scholarly journals The relation between the high speed submerged cavitating jet behaviour and the cavitation erosion process

2016 ◽  
Vol 83 ◽  
pp. 27-38 ◽  
Author(s):  
Ezddin Hutli ◽  
Milos S. Nedeljkovic ◽  
Nenad A. Radovic ◽  
Attila Bonyár
Keyword(s):  
High Speed ◽  
Cavitation Erosion ◽  
Erosion Process ◽  
Cavitating Jet

Combined Numerical and Experimental Investigation of the Cavitation Erosion Process

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Wang Jian ◽  
Martin Petkovšek ◽  
Liu Houlin ◽  
Brane Širok ◽  
Matevž Dular
Keyword(s):  
Experimental Investigation ◽  
High Pressure ◽  
High Speed ◽  
Cavitation Erosion ◽  
The Other ◽  
Damage Growth ◽  
Erosion Process ◽  
Time Step ◽  
Erosion Damage ◽  
Flow Simulations

We are comparing results of numerical simulations against high-speed simultaneous observations of cavitation and cavitation erosion. We performed fully compressible, cavitating flow simulations to resolve the formation of the shock waves at cloud collapse—these are believed to be directly related to the formation of the damage. Good agreements were noticed between calculations and tests. Two high pressure peaks were found during one cavitation cycle. One relates to the cavitation collapse and the other one corresponds to the cavitation shed off, both contributing to a distinctive stepwise erosion damage growth pattern. Additional, more precise, simulations with much shorter time step were performed to investigate the processes of cavitation collapse and shedding off in more detail. There the importance of small cavitation structures which collapse independently of the main cloud was found. The present work shows a great potential for future development of techniques for accurate predictions of cavitation erosion by numerical means only.

Cavitation erosion behavior of hydraulic concrete under high-speed flow

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xin Wang ◽  
Ting-Qiang Xie
Keyword(s):  
Cavitation Bubble ◽  
High Speed ◽  
Cavitation Erosion ◽  
Concrete Strength ◽  
Bubble Collapse ◽  
High Speed Flow ◽  
Content Type ◽  
Erosion Behavior ◽  
Hydraulic Concrete ◽  
Speed Flow

Purpose Cavitation erosion has always been a common technical problem in a hydraulic discharging structure. This paper aims to investigate the cavitation erosion behavior of hydraulic concrete under high-speed flow. Design/methodology/approach A high-speed and high-pressure venturi cavitation erosion generator was used to simulate the strong cavitation. The characteristics of hydrodynamic loads of cavitation bubble collapse zone, the failure characteristics and the erosion development process of concrete were investigated. The main influencing factors of cavitation erosion were discussed. Findings The collapse of the cavitation bubble group produced a high frequency, continuous and unsteady pulse load on the wall of concrete, which was more likely to cause fatigue failure of concrete materials. The cavitation action position and the main frequency of impact load were greatly affected by the downstream pressure. A power exponential relationship between cavitation load, cavitation erosion and flow speed was observed. With the increase of concrete strength, the degree of damage of cavitation erosion was approximately linearly reduced. Originality/value After cavitation erosion, a skeleton structure was formed by the accumulation of granular particles, and the relatively independent bulk structure of the surface differed from the flake structure formed after abrasion.

Numerical Prediction of Various Cavitation Erosion Mechanisms

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Ignacijo Biluš ◽  
Marko Hočevar ◽  
Matevž Dular ◽  
Luka Lešnik
Keyword(s):  
Experimental Work ◽  
High Speed ◽  
Cavitation Erosion ◽  
Cavitating Flow ◽  
Numerical Prediction ◽  
Quantitative Prediction ◽  
Navier Stokes ◽  
Erosion Mechanisms ◽  
Recent Experimental Work ◽  
Collapse Phase

Abstract Numerical prediction of cavitation erosion is a great scientific and technological challenge. In the past, many attempts were made—many successful. One of the issues when a comparison between a simulation and erosion experiments is made, is the great difference in time scale. In this work, we do not attempt to obtain quantitatively accurate predictions of erosion process but concentrate qualitatively on cavitation mechanisms with quantitative prediction of pressure pulses which lead to erosion. This is possible, because of our recent experimental work on simultaneous observation of cavitating flow and cavitation erosion by high speed cameras. In this study, the numerical simulation was used to predict details of the cavitation process during the vapor collapse phase. The fully compressible, cavitating flow simulations were performed to resolve the formation of the pressure waves at cavitation collapse. We tried to visualize the mechanisms and dynamics of vapor structures during collapse phase at the Venturi geometry. The obtained results show that unsteady Reynolds-averaged Navier–Stokes (URANS) simulation of cavitation is capable of reproducing four out of five mechanisms of cavitation erosion, found during experimental work.

Mechanism of Cavitation Erosion at the Exit of a Long Orifice

2003 ◽  
Author(s):  
Yoshinori Yagi ◽  
Michio Murase ◽  
Keiichi Sato ◽  
Shuji Hattori
Keyword(s):  
High Speed ◽  
Cavitation Erosion ◽  
Propagation Speed ◽  
Video Camera ◽  
Concentric Circle ◽  
Collapse Mechanism ◽  
Pressurized Water ◽  
Flow Passage ◽  
Cavity Collapse ◽  
A Chain

We carried out experiments to clarify the mechanism of cavitation erosion at the exit of a long orifice equipped at a pressure-reducing line in a pressurized water reactor (PWR). In order to ascertain the mechanism of cavitation erosion at the first stage and progression stage, we used a high-speed video camera. As a result, we observed cavity collapse near the exit of the orifice under oscillating flow conditions, which might be a major factor in the first stage of erosion at the exit of the orifice. To simulate the progression stage, we used an orifice with a cone-shaped flow passage at its exit, corresponding to an orifice diffuser. We observed cavity collapse near the exit, after which cavities that existed upstream in the cone shape collapsed in a manner similar to a chain reaction. The propagation speed varied with the quantity of cavities in the cone-shaped flow passage and cavities collapsed in a concentric circle pattern. Thus, the cavity collapse mechanism was concluded as follows: a pressure wave (shock wave) was generated by cavity collapse near the exit, then propagated upwards, and consequently caused cavity collapse upstream. This mechanism might promote cavitation erosion in an upward direction.

scholarly journals Mitigating cavitation erosion using biomimetic gas-entrapping microtextured surfaces (GEMS)

2020 ◽  
Vol 6 (13) ◽  
pp. eaax6192 ◽  
Author(s):  
Silvestre Roberto Gonzalez-Avila ◽  
Dang Minh Nguyen ◽  
Sankara Arunachalam ◽  
Eddy M. Domingues ◽  
Himanshu Mishra ◽  
...  
Keyword(s):  
Solid Surface ◽  
Surface Hardening ◽  
High Speed ◽  
Cavitation Erosion ◽  
Flow Problem ◽  
Vapor Bubbles ◽  
Cavitation Damage ◽  
Cavitation Bubbles ◽  
Microtextured Surfaces ◽  
High Speed Flows

Cavitation refers to the formation and collapse of vapor bubbles near solid boundaries in high-speed flows, such as ship propellers and pumps. During this process, cavitation bubbles focus fluid energy on the solid surface by forming high-speed jets, leading to damage and downtime of machinery. In response, numerous surface treatments to counteract this effect have been explored, including perfluorinated coatings and surface hardening, but they all succumb to cavitation erosion eventually. Here, we report on biomimetic gas-entrapping microtextured surfaces (GEMS) that robustly entrap air when immersed in water regardless of the wetting nature of the substrate. Crucially, the entrapment of air inside the cavities repels cavitation bubbles away from the surface, thereby preventing cavitation damage. We provide mechanistic insights by treating the system as a potential flow problem of a multi-bubble system. Our findings present a possible avenue for mitigating cavitation erosion through the application of inexpensive and environmentally friendly materials.

scholarly journals Cavitation erosion testing of different cavitation-resistent materials and coatings using the cavitating jet method

2019 ◽  
Vol 240 ◽  
pp. 062057
Author(s):  
Pavel Rudolf ◽  
Martin Juliš ◽  
Lenka Klakurková ◽  
Pavel Gejdoš ◽  
Martin Hudec
Keyword(s):  
Cavitation Erosion ◽  
Erosion Testing ◽  
Cavitating Jet

scholarly journals Cavitation Erosion – Phenomenon and Test Rigs

2018 ◽  
Vol 18 (2) ◽  
pp. 15-26 ◽  
Author(s):  
A. K. Krella ◽  
D. E. Zakrzewska
Keyword(s):  
Cavitation Erosion ◽  
Erosion Resistance ◽  
Test Design ◽  
Test Device ◽  
Test Conditions ◽  
Cavitation Erosion Resistance ◽  
Cavitating Jet

AbstractThe cavitation and cavitation erosion phenomenon have been shortly presented. The main four types of test rigs to investigate the cavitation erosion resistance have been shown. Each type of test design is described and an example of a design is shown. A special attention has been payed to the designs described in the International ASTM Standards: a vibratory design and a cavitating jet cell. There was shown that the design of a test device and the test conditions affect the resistance to cavitation erosion of a material.

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