Shadowgraph Imaging of Cavitating Jet

Watanabe, Ryuta; Kikuchi, Takayuki; Yamagata, Takayuki; Fujisawa, Nobuyuki

doi:10.4236/jfcmv.2015.33010

Cited by 16 publications

(6 citation statements)

References 13 publications

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“…Similar setups have been experimentally studied by e.g. Berger (1983); Fujisawa et al (2019Fujisawa et al ( , 2017; Kleinbreuer (1979); Watanabe et al (2015Watanabe et al ( , 2016. We carry out fully compressible high-resolution simulations of two operating points covering different erosion intensities.…”

Section: Introductionmentioning

confidence: 91%

Numerical prediction of erosion due to a cavitating jet

Trummler,

Schmidt,

Adams

2022

Preprint

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We numerically investigate the erosion potential of a cavitating liquid jet by means of highresolution finite volume simulations. As thermodynamic model, we employ a barotropic equilibrium cavitation approach, embedded into a homogeneous mixture model. To resolve the effects of collapsing vapor structures and to estimate the erosion potential, full compressibility is considered.Two different operating points featuring different cavitation intensities are investigated and their erosion potential is estimated and compared. Different methods are used for this purpose, including collapse detection (Mihatsch et al., 2015), maximum pressure distribution on the wall, and a new method of generating numerical pit equivalents. The data of numerical pit equivalents is analyzed in detail and compared with experimental data from the literature. Furthermore, a comprehensive grid study for both operating points is presented.

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Section: Introductionmentioning

confidence: 91%

Numerical prediction of erosion due to a cavitating jet

Trummler,

Schmidt,

Adams

2022

Preprint

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“…Yang Y et al [12][13][14] captured the unsteady flow characteristics of a high-pressure cavitation jet at three different angles through high-speed photography experiments, and extracted its growth, shedding and collapse information from high-speed images. Ryuta Watanabe et al [15,16] applied the POD image processing technology to the high-speed image analysis of a cavitation jet, and analyzed the position of the cavitation bubble collapse through an algorithm. Peng C et al [17] analyzed the time-frequency distribution of cavitation clouds by using the orthogonal decomposition (POD) method, and concluded that the intensity of the cavitation erosion was determined by the bubble concentration and rupture strength on the sample surface.…”

Section: Introductionmentioning

confidence: 99%

Effect of Nozzle Outlet Shape on Cavitation Behavior of Submerged High-Pressure Jet

et al. 2021

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A submerged high-pressure water jet is usually accompanied by severe cavitation phenomenon. An organ pipe nozzle can greatly improve the cavitation performance of the jet, making use of the self-excited oscillation of the flow. In order to study the effect of organ pipe nozzles of different nozzle outlet shapes on cavitation behavior of submerged high-pressure jet, in this paper we build a high-pressure cavitation jet experiment system and carried out a high-speed photography experiment to study cavitation cloud characteristics of a high-pressure submerged jet. Two organ pipe nozzles with and without a whistle were compared. The dynamic characteristics of the cavitation cloud was extracted through the POD method, it was found that the result effectively reflect the dynamic characteristics of the cavitation jet. The reconstruction coefficients of mode-1 obtained by the POD can better reflect the periodic time-frequency characteristics of cavitation development. The effect of the nozzle outlet shape on the cavitation behavior of organ pipe nozzle was analyzed based on unsteady numerical simulation, and it was found that the jet generated by the nozzle with a divergent whistle had a larger vorticity in the shear layer near the outlet. Further, stronger small-scale vortex and much severe cavitation occurred from the nozzle with a divergent whistle.

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“…At the same time, optical technology was used to capture the flashing phenomenon while the bubbles collapse, which proves the existence of the high-energy shock wave. Watanabe et al [28] applied POD image processing technology to high-speed image analysis of cavitation jets and captured the location of cavitation collapse. Fujisawa et al [13] conducted high-speed photography and schlieren shooting on the high-pressure submerged jet.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Unsteady Characteristics and the Impact Performance of a High-Pressure Submerged Cavitation Jet

Yang

Shi

et al. 2020

Shock and Vibration

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High-pressure submerged cavitation jet is widely used in the fields of material peening, petroleum drilling, and ocean engineering. The impact performance of the jet with intensive cavitation is related to the factors such as working condition and the nozzle geometry. To reveal the relationship between the nozzle divergent angle and the jet pressure on the unsteady characteristics of the jet, high-speed photography with frame rate of 20000 fps is used to record the image of the cavitation clouds. Grayscale analysis algorithm developed in MATLAB is used to study the effects of injecting condition on the special structure, unsteady characteristics, and shedding frequency of the cavitation bubbles. The impact load characteristics of the cavitation jet with different cavitation numbers and stand-off distances are recorded using a high-response pressure transducer. It is found that the cavitation number is the main factor affecting the cavitation morphology of the submerged jet. The lower the cavitation number is, the more intense the cavitation occurs. The outlet divergent angle of the convergent-divergent nozzle also has a significant influence on the development of the cavitation clouds. In the three nozzles with the outlet divergent angles of 40°, 80°, and 120°, the highest bubble concentration is formed usinga nozzle with a divergent angle of 40°, but the high-concentration cavitating bubbles are only distributed in a very small range of the nozzle outlet. The cavities generated by using the nozzle with a divergent angle of 80° can achieve good results in terms of concentration and distribution range, while the nozzle with divergent angle of 120° has lower cavitation performance due to the lack of the constraint at the outlet which intensifies the shear stress of the jet. According to the result of frame difference method (FDM) analysis, the jet cavitation is mainly formed in the vortex structure generated by the shearing layer at the nozzle exit, and the most severe region in the collapse stage is the rear end of the downstream segment after the bubble cloud sheds off. The impact load of the cavitation jet is mainly affected by the stand-off distance of the nozzle from the impinged target, while the nozzle outlet geometry also has an effect on the impact performance. Optimizing the stand-off distance and the outlet geometry of the nozzles is found to be a good way to improve the performance of the cavitation jet.

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Shadowgraph Imaging of Cavitating Jet

Cited by 16 publications

References 13 publications

Numerical prediction of erosion due to a cavitating jet

Numerical prediction of erosion due to a cavitating jet

Effect of Nozzle Outlet Shape on Cavitation Behavior of Submerged High-Pressure Jet

Experimental Study on the Unsteady Characteristics and the Impact Performance of a High-Pressure Submerged Cavitation Jet

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