Alberto Vazquez Naranjo | UNAM Universidad Nacional Autónoma de México (original) (raw)

Papers by Alberto Vazquez Naranjo

Observations of air bubble growth in a quiescent liquid and in a liquid cross-flow by means of a ... more Observations of air bubble growth in a quiescent liquid and in a liquid cross-flow by means of a high-speed camera and piezoelectric-hydrophone in a synchronous experimental setup are performed. Using the passive acoustical method, one observes a beat-wave phenomenon when the feed magnitude of liquid cross-flow is increased from 43 to 128 mm/s and this is corroborated by the appearance of peaks in spectral and spectrogram analyses respectively. A fit to experimental data by a theoretical-model indicates that the beat-signal is the result of under and overdamped systems. The bubble video-images show the asymmetric travel of bubble-surface ripples after the neck collapse. The acoustic comparison exhibits a beat signal as a result of capillary -wave superposition, which is in agreement with earlier results on bubble fragmentation in a locally sheared flow.

Three methods for measuring the volume and the equivalent radius of air bubbles at detachment fro... more Three methods for measuring the volume and the equivalent radius of air bubbles at detachment from the tip of different capillary tubes in quiescent water were tested. The aim was to provide an accurate cross-calibration of two of the methods against a standard laboratory method. The inverted funnel method is the laboratory standard and performed within a 0.5% repeatability error for 50 bubble sets. The passive acoustic method performed within an accuracy between 97% and 99% with respect to the inverted funnel method. The photographic method gave an accuracy between 88% and 96%. After improvement of the photographic method by an empirical cutting edge criterion, its accuracy was raised between 95% and 99%. The bubble shape at detachment was found to be fitted by a CassiniÕs oval or by a BernoulliÕs lemniscate according to the formation time. Qualitative observations on the bubble formation stage indicated an early vertical nose growth for the larger diameter capillary tubes at short formation times. The major-axis vertical and horizontal lengths were measured as functions of time at the formation stage.

Patterns were generated inside a horizontal cylinder rotating at low speeds. The cylinder was fil... more Patterns were generated inside a horizontal cylinder rotating at low speeds. The cylinder was filled with a very low volume liquid fraction of 1.8% of Newtonian fluid and the rotation speed ranged between 0.08 and 5.2 s À1 . A novel laser-plane technique was utilized to obtain time series from each pattern. This enabled the characterization of fluid patterns using Fourier spectral (FS) and dynamical-systems (chaotic) techniques such as the recurrence map, correlation dimension (D 2 ) and Hurst exponent (H). Four patterns were found (fingers, furrows, waterfall and smooth tooth) before annular flow was reached. The results indicate that the FS technique not is suitable for flow pattern characterization; and H only has the ability to indicate a possible pattern change. The best tool for indicating the pattern transitions and the inner coat liquid evolution was found to be recurrence maps and D 2 .

Experiments were performed on both the acoustic and pressure signals produced by bubbles formed f... more Experiments were performed on both the acoustic and pressure signals produced by bubbles formed from an underwater nozzle. The data were analyzed by a comprehensive set of spectral and nonlineardynamical techniques. As air flow rates increase, it is well known that such flows became chaotic. However, the present study of both acoustic and pressure signals showed that chaos could appear in different regimes and was manifested in different ways in the acoustic and pressure signals. The use of different time delays for the chaotic analysis of acoustic and pressure signals were found necessary. The acoustic signals offer data primarily on the bubble size while the pressure signals offer data primarily on the bubble production rate. The present results suggest that chaos can appear in the bubble size and bubble production rate independently.

An arrangement of plates was built using two minerals, calcite and hematite, deposited on glass (... more An arrangement of plates was built using two minerals, calcite and hematite, deposited on glass (slides). The plates were placed in Chilapa de Alvarez city, in the southeast of Mexico. The goal of this work is to prove that mineral plates perform better than glass in nocturnal radiative cooling phenomena. The results obtained are that the glass/hematite plate collected 1.2-1.5 × 10 −3 l of water and the glass/calcite plate only 0.71-0.75 × 10 −3 l; meanwhile dew was not observed on a glass plate without minerals.

Observations of air bubble growth in a quiescent liquid and in a liquid cross-flow by means of a ... more Observations of air bubble growth in a quiescent liquid and in a liquid cross-flow by means of a high-speed camera and piezoelectric-hydrophone in a synchronous experimental setup are performed. Using the passive acoustical method, one observes a beat-wave phenomenon when the feed magnitude of liquid cross-flow is increased from 43 to 128 mm/s and this is corroborated by the appearance of peaks in spectral and spectrogram analyses respectively. A fit to experimental data by a theoretical-model indicates that the beat-signal is the result of under and overdamped systems. The bubble video-images show the asymmetric travel of bubble-surface ripples after the neck collapse. The acoustic comparison exhibits a beat signal as a result of capillary -wave superposition, which is in agreement with earlier results on bubble fragmentation in a locally sheared flow.

Three methods for measuring the volume and the equivalent radius of air bubbles at detachment fro... more Three methods for measuring the volume and the equivalent radius of air bubbles at detachment from the tip of different capillary tubes in quiescent water were tested. The aim was to provide an accurate cross-calibration of two of the methods against a standard laboratory method. The inverted funnel method is the laboratory standard and performed within a 0.5% repeatability error for 50 bubble sets. The passive acoustic method performed within an accuracy between 97% and 99% with respect to the inverted funnel method. The photographic method gave an accuracy between 88% and 96%. After improvement of the photographic method by an empirical cutting edge criterion, its accuracy was raised between 95% and 99%. The bubble shape at detachment was found to be fitted by a CassiniÕs oval or by a BernoulliÕs lemniscate according to the formation time. Qualitative observations on the bubble formation stage indicated an early vertical nose growth for the larger diameter capillary tubes at short formation times. The major-axis vertical and horizontal lengths were measured as functions of time at the formation stage.

Patterns were generated inside a horizontal cylinder rotating at low speeds. The cylinder was fil... more Patterns were generated inside a horizontal cylinder rotating at low speeds. The cylinder was filled with a very low volume liquid fraction of 1.8% of Newtonian fluid and the rotation speed ranged between 0.08 and 5.2 s À1 . A novel laser-plane technique was utilized to obtain time series from each pattern. This enabled the characterization of fluid patterns using Fourier spectral (FS) and dynamical-systems (chaotic) techniques such as the recurrence map, correlation dimension (D 2 ) and Hurst exponent (H). Four patterns were found (fingers, furrows, waterfall and smooth tooth) before annular flow was reached. The results indicate that the FS technique not is suitable for flow pattern characterization; and H only has the ability to indicate a possible pattern change. The best tool for indicating the pattern transitions and the inner coat liquid evolution was found to be recurrence maps and D 2 .

Experiments were performed on both the acoustic and pressure signals produced by bubbles formed f... more Experiments were performed on both the acoustic and pressure signals produced by bubbles formed from an underwater nozzle. The data were analyzed by a comprehensive set of spectral and nonlineardynamical techniques. As air flow rates increase, it is well known that such flows became chaotic. However, the present study of both acoustic and pressure signals showed that chaos could appear in different regimes and was manifested in different ways in the acoustic and pressure signals. The use of different time delays for the chaotic analysis of acoustic and pressure signals were found necessary. The acoustic signals offer data primarily on the bubble size while the pressure signals offer data primarily on the bubble production rate. The present results suggest that chaos can appear in the bubble size and bubble production rate independently.

An arrangement of plates was built using two minerals, calcite and hematite, deposited on glass (... more An arrangement of plates was built using two minerals, calcite and hematite, deposited on glass (slides). The plates were placed in Chilapa de Alvarez city, in the southeast of Mexico. The goal of this work is to prove that mineral plates perform better than glass in nocturnal radiative cooling phenomena. The results obtained are that the glass/hematite plate collected 1.2-1.5 × 10 −3 l of water and the glass/calcite plate only 0.71-0.75 × 10 −3 l; meanwhile dew was not observed on a glass plate without minerals.