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A Real-Time Method for Estimating Viscous Forebody Drag CoefficientsThis 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.
Document ID
20000011505
Acquisition Source
Armstrong Flight Research Center
Document Type
Conference Paper
Authors
Whitmore, Stephen A. (NASA Dryden Flight Research Center Edwards,CA United States)
Hurtado, Marco (NASA Dryden Flight Research Center Edwards,CA United States)
Rivera, Jose (University of South Florida Tampa, FL United States)
Naughton, Jonathan W. (Wyoming Univ. Laramie, WY United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 2000
Subject Category
Aircraft Design, Testing And Performance
Report/Patent Number
NASA/TM-2000-209015
AIAA Paper 2000-0781
H-2394
NAS 1.15:209015
Meeting Information
Meeting: 38th Aerospace Sciences
Location: Reno, NV
Country: United States
Start Date: January 10, 2000
End Date: January 13, 2000
Funding Number(s)
PROJECT: RTOP 529-50-04-T2-RR
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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