Experimental investigations of deterministic chaos appearance in bubbling flow

Abstract

In the experiment, bubbles were generated from the brass nozzle with the inner diameter of 1.1 mm submerged in the glass tank (400 × 400 × 700 mm) filled with distillated water. Pressure fluctuations and signal from the laser-phototransistor sensor were recorded simultaneously. The movement of bubble wall was measured using a high speed camera and image processing technique. Results of analysis of images have been correlated with pressure and laser-phototransistor signals. In the analysis the Fourier spectrum, wavelet spectrum and non-linear methods (mutual information, attractor reconstruction, largest Lyapunov exponent and correlation dimension) have been used. The three applied in the paper techniques of measurement of dynamical properties of bubbling allow us to discuss in detail the mechanisms of different chaotic behaviors of bubbling. Two ranges of the air volume flow rate with different kinds of bubble chaotic behaviors have been identified. For the air volume flow rate less than 0.2 l/min the air pressure chaotic fluctuations do not cause the significant chaotic changes of bubble departure frequencies. When the air volume flow rate increases above the 0.2 l/min, the interaction between departing bubbles causes nonperiodic bubble wall movement, and then the appearance of chaotic changes of bubble departure frequency.