前掠翼气动特性研究

On Forward-Swept Wing's Aerodynamic Characteristics

为适应飞机新布局发展的需要,进行了前掠翼空气动力特性的低速实验研究。研究内容包括:单独机翼和翼身组合体的纵横向气动特性、流谱及旋涡特性。研究结果表明:前掠翼具有良好的升阻特性,力矩特性及失速特性,可以提供较大的可用升力和良好的大迎角大侧滑角机动性。以上优点在翼身组合体上更为明显。实验发现前掠翼后缘出现后缘涡,观察了前掠翼特有的前后缘涡系的发生和发展,分析了产生前后缘涡系的原因及前后缘涡系对气动特性的影响。

Based on the results,of oil flow visualization and vortex measurement,the flow mechanism and aerodynamic characteristics of forward-swept wing are investigated.The aerodynamic characteristics of forward-swept wings have been an interesting subject for aerodynamicists and aircraft designers in recent years [1,2,5,6,7].The vast majority of the investigations have been limited to aerodynamic characteristics of forward-swept wing as compared with those of backward-swept wing[5 et al].The main contribution of the present paper is to offer a comparatively thorough discussion of important aspects of flow pheno- mena as related to wing aerodynamic characteristics.This paper studies expe- imentaly wing alone and wing-body combination.The main conclusions are as follows: 1)The variation of wing aerodynamic characteristics is largely determined by the occurrence,development,and break-up of wing's leading edge and trail- ing edge vortices,especially for the forward-swept wings. 2)It is experimentally found that when the angle of attack increases.vortex occurs at the trailing edge of the forward-swept wing,and this vortex is secon- dary to that of the leading edge.Such vortex is stronger than that for swept-back wing and its control region on wing area is also larger;so its effect on surface- flow and aerodynamic characteristics is much more noticeable,especially at high angles-of-attack. 3)The forward-swept wings possess good lift,drag,and moment characteri- stics,especially their PST(post-stall)behaviour.Good PST behavior is indis- pensable to new-generation aircraft(Herbst's new idea of“supermaneuverability”). 4)The flow separation on an forward-swept wing first starts inboard and remains attachad at the tip.Thus,the forward-swept wing has very impressive roll control,even at very high angles of attack,because the attached tip flow on the forward-swept wing allows ailerons to remain effective with high control power.For this reason the forward-swept wing may be able to provide good maneuverability at high angle of attack and at high sideslip area.This is also essential for“supermaneuverability aircraft”.