Crua, C.

de Sercey, G.

Stetsyuk, V.

Turner, J.

University of Huddersfield Repository

University of Huddersfield RepositoryStetsyuk, V., Crua, C., de Sercey, G. and Turner, J.Experimental study of primary atomisation in the near-nozzle region of diesel fuel spraysOriginal CitationStetsyuk, V., Crua, C., de Sercey, G. and Turner, J. (2015) Experimental study of primary atomisation in the near-nozzle region of diesel fuel sprays. In: Jets and Vortex rings, 14 July 2015, University of Brighton. (Unpublished) This version is available at http://eprints.hud.ac.uk/28061/The University Repository is a digital collection of the research output of theUniversity, available on Open Access. Copyright and Moral Rights for the itemson this site are retained by the individual author and/or other copyright owners.Users may access full items free of charge; copies of full text items generallycan be reproduced, displayed or performed and given to third parties in anyformat or medium for personal research or study, educational or not-for-profitpurposes without prior permission or charge, provided:• The authors, title and full bibliographic details is credited in any copy;• A hyperlink and/or URL is included for the original metadata page; and• The content is not changed in any way.For more information, including our policy and submission procedure, pleasecontact the Repository Team at: E.mailbox@hud.ac.uk.http://eprints.hud.ac.uk/Centre for Automotive EngineeringUniversity of Brighton14th, July, 2015, Research WorkshopViacheslav Stetsyuk, Cyril Crua, Guillaume de Sercey, Jack TurnerExperimental study of primary atomisation in the near-nozzle region of diesel fuel sprays1. Objectives2. Operating conditions3. Spray A injector4. Experimental setup5. Image processing and analysis6. Results7. Conclusions2Introduction3Objectives- Engine Combustion NetworkExp. Priority 5 1 4 2 7 3 6Oxygen Temperature[K]Density[kg/m3]Inj. Pressure[bar]Fuel Inj. Duration[ms]NozzleSpray A standard 0%, 15% 900 22.8 1500 n-dodecane 1.5 0.090 mm, axial hole2 21% 800 15.2 1000 n-heptane 4 3-hole, 145 angle, Spray B3 13% 1000 7.6 50077% n-dodecane, 23% m-xylene0.5/0.5 dwell/0.5 0.2 mmSpray C4 19% 1200 45.6 200050% n-dodecane, 50% iso-octane0.3/0.5 dwell/1.2 -5 17% 700 30.4 - - - -6 11% 950 - - - - -7 - 850 - - - - -8 - 1100 - - - - -9 - 750 - - - - -4Operating conditionsLegendCompletedIn progressNot metFuel temperature at nozzle 363 K (90°C)  403 K (130°C)Common rail GM Part number 97303659Common rail volume/length 22 cm3/28 cmDistance from injector inlet to common rail 24 cmTubing inside and outside diameters Inside: 2.4 mm. Outside: 6-6.4 mm.Fuel pressure measurement 7 cm from injector inlet / 24 cm from nozzle• Injector: Spray A.2 nozzle #201.02– From second batch of Spray A injectors, purchased by IFPEN (Malbec et al. 2013 papers.sae.org/2013-24-0037) New STL file for #201.02 generated by University of Bergamo (Prof. Santini)5Spray A injectorX-ray µCT(University of Bergamo)Optical microscopy(University of Brighton)InjectorSerial #Exit diameter[μm]K-factor Inlet radius[μm]201.02 93.9 1.8 30• Reciprocating RCM based on Ricardo Proteus (2 stroke engine)• Operated at 500 rpm• TDC conditions: 5 MPa, 720 K• Quiescent air motion at start of injection (no swirl)• 3 optical accesses• Multiple injection strategy/injection frequency 6Experimental setup – Rapid compression machinePressure (ICP)Temperature (ICT)from Ricardo WAVETemperature at TDC was computed by Ricardo WAVEby fitting measured ICP with simulated ICP (WAVE) 7Experimental setup – Fuel temperature controlInstrumented Siemens injector was used to measure injector tip temperatureInjector tip and fuel channel temperatures Measured tip temperature: 195-220 oC ECN target 90 oC Injector cooling was needed working rangeFuel channel thermocoupleTip thermocoupleneedle8Experimental setup – Fuel temperature control Directly cooled injector stem ΔT tip ≈ 80-100 oC 130< Tip temperature < 135 oC for 120 minECN targetFuel line temperature as a function of time for cooled and uncooled injectors9Experimental setup – High-speed videoMicroscope working distance 95 - 122 mmMicroscope NA = 0.156 - 0.20Microscope DOF = 0.01 - 0.02 mmShadowgraphy setup based on Crua et al. (2015) Fuel 157 doi.org/4F3• New camera: 29 megapixel (4400x6600 pixels) dual-frame• Scale factor: 0.56 µm/pixel (2.46x3.70 mm)• MTF at 10%: 250 cycles/mm  2 µm object10Experimental setup – Long distance microscopy• Acquired ~7,400 dual-frame images for Spray A (815 GB)• Data set covers x = 0 to 8 mm (y = ± 1.2 mm;  z = ±10 µm)Currently processing for droplet size distributionsStill need to process velocity fields, and acquire Spray B data11Test conditions for long-distance microscopySpray A Spray B1500bar1000bar500bar1500Bar1000bar500barStart of injection acquired,inprogressnotplannedinprogressSOI+0.5ms completed being completedEnd of injection processed12Image processingWavelet filter12bit raw image1. Convolution with wavelet2. Threshold at 30% of intensity range3. Measure droplet’s projected area4. Calculate eq. diameter d =  A π5. Correct diameters based on NIST-calibrated target (1.9 to 101.6 µm)1.9 3.1 3.7 4.8 5.9 7.0 7.6 8.8 10.1• Algorithm correctly identifies many of the small liquid structures (left of figure below), without producing significant false positives in blurred regions (right of figure below)13Image processing (0.5 ms after start of injection)• Vapour emerges with vortex ring motion• Followed by liquid jet and droplets• Droplets present at liquid interface14Results: Start of injection – 1500 barAxial distance from orifice [mm]15Results: 0.5 ms after start of injection – 1500 bar• Droplets visible at spray periphery• Surrounded by vaporised fuel• Pressure waves often visible along spray periphery.• Not expected to occur for multi-hole nozzles, but could affect Spray A droplet formation, mixing and optical resolutionPressure wave spacing: 100 to 150 µmClusters of droplets surrounded by vapourOptically thinregion ~100 µmDroplet density16Results: Steady-state phase 1500 barMedian diameter = 5.8 µmMedian diameter• 1,575 images => 619,756 droplets• Droplet data merged into 50x50 µm2 bins• Droplet count: 200-1000 droplets/bin• SMD in the optically-thin periphery of the spray is 6 – 8 µmSauter Mean Diameter (D32)17Results: Steady-state phase – 1500 barStatistics for x = 1, 2, 4, 6 ±0.25 mm (y = ±1.2 mm; z = ±10 µm) from orifice 18Analysis – Comparison between 500 and 1500 barSMD 1500 bar • Marginally larger SMD at 500 bar, compared to 1500 bar, especially after 6 mm• Asymmetrical distributions observed in both cases (SMD, drop count, median diameter)SMD 500 bar• Large variations in– droplet position– droplet size– droplet shape19Results: End of injection – 1500 bar• Droplet size distributions measured in near-nozzle, optically-thin (≈ 100 µm), regions• Droplet sizes appear normally distributed, and independent of radial position• Processed data available for ECN4Comparison with simulations• Data processing is ongoing: can still produce new droplet binning, locations, etc…Future plans• Spray B in progress, expected to be completed after ECN4 meeting (September 2015)• Velocimetry data (Sprays A and B)• Droplet shape analysis for end of injection (Sprays A and B)• All raw & processed data will be made public to promote comparison with simulations, and development of new image analysis techniques20ConclusionsEquipmentEPSRC Engineering Instrument PoolBP Global Fuels TechnologyFundingBP Global Fuels TechnologyEPSRC (grant EP/K020528/1)21Acknowledgments

Experimental study of primary atomisation in the near-nozzle region of diesel fuel sprays

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