Formula for Upstream Pressure, Nozzle Geometry and Frequency Correlation in Shedding/Discharging Cavitation Clouds Determined by Visualization of Submerged Cavitating Jet

2007 ◽  
pp. 194-197
Author(s):  
E. A. F. Hutli ◽  
M. S. Nedeljkovic
Keyword(s):  
Nozzle Geometry ◽  
Frequency Correlation ◽  
Upstream Pressure ◽  
Cavitating Jet ◽  
Pressure Nozzle

Frequency in Shedding/Discharging Cavitation Clouds Determined by Visualization of a Submerged Cavitating Jet

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Ezddin A. F. Hutli ◽  
Milos S. Nedeljkovic
Keyword(s):  
Shape Analysis ◽  
High Speed ◽  
Simple Formula ◽  
Injection Pressure ◽  
Nozzle Geometry ◽  
Bubble Collapse ◽  
Cloud Cavitation ◽  
Jet Structure ◽  
Cavitating Jet ◽  
Pressure Nozzle

Visualization of a highly submerged cavitating water jet was done by high-speed camera photography in order to study and understand the jet structure and the behavior of cloud cavitation within time and space. The influencing parameters, such as injection pressure, nozzle diameter and geometry, and nozzle direction (convergent and divergent), were experimentally proven to be very significant. Periodical shedding and discharging of cavitation clouds have been also analyzed and the corresponding frequency was determined by cloud shape analysis. Additionally, the dependence of this frequency on injection pressure and nozzle geometry has been analyzed and a simple formula of correspondence has been proposed. The formula has been tested on self-measured and literature data. The recordings of sonoluminescence phenomenon proved the bubble collapse everywhere along the jet.

scholarly journals Influences of hydrodynamic conditions, nozzle geometry on appearance of high submerged cavitating jets

2013 ◽  
Vol 17 (4) ◽  
pp. 1139-1149 ◽  
Author(s):  
Ezddin Hutli ◽  
Salem Abouali ◽  
Ben Hucine ◽  
Mohamed Mansour ◽  
Milos Nedeljkovic ◽  
...  
Keyword(s):  
Digital Camera ◽  
Injection Pressure ◽  
Nozzle Geometry ◽  
Geometrical Parameters ◽  
Main Role ◽  
Visualization System ◽  
Divergent Flow ◽  
Cavitation Phenomenon ◽  
And Performance ◽  
Cavitating Jet

Based on visualization results of highly-submerged cavitating water jet obtained with digital camera, the influences of related parameters such as: injection pressure, nozzle diameter and geometry, nozzle mounting (for convergent / divergent flow), cavitation number and exit jet velocity, were investigated. In addition, the influence of visualization system position was also studied. All the parameters have been found to be of strong influence on the jet appearance and performance. Both hydro-dynamical and geometrical parameters are playing the main role in behavior and intensity of cavitation phenomenon produced by cavitating jet generator. Based on our considerable previous experience in working with cavitating jet generator, the working conditions were chosen in order to obtain measurable phenomenon.

Research on erosion characteristics of a novel cavitation nozzle under nonsubmerged condition

2020 ◽  
pp. 095440622093773
Author(s):  
Huanlong Liu ◽  
Zeping Cao ◽  
Chixin Xie ◽  
Guanpeng Chen ◽  
Dafa Li ◽  
...  
Keyword(s):  
Surface Cleaning ◽  
Enhancement Effect ◽  
Submerged Condition ◽  
Force Curve ◽  
Cavitation Effect ◽  
Fluent Software ◽  
Brass Surface ◽  
The Impact ◽  
Cavitating Jet ◽  
Pressure Nozzle

When a cavitating jet enters the atmosphere directly, its cavitating effect weakens rapidly, and the erosion energy it produces cannot be fully utilized. Regarding the problem that existing cavitation nozzles are only used in submerged condition, methods to improve the erosion ability of cavitation jets under nonsubmerged condition are studied. The nozzle is visually simulated using Fluent software, and the results show that the dynamic submerged environment at the outlet effectively expands the nearby low-pressure cavitation area. The enhancement effect of the annular cavitation nozzle on the jet cavitation effect in the atmosphere domain is verified by measuring the impact force curve of the jet and through erosion tests on brass surface. Cleaning and derusting tests show that the annular cavitation nozzle has stronger derusting ability than the high-pressure nozzle under nonsubmerged condition and under the same pressure, demonstrating that the cleaning and derusting effect mainly comes from the collapse of cavitation bubbles.

Effect of Cavitation Number on the Improvement of Fatigue Strength of Carburized Steel Using Cavitation Shotless Peening

2004 ◽  
Vol 261-263 ◽  
pp. 1245-1250 ◽  
Author(s):  
D.O. Macodiyo ◽  
H. Soyama ◽  
Masumi Saka
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
High Speed ◽  
Compressive Residual Stress ◽  
Cavitation Number ◽  
Material Surface ◽  
Carburized Steel ◽  
Upstream Pressure ◽  
Cavitating Jet ◽  
Cavitation Shotless Peening

Peening can be used to produce a layer of compressive residual stress at the surface of components which are subject to fatigue or stress corrosion, thereby retarding crack initiation and/or impeding the development of new cracks and hence improving their fatigue life. We have developed a new peening method, Cavitation Shotless Peening (CSP), which makes use of cavitation impacts induced by the collapse of the cavitation bubbles to produce compressive residual stress and work hardening on the material surface. CSP is a surface enhancement technique which differs with shot peening in that shots are not used. CSP uses a submerged high-speed water jet with cavitation, herein referred to as a cavitating jet, whose intensity and occurring region can be controlled by parameters such as upstream pressure and nozzle size. Cavitation number , which is defined by the ratio of upstream pressure to downstream pressure, is the main parameter of the cavitating jet. In this paper, the pit distribution on the specimen was observed with cavitating numbers  = 0.0057 and  = 0.0142. The improvement of fatigue strength and introduction of residual stress were investigated for both conditions using carburized alloy steel (JIS SCM415). It was evident from a comparison between non-peened and cavitation shotless peened specimens that the cavitation number has influence on the fatigue strength of metallic materials. Comparison of shot peened and CSP specimens has also been discussed.

Enhancing the Aggressive Intensity of a Cavitating Jet by Introducing Water Flow Holes and a Long Guide Pipe

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Hirokazu Kamisaka ◽  
Hitoshi Soyama
Keyword(s):  
Mass Loss ◽  
Water Flow ◽  
High Speed ◽  
Pure Aluminum ◽  
Video Camera ◽  
Nozzle Geometry ◽  
High Speed Video ◽  
High Speed Video Camera ◽  
Erosion Area ◽  
Cavitating Jet

Abstract It is known that the geometry of the nozzle has a great effect on the aggressive intensity of a cavitating jet. In previous reports, various nozzle geometries were proposed, and improvements made to the aggressive intensity were reported. However, no detailed description of the reasons why the aggressive intensity is improved by these various geometries was given. In this study, we conducted erosion tests on pure aluminum Japanese Industrial Standards JIS A1050P using 11 different nozzles with different geometries downstream from the throat outlet in order to understand the effects of the nozzle geometry on the aggressive intensity. In addition, in order to investigate the characteristics of the cavitating jet produced by each nozzle, measurements of the erosion areas, images of the cavitating jet using a high-speed video camera, and measurements of the impingement pressure of the cavitating jet were taken, and correlations between the parameters were obtained. It was found that the nozzle with the largest mass loss was a nozzle with water flow holes near to the throat outlet and a long guide pipe (LGP). The mass loss was 2.5 times that of the previously reported optimum geometry nozzle. Very high correlations were obtained between the mass loss, the inner diameter of the annular erosion area, the impingement pressure measured at the same standoff distance and the cavitation cloud lifetime. Based on these results and the images of the cavitating jets taken with the high-speed video camera, a new cavitating jet progression process is proposed.

Influence of Torch Nozzle Geometry on Plasma Jet Properties

1997 ◽  
Vol 7 (6) ◽  
pp. 1361-1375 ◽  
Author(s):  
O. H. Chang ◽  
A. Kaminska ◽  
M. Dudeck
Keyword(s):  
Plasma Jet ◽  
Nozzle Geometry

High-Speed Imaging to Study an Auto-Oscillating Vocal Fold Replica for Different Initial Conditions

2017 ◽  
Vol 09 (05) ◽  
pp. 1750064 ◽  
Author(s):  
A. Van Hirtum ◽  
X. Pelorson
Keyword(s):  
Vocal Fold ◽  
High Speed ◽  
Initial Conditions ◽  
Vocal Folds ◽  
High Speed Imaging ◽  
Human Voice ◽  
Manual Intervention ◽  
Geometrical Features ◽  
Upstream Pressure

Experiments on mechanical deformable vocal folds replicas are important in physical studies of human voice production to understand the underlying fluid–structure interaction. At current date, most experiments are performed for constant initial conditions with respect to structural as well as geometrical features. Varying those conditions requires manual intervention, which might affect reproducibility and hence the quality of experimental results. In this work, a setup is described which allows setting elastic and geometrical initial conditions in an automated way for a deformable vocal fold replica. High-speed imaging is integrated in the setup in order to decorrelate elastic and geometrical features. This way, reproducible, accurate and systematic measurements can be performed for prescribed initial conditions of glottal area, mean upstream pressure and vocal fold elasticity. Moreover, quantification of geometrical features during auto-oscillation is shown to contribute to the experimental characterization and understanding.

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