Published: 01 May 2016

Schlieren method for the visualization of indoor air flows

For years, scientists from the Faculty of Civil Engineering and the Faculty of Architecture and Urban Studies have been researching energy-efficient solutions to improve the indoor climate. Starting in 2017, a new method will be used to increase the measurement accuracy of research results in the field of indoor climate control. The Thuringian Ministry of Economics, Science and Digital Society (TMWWDG) supports the research project and provides the necessary financial resources.

Due to the increased standard of living, expectations regarding the comfort of living and working spaces have risen, making building air conditioning increasingly important, even in moderate climate zones. This is accompanied by an increase in energy requirements, which places the focus on research and development of new, energy-saving methods, components and operating modes.

Together with a team of scientists, Prof. Dr.-Ing. Conrad Völker, Head of the Chair of Building Physics, is investigating which factors influence the indoor climate and thus our well-being. The core of the investigations is the simulation of the most diverse climatic conditions in a closed room equipped with sensors, the so-called climate chamber. With the help of the manikin "Feelix" (from "feel"), a thermal model with heating wires running under the surface, the researchers simulate a skin temperature similar to that of humans and test how this changes with changing room climate. With the additional funds provided by the TMWWDG, new equipment will be purchased to supplement this existing system, thus enabling the application of the so-called Schlieren method.

About the Schlieren method

The Schlieren method is a method for visualizing and measuring indoor air flows. With this method, fluctuations in the refractive index of the air are visualized, which can, for example, make thermal convection movements visible. Essentially, the system consists of a mirror with the precision of an astronomical telescope, a light source and a high-resolution camera.

The Chair of Building Physics has been working on schlieren and shadow methods for some time. In order to test the applicability of the method for the research of indoor climate control, M.Sc. Thomas Möller and master student Luca Noll travelled to Singapore and the USA to visit the two only universities in the world that currently have large Schlieren systems. "With the Schlieren mirror, our climate chamber, which is already well equipped with the thermal manikin Feelix and extensive measurement technology, will be unique in the world. This will help us to advance both basic and application-oriented research in the field of indoor climate control. The aim is to develop a room air-conditioning system that is both energy-efficient and thermally comfortable," explains Völker.

Völker is convinced that a cooperation with the Technical University of Ilmenau (Department of Fluid Mechanics, Prof. Dr. Jörg Schumacher) as well as the Materials Research and Testing Institute Weimar (MFPA, Prof. Dr.-Ing. habil. Carsten Könke) would result in numerous application possibilities for the Schlieren process.

Funding agency:
The project belongs to the specialization field "Sustainable use of energy and resources" of the Free State of Thuringia, TMWWDG

The project on which these results are based was supported by the Free State of Thuringia under the number 2015 FGI 0005 and co-financed by European Union funds within the framework of the European Regional Development Fund.

Project duration:
5/2016 - 2/2018

contact person:
Prof. Dr.-Ing. Conrad Völker
phone (+49) 03643 584647

Thomas Möller
phone (+49) 03643 583432