NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Collections About News Help Login
Back to Results
Suppression of Dynamic Stall by Steady and Pulsed Upper-Surface BlowingThe Boeing-Vertol VR-7 airfoil was experimentally studied with steady and pulsed upper-surface blowing for sinusoidal pitching oscillations described by alpha = alpha(sub m) + 10 deg sin(omega t). The tests were conducted in the U.S. Army Aeroflightdynamics Directorate's Water Tunnel at NASA Ames Research Center. The experiment was performed at a Reynolds number of 100,000. Pitch oscillations with alpha(sub m) = 10 deg and 15 deg and with reduced frequencies ranging from k = 0.005 to 0.15 were examined. Blowing conditions ranged from C(sub mu) = 0.03 to 0.66 and F(+) = 0 to 3. Unsteady lift, drag, and pitching-moment loads were measured, and fluorescent-dye flow visualizations were obtained. Steady, upper-surface blowing was found to be capable of trapping a separation bubble near the leading edge during a portion of the airfoil's upward rotation. When this occurred, the lift was increased significantly and stall was averted. In all cases, steady blowing reduced the hysteresis amplitudes present in the loads and produced a large thrust force. The benefits of steady blowing diminished as the reduced frequency and mean angle of oscillation increased. Pulsed blowing showed only marginal benefits for the conditions tested. The greatest gains from pulsed blowing were achieved at F(+) = 0.9.
Document ID
19960016595
Acquisition Source
Ames Research Center
Document Type
Technical Publication (TP)
Authors
Weaver, D. (California Polytechnic State Univ. San Luis Obispo, CA United States)
McAlister, K. W. (Army Aviation Research and Development Command Moffett Field, CA United States)
Tso, J. (California Polytechnic State Univ. San Luis Obispo, CA United States)
Date Acquired
September 6, 2013
Publication Date
February 1, 1996
Subject Category
Aerodynamics
Report/Patent Number
A-95103
NAS 1.60:3600
NASA-TP-3600
USAATCOM-95-A-005
Accession Number
96N22239
Funding Number(s)
PROJECT: RTOP 505-59-87
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Related Records

There are no records associated with this record.
No Preview Available