摘要
为了充分探讨近距耦合鸭式布局在大迎角机动飞行中的气动特点和控制技术,通过总结大量的流动显示和测力测压实验,以大迎角下鸭翼涡和主翼涡的干扰机理研究结果为基础,开展了鸭式布局涡系控制研究,旨在提出一种有效可行的大迎角鸭翼涡控制技术。结果表明:在鸭式布局中,鸭翼涡和主翼涡之间的干扰方式主要表现为涡系诱导、卷绕和破裂,特别是在大迎角下鸭翼涡与主翼涡在主翼头部区域通过诱导作用,在向下游发展中相互卷绕合并成单一集中涡,该集中涡后期因受逆压梯度和黏性的作用而出现破裂,由此将会明显损失涡升力,同时增加阻力。在这种情况下,如果对鸭翼进行展向吹气,可通过控制鸭翼涡,影响主翼涡的演变,改变涡系的诱导和卷绕,从而可以有效延迟主翼涡的破裂,达到增升减阻的作用。鸭翼展向脉冲吹气是通过迟滞效应而节省吹气量的有效方法,实验发现提高占空比、脉冲频率,可以使布局在较低的引气量下达到连续吹气的增升效果;在相同的增升效果下,脉冲频率越高,脉冲占空比越大,节省的吹气量也越大,在28°迎角时以0.3的吹气动量系数进行频率为5 Hz、占空比为0.2的脉冲吹气,即可达到以0.25的吹气动量系数连续吹气的升力幅值,节省吹气量可达76%。
The vortex interaction mechanism and control technology of the close-coupled canard configuration at high angles of attack have been reviewed,and the vortex control technology of canard-span wise continuous or pulse blowing have been analyzed and discussed in detail.The results show that the aerodynamic performances could be improved at middle and large angles of attack in canard configuration through the interactions between the canard vortex and the wing vortex.The flow field near the apex of the main wing is affected by the down-wash effect of the canard,in the following downstream development,the co-rotating vortex pair gradually merges into a single stable concentrated vortex by mutual introduction,and finally develops into the concentrated vortex breakdown.Through canard-spanwise blowing,the vortex interactions on the wing might be transformed so the vortex breakdown could be delayed,therefore the maximum lift and stall angle could be further enlarged and the drag force could be reduced.The canard-spanwise pulse blowing can save the blow volume through the hysteresis effect.Either larger duty ratio or higher pulse frequency is conducive to achieve the target lift with a lower bleed air volume.With the same lift increment,the higher the pulse frequency,the smaller the corresponding pulse duty ratio,and the greater the amount of blowing could be saved.For instance,compared with continuous blowing with volume coefficient of 0.25 at 28°,the pulse blowing with volume coefficient of 0.3 could achieve the same lift amplitude under the frequency of 5 Hz and duty cycle of 0.2,which saves the air volume up to 76%.
作者
刘沛清
易渊
LIU Peiqing;YI Yuan(Lu Shi Jia Laboratory,Beihang University,Beijing 100191,China)
出处
《空气动力学学报》
CSCD
北大核心
2020年第6期1034-1046,I0001,共14页
Acta Aerodynamica Sinica
基金
国家自然科学基金(11772033)。
关键词
鸭式布局
大迎角
涡控制
涡融合
展向吹气
脉冲吹气
canard configuration
high angle of attack
vortex control
vortex merger
spanwise blowing
pulseblowing