We’re big fans of Professor Gary S. Settles and his colleagues with their very cool schlieren camera work at Pennsylvania State University. We feature a number of their images and videos in our IEQ education programs – you can see them over at the https://www.healthyheating.com/ site.
Well today we got a heads up from Dr. Stefano Schiavon from the Center for the Built Environment, University of California, Berkeley that Dr. Settles with his colleague Dr. Michael J. Hargather have a paper published in the October issue of ASHRAE’s HVAC&R Research titled, “Background-oriented schlieren visualization of heating and ventilation flows: HVAC-BOS”
You’ll want to obtain this document if you have an interest in the field.
Abstract: There is an important need for simple methods to visualize and measure whole-field airflow patterns in the HVAC field. The background-oriented schlieren (BOS) method is presented here as an answer to this need—a simple and effective method for visualizing refractive HVAC flow fields in situ. The equipment required is simple, portable, inexpensive, and readily available, thus superseding some previous approaches, including lens-and-grid schlieren techniques that require large fixed installations. For BOS a custom random-dot background pattern is used, and imaging is done by a consumer-grade digital single-lens-reflex (SLR) camera. After covering the principles of BOS, examples are shown of visualized airjets and plumes from heating vents and registers, a space-heater, a tea kettle, and a human thermal plume and cough. BOS images of candle plumes are also used to explore several different visualization approaches, equipment arrangements, and image color scales. While current results are purely-qualitative visualizations, quantitative temperature measurements can also be made in certain cases where the flow is approximately two dimensional. Finally, BOS lends itself well to certain HVAC chores, such as the diagnosis of commercial kitchen ventilation airflows.
Citation: Michael J. Hargather & Gary S. Settles (2011): Background-oriented schlieren visualization of heating and ventilation flows: HVAC-BOS, HVAC&R Research, 17:5, 771-780
Article link: <https://www.tandfonline.com/doi/abs/10.1080/10789669.2011.588985>
Have a look at some of the images from the PSU website and imagine being able to obtain these wonderfully useful photographs - to see that which was once invisible to the naked eye. Be sure to also check out the video we have featured at the website from our friends at Science Photo Library courtesy of donations from site visitors. A heads up it’s a large file - allow at least 120 seconds to load…best to grab a cup of coffee and come back in a few minutes - it’s well worth the wait.
For those of us who study indoor environmental quality this tool is like adding a third or fourth dimension to our understanding of fluid flow and its influence on occupant comfort.
A big thanks to Dr. Schiavon for bringing this to our attention.
Links of interest:
Dr. Gary Settles
Gas Dynamics Laboratory
Penn State University
Dr. Michael J. Hargather
Gas Dynamics Laboratory, Department of Mechanical and Nuclear Engineering
Penn State University
Dr. Stefano Schiavon
Center for the Built Environment
University of California, Berkeley