Fabrication and Characterization of a Large-array Surface-mount Hot-film
Open Access
- Author:
- Wang, Sean
- Graduate Program:
- Aerospace Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 17, 2023
- Committee Members:
- Mark A Miller, Thesis Advisor/Co-Advisor
Xin Ning, Committee Member
Amy Pritchett, Program Head/Chair
Tamy Guimarães, Committee Member - Keywords:
- Hot-film
Array
PIV
Surface-mounted
Large-scale
Fabrication
Anemometry
Characterization - Abstract:
- A surface-mounted hot-film is a thin, flexible resistive sensor that can be used to measure the velocity, wall shear stress, or temperature in a flow. The flexible and compact nature of hot-films combined with their broad measurement capabilities make them versatile sensors for measuring flow on a variety of surfaces. This thesis is aimed at developing and characterizing a hot-film array for large-scale applications such as wind turbines and natural laminar flow airfoils. A fabrication method was created for for a large surface-mounted hot-film array, outlining the steps in the fabrication process and materials used. In addition to fabrication, an analysis of the hot-film response under static and dynamic conditions was also performed. Driving of the hot-film using both a constant current anemometer as well as a constant temperature anemometer was explored, which found that the constant current anemometer was too unreliable and inconsistent for assessment of the flow. An alternative measure of the hot-film output(s) was also explored in the integrated variance of the voltage output, which showed variation due to a change in the flow condition over the sensor. Fluorescent oil-film and particle image velocimetry were used to validate the variance output of the hot-film(s) under static conditions, and confirmed generally that a higher variance value, on the order 10^−4 V, indicated attached or unsteady flow, and lower variance values, 10^−6-10^−7 V, indicated separated or low velocity flow. Gusting inflow in dynamic testing was used to evaluate the hot-film performance under unsteady conditions, which seemed to generally corroborate the integrated variance values measured during static testing. However, uncertainties in the dynamic PIV results due to unsteady flow and limited image samples did not allow for definitive conclusions to be drawn for the hot-films under unsteady conditions.