Development of Unsteady Background-oriented Schlieren System in an Indraft Supersonic Wind Tunnel

Li, G., Wu, J., Kontis, K. , Wit, S. and Fan, Z. (2021) Development of Unsteady Background-oriented Schlieren System in an Indraft Supersonic Wind Tunnel. In: 11th Asia Conference on Mechanical and Aerospace Engineering ACMAE, Chengdu, China, 25-27 Dec 2020, 012052. ISBN 1742-6588 (doi: 10.1088/1742-6596/1786/1/012052)

Abstract

To visualize the flow in the test section of an indraft supersonic wind tunnel in the University of Glasgow as long as possible, a background-oriented schlieren system was built up preliminarily. A MATLAB program based on a random dot algorithm developed in this study provides a fully customizable tool to generate background patterns with different sizes and dot densities. Background patterns produced by the in-house developed program then can be printed by a common ink-jet printer. To enhance the signal-noise ratio of the measurement system, white reflective film sheets, or semi-transparent paper can be employed. The correlation algorithm base on fast Fourier transform that is also applicable for PIV was chosen to process background oriented schlieren images. A validation test was performed to visualize the flow structure around a Pitot tube at M = 2.0. The experimental result proves that the BOS system established in this study is capable of visualizing the supersonic flow structure around the Pitot tube and sensitive enough to reveal weak density changes produced by the boundary layer, expansion waves, and weak oblique shock waves. Next, the current BOS system will be improved further by increasing the intensity of light sources to shorten the exposure time, using new cameras with better spatial resolution, and optimizing the background pattern.

• Item Type: Conference Proceedings
• Additional Information: Published in Journal of Physics: Conference Series, Vol. 1786:012052
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Li, Mr Guoshuai and Kontis, Professor Konstantinos
• Authors: Li, G., Wu, J., Kontis, K., Wit, S., and Fan, Z.
• College/School: College of Science and Engineering; College of Science and Engineering > School of Engineering > Autonomous Systems and Connectivity
• ISBN: 1742-6588
• Copyright Holders: Copyright © 2021 IOP Publishing
• First Published: First published in Journal of Physics: Conference Series 1786:012052
• Publisher Policy: Reproduced under a Creative Commons License