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M.S.
Research
William
J. Dalling
Resume
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OBJECTIVE: DESIGN AND IMPLEMENT A MEANS OF MEASURING WALL
SHEAR STRESS
ON A SURFACE WITH DISTRIBUTED ROUGHNESS |
| The design objective was to design
and implement a way to directly measure the wall shear stress that was
acting at critical locations on the flat and rough plate models.
These results could then be used as a comparison to other methods being
implemented.
A literature review revealed a variety of ways to measure wall shear stress
which can be viewed in a methods
chart (ppt) and a Comparison
Table A floating element sensor was chosen because of
it's ability to make direct shear measurements and it's compatibility to a
distributed rough surface. In this application, the floating sensor
will use strain gauges to detect "displacement" of the element
due to the shear stress. It is critical that the floating element be
aligned flush with the test surface. This is achieved with the use
of springs and alignment screws. |
See
design notes on Floating Element Sensor
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Design
Evolution of Floating Element Sensors
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Prototype #1, Square element Design
w/Flexure Beams |
Prototype #1 assembled on Calibration
Jig |
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Prototype
#2, Round Element Sensor pre-assembled |
Assembled
view of Prototype #2 with sensor casing |
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Each Floating
Element sensor is supported with flexure beams which are sensitive to the
fluid flow. Sensors will be mounted so that the element is flush
with top surface of test plate. Each flexure beam will be
instrumented with two strain gauges (forming a full bridge circuit) and
will output a signal proportional to the wall shear stress.
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FLEXURE BEAMS WITH STRAIN GAUGES |
SENSOR ON STAGING TEST PLATE WITH
FLUSH SURFACE |
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