The interaction between atomizing air and a liquid sheet initiates interfacial instabilities that develop into large amplitude waves, which ultimately promote liquid disintegration. However, to reduce atomizing airflow, the dynamic influence of the surrounding gas is not sufficient to affect the inner core of the liquid. In other words, the characteristic length scales of perturbation promoting break-up are small in comparison with the initial liquid momentum. Therefore, to enhance the disintegration process, the intact liquid-core near the nozzle outlet must be influenced by artificial or external excitations. To accomplish this, the present investigation employed a plane laminar liquid-sheet that was perturbed by acoustic excitations at an optimum frequency through the impinging air-streams.

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The investigation focuses on optimizing the length of wind-pipe that transmits acoustic energy from the compression driver to the cavity of twin-fluid atomizers. To accomplish this objective, the primary variable of stability, that is, the breakup length of liquid jet and sheet under acoustic perturbations has been experimentally characterized for a range of wind-pipe length and liquid velocity. The analysis considers liquid phase Weber number in the range of 0.7–8, and the results are compared with primary breakup data without acoustic perturbations. The range of Weber number tested belongs to Rayleigh breakup zone, so that inertia force is negligible compared to surface tension force. It shows the existence of unique stability functions based on dimensionless products up to an optimum wind-pipe length, which extends greater for liquid sheet configuration. The present results may find relevance in atomizer design that utilizes acoustic source to enhance liquid column breakup processes.