Characterization of atomization and breakup of acoustically levitated drops with digital holography

Abstract

A digital holographic particle tracking velocimetry system is applied to quantitatively study the drop atomization induced by capillary waves, and the breakup caused by increased sound pressure levels. A wavelet-based algorithm is used for particle detection and autofocusing with a wide size range of 20 μm-2 mm. To eliminate the influence of large particles on small particles, a two-step detection method is adopted. Large drops are first characterized and simulated by a diffraction-based model. Then the contributions of the drops are subtracted from the original hologram followed by the detection of small droplets. Finally, the velocity and size distribution of the secondary droplets are obtained from the experimental holograms. The results demonstrate the validity of the digital in-line holographic technique for the atomization and breakup study of acoustically levitated drops.

Computational Methods for the Investigation of Liquid Drop Phenomena in External Gas Flows

“…There are 117295 unresolved drops of 0.00625 mm radius. where r is the radius of the product drop,r is the mean of r. The fits are in good agreement with the only available experimental data from Yao et al [95] which is limited to the bag breakup regime. By calculating the sum of squared errors (SSE),…”

“…The final product drop size distribution of the resolved drops for the bag breakup, shown in Fig. 3.24, is calculated by combining these two drop size data and is in good agreement with the experimental observations of Yao et al [95]. As is seen in Table 3.8, there are 162 resolved drops, and the mean radius of these drops is 0.0528 mm.…”

Recognition of Multiscale Dense Gel Filament-Droplet Field in Digital Holography With Mo-U-Net

“…One of the common challenges in filament-droplet field characterization during secondary breakup is accurately detecting and segmenting the object from background. Nowadays, threshold algorithms [22] especially adaptivethreshold methods (ATM) [23][24][25] are widely employed. The threshold value is calculated based on models originally derived from image by direct photography, while the reconstructed slice image in DIH has intrinsic twin-image noises.…”

Self-calibrated global rainbow refractometry: a dual-wavelength approach

“…Accurate measurements and control of the key parameters of droplets in the complex atomization or a spray flow field play an instructive role in mechanism studies of multiphase flows and in the optimization of specific industrial processes. Among the advanced optical measurement techniques [1][2][3][4] for characterizing droplets, rainbow refractometry [5][6][7] has been shown to be a powerful tool for its advantages in simultaneously measuring the size/size distribution (individual droplet/polydispersed droplet cloud) and refractive index. Thereafter, the temperature [8] , concentration [9] , solution components [10] , and other characterization parameters can be determined on the basis of prior knowledge of their relationships with the measured refractive index.…”