DOI: 10.1615/ICHMT.1997.IntSymLiqTwoPhaseFlowTranspPhen
ISBN Print: 1-56700-162-9
ANALYSIS OF NONPARALLEL FLOW EFFECTS ON THE INSTABILITY OF A CAPILLARY JET IN ANOTHER IMMISCIBLE FLUID
摘要
The capillary instability of a contracting jet has been studied experimentally. Measurements of the jet diameter oscillations in time for different cross sections of the jet are reported. The oscillations of the diameter are made visible by a laser sheet oriented perpendicularly to the jet axis. Jet contraction is controlled by varying the density of the surrounding fluid (continuous phase). The temporal series are analysed by Fast Fourier Transform (FFT). In the different cross sections along the jet the power spectra density (PSD) have similar behaviour showing variable frequencies band centered at some characteristic frequency. When the densities difference between the phases is small (i.e. the jet contraction is negligible) the observations show regular and almost sinusoidal diameter oscillations, whose characteristic wave length is equal to that of the fastest growing disturbances calculated for a jet of a nozzle diameter. When the densities difference increases the diameter oscillations become of a more complicated form but the wave length remains close to that defined by the nozzle diameter.