On the mechanisms of cavitation erosion – Coupling high speed videos to damage patterns

Dular, Matevž; Petkovšek, Martin

doi:10.1016/j.expthermflusci.2015.06.001

Cited by 106 publications

(45 citation statements)

References 18 publications

(26 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Under these circumstances, cavitation has been found to develop inside fuel injection nozzles at the early studies of Badock et al (1999), Bergwerk (1959), Chaves et al (1995) and Nurick (1976), followed by Arcoumanis et al (2000), Blessing et al (2003), Mitroglou et al (2014) and Roth et al (2002) in more realistic real-size nozzle geometries offering optical access; equally helpful studies performed in transparent enlarged nozzle replicas [selectively (Andriotis et al 2008;Arcoumanis et al 2000;Miranda et al 2003; Mitroglou and Gavaises 2013;Powell et al 2000)] also indicate that cavitation plays an increasingly significant role in the nozzle's internal flow structure and development. Cavitation inside an injection hole is believed to enhance spray atomisation, either directly through the implosion of cavitation bubbles or indirectly because it increases turbulence in the nozzle flow (Badock et al 1999;Walther 2002); unfortunately, under certain circumstances induces erosion (Dular and Petkovšek 2015;Koukouvinis et al 2016) that may lead to catastrophic failures. Moreover, cavitation inside the injection holes promotes shot-toshot spray instabilities (Mitroglou et al 2011(Mitroglou et al , 2012Suh and Lee 2008), which, in turn, are responsible for poor combustion efficiency and increased emissions (Hayashi et al 2013).…”

mentioning

confidence: 99%

Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows

et al. 2016

View full text Add to dashboard Cite

efficiency of such engines. Among others, the fuel injection equipment (FIE) is a key component for improving the efficiency of environmentally friendly engines. Recent advances dictate the use of extra high injection pressures, of the order of 3000 bar and tiny flow passages (injection holes) of the order of 100-250 μm in diameter, for improved fuel atomisation and combustion efficiency. Under these circumstances, cavitation has been found to develop inside fuel injection nozzles at the early studies of Badock et al. (1999), Bergwerk (1959), Chaves et al. (1995) and Nurick (1976), followed by Arcoumanis et al. (2000), Blessing et al. (2003), Mitroglou et al. (2014) and Roth et al. (2002) in more realistic real-size nozzle geometries offering optical access; equally helpful studies performed in transparent enlarged nozzle replicas [selectively (Andriotis et al. 2008;Arcoumanis et al. 2000;Miranda et al. 2003; Mitroglou and Gavaises 2013;Powell et al. 2000)] also indicate that cavitation plays an increasingly significant role in the nozzle's internal flow structure and development. Cavitation inside an injection hole is believed to enhance spray atomisation, either directly through the implosion of cavitation bubbles or indirectly because it increases turbulence in the nozzle flow (Badock et al. 1999;Walther 2002); unfortunately, under certain circumstances induces erosion (Dular and Petkovšek 2015;Koukouvinis et al. 2016) that may lead to catastrophic failures. Moreover, cavitation inside the injection holes promotes shot-toshot spray instabilities (Mitroglou et al. 2011(Mitroglou et al. , 2012Suh and Lee 2008), which, in turn, are responsible for poor combustion efficiency and increased emissions (Hayashi et al. 2013). Two distinct macroscopic forms of cavitation have been identified, which are referred to as geometryinduced and vortex or 'string' cavitation. The former can be, partially or totally, suppressed by appropriate design of the inlet hole curvature and non-cylindrical injection hole Abstract The flow inside a purpose built enlarged singleorifice nozzle replica is quantified using time-averaged X-ray micro-computed tomography (micro-CT) and highspeed shadowgraphy. Results have been obtained at Reynolds and cavitation numbers similar to those of real-size injectors. Good agreement for the cavitation extent inside the orifice is found between the micro-CT and the corresponding temporal mean 2D cavitation image, as captured by the high-speed camera. However, the internal 3D structure of the developing cavitation cloud reveals a hollow vapour cloud ring formed at the hole entrance and extending only at the lower part of the hole due to the asymmetric flow entry. Moreover, the cavitation volume fraction exhibits a significant gradient along the orifice volume. The cavitation number and the needle valve lift seem to be the most influential operating parameters, while the Reynolds number seems to have only small effect for the range of values tested. Overall, the study demonstrates that use of micro-CT can ...

show abstract

mentioning

confidence: 99%

Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Furthermore, a coherent vapour structure can be clearly seen to have been detached from the main cloud cavity and being convected downstream by the main flow. Since the collapse of coherent cavitating vortices has been linked to increased erosion aggression [30,35], accurate identification of the exact locations of vortex-cavitation inception and collapse is of high value when referring to injector nozzle flows. In order to be able to clearly identify a vapour cloud separation in the examined geometrical layout, initially, the grayscale range of the high-speed images was inverted (complimentary image), i.e.…”

Section: Methodsmentioning

confidence: 99%

Cloud cavitation vortex shedding inside an injector nozzle

Mitroglou

Stamboliyski

Karathanassis

et al. 2017

Experimental Thermal and Fluid Science

View full text Add to dashboard Cite

This is the accepted version of the paper.This version of the publication may differ from the final published version. Abstract. The development and collapse of cloud cavitation and its link to surface erosion within a transparent test single-orifice nozzle operating with a closed Diesel fuel hydraulic circuit, has been characterized using high-speed imaging. Data have been obtained for a range of cavitation and Reynolds numbers under fixed lift positions. Post processing of a large number of images acquired with short exposure time (1μs) allowed the elucidation of the distinct flow phenomena associated with the highly transient two-phase flow. At the inlet of the flow orifice, the vapour cloud was found to occupy the largest part of the nozzle hole crosssection. Coherent vortical structures of a hairpin shape have been detected to onset at the closure region of this vapour cloud and shed downstream in a fully transient manner. The effect of the operating parameters on the temporal and spatial characteristics with regards to the emergence and collapse of the hairpin vortices has been quantified. It has been established that the cavitation-vortex shedding was taking place in a periodical manner, characterized by a Strouhal number. Permanent repository link

show abstract

“…When the surface of the underwater component generates high‐speed water flow, the water flow generates a large amount of bubbles and microjets due to the uneven pressure. The surface of the material will be repeatedly impacted by air bubbles and microjets . Pitting and voids will be generated on the surface of the material, which lead to a sharp drop in material strength, thus affecting service life and seriously threatening the normal and safe operation of the components .…”

Section: Introductionmentioning

confidence: 99%

“…The surface of the material will be repeatedly impacted by air bubbles and microjets. 4,5 Pitting and voids will be generated on the surface of the material, which lead to a sharp drop in material strength, thus affecting service life and seriously threatening the normal and safe operation of the components. 6 Therefore, mitigating the cause of corrosion and ensuring the safe operation and servicing life of underwater overcurrent components have important and far-reaching significance.…”

Section: Introductionmentioning

confidence: 99%

Outstanding cavitation erosion resistance of hydrophobic polydimethylsiloxane‐based polyurethane coatings

Qiao

Chen

Zhang

et al. 2019

J of Applied Polymer Sci

View full text Add to dashboard Cite

Cavitation erosion will create shock waves and water jets in turbulent flows. These impact pressures will affect the surface, which will lead to crack propagation and severe material degradation. In this study, we have developed hydrophobic polydimethylsiloxane‐based polyurethanes (Si‐PUx) with hydroxypropyl polydimethylsiloxane (H‐PDMS) and polytetramethylene glycol (PTMG) as mixed soft segments and 2,4‐tolylene diisocyanate, 1,4‐butanediol, triethanolamine as hard segments via a polycondensation reaction and studied its properties. The cavitation wear experiment showed that the cavitation erosion resistance of Si‐PUx coating continuously improved with the increase of H‐PDMS content, while the adhesion force of Si‐PUs reduced with the increasing of H‐PDMS content. The surface of Si‐PUx coating after cavitation test was observed using an optical microscope and three‐dimensional profiler. The cumulative mass loss of Si‐PUx with 12.5 wt % H‐PDMS was only 2.96 mg and the surface showed no obvious holes and cracks after 80 h cavitation. The results showed that cavitation resistance had a correlation with degree of water resistance, hardness, adhesion strength, and dynamic mechanical properties of coating. It seemed that the Si‐PUx coating could withstand a longer period cavitation erosion resistance compared to high strength epoxy, which could be used as protective coating for flow components under water. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47668.

show abstract

On the mechanisms of cavitation erosion – Coupling high speed videos to damage patterns

Cited by 106 publications

References 18 publications

Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows

Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows

Cloud cavitation vortex shedding inside an injector nozzle

Outstanding cavitation erosion resistance of hydrophobic polydimethylsiloxane‐based polyurethane coatings

Contact Info

Product

Resources

About