This study investigates the effect of chordwisely modulated tip injection on the
flow and turbulence characteristics of the tip vortex through experimental
measurements downstream of a rectangular half-wing that has an aspect ratio of
three. This injection technique involves spanwise jets at the tip that are issued from
a series of holes along the chord line normal to the freestream flow direction. The
injection mass flow rate from each hole is individually controlled using computer
driven solenoid valves and therefore the flow injection geometrical pattern at the
tip can be adjusted to any desired waveform shape, with any proper injection
velocity. The measurements are performed in a blow-down wind tunnel using
Constant Temperature Anemometry and Kiel probe traverses as well as
Stereoscopic Particle Image Velocimetry. Current data show consistent trends with
v
previously observed effects of steady uniform tip injection such as the upward and
outward motion of the vortex as well as increased levels of turbulence within the
vortex core. The vortex size gets bigger with injection and the total pressure levels
get reduced significantly near the vortex core. The injection pattern also seems to
affect the size of the wing wake as well as the wake entrainment characteristics of
the tip vortex. Depending on the injection waveform pattern and injection
momentum coefficient the helicoidal shape of the tip vortex also seems to get
affected.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12613780/index.pdf |
| Date | 01 September 2011 |
| Creators | Ostovan, Yashar |
| Contributors | Oguz, Uzol |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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