| Title |
Effect of a Preprocessing Method on Inverting Chemiluminescence Images of Flames Burning Substitute Natural Gas |
| Authors |
Kwangho Ahn ; Wonjoon Song ; Dongjin Cha |
| DOI |
http://dx.doi.org/10.6110/KJACR.2015.27.12.609 |
| Keywords |
화염구조 ; OH* 자발광 ; 디지탈영상 전처리 ; 아벨 역변환 ; 대체천연가스 Flame structure ; OH* chemiluminescence ; Digital image preprocessing ; Abel inversion ; Substitute natural gas(SNG) |
| Abstract |
A preprocessing scheme utilizing multi-division of the ROI (region of interest) in a chemiluminescence image during inversion is proposed. The resulting inverted image shows the flame's structure, which can be useful for studying combustion instability. The flame structure is often quantitatively visualized with PLIF (planar laser-induced fluorescence) images as well. The chemiluminescence image, which is a line-integral of the flame, needs to be preprocessed before inversion, mainly due to the inherent noise and the assumption of axisymmetry during the inversion. The feasibility of the multi-division preprocessing technique has been tested with experimentally-obtained OH PLIF and OH* chemiluminescence images of jet and swirl-stabilized flames burning substitute natural gas (SNG). It turns out that the technique outperforms two conventional methods, specifically, the technique without preprocessing and the one with uni-division, reconstructing the SNG flame structures much better than its two counterparts when compared using corresponding OH PLIF images. The characteristics of the optimum degree of polynomials to be applied for curve-fitting of the flame region data for the multi-division method involving two flames has also been investigated. |