국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	A REAL-TIME METHOD FOR ESTIMATING VISCOUS FOREBODY DRAG COEFFICIENTS
저자	Stephen A. Whitmore, Marco Hurtado, Jose Rivera and Jonathan W. Naughton
Keyword	Base drag; Boundary layer; Hypersonic vehicles; Skin friction
URL	http://www.dfrc.nasa.gov/DTRS/2000/PDF/H-2394.pdf
보고서번호	NASA-TM-2000-209015
발행년도	2000
출처	NASA Dryden Flight Research Center
ABSTRACT	This paper develops a real-time method based on the law of the wake for estimating forebody skin-friction coefficients. The incompressible law-of-the-wake equations are numerically integrated across the boundary layer depth to develop an engineering model that relates longitudinally averaged skin-friction coefficients to local boundary layer thickness. Solutions applicable to smooth surfaces with pressure gradients and rough surfaces with negligible pressure gradients are presented. Model accuracy is evaluated by comparing model predictions with previously measured flight data. This integral law procedure is beneficial in that skin-friction coefficients can be indirectly evaluated in real-time using a single boundary layer height measurement. In this concept a reference pitot probe is inserted into the flow, well above the anticipated maximum thickness of the local boundary layer. Another probe is servomechanism-driven and floats within the boundary layer. A controller regulates the position of the floating probe. The measured servomechanism position of this second probe provides an indirect measurement of both local and longitudinally averaged skin friction. Simulation results showing the performance of the control law for a noisy boundary layer are then presented.