Development of empirical correlations for sustainable breakup characterization of water and high-viscous oil sheets under acoustic perturbations using high-speed imaging

Abstract

Efficient techniques for breaking liquid columns into smaller droplets are highly valued in atomization and spray dynamics research. The investigation focussed on the development of a miniature acoustic atomizer to disrupt high-viscosity liquid sheets using precisely tuned acoustic frequencies. The key innovation of this study is the design and fabrication of a compact liquid sheet acoustic atomizer that efficiently utilizes acoustic energy to produce high-quality sprays. This study employs minimal power for liquid disintegration compared to the high-power demands of other air-assisted systems, aiming to promote sustainable growth. Dynamic acoustic calibration was employed to determine the dominant frequency, likely establishing a standing wave within the atomizer cavity. At resonance, this standing wave effectively transfers acoustic energy to the liquid sheet, significantly enhancing its fragmentation. The breakup dynamics of water and SAE 40 oil were captured using high-speed imaging coupled with backlit flow visualization techniques.

Morphological characteristics of the breakup process were qualitatively analyzed using ImageJ, an open-source image processing tool. Subsequently, quantitative analysis has been carried out to the formulate breakup stability empirical results. The minimum breakup length of 7.6 mm and maximum spray angle of 115° and maximum breakup frequency of 1960 Hz was noticed for water sheet breakup. Better correlations have been established for breakup length, spray angle, breakup frequency, interfacial wavelength and critical wave number as a function of newly proposed acoustic number. This provides valuable insights into the role of acoustic energy in the high viscous liquid breakup. The study underscores significant advancements in optimizing acoustic atomization with broad industrial implications. Further studies may focus on refining compression driver designs and noise filtration techniques to achieve enhanced control and efficiency, expanding the applicability of acoustic atomizers.