Development of a background-oriented schlieren technique with telecentric lenses for supersonic flow

23rd AIVELA (the Italian Association of Laser Velocimetry and non invasive diagnostics) Annual Meeting 2015

Cozzi, F.^1 ; Gö Ttlich, E.^3 ; Angelucci, L.^2 ; Dossena, V.^1 ; Guardone, A.^2

Politecnico Milano, Dipartimento di Energia, Via Lambruschini 4, Milano

20156, Italy^1

Politecnico di Milano, Dipartimento di Scienze e Tecnologie Aerospaziali, Via Lambruschini 4, Milano

20156, Italy^2

Graz University of Technology, Institute for Thermal Turbomachinery and Machine Dynamics, Inffeldgasse 25/A, Graz

8010, Austria^3

关键词: Background oriented schlieren;    Cross-correlation algorithm;    Density gradients;    Measurement accuracy;    Optical technique;    Reduction techniques;    Spatial resolution;    Transparent media;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/778/1/012006/pdf
DOI  :  10.1088/1742-6596/778/1/012006

来源: IOP

【 摘 要 】

Background oriented schlieren (BOS) is a quantitative optical technique which exploits light deflection occurring in non-homogeneous transparent media. It allows to indirectly measure the density gradients by analysing the apparent displacement of features of a background pattern when imaged through the investigated flow. Thanks to its simple set-up and to the consolidated data reduction technique based on cross-correlation algorithms the BOS technique has progressively attracted the interest of the researchers. In this work a BOS system using a telecentric lens system has been set up in order to improve measurement accuracy and to avoid 3D effects arising from using conventional entocentric lenses. The design of the telecentric lens system is reported along with an analysis of its performance in term of spatial resolution. Some preliminary tests on a supersonic flows are also reported.