TURBULENT BOUNDARY LAYER FLOW OVER SURFACE-MOUNTED CIRCULAR CAVITIES

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TURBULENT BOUNDARY LAYER FLOW OVER
SURFACE-MOUNTED CIRCULAR CAVITIES
Background
Cavity flows include the flow over vehicle
features such as landing gear wheel wells on
aircraft and sun roofs on automobiles. Cavity
flows can greatly increase drag and noise.
Deployed landing gear on a Dassault Mirage 2000
aircraft. (Photo from www.airliners.net)
Objective
To understand and control the asymmetric flow for
circular cavities with h/D 0.5, and to probe
for a link between drag trends and frequency
signatures.
Top and Side views of experimental cavity setup.
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Research Carried Out
Testing was done in a wind tunnel with a
surface-mounted cavity model. Mean and
fluctuating surface pressure distributions were
measured in the cavity. Velocity profiles were
measured in the cavity wake using a hot-wire
probe.
Above Streamwise wake velocity for two cavity
depths (blue spots indicate higher streamwise
velocity loss), Below Left Acoustic spectra at
three cavity depths
Key Findings
A reliable control mechanism was developed for
the flow at h/D 0.5 and a strong peak was found
at 150 Hz for this geometry, suggesting that it
may be related to the flow asymmetry and extra
drag.