Secondary Atomization: Drop Breakup in a Continuous Air Jet

Understanding drop breakup will optimize aircraft engine performance, reduce agro-chemical overspray, and improve pharmaceutical tablet efficacy. Large fuel fragments in engines lead to lowered fuel economy and higher pollutant emissions, while small drops yield more agro-spray drift into surrounding residential and environmental zones. Better pharmaceutical tablets will improve drug uptake and patient comfort. Engineers and scientists are currently unable to predict the number, size, and velocity of fragments formed during important drop breakup processes. Therefore, we are required to measure these quantities. We use digital inline holography (DIH) to record three-dimensional diameter and position data for fragments formed during multi-mode breakup. DIH provides 3D images at framing rates 300 times faster than in an IMAX theater. A laser is used as the light source and a high speed camera records the breakup events to video files. A MATLAB script is used to extract the diameters and positions of all fragments in the spray. The data is sorted into bins and histograms are produced which describe the probability of observing a fragment of any particular size and speed. Results show size histograms with more than one peak, a finding in direct contradiction to the last 40 years of spray research. Multiple peaks are indicative of fragmentation processes that occur due to multiple breakup mechanisms, with the number of histogram peaks corresponding to the number of mechanisms (some combination of bag, rim, and/or stamen breakup modes). The histograms will be useful to those modeling sprays in gas turbine engines and industrial sprayers

Tuning Non-Isothermal Crystallization Kinetics between Fe₂₀Co₂₀Ni₂₀Cr₂₀(P_0.45B_0.2C_0.35)₂₀ High-Entropy Metallic Glass and the Predecessor Fe₇₅Cr₅P₉B₄C₇ Metallic Glass

In the present work, comparisons of non-isothermal crystallization kinetics between Fe20Co20Ni20Cr20(P0.45B0.2C0.35)20 high-entropy metallic glass (HEMG) and the predecessor Fe75Cr5P9B4C7 metallic glass (MG) were performed with X-ray diffraction and differential scanning calorimetry approaches. The HEMG possesses a harsher crystallization process compared with the predecessor MG, deriving from a higher triggering energy for all the characteristic transitions and local activation energy along with a smaller local Avrami exponent and a growth with pre-existing nuclei. Meanwhile, the glass transition is the easiest process, but the nucleation of the second crystallization case is the hardest transition for the HEMG. However, the predecessor MG possesses distinctly different crystallization features of a moderate difficulty for the glass transition, the harshest process for the growth transition of the second crystallization case, and a crystallization of growth with a diverse nucleation rate. These results conclusively prove that the non-isothermal crystallization kinetics can be significantly changed after the present high-entropy alloying with the substitution of similar solvent elements Co, Ni, and Cr with Fe in Fe75Cr5P9B4C7 MG. Moreover, the two alloys possess a strong glassy formation melt with high thermal stability and diverse crystallized products after non-isothermal crystallization

Direct measurement of particle size and 3D velocity of a gas–solid pipe flow with digital holographic particle tracking velocimetry

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3D imaging of individual burning char and volatile plume in a pulverized coal flame with digital inline holography

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Simultaneous 3D temperature and velocity field measurements of micro-flow with laser-induced fluorescence and micro-digital holographic particle tracking velocimetry: Numerical study

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Direct particle depth displacement measurement in DHPTV using spatial correlation of focus metric curves

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Characterizations of near-field transparent particle holography using Debye series

International audienceEffects of light with different scattering processes (diffraction, reflection, transmission, and refractions etc.), on the typical phenomena in the transparent particle holography in the near field are revealed with the Debye series decomposition