Miguel Balzan - Academia.edu (original) (raw)
Papers by Miguel Balzan
In two-phase gas/liquid (TPGL) sprays, traditional dimensionless numbers are limited in their use... more In two-phase gas/liquid (TPGL) sprays, traditional dimensionless numbers are limited in their use of understanding atomization behaviour. In TPGL sprays, the important dimensionless numbers are: Stokes Number (St), Reynolds Number (Re), Froude Number (Fr), Galileo Number (Ga), aerodynamic Weber Number (Weg), Eotvos number (Eo), and Ohnesorge number (Oh). These numbers are very useful when explaining the droplet break-up mechanism further downstream of the spray. As an example, in this study it was observed that the Weg and Re decreased remarkably with the radial distances (r) before the Wecrit limit (‘crit’ stands for critical). However the Weg and Re decreased slowly with the variation of the gas-to-liquid ratio ( ) values after the Wecrit limit indicating that no further break-ups would occur after this limit. In this study, radial and axial TPGL spray profiles were measured using a Phase-Doppler-Particle-Analyzer (PDPA) system. The diameter of the nozzle was 3.10 mm. The experime...
Colloids and Surfaces A: Physicochemical and Engineering Aspects
The Canadian Journal of Chemical Engineering, 2016
A study was performed to characterize the different bubble formation regimes that occur during th... more A study was performed to characterize the different bubble formation regimes that occur during the process of gas jet injection into a liquid cross flow in a conduit. Air was injected perpendicularly into a turbulent, fully developed water flow circulating through a 12.7 mm square channel. Three different gas injectors, with diameters of 0.27 mm, 0.52 mm, and 1.59 mm were used. The bulk water velocity values ranged between 1.1 and 4.3 m/s. The effects that the gas injection velocity, liquid mean velocity and injection gas injection diameter have on the process of bubble generation were investigated. A high-speed visualization technique was used to determine the regimes near the gas inlet region. Four distinct regimes were identified: Single Bubbling (SB), Pulse (P), Elongated Jetting (EJ) and Atomizing Jetting (AJ). It was observed that the shift between regimes occurs gradually, producing the need to identify transitional regions: SBP and PTJ. Sets of independent dimensionless variables were used to categorize the proposed regimes using bubble formation maps. It was determined that the injection diameter plays a primary role in jet formation: as the injection diameter increased, the observable number of regimes decreased, indicating a more stable and continuous process of bubble generation. Empirical correlations that delimit the boundaries between ordered and chaotic bubble generation are presented. This article is protected by copyright. All rights reserved
Journal of Fluids Engineering
The bubble formation frequency from a single-orifice nozzle subjected to the effects of a crossfl... more The bubble formation frequency from a single-orifice nozzle subjected to the effects of a crossflowing liquid was investigated using high-speed shadowgraphy, combined with image analysis and signal processing techniques. The effects of the nozzle dimensions, orientation within the conduit, liquid cross-flow velocity, and gas mass flow rate were evaluated. Water and air were the working fluids. Existing expressions in the literature were compared to the experimental values obtained. The expressions showed modest agreement with the experimental mean average frequency magnitude. It was found that increasing the gas injection diameter could decrease the bubbling frequency approximately 12% until reaching a certain value (0.52 mm). Further increasing the nozzle dimensions increase the frequency by around 20%. Bubbling frequency is more sensitive to the liquid velocity where changes up to 63% occurred when the velocity was raised from 3.1 to 4.3 m/s. Increasing gas mass flow rates decreas...
Multiphase Science and Technology, 2014
Bubble formation from a gas jet in a liquid cross flow inside the mixing conduit of an effervesce... more Bubble formation from a gas jet in a liquid cross flow inside the mixing conduit of an effervescent atomizer is studied using flow visualization. Air injection rates were varied from 0.99 9 10 -5 to 4.94 9 10 -5 kg/s, while maintaining a constant liquid cross-flow rate of 0.298 kg/s. Though gas-liquid ratio (GLR) and flow velocities dominate bubble formation, intermittent choking at the exit nozzle is shown to have a morphological impact on the bubbly flow. This impact is visible as a pressure wave that propagates upstream from the nozzle exit. This pulse is found to have a strong influence on bubble formation at the gas injection location leading to bubble distortion and breakup. In most cases, a liquid jet is observed to propagate through the centreline of larger bubbles as the pressure pulse passes.
Two phase atomization Horizontal nozzle High speed video shadowgraph Stroboscopic back scattered ... more Two phase atomization Horizontal nozzle High speed video shadowgraph Stroboscopic back scattered imagery Phase Doppler Particle Anemometer a b s t r a c t
In two-phase gas/liquid (TPGL) sprays, traditional dimensionless numbers are limited in their use... more In two-phase gas/liquid (TPGL) sprays, traditional dimensionless numbers are limited in their use of understanding atomization behaviour. In TPGL sprays, the important dimensionless numbers are: Stokes Number (St), Reynolds Number (Re), Froude Number (Fr), Galileo Number (Ga), aerodynamic Weber Number (Weg), Eotvos number (Eo), and Ohnesorge number (Oh). These numbers are very useful when explaining the droplet break-up mechanism further downstream of the spray. As an example, in this study it was observed that the Weg and Re decreased remarkably with the radial distances (r) before the Wecrit limit (‘crit’ stands for critical). However the Weg and Re decreased slowly with the variation of the gas-to-liquid ratio ( ) values after the Wecrit limit indicating that no further break-ups would occur after this limit. In this study, radial and axial TPGL spray profiles were measured using a Phase-Doppler-Particle-Analyzer (PDPA) system. The diameter of the nozzle was 3.10 mm. The experime...
Colloids and Surfaces A: Physicochemical and Engineering Aspects
The Canadian Journal of Chemical Engineering, 2016
A study was performed to characterize the different bubble formation regimes that occur during th... more A study was performed to characterize the different bubble formation regimes that occur during the process of gas jet injection into a liquid cross flow in a conduit. Air was injected perpendicularly into a turbulent, fully developed water flow circulating through a 12.7 mm square channel. Three different gas injectors, with diameters of 0.27 mm, 0.52 mm, and 1.59 mm were used. The bulk water velocity values ranged between 1.1 and 4.3 m/s. The effects that the gas injection velocity, liquid mean velocity and injection gas injection diameter have on the process of bubble generation were investigated. A high-speed visualization technique was used to determine the regimes near the gas inlet region. Four distinct regimes were identified: Single Bubbling (SB), Pulse (P), Elongated Jetting (EJ) and Atomizing Jetting (AJ). It was observed that the shift between regimes occurs gradually, producing the need to identify transitional regions: SBP and PTJ. Sets of independent dimensionless variables were used to categorize the proposed regimes using bubble formation maps. It was determined that the injection diameter plays a primary role in jet formation: as the injection diameter increased, the observable number of regimes decreased, indicating a more stable and continuous process of bubble generation. Empirical correlations that delimit the boundaries between ordered and chaotic bubble generation are presented. This article is protected by copyright. All rights reserved
Journal of Fluids Engineering
The bubble formation frequency from a single-orifice nozzle subjected to the effects of a crossfl... more The bubble formation frequency from a single-orifice nozzle subjected to the effects of a crossflowing liquid was investigated using high-speed shadowgraphy, combined with image analysis and signal processing techniques. The effects of the nozzle dimensions, orientation within the conduit, liquid cross-flow velocity, and gas mass flow rate were evaluated. Water and air were the working fluids. Existing expressions in the literature were compared to the experimental values obtained. The expressions showed modest agreement with the experimental mean average frequency magnitude. It was found that increasing the gas injection diameter could decrease the bubbling frequency approximately 12% until reaching a certain value (0.52 mm). Further increasing the nozzle dimensions increase the frequency by around 20%. Bubbling frequency is more sensitive to the liquid velocity where changes up to 63% occurred when the velocity was raised from 3.1 to 4.3 m/s. Increasing gas mass flow rates decreas...
Multiphase Science and Technology, 2014
Bubble formation from a gas jet in a liquid cross flow inside the mixing conduit of an effervesce... more Bubble formation from a gas jet in a liquid cross flow inside the mixing conduit of an effervescent atomizer is studied using flow visualization. Air injection rates were varied from 0.99 9 10 -5 to 4.94 9 10 -5 kg/s, while maintaining a constant liquid cross-flow rate of 0.298 kg/s. Though gas-liquid ratio (GLR) and flow velocities dominate bubble formation, intermittent choking at the exit nozzle is shown to have a morphological impact on the bubbly flow. This impact is visible as a pressure wave that propagates upstream from the nozzle exit. This pulse is found to have a strong influence on bubble formation at the gas injection location leading to bubble distortion and breakup. In most cases, a liquid jet is observed to propagate through the centreline of larger bubbles as the pressure pulse passes.
Two phase atomization Horizontal nozzle High speed video shadowgraph Stroboscopic back scattered ... more Two phase atomization Horizontal nozzle High speed video shadowgraph Stroboscopic back scattered imagery Phase Doppler Particle Anemometer a b s t r a c t