Date of Award

12-2017

Degree Name

Master of Science in Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Dr. Tianshu Liu

Second Advisor

Dr. Parviz Merati

Third Advisor

Dr. Javier Montefort

Access Setting

Masters Thesis-Open Access

Abstract

This thesis describes how the Global Luminescent Oil-Film (GLOF) Skin-Friction Meter can be applied experimentally to extract skin-friction from a set of images. In this study, the effect of oil viscosity, experimental sample size, and step size were considered to see how they would affect the extracted skin-friction using the GLOF method. These results were then compared to published literature on skin-friction diagnostics of delta wings, based on observations of critical characteristics such as reattachment and separation lines. Delta wings of 50°, 55°, 60°, 65°, and 70° sweep angles were built and placed in the Small Wind Tunnel (SWT) at the Applied Aerodynamics Laboratory (AAL) in Western Michigan University (WMU). Luminescent oil was then applied to the surface of the delta wings and images were taken at different angle of attacks. All experiments were performed with a freestream velocity of 20 meters per second, and a corresponding Reynolds number of 250,000.

A study of step size, sample size, and oil viscosity showed that the extracted skin-friction fields are sensitive to these variables and that they are not mutually independent. The lack of numerical simulations and experiments performed at the same Reynolds and Mach number, means that the discussion in this thesis was largely observational in nature. In a nutshell, GLOF has the ability to quantitatively measure skin-friction on a global scale, which is desirable when trying to understand the interaction between the flow and the surface boundary layer for complex flows.

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