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Perturbations of the depth of liquid penetration into the capillary during bubble departures

Dzienis Paweł

Acta Mechanica et Automatica

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2021

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Vol. 15, no. 4

254--259

EN

In the present paper, the influence of bubble size on liquid penetration into the capillary was experimentally and numerically studied. In the experiment, bubbles were generated from a glass capillary (with an inner diameter equal to 1 mm) in a glass tank containing distilled water, tap water or an aqueous solution of calcium carbonate. These liquids differ in the value of their surface tension, which influences the bubble size. During experimental investigations, air pressure fluctuations in the gas supply system were measured. Simultaneously, the videos showing the liquids’ penetration into the capillary were recorded. Based on the videos, the time series of liquid movements inside the capillary were recovered. The numerical models were used to study the influence of bubble size on the velocity of liquid flow above the capillary and the depth of liquid penetration into the capillary. It was shown that the air volume flow rate and the surface tension have the greatest impact on the changes of pressure during a single cycle of bubble departure (Δp). The changes in pressure during a single cycle of bubble departure determine the depth of liquid penetration into the capillary. Moreover, the values of Δp and, consequently, the depth of liquid penetration can be modified by perturbations in the liquid velocity above the capillary outlet.

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Non-linear analysis of air pressure fluctuations during bubble departure synchronisation

Dzienis Paweł, Mosdorf Romuald, Wyszkowski Tomasz, Rafałko Gabriela

Acta Mechanica et Automatica

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2019

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Vol. 13, no. 3

158--165

EN

In the recent paper, non-linear methods of data analysis were used to study bubble departure synchronisation. In the experiment, bubbles were generated in engine oils from two neighbouring brass nozzles (with an inner diameter of 1 mm). During the experiment, the time series of air pressure oscillations in the air supply system and voltage changes on phototransistor were recorded. The analysis of bubble departure synchronisation was performed using a correlation coefficient. The following methods of non-linear data analysis are considered. Fast Fourier Transformation, autocorrelation, attractor reconstruction, correlation dimension, largest Lyapunov exponent and recurrence plot analysis were used to examine the correlation between bubbles behaviour and character of pressure fluctuations. Non-linear analysis of bubble departure synchronisation revealed that the way of bubble departures from two neighbouring nozzles does not depend simply on the character of pressure fluctuations in the nozzle air supply systems. The chaotic changes of the air pressure oscillations do not always determine the chaotic bubble departures.

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Synchronization of data recorded using acquisition stations with data from camera during the bubble departure

Dzienis P., Mosdorf R.

Advances in Science and Technology. Research Journal

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2013

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Vol. 7, nr 20

29--34

EN

In this study the first part of the experimental data was recorded in a data acquisition station, and another one was recorded with a high speed camera. The data recorded using the acquisition station was recorded with higher frequency than the time between two subsequent frames of the film. During the analysis of the experimental data the problem was related to the synchronization of measurement from acquisition station and data recorded with a camera. In this paper the method of synchronization of experimental data has been shown. A laser- phototransistor system has been used. The data synchronization was required in scaling of sampling frequency in the investigated time series.