Analytical Investigation of the Influence of Air Bubble Size on the Determination of the Air Content of Freshly Mixed Concrete

1988 ◽  
Vol 10 (1) ◽  
pp. 29 ◽  
Author(s):  
PA Wedding ◽  
KC Hover
Keyword(s):  
Bubble Size ◽  
Analytical Investigation ◽  
Air Bubble ◽  
Air Content ◽  
Mixed Concrete

Bubble size and air content of wet fibre foams in axial mixing with macro-instabilities

2013 ◽  
Vol 436 ◽  
pp. 1130-1139 ◽  
Author(s):  
Ahmad M. Al-Qararah ◽  
Tuomo Hjelt ◽  
Antti Koponen ◽  
Ali Harlin ◽  
Jukka A. Ketoja
Keyword(s):  
Bubble Size ◽  
Air Content

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.

Prediction of Oxygen Transfer Rates from Simple Measurements of Bubble Characteristics

1991 ◽  
Vol 23 (10-12) ◽  
pp. 1941-1950 ◽  
Author(s):  
H. J. Pöpel ◽  
M. Wagner
Keyword(s):  
Oxygen Transfer ◽  
Transfer Rate ◽  
Tap Water ◽  
Oxygen Transfer Rate ◽  
Absorption Method ◽  
Air Bubble ◽  
Air Content ◽  
Lower Accuracy ◽  
Potential Improvement ◽  
Bubble Characteristics

The oxygen transfer rate (OTR) in tap water is generally determined by the instationary absorption method, a precise but rather time consuming and tedious method. Moreover, large quantities of sodium sulfite and water are used in practice when testing aeration equipment in larger tanks. Therefore, a model is proposed by which the oxygen transfer rate can be calculated on the basis of simple and rapid measurements of the air bubble size and its distribution and of the total air content in the water applying a recently developed technique. The accuracy of this method is checked by the absorption method and can be rated as reasonable (0 to 13 % deviation). Greater accuracy is obtained at smaller bubbles (<3 mm) and improvements in this respect are proposed. The proposed method of calculating the OTR from air bubble measurements is considered as a potential improvement of the usual absorption method. Due to its still lower accuracy it can be used at present only in conjunction with the latter method, reducing its chemical and water consumption.

Bubble Behaviour in Viscous Flows: Experimental and Numerical Determination of 3D-Trajectories

2006 ◽  
Author(s):  
Sylvain Chaminade ◽  
Jean Toutain ◽  
Stefan Dilhaire ◽  
Eric Arquis ◽  
Christine Marraud ◽  
...  
Keyword(s):  
Viscous Flows ◽  
Coupling Model ◽  
Light Sources ◽  
Visualization Method ◽  
Air Bubble ◽  
Video Cameras ◽  
Silicon Oil ◽  
Selection Of ◽  
Bubble Behaviour

We studied the air bubble behavhiour in viscous flows. A one-way coupling model was developed, based on lagrangian method. In order to validate this model, experiments were carried out. Our experimental installation was based on shadow visualization method. Bubbles were introduced in a transparent Plexiglas tank filling with viscous fluid (e.g. silicon oil) and were illuminated by diffused lights. In order to reconstruct 3D-trajectories, two video cameras, orthogonally placed, took pictures of shape bubbles and a post treatment of images acquired allowed us to determine the position of the center and the radius of each bubble. Thus, from this information of each plane, we could determine the 3D parameters of bubbles. Superluminescent LEDs with different wave-lengths were used as light sources. The choice of the wavelengths for each plane illumination and the selection of appropriated RGB filter of CCD sensor allowed us to prevent dissymmetry of bubble shape which was due to parasitic orthogonal illumination. Numerical results agree with experimental data.

Adaptation des procédés stéréologiques à la mesure des bulles d'air et des fissures dans le béton

1983 ◽  
Vol 10 (3) ◽  
pp. 415-428 ◽  
Author(s):  
Jules Houde ◽  
Serge Meilleur
Keyword(s):  
Crack Density ◽  
Three Dimensional ◽  
Total Porosity ◽  
Air Bubble ◽  
Air Content ◽  
Projected Length ◽  
Measuring Techniques ◽  
Plastic Concrete ◽  
Image Analyser ◽  
Bubble Sizes

Mathematical morphometry is the science of classifying forms through parameters such as length, area, perimeter, and projected length. Image analysers have been built to measure these parameters rapidly. Stereological equations are used to define three-dimensional characteristics from elementary count operations made in a plane.These techniques were used to characterize the air bubble system of six different concretes. All measurements were made on polished sections with a linear traverse apparatus as well as with an image analyser. The precision of the data obtained is about equal with both measuring techniques. The image analyser was able to measure the air content and the spacing factor in one-eighth of the time necessary for a linear traverse; moreover, histograms of the bubble sizes were readily available.Measurements of cracks caused by early freezing of plastic concrete made on the linear traverse apparatus, coupled with total porosity measurements by the image analyser, were used to relate the decrease of compressive strength to the increased crack density.

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