Abstract
In this study, an optical imaging method was developed for the measurements of the sizes and velocities of droplets in sprays. Double-exposure single-frame spray images were captured by the imaging system. An image processing program was developed for the measurements of the sizes and positions of individual particles including separation of the overlapped particles and particle tracking and pairing at two time instants. To recognize and separate overlapping particles, the morphological method based on watershed segmentation as well as separation using the perimeter and convex hull of image was used consecutively. Better results in separation were obtained by utilization of both methods especially for the multiple or heavily-overlapped particles. The match probability method was adopted for particle tracking and pairing after identifying the positions of individual particles and it produced good matching results even for large particles like droplets in sprays. Therefore, the developed optical imaging method could provide a reliable way of analyzing the motion and size distribution of droplets produced by various sprays and atomization devices.
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Abbreviations
- D E :
-
Euclidian distance function
- M :
-
Number of possible match points in the second pulse
- P ij :
-
Match probability that Xi would coincide toY j
- Pi*:
-
No-match probability thatX i has no-correspondingY j
- T m :
-
Threshold radius for maximum movement
- T n :
-
Threshold radius for neighborhood
- T q :
-
Threshold radius for quasi-solidity
- X i :
-
Particle in the first pulse image
- Y j :
-
Particle in the second pulse image
- (n):
-
Number of iteration step
- ∼:
-
Non-normalized probability
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Choo, Y., Kang, B. Extraction of sizes and velocities of spray droplets by optical imaging method. KSME International Journal 18, 1236–1245 (2004). https://doi.org/10.1007/BF02983298
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DOI: https://doi.org/10.1007/BF02983298