The effect of jet flow pulsing and blowing ratio on a jet in cross flow has
been investigated. Preliminary jet flow studies were performed without cross flow
and an extensive study of jet with cross flow was done for a total of nine test
cases. The effect of velocities ratios of 0.85 and 3.4, as well as pulsing the jet flow
at 20Hz, was investigated in the near and far field of the jet. A comparison
between the jet in cross flow and an inclined cylinder in cross flow was also
performed.
Hot film measurements were taken within a grid of the flow field in the jet
symmetry plane and out of the symmetry plane. Instantaneous velocities were
generated at each location and mean velocity, RMS values, Reynolds stresses and
mean vorticity were calculated and compared for each case.
The higher velocity ratio case (VR=3.4) caused the jet flow to lift up
from the wall penetrating into the cross flow compared to the lower velocity ratio
case (VR=0.85) where the jet fluid remained attached to the wall and no lift off
was observed. The higher velocity ratio case resulted in increased mean
velocities, RMS values, Reynolds stresses and mean vorticity throughout the flow
field compared to the low velocity ratio case. Secondary turbulent structures were
discovered in the wake region of the inclined cylinder. Similar structures were
absent in the downstream flow region during the jet in cross flow experiments.
There was no significant effect on the jet trajectory as a result of jet
pulsing. For both velocity ratio cases the jet trajectory remained similar to the
steady cases. Jet pulsing increased the instantaneous velocity RMS levels and
Reynolds stresses in the near field of the jet, but did not seem to affect the RMS
levels and Reynolds stresses beyond x/d=4.
Jet pulsing had a significant effect on the distribution of spectral energy.
Distinct energy peaks are generated at the pulsing frequency and its harmonics.
The distinct spectral peaks were largest close to the jet exit and within the jet
flow, but were detectable throughout the entire flow field. / Graduation date: 2003
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/31689 |
| Date | 29 October 2002 |
| Creators | Stander, Arjan |
| Contributors | Liburdy, James A., Pence, Deborah V. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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