Frequency Analysis of Disintegrating Liquid Column

Frequency characteristics of the surface wave on a liquid jet injected from a round nozzle into the stationary air were experimentally investigated to understand the disintegration phenomena. Amplitude of the surface wave was detected by a photo-sensor at the various axial positions of the jet. Obtained signals of the photo-sensor were processed by the FFT analyzer. Structure of the frequency spectrum and auto-correlation in a dripping, laminar jet and turbulent jet regions was investigated in detail. As the result, discrete peaks of the spectrum components were observed in the dripping and laminar jet regions. In the turbulent jet region, the broad band components were appeared in the spectrum. In order to measure the frequency of disintegration, the dominant frequencies at the breakup point on the jet were investigated. The variation of the dominant frequency was described as a function of the Reynolds number and was compared with the breakup length of the jet It was confirmed that the disintegration frequency strongly correlated with the breakup length. The secondly higher peak in the auto-correlation function was a good indicator for the regularity of disintegration period. In the dripping region, highly regular state and irregular state were appeared in dependence on the injection flow rate. The regularity levels of the laminar and turbulent jet disintegration were almost same and were independent to the Reynolds number.