EFFECT OF PIEZOELECTRIC TRANSDUCER MODULATION ON LIQUID SHEET DISINTEGRATION

A stroboscope photographic technique was used to investigate the mecha nism associated with the disintegration of a conical liquid sheet that is modulated by a piezoelectric driver. The effects of fluid viscosit y, driving frequency, and input perturbation power were characterized with respect to the skeet breakup length. The experimental results ind icate that the breakup length decreases with increasing input modulati on power only at resonant frequencies. This effect is attributed to wa ves imposed along the liquid sheet surface that amplify wave-mode and rim-mode disintegration, and assist in liquid sheet breakup. The wavel ength generated by the modulation was found to depend on the driving f requency and fluid density. The resonant driving frequency is affected slightly by the fluid density. For our experimental arrangement, art optimum driving frequency, for which the liquid breakup length is a mi nimum, was found to occur at about 10 kHz. Increasing the liquid visco sity impedes the spray development and lengthens the sheet disintegrat ion. Modulation enhances the disintegration of lower-viscosity fluids but is less effective for higher-viscosity fluids. Higher input modula tion power enhances disintegration. The relationship between the break up length and the modulation power is consistent with the analytical s olution suggested by Clark and Dombrowski [1] for breakup of an invisc id two-dimensional flat sheet.