Role of Nozzles with Air Holes in Air Entrainment by a Water Jet

2003 ◽  
Vol 38 (4) ◽  
pp. 785-795 ◽  
Author(s):  
M. Emin Emiroglu ◽  
Ahmet Baylar
Keyword(s):  
Experimental Study ◽  
Nozzle Exit ◽  
Negative Pressure ◽  
Air Entrainment ◽  
Water Jet ◽  
Entrainment Rate ◽  
Air Bubbles ◽  
Air Entrainment Rate ◽  
Plunging Water Jet

Abstract When a water jet impinges a pool of water at rest, air bubbles may be entrained and carried a distance below the pool's surface. This process is called plunging water jet entrainment and aeration. This paper describes an experimental study of the air entrainment rate of circular nozzles with and without air holes, and in particular, the effect of varying numbers and positions of air holes and distance between the location of the air holes and nozzle exit. A negative pressure occurred due to the air holes on the circular nozzles. This phenomenon affected air entrainment. The differences in air entrainment rate were related to changes in the jet shape. It was demonstrated that the air entrainment rates of the circular nozzles with air holes were significantly higher than those of circular nozzles without air holes.

The Effect of Nozzle Type on Air Entrainment by Plunging Water Jets

2002 ◽  
Vol 37 (3) ◽  
pp. 599-612 ◽  
Author(s):  
Tamer Bagatur ◽  
Ahmet Baylar ◽  
Nusret Sekerdag
Keyword(s):  
Penetration Depth ◽  
Oxygen Transfer ◽  
Free Water ◽  
Air Entrainment ◽  
Water Jet ◽  
Transfer Efficiency ◽  
Entrainment Rate ◽  
Water Jets ◽  
Air Entrainment Rate ◽  
Oxygen Transfer Efficiency

Abstract In this study, for the plunging water jet aeration system using various inclined nozzle types, bubble penetration depth, air entrainment rate, water jet expansion, effect of water jet circumference at impact point, oxygen transfer coefficient and oxygen transfer efficiency which changed depending on the water jet velocity, were researched in an air-water system. Numerous studies were conducted with circular nozzles. The present study describes new experiments performed with different nozzle types. Three types of nozzles were examined, i.e., those with circular, ellipse and rectangle duct with rounded ends. Experimental results showed that water jets produced with ellipse and rectangle duct with rounded ends nozzles have very different flow characteristics, entrainment patterns on free water jet surface, and submerged water jet region within the receiving tank. Higher air entrainment rate and oxygen transfer efficiency was observed in the rectangle duct with rounded ends nozzle due to water jet expansion. Bubble penetration depth, however, is lower for the rectangle duct with rounded ends nozzle than for the other nozzles. The ellipse nozzle provided the highest bubble penetration depth. These results showed that it is appropriate to use ellipse nozzle in aeration of deep pool and rectangle duct with rounded ends nozzle in the applications where high bubble concentration is desirable.

scholarly journals The Effects of Downcomer Diameter on an Air Entrainment of Vertical Plunging Water Jet on The Water Surface

2021 ◽  
Vol 81 (2) ◽  
pp. 89-97
Author(s):  
Warjito ◽  
Ridho Irwansyah ◽  
Iqbal Yudianto ◽  
Leonardo Fabianto ◽  
Arya Amardani ◽  
...  
Keyword(s):  
High Speed ◽  
Qualitative Data ◽  
Bubble Formation ◽  
Air Entrainment ◽  
Water Jet ◽  
Water Desalination ◽  
Entrainment Rate ◽  
Clean Water ◽  
Depth Of Penetration ◽  
Plunging Water Jet

The difficulty in finding clean water is issued to become Indonesia’s problem in 2025. Seawater processing to produce clean water for commonly used or called water desalination will be a promising solution to solve the problem of clean water scarcity. One of the seawater desalination processes is to utilize micro-bubbles generated from air entrainment. Air entrainment is a phenomenon where the surrounding air is trapped in the water and forms a bubble. Using the vertical plunging jet setup will lead to bubble formation as a result of the collision between the vertical water jet and the pond surface below it. This study determines the effect of downcomer diameter on the parameters that influence the parameter of air entrainment quality by using a vertical plunging jet configuration. Some set up tools that support research consists of pumps, nozzle, downcomer, airflow meter, anemometer, and water pond. Results of the research are in the form of qualitative data such as videos and photos, by using a high-speed camera with backlighting. The qualitative data obtained will be processed with an image processing program to acquire quantitative data. The results of the study revealed that the downcomer diameter affects the air entrainment rate. On the other hand, jet velocity affects the area of dispersion and depth of penetration.

Experimental Study of the Influence of Different Weir Types on the Rate of Air Entrainment

2003 ◽  
Vol 38 (4) ◽  
pp. 769-783 ◽  
Author(s):  
M. Emin Emiroglu ◽  
Ahmet Baylar
Keyword(s):  
Experimental Study ◽  
Air Entrainment ◽  
Entrainment Rate ◽  
Empirical Correlations ◽  
Air Entrainment Rate ◽  
Maximum Penetration Depth ◽  
Longitudinal Slope ◽  
Maximum Penetration ◽  
Labyrinth Weirs ◽  
Better Than

Abstract Aeration is used in water treatment to alter the concentration of dissolved gases, to strip volatile organics, and to reduce tastes and odours. This can be obtained by creating turbulence in the water. One method of producing such turbulence is via the overflow jets downstream of weir structures. This paper investigates the effect of varying weir types on the air entrainment rate. Empirical correlations predicting the maximum penetration depth and air entrainment rate were developed for different weir types. It is demonstrated that the air entrainment rate of the broad-crested weirs is generally much better than for the sharp-crested weir and the labyrinth weirs. The air entrainment rate increased as the weir longitudinal slope of the broad-crested weirs and the weir sill slope of the labyrinth weirs became larger.

scholarly journals Air entrainment by inclined circular plunging water jets with various impingement heights

2020 ◽  
Vol 20 (8) ◽  
pp. 3478-3486
Author(s):  
Yiyi Ma ◽  
Luchen Zhang ◽  
Yu Yang ◽  
Ping Wei
Keyword(s):  
Experimental Study ◽  
Surface Roughness ◽  
Water Surface ◽  
Jet Impingement ◽  
Air Entrainment ◽  
Entrainment Rate ◽  
Water Jets ◽  
Air Entrainment Rate ◽  
Jet Breakup ◽  
Early Increase

Abstract This paper presents an experimental study on air entrainment by inclined circular plunging water jets issued from long nozzles with various jet impingement heights up to 6.1 m. Particular attention was paid to the jets having a large impingement height, and which disintegrated into small droplets before reaching the water surface. The dominant sizes and velocities of the droplets generated by jet breakup were 1–4 mm and 4–9 m/s. The results show that for plunging water jets having the same hydraulic head, the air entrainment rate increased as the jet impingement height at first grew, then dropped as the jet impingement height kept increasing. The early increase in the air entrainment rate was due to the growth of jet surface roughness, while the later decrease was caused by the water jet disintegration. The momentum of the plunging jet decreased dramatically due to the reduced mass and the significant energy dissipation through the atmosphere caused by jet disintegration. This led to a much smaller penetration depth and air entrainment rate compared to with a continuous jet.

The effect of sharp-crested weir shape on air entrainment

2002 ◽  
Vol 29 (3) ◽  
pp. 375-383 ◽  
Author(s):  
Ahmet Baylar ◽  
M Emin Emiroglu
Keyword(s):  
Air Entrainment ◽  
Entrainment Rate ◽  
Air Bubbles ◽  
Cross Sectional ◽  
Aquatic Life ◽  
Plunge Pool ◽  
Air Entrainment Rate ◽  
Rivers And Streams ◽  
Entrained Air ◽  
Better Than

Aeration in the waters of rivers and streams is very important to the quality and existence of aquatic life. If the overfall jets downstream of weir structures plunges into a plunge pool, entrained air bubbles will contribute to aeration. This paper investigates sharp-crested weirs having different cross-sectional geometry and their effect on the air entrainment rate. It is demonstrated that the air entrainment rate of a 30° triangular sharp-crested weir is better than that of the other sharp-crested weirs tested. Moreover, variation in the number of V-notches over the width of the weir plate was studied for 30° triangular sharp-crested weirs. The 30° triangular sharp-crested weir with two V-notches was found to have higher values of air entrainment rate.Key words: aeration, air entrainment rate, plunging overfall jet, sharp-crested weir.

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