Study on the disintegration of a liquid film by air impingement

A contact needle method is used to investigate the effects of air impingement on the disintegration of a fan-shaped liquid film. The amplitude of the wave on the sheet with relatively high liquid velocity or air impingement is shown to increase exponentially with time initially, and to reach a critical value. For waves of small amplitude, the growth rate increases with relative velocity, while for waves of large amplitude, the growth rate is reduced due to the effects of air resistance, and the disintegration is caused by the deformation of waves and by collision with following waves. Air impingement plays an agitating role, forming a large initial wave on the sheet and causing more rapid disintegration. The three disintegration patterns with an impinging air flow found are: disintegration by the growth and deformation of a long sinusoidal wave, disintegration by shear force and disintegration by instantaneous tear-off.