Laser marked shadowgraphy: a novel optical planar technique for the study of microbubbles and droplets

Abstract

A novel combination of backlighting and Glare Point Velocimetry and Sizing (GPVS) is proposed to measure the size distribution of microbubbles (or microdroplets). This new technique, which we will call Laser Marked Shadowgraphy or LMS, avoids sizing out-of-focus bubbles (or droplets) and the associated bias error. Compared to backlighting, this combination also improves the precision of the diameter measurement and allows void fraction measurements.Compared with GPVS, a more robust image processing is obtained. The applicability of the developed technique is demonstrated on a cloud of electrochemically generated hydrogen bubbles.

Experimental studies on the terminal velocity of air bubbles in water and glycerol aqueous solution

“…As a tele-centric setup was not used, the third source causing the error is associated with the calibration/magnification determination. According to the studies of Bongiovanni et al [49] and Dehaeck et al [50], an estimation of the maximum error in determining the bubble edge is ± 4.5 pixel. Hence, when the bubble diameter is in the range of 0.12-0.5 mm, the spatial resolution is 0.01 mm/pixel, the error will be in the range of ±9% to ± 37.49%.…”

Integral characteristics of water droplet evaporation in high-temperature combustion products of typical flammable liquids using SP and IPI methods

“…Such panoramic optical techniques as SP [29,30] and IPI [31e34] contributed to measuring the sizes (radii) of atomized water droplets (R d ¼ 0.05e0.35 mm). In the case of the SP method [29,30], the cross-correlation complex was additionally equipped with diffuse screen 24. This screen was connected to laser 18 by the optical fiber and applied to provide backlight for moving water droplets (Fig.…”

Temperature of gases in a trace of water droplets during their motion in a flame

“…The experimental set-up, fig. 1, included four basic groups of equipment, -assembly for temperature measurements (items 2, 3), -equipment for monitoring and recording the parameters of droplet and high-temperature gas-flows (items 4-7), -tools for creating an atomized droplet flow (items 8-10), and -tools for creating a high-temperature gas-flow (items [12][13][14][15][16].…”