Unsteady aerodynamic characteristics of a translating rigid wing at low Reynolds number
Abstract
Rectilinearly surging wings are investigated under several different velocity profiles and incidence angles. The primary wing studied here was an aspect ratio 4 rectangular flat plate. Studies on acceleration distance, ranging from 0.125c to 6c, and incidence angles 5°–45° were performed to obtain a better understanding of the force and moment histories during an extended surge motion over several chord-lengths of travel. Flow visualization and particle image velocimetry were performed to show the flow structures responsible for variations in force and moment coefficients. It was determined that the formation and subsequent shedding of a leading edge vortex correspond to oscillations in force coefficients for wings at high angle of attack. Comparing unsteady lift results to static force measurements, it was determined that for cases with large flow separation, even after 14 chords traveled at a constant velocity, the unsteady forces do not converge to the fully developed values. Forces were then broken up into circulatory and non-circulatory components to identify individual contributors to lift. Although it was observed that the “fast” and “slow” cases produced nearly identical vortex trajectories, circulation measurements confirmed that the faster acceleration case generates more vorticity in the form of a tighter, more coherent vortex and produces significantly more circulation than the slower acceleration case, which is consistent with the difference in force production.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Dec 01, 2015
- Source ID
- 10.1063/1.4936396
Entities
People
- Anya R. Jones
- Field Manar
- Kenneth Granlund
- Michael Ol
- Peter Mancini
Organizations
- Air Force Office of Scientific Research
- Air Force Research Laboratory
- United States Army Research Laboratory
- University of Maryland