Development of a cantilever beam, capacitive sensing, skin friction gage and supporting instrumentation for measurements

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.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Mechanical Engineering

Department dc:contributor.department

Mechanical Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1993

Author dc:creator

• Horvath, Istvan

Chair dc:contributor.committeechair

• Wicks, Alfred L.

Committee members dc:contributor.committeemember

• Diller, Thomas E.
• Dancey, Clinton L.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-06162009-063052

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/43315