An experimental/numerical assessment over the influence of the dissolved air on the instantaneous characteristics/shedding frequency of cavitating flow

Wróblewski, Włodzimierz; Bochon, Krzysztof; Majkut, Mirosław; Malekshah, Emad Hasani; Rusin, Krzysztof; Strozik, Michał

doi:10.1016/j.oceaneng.2021.109960

Cited by 9 publications

(4 citation statements)

References 42 publications

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“…This technology has been used to investigate water jet flows and develop new usages [1]. Cavitating jet in air [2], multifunction cavitation [3][4][5][6], and Water Jet Cavitation (WJC) [7,8] are some of the available water jet processing methods. This study investigated WJC technology, which involves processing a workpiece surface using a high-speed underwater cavitation jet in a water-filled tank.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Cavitation Water Jet Shock as a Newly Technology on Micro-Forming Process

Quaisie

Yambah

Tabie³

et al. 2023

Eng. Technol. Appl. Sci. Res.

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This article proposes a novel technology called water jet cavitation shock micro-forming to fabricate micro-features on 304 stainless steel foils with a thickness of 100µm, using a cavitation nozzle with an incident pressure of 8 to 20MPa. This study investigated the surface morphology of the formed part, the influence of incident pressure, target distance, and impact time on the forming depth, and analyzed the punching phenomenon of the formed components. The experimental results after the water jet cavitation shocking indicated that the surface morphology of the formed part of the 304 stainless foil sample had good quality and no conventional defects such as die scratches and cracks. Furthermore, when the incident pressure was 20MPa, the height of the uniform-shaped spherical cap exceeded 262µm. The forming depth increased with increasing incident pressure and impact time. Under an incident pressure of 20MPa, with the increase of target distance, the average depth of the formed part increased at first and then decreased. Finally, the analysis of the blanking phenomenon indicated that when the incident pressure increased to 30MPa, the workpiece was completely blanked. This is mainly because, under this incident pressure, the shockwave pressure generated by the collapse of the bubble deforms the workpiece beyond the stress limit of the material itself.

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Section: Introductionmentioning

confidence: 99%

The Effect of Cavitation Water Jet Shock as a Newly Technology on Micro-Forming Process

Quaisie

Yambah

Tabie³

et al. 2023

Eng. Technol. Appl. Sci. Res.

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“…Cavitation is known as a sudden phase change phenomenon, which usually can be observed in high-speed flow and is due to low-pressure regions falling below the local saturation pressure of the operating fluid. This phenomenon exists in many applications such as hydro-power turbines, high-speed propellers, pumps and rockets [1][2][3][4]. The existence of highly dynamic cavitating flow, in particular with intensive cavity breakup, may lead to severe destructive effects such as erosion on the surface of the object, vibration, noise and high-frequency pressure fluctuations [5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Experimental analysis on unsteady characteristics of sheet/cloud cavitating Venturi flow under the effect of dissolved air

2023

Archives of Thermodynamics

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The highly dynamic and unsteady characteristics of the cavitating flow cause many negative effects such as erosion, noise and vibration. Also, in the real application, it is inevitable to neglect the dissolved air in the water, although it is usually neglected in the previous works to reduce the complexity. The novelty of the present work is analysing the impact of dissolved air on the average/unsteady characteristics of Venturi flow by conducting sets of experimental tests. For this purpose, two different amounts of dissolved air at five pressure levels (i.e. five different sets of cavitation numbers) were considered in the study of cavitating flow inside a Venturi nozzle. The fast Fourier transform analysis of pressure fluctuations proved that the shedding frequency reduces almost by 50% to 66%, depending on the case, with adding the amount of dissolved air. However, the reduction of 14% to 25% is achieved by the vibration transducers. On the other hand, the cavity enlarges as well as bubbly flow is observed in the test chamber at a higher level of dissolved air. Furthermore, it is observed that the re-entrant jet, as the main reason for the cavity detachment, is more effective for the detachment process in cases with a lower level of dissolved air, where the re-entrant jet front penetrates more toward the leading edge.

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“…Further to many effective parameters on the cavitating flow, the dissolved air can be known as an influential factor, which has not been fully analyzed by the researchers. Recently, Wróblewski et al (2021a) analyzed the effects of dissolved air on the cavitating flow around the Clark Y hydrofoil and the corresponding unsteady characteristics and shedding frequencies based on numerical simulations and experimental observations. They used the three phases model to consider liquid, vapor and air as three governing phases.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of modified turbulent viscosity on shedding dynamic of three-phase cloud cavitation around hydrofoil – numerical/experimental analysis

Malekshah

Wróblewski

Bochon

et al. 2022

HFF

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Purpose This paper aims to focus on the cavitating flow around the Clark-Y hydrofoil when the dissolved air is taken into account as the third phase. As the RNG k-epsilon model yields poor prediction due to overestimation of viscosity, the modification approaches including density corrected method, filter-based model and filter-based density correction model are used, and the turbulence model is modified. Also, the numerical results are compared with the experimental data. Design/methodology/approach The cavitating flow is known as a complex multi-phase flow and appeared in the regions where the local pressure drops under saturation vapor pressure. Many researches have been conducted to analyze this phenomenon because of its significant impact on the erosion, vibration, noise, efficiency of turbomachines, etc. Findings The experiments are conducted in a rectangular test section equipped with Clark-Y hydrofoil providing cavity visualization, instantaneous pressure and vibration fluctuations. The simulations are carried out for different cavitation numbers with and without dissolved air. The Fast Fourier Transform, continues wavelet transform and temporal-spatial distribution of gray level are implemented to extract and compare the shedding frequency of experiments and numerical predictions and cavitation evolution. It is concluded that the flow structure, shedding frequency and time-averaged characteristics are highly influenced by the dissolved air. Also, the numerical prediction will be more satisfactory when the modified turbulence models are applied. Originality/value To the best of the authors’ knowledge, the originality of this study is the modification of the turbulence model for better prediction of cavitating flow, and the validation of numerical results with corresponding experimental data.

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An experimental/numerical assessment over the influence of the dissolved air on the instantaneous characteristics/shedding frequency of cavitating flow

Cited by 9 publications

References 42 publications

The Effect of Cavitation Water Jet Shock as a Newly Technology on Micro-Forming Process

The Effect of Cavitation Water Jet Shock as a Newly Technology on Micro-Forming Process

Experimental analysis on unsteady characteristics of sheet/cloud cavitating Venturi flow under the effect of dissolved air

Evaluation of modified turbulent viscosity on shedding dynamic of three-phase cloud cavitation around hydrofoil – numerical/experimental analysis

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