Cavitation in Fuel Injection Systems for Spray-Guided Direct Injection Gasoline Engines

Papoulias, D.; Giannadakis, E.; Mitroglou, Nicholas; Gavaises, Manolis; Theodorakakos, A.

doi:10.4271/2007-01-1418

Cited by 17 publications

(9 citation statements)

References 12 publications

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“…In the context of this, optical access to the nozzle is invaluable. Most studies to date have focused on cavitation imaging inside optical models of diesel nozzles, typically enlarged by factors [15][16][17][18][19][20][11][12][13][14][15] with some studies on real-size nozzles with optical access (ranging from 0.2 to 1.5 mm in diameter with various hole lengths). [5][6][7][8][9][10][16][17][18][19][20][21][22] Limited experimental work can be found on quantitative flow data in real or large-scale diesel or spark-ignition injectors, for example, particle image velocimetry (PIV) work by Aleiferis et al 23,24 in 103 and 203 models, and also by Allen et al, 7 Khoo and Hargreave 8 and Walther et al 25,26 in real-size pressure-swirl (for sparkignition engines) and single/multi-hole diesel injectors, respectively.…”

Section: Spray Characteristicsmentioning

confidence: 99%

Development of a real-size optical injector nozzle for studies of cavitation, spray formation and flash-boiling at conditions relevant to direct-injection spark-ignition engines

Butcher

Aleiferis

Richardson

2013

International Journal of Engine Research

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High-pressure multi-hole injectors for direct-injection spark-ignition engines have shown enhanced fuel atomisation and flexibility in fuel targeting by selection of the number and angle of the nozzle holes. The nozzle internal flow is known to influence the characteristics of spray formation; hence, understanding its mechanisms is essential for improving mixture preparation. However, currently, no data exist for fuel temperatures representative of real engine operation, especially at low-load high-temperature conditions with early injection strategies that can lead to phase change due to fuel flashboiling upon injection. This challenge is further complicated by the predicted fuel stocks, which may include new (e.g. bio-derived) components. The physical/chemical properties of such components can differ markedly from gasoline, and it is important to have the capability to study their effects on in-nozzle flow and spray formation, taking under consideration their different chemical compatibilities with optical materials as well. The current article presents the design and development of a real-size quartz optical nozzle, 200 mm in diameter, suitable for high-temperature applications and also compatible with new fuels such as alcohols. First, the internal geometry of a typical real multi-hole injector was analysed by electron microscopy. Mass flow was measured, and relevant fluid mechanics dimensionless parameters were derived. Laser and mechanical drilling of the quartz nozzle holes were compared. Abrasive flow machining of the optical nozzles was also performed and analysed by microscopy in comparison to the real injector. Initial validation results with a highspeed camera showed successful imaging of microscopic in-nozzle flow and cavitation phenomena, coupled to downstream spray formation, under a variety of conditions including high fuel temperature flash-boiling effects. The current work used gasoline and iso-octane to provide proof-of-concept images of the optical nozzle, and future work will include testing of a range of fuels, some of which will also be bio-derived.

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Section: Spray Characteristicsmentioning

confidence: 99%

Development of a real-size optical injector nozzle for studies of cavitation, spray formation and flash-boiling at conditions relevant to direct-injection spark-ignition engines

Butcher

Aleiferis

Richardson

2013

International Journal of Engine Research

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“…By ~7° CA ASOI these are no longer distinguishable as two separate plumes, having merged into a single plume with significantly reduced radial penetration. The effect of nozzle angles and specific geometries have also been reported to affect the internal flow of the injector and the levels of fuel atomization arising from different cavitation regimes inside the nozzles [25][26][27].…”

Section: ° Mirrormentioning

confidence: 99%

Characteristics of Ethanol, Butanol, Iso-Octane and Gasoline Sprays and Combustion from a Multi-Hole Injector in a DISI Engine

Serras-Pereira

Aleiferis

Richardson³

et al. 2008

SAE Int. J. Fuels Lubr.

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Recent pressures on vehicle manufacturers to reduce their average fleet levels of CO 2 emissions have resulted in an increased drive to improve fuel economy and enable use of fuels developed from renewable sources that can achieve a net reduction in the CO 2 output of each vehicle. The most popular choice for spark-ignition engines has been the blending of ethanol with gasoline, where the ethanol is derived either from agricultural or cellulosic sources such as sugar cane, corn or decomposed plant matter. However, other fuels, such as butanol, have also arisen as potential candidates due to their similarities to gasoline, e.g. higher energy density than ethanol. To extract the maximum benefits from these new fuels through optimized engine design and calibration, an understanding of the behaviour of these fuels in modern engines is necessary. In particular, the use of direct injection spark-ignition technology requires spray formation and combustion characteristics to be quantified in order to improve both injector design and operating strategies. To this end an optical investigation of spray development and combustion was undertaken in a single-cylinder direct-injection spark-ignition engine with a centrally mounted multi-hole injector. Specifically, crank-angle resolved imaging studies were performed and batches of images from 100 consecutive cycles were acquired with synchronised in-cylinder pressure logging. The engine was motored and fired at 1500 RPM stoichiometrically under part load (0.5 bar intake pressure), with injection timing set early in the intake stroke to promote homogeneous mixture formation. The effects were investigated at engine coolant temperatures of 20 °C and 90 °C using gasoline, iso-octane, ethanol and butanol. Projected spray areas as seen through the piston crown were calculated to reveal information about the atomization and evaporation processes for each fuel. Additionally, flame areas and centroids were calculated to analyse the combustion process relative to measured in-cylinder pressure histories.

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“…In addition, cavitation images obtained in real-size nozzles incorporating transparent windows as well as measurements of the nozzle discharge coefficient have further been used for model validation. Finally, it is worth mentioning that extensions of the present model, linking cavitation with erosion and its application to new, emerging fuel systems for gasoline direct injection engines have been recently presented by Gavaises et al (2007) and Papoulias et al (2007), respectively, adding to the model's predictive capability over a wide range of applications and nozzle configurations.…”

Section: Introductionmentioning

confidence: 99%

Modelling of cavitation in diesel injector nozzles

2008

Self Cite

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This is the unspecified version of the paper.This version of the publication may differ from the final published version. A computational fluid dynamics cavitation model based on the Eulerian-Lagrangian approach and suitable for hole-type diesel injector nozzles is presented and discussed. Permanent repository link Modelling of cavitation in diesel injector nozzles E. G I A N N A D A K I S, M. G A V A I S E S A N D C. A R C O U M A N I SThe model accounts for a number of primary physical processes pertinent to cavitation bubbles, which are integrated into the stochastic framework of the model. Its predictive capability has been assessed through comparison of the calculated onset and development of cavitation inside diesel nozzle holes against experimental data obtained in real-size and enlarged models of single-and multi-hole nozzles. For the real-size nozzle geometry, high-speed cavitation images obtained under realistic injection pressures are compared against model predictions, whereas for the largescale nozzle, validation data include images from a charge-coupled device (CCD) camera, computed tomography (CT) measurements of the liquid volume fraction and laser Doppler velocimetry (LDV) measurements of the liquid mean and root mean square (r.m.s.) velocities at different cavitation numbers (CN) and two needle lifts, corresponding to different cavitation regimes inside the injection hole. Overall, and on the basis of this validation exercise, it can be argued that cavitation modelling has reached a stage of maturity, where it can usefully identify many of the cavitation structures present in internal nozzle flows and their dependence on nozzle design and flow conditions.

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Cavitation in Fuel Injection Systems for Spray-Guided Direct Injection Gasoline Engines

Cited by 17 publications

References 12 publications

Development of a real-size optical injector nozzle for studies of cavitation, spray formation and flash-boiling at conditions relevant to direct-injection spark-ignition engines

Development of a real-size optical injector nozzle for studies of cavitation, spray formation and flash-boiling at conditions relevant to direct-injection spark-ignition engines

Characteristics of Ethanol, Butanol, Iso-Octane and Gasoline Sprays and Combustion from a Multi-Hole Injector in a DISI Engine

Modelling of cavitation in diesel injector nozzles

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