Investigation of cavitation in real size diesel injection nozzles

Badock, Christoph; Wirth, Ralf; Fath, Ayatullah Muhammadin Al; Leipertz, Alfred

doi:10.1016/s0142-727x(99)00043-0

Cited by 155 publications

(90 citation statements)

References 12 publications

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“…the ratio of forces that support versus those that suppress cavitation. Critical cavitation numbers (or incipient cavitation numbers) based on this definition have been found to fall in the range of 0.5 to 10, with associated critical Reynolds numbers of between 5,000 and 30,000 [2,3,9,13,15,18].…”

Section: Cavitation Numbermentioning

confidence: 99%

“…Most previous studies have focused on cavitation imaging in optical models of Diesel nozzles, typically enlarged 20, with few studies on real-size nozzles [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Moreover, only limited work can be found on quantitative flow data in scaled-up or real Diesel and gasoline injectors, e.g.…”

Section: Introductionmentioning

confidence: 99%

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Cavitation, primary break-up and flash boiling of gasoline, iso-octane and n-pentane with a real-size optical direct-injection nozzle

Serras-Pereira

Romunde

Aleiferis

et al. 2010

Fuel

130

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Improvements to the direct-injection spark-ignition combustion system are necessary if the potential reductions in fuel consumption and emissions are to be fully realized in the near future. One critical link in the optimization process is the design and performance of the injectors used for fuel atomization. Multi-hole injectors have become the state-of-the-art choice for gasoline direct injection engines due to their flexibility in fuel targeting by selection of the number and angle of the nozzle holes, as well as due to their demonstrated stability of performance under a wide range of operating conditions. Recently there has been increased attention devoted to the study of the flow through the internal passages of injectors because of the presence of particular fluid phenomena, such as large scale vortical motion and cavitation patterns, which have been shown to influence the characteristics of primary break-up. Understanding how cavitation can be used to improve spray atomisation is essential for optimising mixture preparation quality under early injection and stratified engine operating conditions but currently no data exist for injector-body temperatures representative of real engine operation, particularly at low-load conditions that can also lead to phase change due to fuel flash boiling. This paper outlines results from an experimental imaging investigation into the effects of fuel properties, temperature and pressure conditions on the extent of cavitation, flash boiling and, subsequently, primary break-up. This was achieved by the use of a real-size transparent nozzle of a gasoline injector from a modern direct-injection combustion system. Gasoline, iso-octane and n-pentane fuels were used at 20 and 90 °C injector-body temperatures for ambient pressures of 0.5 bar and 1.0 bar in order to simulate early homogeneous injection strategies for part-load and wide-open-throttle engine operation.3

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Section: Cavitation Numbermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cavitation, primary break-up and flash boiling of gasoline, iso-octane and n-pentane with a real-size optical direct-injection nozzle

Serras-Pereira

Romunde

Aleiferis

et al. 2010

Fuel

130

View full text Add to dashboard Cite

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“…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

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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 ...

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“…In order to obtain the atomization characteristics due to the cavitation in the nozzle flow, the visualization of the cavitation need to perform by the flow visualization system, and atomization characteristics such as Sauter mean diameter (SMD) and droplet mean velocity is determined by using a particle analyzer system [16]- [18]. The pictures of the light sheet experiment taken with a CCD camera were compared with photographs taken by the shadowgraph technique under the same injection conditions [19]- [21]. As a result the cavitation films could be observed as thin objects which do not extend into the internal flow of the injection nozzle.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Flow Pattern inside a Diesel Engine Injection Nozzle to Determine the Relationship between Various Flow Parameters and the Occurrence of Cavitation

Bastawissi¹,

Elkelawy²

2014

ENG

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In diesel engines the fuel injection system produces the spray, which directly affects the combustion of the fuel, which in turn determines the production of pollutants. In spite of this, the details of this causal relationship remain unclear. There is, however, a lack of quantitative experimental data for determining and visualizing the cavitation inside real size diesel injector nozzle. The present work is devoted to analyze analytically the flow pattern inside the nozzle of a diesel engine working with hydrocarbon fuel (Diesel fuel) and to predict the relationship between the various flow parameters and occurrence of fuel cavitation in such nozzles. Basic physical parameters affecting this phenomenon are identified and quantified while the effect of nozzle geometry, fuel injection pressure, and engine cylinder temperature upon the flow pattern and occurrence of cavitation in such nozzles are assessed. In this study, a commercial computational fluid dynamics (CFD) package (FLUENT-T grid) is used while a computational grid is generated for the real geometry of diesel injector nozzle using (ANSYS). The suitability of the generated computational grid to give reliable results is examined using the suitable procedures and techniques. The results indicated that, cavitation modeling has reached a stage of maturity and it can usefully identify many of the cavitation structures present in internal nozzle flows and their dependence on nozzle design and flow conditions. The qualitative distributions and comparison of cavitation inception and distribution as well as flow parameters at the nozzle exit are also studied.

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Investigation of cavitation in real size diesel injection nozzles

Cited by 155 publications

References 12 publications

Cavitation, primary break-up and flash boiling of gasoline, iso-octane and n-pentane with a real-size optical direct-injection nozzle

Cavitation, primary break-up and flash boiling of gasoline, iso-octane and n-pentane with a real-size optical direct-injection nozzle

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

Investigation of the Flow Pattern inside a Diesel Engine Injection Nozzle to Determine the Relationship between Various Flow Parameters and the Occurrence of Cavitation

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