Shock-Excited Pulsations of Large Air Bubbles in Water

1974 ◽  
Vol 96 (4) ◽  
pp. 389-393 ◽  
Author(s):  
F. B. Jensen
Keyword(s):  
Shock Wave ◽  
Thermal Behavior ◽  
Bubble Size ◽  
Air Bubbles ◽  
Pressure Measurements ◽  
Photographic Recording ◽  
Attenuation Effect ◽  
Air Bubble ◽  
Direct Pressure ◽  
Bubble Sizes

The interaction between an air bubble in water (d0 = 10–30 mm) and a shock wave generated by a small detonator (0.8 g) is studied. On the basis of direct pressure measurements inside pulsating bubbles and simultaneous photographic recording of the diameter variations, the overall thermal behavior of the gas in the bubbles is determined. It is found that the pulsation process is nearly adiabatic for the bubble sizes considered. The measured maximum pressures inside pulsating bubbles are given as a function of bubble size and distance from the explosion. From these results, the total energy absorbed by a bubble is calculated as a measure of the attenuation effect of a single bubble on a shock wave.

scholarly journals On the breakup of an air bubble injected into a fully developed turbulent flow. Part 1. Breakup frequency

1999 ◽  
Vol 401 ◽  
pp. 157-182 ◽  
Author(s):  
C. MARTÍNEZ-BAZÁN ◽  
J. L. MONTAÑÉS ◽  
J. C. LASHERAS
Keyword(s):  
Bubble Size ◽  
Critical Diameter ◽  
Air Bubble ◽  
Wide Range ◽  
Fully Developed Turbulent Flow ◽  
Flow Part ◽  
Bubble Sizes ◽  
Rate Of Dissipation ◽  
Processing Techniques ◽  
Good Agreement

The transient evolution of the bubble-size probability density functions resulting from the breakup of an air bubble injected into a fully developed turbulent water ow has been measured experimentally using phase Doppler particle sizing (PDPA) and image processing techniques. These measurements were used to determine the breakup frequency of the bubbles as a function of their size and of the critical diameter Dc defined as Dc = 1.26 (σ/ρ)3/5ε−2/5, where ε is the rate of dissipation per unit mass and per unit time of the underlying turbulence. A phenomenological model is proposed showing the existence of two distinct bubble size regimes. For bubbles of sizes comparable to Dc, the breakup frequency is shown to increase as (σ/ρ)−2/5ε−3/5 √D/Dc−1, while for large bubbles whose sizes are greater than 1.63Dc, it decreases with the bubble size as ε1/3D−2/3. The model is shown to be in good agreement with measurements performed over a wide range of bubble sizes and turbulence intensities.

Factor Affecting Bubble Creation and Bubble Size

2011 ◽  
Author(s):  
Ammar A. T. Alkhalidi ◽  
Ryo S. Amano
Keyword(s):  
Flow Rate ◽  
Computational Fluid Dynamic ◽  
Bubble Size ◽  
Fluid Dynamic ◽  
Air Bubbles ◽  
Hole Size ◽  
Critical Factors ◽  
Water Pool ◽  
Factors Affecting ◽  
Air Bubble

This paper presents the factors affecting air bubble size when air is injected through a perforated membrane into a water pool. Critical factors that govern the size of air bubbles are the air pressure and the flow rate as well as the hole size of the diffuser membrane. In order to have a better understanding of how bubble size can be affected and what the most effecting conditions are, the study was conducted in a computational fluid dynamic (CFD) investigation, which was validated by the experimental results.

scholarly journals Measurement of the air bubble size and velocity from micro air bubble generation (MBG) in diesel using optical methods

2020 ◽  
Author(s):  
Bader A. Alfarraj ◽  
Abdullah M. Alkhedhair ◽  
Ahmed A. Al-Harbi ◽  
Wojciech Nowak ◽  
Saleh A. Alfaleh
Keyword(s):  
Size Distribution ◽  
Optical System ◽  
Bubble Size ◽  
Bubble Radius ◽  
Optical Methods ◽  
Objective Lens ◽  
Air Bubbles ◽  
Generation Process ◽  
Bubble Generation ◽  
Air Bubble

Abstract In this paper, we determine the bubble size and velocity from air bubble generation (MBG) in a diesel using optical methods. A KTM Series Pump was used to generate micro air bubbles in diesel. The air bubble radius and velocity measurements can be useful parameters to optimize the bubble generation process. Two optical systems were used for measurement air bubble sizes and their velocities in diesel. First, the optical system without an objective lens was used to determine the velocity of air bubbles in diesel. Another optical system with a 10× objective lens was used to obtain the size distribution of air bubbles generated in diesel. An available optical system with a 10× objective lens can detect a bubble diameter greater than 3.3 µm that air bubble images were processed using the ImageJ program. We measured the size distribution of air bubbles generated using the ImageJ program. The micro air bubble radius measured in diesel was found to be 6.26 µm in the sample after a month from air bubble generation. In addition, the particle image velocimetry (PIV) technique was used to measure the velocity field. Then, we used the OpenPIV program for PIV image processing. The highest velocity distribution was determined to be 90 mm/s for diesel without air bubbles and 20 mm/s for diesel with air bubbles after a month of the bubble generation.

Air occlusion in insulin pumps of children and adolescents with type 1 diabetes

2020 ◽  
Vol 33 (2) ◽  
pp. 179-184
Author(s):  
Michelle M. Knoll ◽  
Turaj Vazifedan ◽  
Eric Gyuricsko
Keyword(s):  
Type 1 Diabetes ◽  
Bubble Size ◽  
Insulin Pump ◽  
Air Bubbles ◽  
Office Visits ◽  
Insulin Pumps ◽  
Air Bubble ◽  
The Subject ◽  
Clinically Significant

AbstractBackgroundInsulin pumps are a frequently used technology among youth with type 1 diabetes. Air bubbles within insulin pump tubing are common, preventing insulin delivery and increasing the risk of large glycemic excursions and diabetic ketoacidosis (DKA). We sought to determine the prevalence of air bubbles in insulin pump tubing and identify factors associated with clinically significant air bubbles.MethodsFifty-three subjects were recruited over 65 office visits. The insulin pump tubing was visualized, and any air bubbles were measured by length. The length of air bubbles was then converted to time without insulin at the lowest basal rate. Generalized linear model (GLM) was used to determine the associations between air bubble size and other variables.ResultsOf the 65 encounters, 45 had air bubbles in the tubing. Five (5/65 = 7.7%) encounters had a time without insulin of more than 60 min. Air bubble size was inversely correlated with time since infusion set change (p < 0.001), and directly correlated with age of the subject (p = 0.049).ConclusionsSignificantly more air bubbles were found in the tubing of insulin pumps soon after infusion set change and with older subjects, suggesting a relationship with the technique of filling the insulin cartridge and priming the tubing.

scholarly journals Air Entrainment in the Developing Flow Region of Plunging Jets—Part 2: Experimental

1997 ◽  
Vol 119 (3) ◽  
pp. 603-608 ◽  
Author(s):  
P. D. Cummings ◽  
H. Chanson
Keyword(s):  
Shear Layer ◽  
Flow Region ◽  
Air Entrainment ◽  
Chord Length ◽  
Strong Interactions ◽  
Air Bubbles ◽  
Air Concentration ◽  
Air Bubble ◽  
Wide Range ◽  
Bubble Sizes

When a water jet impinges a pool of water at rest, air bubbles may be entrained and carried away below the pool free surface: this process is called plunging jet entrainment. The study presents new experimental data obtained with a vertical supported jet. Distributions of air concentration and mean air-water velocity, and bubble chord length distributions measured in the developing shear layer are presented. The results indicate that the distributions of void fraction follow closely analytical solution of the diffusion equation. Further, the momentum shear layer and the air bubble diffusion layer do not coincide. Chord length data show a wide range of air bubble sizes and overall the experimental results suggest strong interactions between the entrained air bubbles and the momentum transfer mechanisms.

scholarly journals On the breakup of an air bubble injected into a fully developed turbulent flow. Part 2. Size PDF of the resulting daughter bubbles

1999 ◽  
Vol 401 ◽  
pp. 183-207 ◽  
Author(s):  
C. MARTÍNEZ-BAZÁN ◽  
J. L. MONTAÑÉS ◽  
J. C. LASHERAS
Keyword(s):  
Bubble Size ◽  
Most Probable Number ◽  
Experimental Measurements ◽  
Probable Number ◽  
Air Bubble ◽  
Consistent Manner ◽  
Fully Developed Turbulent Flow ◽  
Flow Part ◽  
Bubble Sizes ◽  
Energy Principles

Based on energy principles, we propose a statistical model to describe the bubble size probability density function of the daughter bubbles resulting from the shattering of a mother bubble of size D0 immersed in a fully developed turbulent water flow. The model shows that the bubble size p.d.f. depends not only on D0, but also on the value of the dissipation rate of turbulent kinetic energy of the underlying turbulence of the water, ε. The phenomenological model is simple, yet it predicts detailed experimental measurements of the transient bubble size p.d.f.s performed over a range of bubble sizes and dissipation rates ε in a very consistent manner. The agreement between the model and the experiments is particularly good for low and moderate bubble turbulent Weber numbers, Wet = ρΔu2(D0)D0/σ where the assumption of the binary breakup is shown to be consistent with the experimental observations. At larger values of Wet, it was found that the most probable number of daughter bubbles increases and the assumption of tertiary breakup is shown to lead to a better fit of the experimental measurements.

scholarly journals Effect of cannulation site on emboli travel during cardiac surgery

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Mira Puthettu ◽  
Stijn Vandenberghe ◽  
Stefanos Demertzis
Keyword(s):  
Cardiac Surgery ◽  
In Vitro Study ◽  
Blood Stream ◽  
Air Bubbles ◽  
Arterial Tree ◽  
Air Bubble ◽  
Cannulation Site ◽  
The Brain

Abstract Background During cardiac surgery, micro-air emboli regularly enter the blood stream and can cause cognitive impairment or stroke. It is not clearly understood whether the most threatening air emboli are generated by the heart-lung machine (HLM) or by the blood-air contact when opening the heart. We performed an in vitro study to assess, for the two sources, air emboli distribution in the arterial tree, especially in the brain region, during cardiac surgery with different cannulation sites. Methods A model of the arterial tree was 3D printed and included in a hydraulic circuit, divided such that flow going to the brain was separated from the rest of the circuit. Air micro-emboli were injected either in the HLM (“ECC Bubbles”) or in the mock left ventricle (“Heart Bubbles”) to simulate the two sources. Emboli distribution was measured with an ultrasonic bubble counter. Five repetitions were performed for each combination of injection site and cannulation site, where air bubble counts and volumes were recorded. Air bubbles were separated in three categories based on size. Results For both injection sites, it was possible to identify statistically significant differences between cannulation sites. For ECC Bubbles, axillary cannulation led to a higher amount of air bubbles in the brain with medium-sized bubbles. For Heart Bubbles, aortic cannulation showed a significantly bigger embolic load in the brain with large bubbles. Conclusions These preliminary in vitro findings showed that air embolic load in the brain may be dependent on the cannulation site, which deserves further in vivo exploration.

Surface pressure measurements in shock wave/boundary-layer interactions

1997 ◽  
Vol 11 (2) ◽  
pp. 164-172
Author(s):  
Yeol Lee ◽  
Sanjay Garg ◽  
Gary S. Settles
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Surface Pressure ◽  
Pressure Measurements ◽  
Wave Boundary Layer ◽  
Wave Boundary

Numerical and Experimental Investigation Into the Effects of Nanoparticle Mass Fraction and Bubble Size on Boiling Heat Transfer of TiO2–Water Nanofluid

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Cong Qi ◽  
Yongliang Wan ◽  
Lin Liang ◽  
Zhonghao Rao ◽  
Yimin Li
Keyword(s):  
Heat Transfer ◽  
Bubble Size ◽  
Boiling Heat Transfer ◽  
Mass Fraction ◽  
Experimental Methods ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Mass Fractions ◽  
Boiling Heat Transfer Coefficient ◽  
Bubble Sizes

Considering mass transfer and energy transfer between liquid phase and vapor phase, a mixture model for boiling heat transfer of nanofluid is established. In addition, an experimental installation of boiling heat transfer is built. The boiling heat transfer of TiO2–water nanofluid is investigated by numerical and experimental methods, respectively. Thermal conductivity, viscosity, and boiling bubble size of TiO2–water nanofluid are experimentally investigated, and the effects of different nanoparticle mass fractions, bubble sizes and superheat on boiling heat transfer are also discussed. It is found that the boiling bubble size in TiO2–water nanofluid is only one-third of that in de-ionized water. It is also found that there is a critical nanoparticle mass fraction (wt.% = 2%) between enhancement and degradation for TiO2–water nanofluid. Compared with water, nanofluid enhances the boiling heat transfer coefficient by 77.7% when the nanoparticle mass fraction is lower than 2%, while it reduces the boiling heat transfer by 30.3% when the nanoparticle mass fraction is higher than 2%. The boiling heat transfer coefficients increase with the superheat for water and nanofluid. A mathematic correlation between heat flux and superheat is obtained in this paper.

scholarly journals Development of Bubble Characteristics on Chute Spillway Bottom

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1129
Author(s):  
Ruidi Bai ◽  
Chang Liu ◽  
Bingyang Feng ◽  
Shanjun Liu ◽  
Faxing Zhang
Keyword(s):  
Size Distribution ◽  
Bubble Size ◽  
Dissipation Rate ◽  
Bubble Diameter ◽  
Bubble Size Distribution ◽  
Impact Zone ◽  
Air Bubble ◽  
Air Supply ◽  
Bubble Characteristics ◽  
The Impact

Chute aerators introduce a large air discharge through air supply ducts to prevent cavitation erosion on spillways. There is not much information on the microcosmic air bubble characteristics near the chute bottom. This study was focused on examining the bottom air-water flow properties by performing a series of model tests that eliminated the upper aeration and illustrated the potential for bubble variation processes on the chute bottom. In comparison with the strong air detrainment in the impact zone, the bottom air bubble frequency decreased slightly. Observations showed that range of probability of the bubble chord length tended to decrease sharply in the impact zone and by a lesser extent in the equilibrium zone. A distinct mechanism to control the bubble size distribution, depending on bubble diameter, was proposed. For bubbles larger than about 1–2 mm, the bubble size distribution followed a—5/3 power-law scaling with diameter. Using the relationship between the local dissipation rate and bubble size, the bottom dissipation rate was found to increase along the chute bottom, and the corresponding Hinze scale showed a good agreement with the observations.

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