Measurement of unsteady boundary layer developed on an oscillating airfoil using multiple hot-film sensors
Measurement of unsteady boundary layer developed on an oscillating airfoil using multiple hot-film sensors
复制标题
DOI：
10.1007/s003480050214
复制
发表时间：
1998-07-01
影响因子：
2.4
通讯作者：
Basu, S
中科院分区：
文献类型：
--
作者：
Lee, T;Basu, S
前缘停滞点、分离点和再附着点的时空演变以及非定常边界层状态在6英寸的上表面发展。使用140个紧密分布的多热膜传感器(MHFS)对Chord NACA 0012翼型模型进行了测量，该模型在静失速角内外以正弦方式振动。MHFS测量结果表明：(1)相对于静态情况，层流分离点和转折点延迟，再附着和再层化随α减小而增加；(2)俯仰运动有助于保持附面层与较大攻角的附面；(3)动态失速过程是由前缘区的湍流分离和尾缘区的反转引起的；(4)动态失速过程不是源于层流分离气泡的破裂，而是湍流边界层的破裂。MHFS的测量还表明，可以同时非侵彻地检测到由翼型运动和流动扰动引起的流动不稳定。非定常边界层的MHFS特征对于研究快速机动飞机、直升机旋翼桨叶和机翼能源机械产生的非定常分离流场是有用的。
The spatial-temporal progressions of the leading-edge stagnation, separation and reattachment points, and the state of the unsteady boundary layer developed on the upper surface of a 6 in. chord NACA 0012 airfoil model, oscillated sinusoidally within and beyond the static-stall angle, were measured using 140 closely-spaced, multiple hot-film sensors (MHFS). The MHFS measurements show that (i) the laminar separation point and transition were delayed with increasing a and the reattachment and relaminarization were promoted with decreasing alpha, relative to the static case, (ii) the pitchup motion helped to keep the boundary layer attached to higher angles of attack over that could be obtained statically, (iii) the dynamic stall process was initiated by the turbulent flow separation in the leading-edge region as well as by the onset of flow reversal in the trailing-edge region, and (iv) the dynamic stall process was found not to originate with the busting of a laminar separation bubble, but with a breakdown of the turbulent boundary layer. The MHFS measurements also show that the flow unsteadiness caused by airfoil motion as well as by the flow disturbances can be detected simultaneously and nonintrusively. The MHFS characterizations of the unsteady boundary layers are useful in the study of unsteady separated flowfields generated by rapidly maneuvering aircraft, helicopter rotor blades, and wing energy machines.