An experimental study was conducted on the spectral characteristics of a round water jet with an annular air flow. The round liquid jet was ranged in the turbulent flow region, whereas the annular air flow is ranged from laminar to semi-turbulent flow. A high-speed video camera and image processing techniques were used to measure the time variations of liquid jet profiles in the radial direction. Power spectra and auto correlations of surface disturbances were calculated using FFT. Surface disturbances having a specific frequency showed the maximum growth rate. This specific frequency increased as the air flow velocity increased. From the results of autocorrelations of surface disturbances, the symmetric mode of surface disturbances showed periodicity, whereas the asymmetric mode showed a random nature. The periods of symmetrical waves became shorter with an increase of air flow velocity. The characteristics of droplet formation due to the disintegration of a liquid jet were also examined. The frequencies of droplet formation were measured from the mass median diameter of droplets and mass flow rates of the liquid jet. They showed reasonable agreements with the frequencies of the surface disturbance having the maximum growth rate.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)