High-Frame-Rate Oil Film Interferometry

<h1><a></a></h1> <p>High-Frame-Rate Oil Film Interferometry</p> <p>Jonathan Charles White</p> <p>This thesis presents the design and implementation of a high-frame-rate oil film interferometry technique (HOFI) used to directly measure skin friction in time dependent flows. Experiments were performed to determine the ability of a high-speed camera to capture oil film interferometry images. HOFI was found to be able to capture these interferometry images at frequencies up to 10⁵ Hz. Steady laminar and turbulent flows were tested. Transient flows tested consisted of a wind tunnel ramping up in velocity and a laminar boundary layer which was intermittently tripped to turbulence by puffing air out of a pressure tap. Flow speeds ranged from 0 to 108 ft/sec and 10 and 50 cSt Dow Corning 200 dimethylpolysiloxane silicone oil was used. The skin friction was determined from the rate of change of the height of the oil film using lubrication theory. The height of the oil film was determined from the high speed camera interferogram images using a MATLAB script which determined fringe spacing by fitting a four-parameter sine wave to the intensity levels in each image. The MATLAB script was able to determine the height of the oil film for thousands of interferogram images in only a few minutes with sub-pixel error in fringe spacing. The skin friction was calculated using the oil film height history allowing for the direct measurement of skin friction in time dependent flows. </p>

Name thesis:degree_name

MS in Mechanical Engineering

Discipline thesis:degree_discipline

Mechanical Engineering

Year dc:date.available

2011

Author dc:creator

• White, Jonathan Charles

Contributors dc:contributor

• Russell Westphal

• oil-film interferometry
• skin friction
• shear stress
• lubrication theory
• unsteady flow
• high speed camera
• Aerodynamics and Fluid Mechanics

Identifier

10.15368/theses.2011.59

OAI identifier oai:identifier

oai:digitalcommons.calpoly.edu:theses-1606