국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	FOREBODY FLOW VISUALIZATION ON THE F-18 HARV WITH ACTUATED FOREBODY STRAKES
저자	David F. Fisher and Daniel G. Murri
Keyword	Aircraft; F-18; Flight; Flight Test; Flow visualization; Forebody; Smoke; Strake; Vortex; Vortical flow
URL	http://www.dfrc.nasa.gov/DTRS/1998/PDF/H-2254.pdf
보고서번호	NASA-TM-1998-206556
발행년도	1998
출처	NASA Dryden Flight Research Center
ABSTRACT	Off-surface smoke flow visualization and extensive pressure measurements were obtained on the forebody of the NASA F-18 High Alpha Research Vehicle equipped with actuated forebody strakes. Test points at alpha = 50 deg were examined in which only one strake was deflected or in which both strakes were deflected differentially. The forebody pressures were integrated to obtain forebody yawing moments. Results showed that small single strake deflections can cause an undesirable yawing moment reversal. At alpha = 50 deg, this reversal was corrected by deploying both strakes at 20 deg initially, then differentially from 20 deg to create a yawing moment. The off-surface flow visualization showed that in the case of the small single strake deflection, the resulting forebody/strake vortex remained close to the surface and caused accelerated flow and increased suction pressures on the deflected side. When both strakes were deflected differentially, two forebody/strake vortices were present. The forebody/strake vortex from the larger deflection would lift from the surface while the other would remain close to the surface. The nearer forebody/strake vortex would cause greater flow acceleration, higher suction pressures and a yawing moment on that side of the forebody. Flow visualization provided a clear description of the strake vorticies fluid mechanics.