Ghosh, A and Boggavarapu, P and Ravikrishna, RV (2019) Methods of evaluation of liquid length measurement for evaporating sprays. In: Journal of Flow Visualization and Image Processing, 26 (4). pp. 359-369.
Full text not available from this repository.Abstract
Liquid-tip penetration for diesel spray from a common rail diesel injection system is measured using diff use backlight imaging (DBI) and Mie-scatt ering techniques under evaporating conditions. Experiments were conducted for three injection pressures of 500 bar, 1000 bar, and 1500 bar, while the ambient nitrogen gas is maintained at 50 bar pressure and 900 K temperature in a high-pressure spray chamber with optical access. Spray images are recorded using a high-speed camera and are post-processed using two methods found in the literature. The simpler of the two involves using a grey level threshold (threshold method) to convert the raw images into binary images and identify the liquid-tip, whereas the other consists of utilizing a line-fi t for the time-averaged centerline intensity variation near the spray-tip (line-fi t method). The results show that for images with good contrast, steady-state liquid lengths obtained from both the recording techniques are similar. However, the line-fi t method applied to ensemble-averaged spray images fails to capture the transient variation of liquid-tip penetration due to signifi cant waviness in the intensity. A comparison of liquid lengths obtained from DBI and Mie-scatt ering methods showed that the line-fi t method underestimates the average liquid length by 9.4 for DBI method and 4.8 for Mie-scatt ering method, as it does not take into account the low-intensity signal near the tip of the spray. The transient variation of liquid-tip penetration is simpler to obtain using the threshold method in comparison with the line-fi t method. Overall, the threshold method of post-processing for either DBI or Mie-scatt ering images is observed to be advantageous over the line-fi t method for obtaining the transient variation of liquid-tip penetration and average liquid length. © 2019 by Begell House, Inc.
| Item Type: | Journal Article |
|---|---|
| Publication: | Journal of Flow Visualization and Image Processing |
| Publisher: | Begell House Inc. |
| Additional Information: | The copyright of this article belongs to Begell House Inc. |
| Keywords: | Binary images; Diesel engines; High speed cameras, Diesel injection systems; Ensemble-averaged; Evaporating sprays; Injection pressures; Intensity variations; Post processing; Threshold methods; Tip penetrations, Liquids |
| Department/Centre: | Division of Mechanical Sciences > Mechanical Engineering |
| Date Deposited: | 07 Apr 2021 11:11 |
| Last Modified: | 07 Apr 2021 11:11 |
| URI: | http://eprints.iisc.ac.in/id/eprint/65462 |
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