摘要
在西北工业大学NF 3风洞通过表面测压和物面油流实验以及在北京航空航天大学1.2m水洞利用染色线显示和激光片光技术,对尖头和钝头拱形细长体大迎角绕流结构和气动特性进行了研究。结果表明,尖头拱形细长体在大迎角下(45°≤α≤60°)表现出非对称多涡的复杂涡系流动现象,相应的截面侧向力CZ沿轴向呈现出类似正弦曲线形式的减幅振荡,并且侧向力幅值较大(1<CZ<3.5);而将尖头改为钝头,CZ的幅值比原来减小2/3(CZ<1),而且在某些滚转角下呈现侧向力分布基本为零的现象。文中分析了侧向力大幅度减小的机理,认为尖拱头部顶端变钝后,物面分离线由开式分离变为闭式分离,并且在顶端背风侧形成U形马蹄涡结构;马蹄涡的作用是约束背风侧2个主涡,抑制非对称的出现。
Experimental study on the flow structure and aerodynamic characteristics over a pointed nose and a blunt nose ogive-cylinder were conducted by streak and laser-induced fluorescence techniques in water tunnel of BUAA, and by surface pressure measurement in wind tunnel of NPU NF-3. The experimental results show that the structure around the pointed nose slender body at high angles of attack(45°≤α≤60°)is multi-asymmetric vortices flow, accompanied by sinusoid like sectional side force distribution, with a swing amplitude of 1<｜C_Z｜<3.5; whereas the pointed nose was changed to a blunt nose, C_Z decrease remarkably to a value of ｜C_Z｜<1, which is 1/3 of previous one, and C_Z even is zero fancily at some different rolling angle states. The paper discusses the mechanism of governing the decrease of side fore distribution. i.e. while the pointed nose was changed to a blunt one, the open type surface separation line becomes a close type, a U shape horse shoe vortex structure forms on the lee side of the slender body. The functions of this structure are to hold in the two main nose vortices,and to restrict the emergence of asymmetry.
出处
《空气动力学学报》
EI
CSCD
北大核心
2004年第1期7-13,共7页
Acta Aerodynamica Sinica
基金
国家自然科学基金(10172017)
翼型叶栅空气动力学国防科技重点实验室基金(00JS51.3.2HK01).
关键词
头部钝度
大迎角空气动力学
涡系结构
飞行器
侧向力
实验
slender body
asymmetric vortices
flow pattern
nose bluntness
high angle of attack aerodynamics
