scholarly journals Numerical Prediction of Cavitation Erosion Intensity in Cavitating Flows around a Clark Y 11.7% Hydrofoil

2010 ◽  
Vol 5 (3) ◽  
pp. 416-431 ◽  
Author(s):  
Naoya OCHIAI ◽  
Yuka IGA ◽  
Motohiko NOHMI ◽  
Toshiaki IKOHAGI
Keyword(s):  
Cavitation Erosion ◽  
Numerical Prediction ◽  
Cavitating Flows ◽  
Erosion Intensity

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.

Numerical Prediction of Cavitation Erosion on a Francis Turbine Runner

2013 ◽  
Vol 655-657 ◽  
pp. 449-456
Author(s):  
Hong Ming Zhang ◽  
Li Xiang Zhang
Keyword(s):  
Cavitation Erosion ◽  
Stokes Equations ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Numerical Prediction ◽  
Francis Turbine ◽  
Navier Stokes ◽  
Transfer Model ◽  
Cavitation Damage ◽  
Turbine Runner

The paper presents numerical prediction of cavitation erosion on a Francis turbine runner using CFD code. The SST turbulence model is employed in the Reynolds averaged Navier–Stokes equations in this study. A mixture assumption and a finite rate mass transfer model were introduced. The computing domain is discretized with a full three-dimensional mesh system of unstructured tetrahedral shapes. The finite volume method is used to solve the governing equations of the mixture model and the pressure-velocity coupling is handled via a Pressure Implicit with Splitting of Operators(PISO) procedure. Comparison the numerical prediction results with a real runner with cavitation damage, the region of higher volume fraction by simulation with the region of runner cavitation damage is consistent.

Experimental Investigations Concerning Erosive Aggressiveness of Cavitation at Different Test Configurations

Volume 3 ◽  
2004 ◽  
Author(s):  
B. Bachert ◽  
M. Dular ◽  
S. Baumgarten ◽  
G. Ludwig ◽  
B. Stoffel
Keyword(s):  
Mass Loss ◽  
Cavitation Erosion ◽  
Evaluation Method ◽  
Experimental Investigations ◽  
Cavitating Flows ◽  
Test Rig ◽  
The Third ◽  
Long Duration ◽  
Initial Stage ◽  
Test Objects

The experimental results, which will be presented in this paper, demonstrate the significant influence of the flow velocity, respectively the rotational speed, on the erosive aggressiveness of cavitating flows. On two of the three investigated test objects, cavitation erosion can only be observed in the initial stage by the so-called pit-count evaluation method. Developed erosion with mass loss is impossible to measure because of the very long duration until mass loss appears. The third test rig generates a very aggressive type of cavitation, so that mass loss, depending on the tested material, will appear after relatively short durations. In addition, the initial stage of cavitation erosion can be observed. Three different techniques were applied to investigate cavitation erosion in the initial and developed stage. Thereby, the capability of methods to quantify erosive effects in dependence of influencing operating parameters has been proven.

scholarly journals Numerical Simulation of Cavitation and Aeration in Discharge Gated Tunnel of a Dam Based on the VOF Method

2011 ◽  
Vol 110-116 ◽  
pp. 2754-2761
Author(s):  
Razieh Jalalabadi ◽  
Norouz Mohammad Nouri
Keyword(s):  
Numerical Simulation ◽  
Cavitation Erosion ◽  
Vof Method ◽  
Bubbly Flows ◽  
Hydraulic Structures ◽  
Cavitating Flows ◽  
Effective Protection ◽  
Two Phase ◽  
Cavitation Inception ◽  
Numerical Studies

Cavitation, usually known as a destructive phenomenon, involves turbulent unsteady two-phase flow. Having such features, cavitating flows have been turned to a challenging topic in numerical studies and many researches are being done for better understanding of bubbly flows and proposing solutions to reduce its consequent destructive effects. Aeration may be regarded as an effective protection against cavitation erosion in many hydraulic structures, like gated tunnels. The paper concerns numerical simulation of flow in discharge gated tunnel of a dam using RNG model coupled with the volume of fluid (VOF) method and the zone which is susceptible of cavitation inception in the tunnel is predicted. Then a vent is considered in the mentioned zone for aeration and the numerical simulation is done again to study the effects of aeration. The results show that aeration is an impressively useful method to exclude cavitation in mentioned tunnels.

Prediction of Cavitation Erosion Intensity Using Large-Scale Diesel Nozzles

2019 ◽  
Author(s):  
Motoya Kambara ◽  
Takanobu Aochi ◽  
Fumiaki Arikawa ◽  
Toshiaki Hijima ◽  
Kazufumi Serizawa
Keyword(s):  
Large Scale ◽  
Cavitation Erosion ◽  
Erosion Intensity

Numerical prediction of cavitation erosion on a ship propeller in model- and full-scale

Wear ◽  
2018 ◽  
Vol 408-409 ◽  
pp. 1-12 ◽  
Author(s):  
Andreas Peters ◽  
Udo Lantermann ◽  
Ould el Moctar
Keyword(s):  
Cavitation Erosion ◽  
Full Scale ◽  
Numerical Prediction ◽  
Ship Propeller

scholarly journals Energy Balance in Cavitation Erosion: From Bubble Collapse to Indentation of Material Surface

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
R. Fortes-Patella ◽  
G. Challier ◽  
J. L. Reboud ◽  
A. Archer
Keyword(s):  
Energy Balance ◽  
International Symposium ◽  
Wave Energy ◽  
Vapor Bubble ◽  
Pressure Wave ◽  
Cavitation Erosion ◽  
Bubble Dynamics ◽  
Bubble Collapse ◽  
Pressure Waves ◽  
Cavitating Flows

An original approach based on energy balance between vapor bubble collapse, emitted pressure wave, and neighboring solid wall response was proposed, developed, and tested to estimate the aggressiveness of cavitating flows. In the first part of the work, to improve a prediction method for cavitation erosion (Fortes-Patella and Reboud, 1998, “A New Approach to Evaluate the Cavitation Erosion Power,” ASME J. Fluids Eng., 120(2), pp. 335–344; Fortes-Patella and Reboud, 1998, “Energetical Approach and Impact Efficiency in Cavitation Erosion,” Proceedings of Third International Symposium on Cavitation, Grenoble, France), we were interested in studying the pressure waves emitted during bubble collapse. The radial dynamics of a spherical vapor/gas bubble in a compressible and viscous liquid was studied by means of Keller's and Fujikawa and Akamatsu's physical models (Prosperetti, 1994, “Bubbles Dynamics: Some Things we did not Know 10 Years Ago,” Bubble Dynamics and Interface Phenomena, Blake, Boulton-Stone, Thomas, eds., Kluwer Academic Publishers, Dordrecht, the Netherlands, pp. 3–15; Fujikawa and Akamatsu, 1980, “Effects of Non-Equilibrium Condensation of Vapor on the Pressure Wave Produced by Collapse of a Bubble in Liquid,” J. Fluid Mech., 97(3), pp. 481–512). The pressure amplitude, the profile, and the energy of the pressure waves emitted during cavity collapses were evaluated by numerical simulations. The model was validated by comparisons with experiments carried out at Laboratoire Laser, Plasma et Procédés Photoniques (LP3-IRPHE) (Marseille, France) with laser-induced bubble (Isselin et al., 1998, “Investigations of Material Damages Induced by an Isolated Vapor Bubble Created by Pulsed Laser,” Proceedings of Third International Symposium on Cavitation, Grenoble, France; Isselin et al., 1998, “On Laser Induced Single Bubble Near a Solid Boundary: Contribution to the Understanding of Erosion Phenomena,” J. Appl. Phys., 84(10), pp. 5766–5771). The efficiency of the first collapse ηwave/bubble (defined as the ratio between pressure wave energy and initial bubble potential energy) was evaluated for different bubble collapses. For the cases considered of collapse in a constant-pressure field, the study pointed out the strong influence of the air contents on the bubble dynamics, on the emitted pressure wave characteristics, and on the collapse efficiency. In the second part of the study, the dynamic response and the surface deformation (i.e., pit profile and pit volume) of various materials exposed to pressure wave impacts was simulated making use of a 2D axisymmetric numerical code simulating the interaction between pressure wave and an elastoplastic solid. Making use of numerical results, a new parameter β (defined as the ratio between the pressure wave energy and the generated pit volume) was introduced and evaluated for three materials (aluminum, copper, and stainless steel). By associating numerical simulations and experimental results concerning pitted samples exposed to cavitating flows (volume damage rate), the pressure wave power density and the flow aggressiveness potential power were introduced. These physical properties of the flow characterize the cavitation intensity and can be related to the flow hydrodynamic conditions. Associated to β and ηwave/bubble parameters, these power densities appeared to be useful tools to predict the cavitation erosion power.

scholarly journals Towards numerical prediction of cavitation erosion

2015 ◽  
Vol 5 (5) ◽  
pp. 20150013 ◽  
Author(s):  
Marc Fivel ◽  
Jean-Pierre Franc ◽  
Samir Chandra Roy
Keyword(s):  
Strain Rate ◽  
Cavitation Erosion ◽  
Split Hopkinson Pressure Bar ◽  
Impact Load ◽  
Test System ◽  
Numerical Prediction ◽  
Bubble Collapse ◽  
Suitable Model ◽  
Loading Conditions ◽  
Material Response

This paper is intended to provide a potential basis for a numerical prediction of cavitation erosion damage. The proposed method can be divided into two steps. The first step consists in determining the loading conditions due to cavitation bubble collapses. It is shown that individual pits observed on highly polished metallic samples exposed to cavitation for a relatively small time can be considered as the signature of bubble collapse. By combining pitting tests with an inverse finite-element modelling (FEM) of the material response to a representative impact load, loading conditions can be derived for each individual bubble collapse in terms of stress amplitude (in gigapascals) and radial extent (in micrometres). This step requires characterizing as accurately as possible the properties of the material exposed to cavitation. This characterization should include the effect of strain rate, which is known to be high in cavitation erosion (typically of the order of several thousands s −1 ). Nanoindentation techniques as well as compressive tests at high strain rate using, for example, a split Hopkinson pressure bar test system may be used. The second step consists in developing an FEM approach to simulate the material response to the repetitive impact loads determined in step 1. This includes a detailed analysis of the hardening process (isotropic versus kinematic) in order to properly account for fatigue as well as the development of a suitable model of material damage and failure to account for mass loss. Although the whole method is not yet fully operational, promising results are presented that show that such a numerical method might be, in the long term, an alternative to correlative techniques used so far for cavitation erosion prediction.

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