摘要
当超声速或高超声速来流经过压缩折角时,由于壁面的位移效应,折角附近往往出现较强的逆压梯度,进而很可能导致流动分离,并伴随着激波与边界层干扰问题的出现.在工程应用中,流动分离会带来诸多不利因素.一个抑制流动分离的有效措施是在折角的上游引入定常的壁面抽吸单元.基于大Reynolds数渐近理论框架下的三层结构理论,文章研究了壁面抽吸抑制层流边界层分离的机理.研究发现,只要抽吸元被安置在折角上游O(R-3/8L)范围内,决定抑制效果的关键参数是抽吸的流量,而与抽吸元的位置无关;同时改变抽吸元的宽度和抽吸速度而保持抽吸流量不变并不影响其对分离区的抑制效果.
When a supersonic or hypersonic flow propagates over a compression ramp , a remarkable adverse pressure gradient may appear near the corner due to the displacement effect of the wall , possibly leading to a separation in the vicinity of the corner , as well as the potential emergence of the shock-boundary-layer interaction.The separation could result in a variety of unfavorable factors in engineering applications.An effective tool to reduce flow separation is to introduce a steady suction slot on the wall upstream of the corner.Based on the triple-deck theory under the large-Reynolds-number asymptotic framework , this paper studied the mechanism of the suppression effect of the wall suction on the laminar-boundary-layer separation.It is found that , as long as the suction slot is arranged at a position O(R -3/8 L) upstream of the corner , the do-minant parameter that determines the suppression effect is the suction flux , which is irrelevant to the location of the suction slot;changing the width and velocity of the suction slot simultaneously but keeping the suction flux unchanged does not affect the suppression effect on the separation zone.
作者
董明
赵慧勇
DONG Ming;ZHAO Hui-yong(Laboratory for High-Speed Aerodynamics , Tianjin 300072 , China;China Aerodynamics Research and Development Center , Mianyang 621000, China)
出处
《气体物理》
2019年第2期17-29,共13页
Physics of Gases
基金
国家自然科学基金(11772224)
关键词
超声速边界层
抽吸
分离
压缩折角
三层结构
supersonic boundary layer
suction
separation
compression ramp
triple deck
