Updating and Automating the Virginia Tech Single-Plate Interferometer

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Virginia Tech

The single-plate interferometer is a powerful flow visualization and aerodynamic measurement tool. It can provide full-field data for the density distribution in a non-intrusive manner, and it can be used for highly unsteady flows. While the device itself represents a large decrease in complexity over other forms of interferometry, the data reduction procedure has traditionally been laborious and difficult. To remove these difficulties and to improve the accuracy of the Virginia Tech interferometer setup, the software has been revamped into a black box design removing the need to handle the code directly. Furthermore, the software has been made to be platform independent by implementing the algorithms using the Java programming language. New hardware has also been added which further simplifies the setup procedure.

The improved setup and the new software is used to study the flow around a film cooled turbine blade in the Virginia Tech cascade wind tunnel. The study of this flowfield is used as a validation for the new algorithms and to illustrate the ease of use of the system. Through this analysis, the density distribution for the entire flowfield is acquired. Furthermore the use of Plexiglas as window material was tried. This proved to work, however the manufacturing processing of these windows proved relatively difficult. Studying the film layer close to the surface proved difficult because of inherent limitations with the single-plate interferometer.

image processing, optics, interferometer, flow visualization, film cooling