Title page for ETD etd-06162009-063052
|Type of Document
||Development of a cantilever beam, capacitive sensing, skin friction gage and suppporting instrumentation for measurements
||Master of Science
|Wicks, Alfred L.
|Dancey, Clinton L.
|Diller, Thomas E.
- Skin friction (Aerodynamics)
|Date of Defense
A cantilever beam type, capacitive sensing, skin friction gage has
been developed. A prototype along with supporting electronics has
been constructed. The cantilever beam gage is a change of area
variable capacitive transducer. It is designed to measure the wall
shear stress in a short duration, supersonic flow. The supporting
electronics consists of an electrical oscillator for frequency
modulation, and a frequency demodulator. The change in capacitance
due to the shear stress in the flow modulates the output signal of
the oscillator, which is then demodulated to extract a voltage
signal which corresponds to the change in capacitance of the gage.
The gage and the electronics were constructed from simple,
inexpensive components for the purpose of proving the concept of a
capacitive sensing transducer. static calibrations have been
completed and statistical analysis has been done to test the
performance of the gage. A 0.12 mV response due to the expected
98.1 g m/s2 force input of the skin friction of the Mach 2.9 design
flow, over the 0.49 in2 (316.1 mm) area of the gage's sensing head,
was measured as the average output of the skin friction gage
instrumented with stainless steel strips.
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