Tomographic shadowgraphy for three-dimensional reconstruction of instantaneous spray distributions
Klinner, Joachim and Willert, Christian (2012) Tomographic shadowgraphy for three-dimensional reconstruction of instantaneous spray distributions. Experiments in Fluids, 53 (2), pp. 531-543. Springer. DOI: 10.1007/s00348-012-1308-2. ISSN 0723-4864.
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Tomographic shadowgraphy is an image-based optical technique capable of reconstructing the three dimensional instantaneous spray distributions within a given volume. The method is based on a multiple view imaging setup with inline illumination provided by current-pulsed LEDs, which results in droplet shadows being projected onto multiple sensor planes. Each camera records image pairs with short inter-framing times that allow the trajectories of the individual droplets to be estimated using conventional threedimensional particle tracking approaches. The observed volume is calibrated with a traversed micro-target. A comparison is made between several photogrammetric and polynomial least-square camera calibration techniques regarding their accuracy in deep volume calibration at magnifications close to unity. A calibration method based on volume calibration from multiple planar homographies at equally spaced z-planes was found to produce the most reliable calibration. The combination of back-projected images at each voxel plane efficiently reproduces the droplet positions in three-dimensional space by line-of-sight (LOS) intensity reconstruction. Further improvement of the reconstruction can be achieved by iterative tomographic reconstruction, namely simultaneous multiplicative algebraic reconstruction technique (SMART). The quality of spray reconstruction is investigated using experimental data from multiple view shadowgraphs of hollow cone and flat fan water sprays. The investigations are further substantiated with simulations using synthetic data.
|Title:||Tomographic shadowgraphy for three-dimensional reconstruction of instantaneous spray distributions|
|Date:||04 May 2012|
|Journal or Publication Title:||Experiments in Fluids|
|In ISI Web of Science:||Yes|
|Page Range:||pp. 531-543|
|Keywords:||spray diagnostics, optical techniques, photogrammetry, three-dimensional imaging, particle tracking velocimetry, camera model|
|HGF - Research field:||Aeronautics, Space and Transport|
|HGF - Program:||Aeronautics|
|HGF - Program Themes:||L ER - Engine Research|
|DLR - Research area:||Aeronautics|
|DLR - Program:||L ER - Engine Research|
|DLR - Research theme (Project):||L - Virtual Engine and Validation Methods|
|Institutes and Institutions:||Institute of Propulsion Technology > Engine Measurement Systems|
|Deposited By:||Dr.phil. Christian Willert|
|Deposited On:||22 Aug 2012 11:18|
|Last Modified:||07 Feb 2013 20:12|
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