Searched for: subject:"cavitation"
(1 - 20 of 56)

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Schenke, S. (author)
Cavitation erosion is a problem in the design of a wide range of fluid machinery involving liquid flows. Ship propellers, rudders, hydro pumps and turbines or diesel injectors are some of the most prominent examples. Cavitation occurs at locations of high local flow velocity, where the pressure may drop so low that the liquid phase vaporizes....
doctoral thesis 2020
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Jahangir, S. (author)
Cavitation is a well-known phenomenon, occurring in a wide range of applications. In most applications, cavitation is undesirable, such as turbines, pumps, ship propellers and diesel injector nozzles. Cavitation can cause material erosion, flow blockage, noise and degradation of equipment over time. The ability to predict the behavior of this...
doctoral thesis 2020
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Ghahramani, Ebrahim (author), Jahangir, S. (author), Neuhauser, Magdalena (author), Bourgeois, Sébastien (author), Poelma, C. (author), Bensow, Rickard E. (author)
In this paper, the cavitating flow around a bluff body is studied both experimentally and numerically. The bluff body has a finite length with semi-circular cross section and is mounted on a surface in the throat of a converging-diverging channel. This set-up creates various 3D flow structures around the body, from cavitation inception to...
journal article 2020
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Codrignani, A. (author), Savio, D. (author), Pastewka, L. (author), Frohnapfel, B. (author), van Ostayen, R.A.J. (author)
In this work we assess the applicability of the adjoint optimization technique for determining optimal surface topographies of two surfaces in relative motion in presence of a thin lubricant films that can cavitate. Among the existing numerical tools for topology optimization in engineering problems, the adjoint method represents a promising...
journal article 2020
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Kooiman, Klazina (author), Roovers, Silke (author), Langeveld, Simone A.G. (author), Kleven, Robert T. (author), Dewitte, Heleen (author), O'Reilly, Meaghan A. (author), Escoffre, Jean Michel (author), Bouakaz, Ayache (author), Verweij, M.D. (author)
Therapeutic ultrasound strategies that harness the mechanical activity of cavitation nuclei for beneficial tissue bio-effects are actively under development. The mechanical oscillations of circulating microbubbles, the most widely investigated cavitation nuclei, which may also encapsulate or shield a therapeutic agent in the bloodstream,...
review 2020
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Saint-Michel, B.F.B. (author), Garbin, V. (author)
Bubbles in complex fluids are often desirable, and sometimes simply inevitable, in the processing of formulated products. Bubbles can rise by buoyancy, grow or dissolve by mass transfer, and readily respond to changes in pressure, thereby applying a deformation to the surrounding complex fluid. The deformation field around a stationary,...
review 2020
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Melissaris, Themistoklis (author), Schenke, S. (author), Bulten, Norbert (author), van Terwisga, T.J.C. (author)
Predicting the cavitation impact loads on a propeller surface using numerical tools is becoming essential, as the demand for more efficient designs, stretched to the limit, is increasing. One of the possible design limits is governed by cavitation erosion. The accuracy of estimating such loads, using a URANS approach, has been investigated....
journal article 2020
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Vrijdag, A. (author), Schuttevaer, D. (author)
Dramatic increases in the underwater acoustic signature of ships have been observed during full scale trials in a seaway, compared to calm water conditions. The observed behaviour can be explained by the interaction of waves, wake field and ship propulsion system dynamics in combination with rudder action and ship motions. This paper explores...
journal article 2019
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Jahangir, S. (author), Ghahramani, Ebrahim (author), Neuhauser, Magdalena (author), Bourgeois, Sébastien (author), Bensow, Rickard E. (author), Poelma, C. (author)
The objective of this study is to investigate the collapsing behavior of cavitation, which leads to erosion. For this purpose, an experimental investigation was performed in a channel with a semi-circular cylinder obstacle at the Hydraulic Laboratory of ANDRITZ HYDRO in Vevey. Cavitation was achieved by employing a range of pressure differences...
conference paper 2019
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Timoshevskiy, Mikhail V. (author), Pervunin, Konstantin S. (author), Markovich, Dmitriy M. (author), Hanjalic, K. (author)
We studied cavitating flow over the suction side of a symmetric 2D foil - a scaled-down model of high-pressure hydroturbine guide vanes (GV) - in different cavitation regimes at several attack angles. High-speed imaging was used to analyze spatial patterns and time dynamics of the gas-vapor cavities, as well as for evaluating the...
conference paper 2019
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Jahangir, S. (author), Wagner, E.C. (author), Mudde, R.F. (author), Poelma, C. (author)
Cavitation is a complicated multiphase phenomenon, where the production of vapor cavities leads to an opaque flow. Exploring the internal structures of the cavitating flows is one of the most significant challenges in this field of study. While it is not possible to visualize the interior of the cavity with visible light, we use X-ray...
journal article 2019
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Schenke, S. (author), van Terwisga, T.J.C. (author)
A new technique is proposed in this study to assess the erosive aggressiveness of cavitating flows from numerical flow simulations. The technique is based on the cavitation intensity approach by Leclercq et al. (2017), predicting the instantaneous surface impact power of collapsing cavities from the potential energy hypothesis (see Hammitt,...
journal article 2019
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Eling, R.P.T. (author)
In the competitive automotive market, the performance of turbochargers is constantly being pushed towards their theoretical optimum. One of the key components of the turbocharger is the rotor-bearing system, which determines the friction losses and noise output and furthermore affects the overall turbocharger efficiency, reliability and cost. In...
doctoral thesis 2018
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Jahangir, S. (author), Wagner, E.C. (author), Mudde, R.F. (author), Poelma, C. (author)
Cavitation is a complex multiphase phenomenon, where the production of vapor bubbles leads to opaqueness of the flow. While it is nearly impossible to visualize the interior of the cavitation region with visible light, we show that with X-ray computed tomography it is possible to obtain the time-averaged void fraction distribution in an...
conference paper 2018
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Melissaris, Themistoklis (author), Bulten, Norbert (author), van Terwisga, T.J.C. (author)
Cavitation occurrence on the propeller blades may have severe effects, such as cavitation noise, vibrations in the aft ship, and material damage on propellers or rudder. While noise and vibrations affect comfort and stability, cavitation erosion might lead to a significant reduction of the propeller efficiency and structural integrity....
conference paper 2018
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Jahangir, S. (author), Hogendoorn, W.J. (author), Poelma, C. (author)
Partial cavitation dynamics in an axisymmetric converging-diverging nozzle are investigated experimentally. Shadowgraphy is used to visualize and analyze different cavitation regimes. These regimes are generated by changing the global static pressure and flow velocity independently. Cloud cavitation is the most interesting and complex regime,...
journal article 2018
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Schenke, S. (author), van Terwisga, T.J.C. (author)
The erosive aggressiveness of idealized cavities collapsing on a flat surface is investigated by numerical simulation, employing the cavitation intensity approach by Leclercq et al (2017) as a measure of the local energy impact rate. We propose a more straight forward formulation of the cavitation intensity model and verify that it satisfies...
conference paper 2018
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Dash, A. (author), Jahangir, S. (author), Poelma, C. (author)
A quantitative analysis of two imaging modalities, shadowgraphy and x-ray imaging, is presented in the framework of void fraction determination. The need for this arises from the fact that shadowgraphs are sometimes utilized to quantify void fraction profiles, which is an unproven method. Time-averaged x-ray images are used to evaluate the...
journal article 2018
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Schenke, S. (author), van Terwisga, T.J.C. (author)
The effect of finite mass transfer rate in combination with temporal resolution on the dynamics of caviting flows is subject of this study. It will be shown that global flow quantities exhibit convergent behaviour with respect to mass transfer rate and time step size in incompressible pressurebased simulation of cavitating flows. It is concluded...
conference paper 2017
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Simbula, A. (author), Schatzl, M. (author), Alpeggiani, F. (author), Andreani, L.C. (author), Schäffler, F. (author), Fromherz, T. (author), Galli, M. (author), Gerace, D. (author)
We report on the realization of high-Q/V photonic crystal cavities in thin silicon membranes, with resonances around 1.55 μm wavelength. The cavity designs are based on a recently proposed photonic crystal implementation of the Aubry-André-Harper bichromatic potential, defined from the superposition of two one-dimensional lattices with a non...
journal article 2017
Searched for: subject:"cavitation"
(1 - 20 of 56)

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