One of the aims of studies related to building physics is to measure indoor airflows that are invisible to the human eye. To measure the air velocity, however, several conventional methods hamper the airflow under investigation due to the existence of sensors (e.g. anemometry) or particles (e.g. particle image velocimetry, PIV).

Alternative methods, like the optical schlieren imaging and the background-oriented schlieren (BOS) method, measure and visualize large-scale airflows non-invasively. Both methods are based on the physical principle of light deflection when light rays enter a medium with a different density. To visualize these density gradients in two dimensions using schlieren imaging, the Chair of Building Physics uses a highly precise schlieren mirror  with a diameter of 1 meter. Similar to the schlieren imaging method,  BOS can also record density gradients 2.5-dimensional or three-dimensional using several cameras. To visualize the air flows, BOS uses an irregular background pattern, which is virtually distorted due to the light rays being deflected. Furthermore, the measuring range is unlimited. Both methods use a high-resolution camera to record the airflows.

In this research project, the basics of both systems are to be further developed and optimized after a comprehensive parameter study. Both methods will be used to obtain qualitativ and quantitativ high-resolution visualizations of indoor airflows. Hence, it will be possible to gain a deeper understanding of indoor airflows.

The schlieren imaging system and the background-oriented schlieren system were awarded with the Thuringian Research Award 2021 in the category "Applied Research".

Funding body:

DFG

Project duration:

09/2020 - 08/2023

Contact:  

Lia Becher M.Sc.
phone +49 3643 584824

Amayu Wakoya Gena M.Sc.
phone +49 3643 584834