Effects of Inlet Surface Roughness, Texture, and Nozzle Material on Cavitation

Chang, Jy-Cheng; Huang, Shouben; Lin, Chih-Ming

doi:10.1615/atomizspr.v16.i3.40

Cited by 11 publications

(5 citation statements)

References 0 publications

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“…Specifically, proper surface roughness can promote the generation of cavitation bubbles, which is in satisfying agreement with the results obtained by Numachi et al [33], who experimentally demonstrated that surface roughness could advance cavitation inception. Similar evidence can also be obtained from the research performed by Chang et al [20].…”

Section: Cavitation Erosion Intensitysupporting

confidence: 87%

“…Based on a numerical investigation on the effects of wall roughness on cavitating flow, Echouchene et al [19] concluded that wall roughness leads to higher shear stresses in the liquid and produces additional disturbance of the velocity and pressure. In addition, Chang et al [20] experimentally found that the nozzle inlet surface roughness can affect the occurrence of cavitation much more than it affects hydraulic flip. Most importantly, in our most recent studies [21] and [22], it has been shown that the nozzle inner surface roughness can have dramatic effects on the axial pressure oscillations as well as the cavitation erosion intensity and efficiency of SRCW.…”

Section: Fig 1 Schematic Diagram Of the Operating Principles Of An Srcw Issuing From An Organ-pipe Nozzlementioning

confidence: 99%

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Effects of Nozzle Inner Surface Roughness on the Performance of Self-Resonating Cavitating Waterjets under Different Ambient Pressures

Deng

Kang

Ding

et al. 2017

SV-JME

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The self-resonating cavitating waterjet (SRCW) has been widely used for many practical and industrial applications since the first recognition of its strong cavitation ability. To further improve the performance of SRCW under ambient pressures, the effects of nozzle inner surface roughness were experimentally studied by impinging the jets on pure aluminium specimens (1070A) at various standoff distances. The typical macroscopic appearances and mass losses of the eroded specimens were used to evaluate the performances of the jets issuing from six organ-pipe nozzles of different inner surface roughness values (0.8 μm, 1.6 μm, 3.2 μm, 6.3 μm, 12.5 μm, and 25 μm). The results show that nozzle inner surface roughness significantly influences the optimum standoff distance and the cavitation intensity, which greatly depends on the ambient pressure. Moreover, it is found that there is always an optimum surface roughness that can remarkably enhance the cavitation erosion capability under each ambient pressure. Specifically, at ambient pressures of 2 MPa and 4 MPa, the surface roughness of 6.3 μm causes the strongest cavitation intensity at standoff distances of 42 mm and 50 mm, respectively. While at ambient pressures of 6 MPa, 8 MPa, and 10 MPa, the surface roughness of 12.5 μm is the one that maximally enhances the intensity at standoff distances of 45 mm, 40 mm, and 35 mm, respectively. Furthermore, the enhanced cavitation intensity is found to improve the impingement power of the high-speed waterjet as well. The present study also helps to provide a guideline for determining the finishing accuracy of inner surface required in the fabrication of organ-pipe nozzles.

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Section: Cavitation Erosion Intensitysupporting

confidence: 87%

Section: Fig 1 Schematic Diagram Of the Operating Principles Of An Srcw Issuing From An Organ-pipe Nozzlementioning

confidence: 99%

Effects of Nozzle Inner Surface Roughness on the Performance of Self-Resonating Cavitating Waterjets under Different Ambient Pressures

Deng

Kang

Ding

et al. 2017

SV-JME

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“…The influence of geometric parameters, as the entrance radius (Soteriou et al 1995;Schmidt et al 1997;Winklhofer et al 2001) or the orifice taper (Winklhofer et al 2003;Payri et al 2005) have been later confirmed experimentally and numerically. An effect of roughness at orifice wall and orifice inlet has been also considered (Jung et al 2008;Chang et al 2006;Winklhofer et al 2003). These studies have shown that very weak variations in the orifice geometry could have a disproportionate influence on cavitation.…”

Section: Introductionmentioning

confidence: 99%

Shadowgraph, Schlieren and interferometry in a 2D cavitating channel flow

Mauger¹,

Méès²,

Michard³

et al. 2012

Exp Fluids

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International audienceCavitation plays an important role in fuel atomization mechanisms but the physics of cavitation and its impact on spray formation and injector efficiency are not well documented yet. Experimental investigations are required to support the development and the validation of numerical models and the design of tomorrow's injectors, in the context of pollutant and fuel consumption reduction. The complexity of modern injectors and the extreme conditions of injection do not facilitate experimental investigations. In this paper, experiments are conducted in a simplified geometry. The model nozzle consists of a transparent 2D micro-channel supplied with a test-oil (ISO 4113). Three different optical techniques are proposed to investigate the channel flow, with the pressure drop between upstream and downstream chambers as a parameter. A shadowgraph-like imaging technique allows the observation of cavitation inception and vapor cavities development throughout the channel. The technique also reveals the presence of density gradients (pressure or temperature) in the channel flow. However, this additional information is balanced by difficulties in image interpretation, which are discussed in the paper. In addition, a combination of Schlieren technique and interferometric imaging is used to measure the density fields inside the channel. The three techniques results are carefully analysed and confronted. These results reveal a wealth of information on the flow, with pressure waves generated by bubble collapses, turbulence in the wake of vapor cavities and bubble survival in flow regions of high pressure. Our results also show that cavitation inception is located in the shear layers between the recirculation zones and the main flow, relatively far from the inlet corner, where the pressure is minimum in average. To explain this behavior, we propose a scenario of cavitation inception based on the occurrence and the growing of instabilities in the shear layers

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“…The inlet surface roughness, texture and nozzle material will affect the occurrence of cavitation and hydraulic flip. Therefore, we paid attention to whether cavitation or hydraulic flip occurs in our experiment (for more detail about cavitation and hydraulic flip see for example Chang et al [14]). Prior to injecting the droplet stream, the required size of the pan fire is defined as the dimensions shown in Fig.…”

Section: Article In Pressmentioning

confidence: 99%