Effect of Bubbles on Flow Induced Vibration Available to Purchase

The effects of a turbulent, bubbly boundary layer on wall skin friction have been investigated in numerous previous studies. However, the impact of such a multiphase flow on fluid-structure interactions has not been studied. To this end, the present project examines experimentally the effect of a bubbly boundary layer on the vibration of a vertical plate. Using a combination of accelerometers and pressure transducers, we simultaneously measure the plate vibrations and wall pressure fluctuations for varying flow rates, gas void fractions, and characteristic bubble sizes. The results show that the presence of bubbles substantially increases both the plate vibrations and the wall pressure fluctuations. The vibrations increase by up to 20 dB compared to the same flow without bubbles. The spectra of vibrations become broad and vary significantly with the characteristic bubble size. The variations with bubble size are consistent with the resonant frequency of the bubbles, indicating that, in addition to changing the compressibility of the medium, individual bubbles act at sources.