机机翼方案上应用内翼1‰c和外翼2‰c的后缘厚度增量后,机翼-机身-短舱-吊挂构型可获得超过2 counts(1 count=阻力系数0.0001)的阻力下降,而不付出机翼厚度和阻力发散性能代价。

Computational fluid dynamics(CFD)method is used to evaluate the benefits of divergent trailing edge(DTE)modification in the wing design of a wide-body airliner.A power function is proposed to describe the disturbance for DTE,and effects of the power number and the trailing-edge thickness on the aerodynamic performance of a supercritical airfoil are studied,with comparison of the difference in the lift force and momentum between two Reynolds numbers,i.e.Re=4×10^(6) and 2×10^(7).It shows that the trailing-edge thickness is a key parameter of the DTE airfoil.For the same trailing-edge thickness,the drag reduction at Re=2×10^(7) is less than that at Re=4×10^(6).By taking into account the transonic drag reduction,subsonic drag and nose-down pitching moment increment at Re=2×10^(7),it is more reasonable to take the trailing-edge thickness around 3‰c.Two applications of the DTE design have been explored,i.e.exchanging for airfoil thickness increment,and adjusting the wing load distribution.With the DTE modification of a supercritical airfoil,a 2‰c increment of the trailing-edge thickness leads to the maximum relative thickness of the airfoil increased from 10.2%to 11.5%,while the lift-drag performance is still kept at the same level of the original one.When a trailing-edge thickness increment of 1‰c at inboard and 2‰c at outboard is applied to the wing of a wide-body airliner,a drag reduction of more than 2 counts(1 count=drag coefficient 0.0001)can be achieved in the wing-fuselage-nacelle-pylon configuration,without any penalty of wing thickness and drag divergence performance loss.