Wind tunnel experiments are conducted to understand the positive pitching moment of a configuration with chined forebody at high angles of attack. Firstly, the trend of pitching moments with angles of attack can be divided into zones of linear growth (0°-15° angle of attack), nonlinear growth (17.5°-32.5° angle of attack) and decay (35°-65° angle of attack). In the zone of linear growth, the pitching moment increases linearly, and the attached flowis observedat first and the inlet leading-edge vortex and wing vortex begin to form as the angles of attack increase. In the nonlinear growth zone, the pitching moment increases nonlinearly, and the nose vortex appears and becomes incrementally strong. Both the inlet leading-edge vortex and wing vortex become more intensive and then begin to burst. In the decay zone, the pitching moment gradually decreases and the nose vortex continues to strengthen and break down at a sufficient high angle of attack. The inlet leading-edge vortex exhibits a decay trend while the wing vortex completely bursts. Secondly, it is observed that the chined forebody is the main contribution component to the positive pitching moment. And the nose vortex over the chine forebody plays a dominant role in generating the positive pitching moment. At 40° angle of attack, due to the strong suction of the nose vortex, the sectional pitching moments reach the maximum at the leading edge of the inlet. In the end, the technique using a forebody spoiler is developed to control the positive pitching moments effectively at high angles of attack. With the forebody spoiler on, the positive pitching moment can be reduced by 62% at 40° angle of attack because by deploying the forebody spoiler, the vorticity of nose vortex is decreased and results in a reduced normal force and positive pitching moment provided by the chined forebody. The downside of the control technique is that the forebody spoiler may lead to some losses in lift and additional drag. The Reynolds number in this paper is 2.59×105 based on the characteristic width of the chined fuselage.
LI Qian
,
DONG Chao
,
QI Zhongyang
,
WANG Yankui
. Pitching moment character and its control using forebody spoiler over a configuration with chined fuselage[J]. ACTA AERONAUTICAET ASTRONAUTICA SINICA, 2019
, 40(4)
: 122448
-122448
.
DOI: 10.7527/S1000-6893.2018.22448
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