Ultrafast X-ray Study of Swirling Hollow-Cone Sprays in the Near-Field
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Transcript of Ultrafast X-ray Study of Swirling Hollow-Cone Sprays in the Near-Field
This work and the use of the APS were supported by US Department of Energy, Office of Science/Basic Energy Science and Energy Efficiency and Renewable Energy/Vehicle Technology
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Ultrafast X-ray Study of Swirling Hollow-Cone Spraysin the Near-Field
Advanced Photon Source, Argonne National Laboratory, US
Objectives Interpretation of near-field flow development of swirling hollow-cone sprays Physical insight on various types of breakups and atomization process
Pinj = 2 MPa, Ambient Gas = N2,Fuel = Gasoline Calibration Fluid (Viscor 16BR)
Ultrafast X-ray Phase-Enhanced Imaging
Temporal Resolution : 150psHigh Energy X-ray : 9.62keV
Spatial Resolution < 1mm
Temporal Spray Development
Outward-Opening Swirl Injector
Opening -‘Skirts’
Closing – ‘Streaks from Weakened Swirl’
X-ray Tomography from APS, ANLOpening -‘Instability Waves’ Steady – ‘Turbulent Flow from High Swirl’
Nozzle Structure(taken using x-ray phase-enhanced imaging)
1mm
Pinj = 2 MPaSteady-stateWhite-Light
11 ns Exposure
W. Cai et al., Appl. Phys. Lett. 83, 1671 (2003)
1mm 1-5% Transmissionat 1 mm location
Visible Light Image
* Setup in XOR 7ID-B in APS, ANL
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A. Opening – ‘Skirts’
500 m Pinj = 5 MPa, 80 s ASOI
Pinj = 2 MPa
Droplet Sizes: 41 ~ 67 m
Low velocity laminar-like flow before swirl motion Dictated by transient pressure and velocity during needle opening
Skirt Ligaments Droplets High injection pressures form thin and long ligaments, and smaller droplets
Pinj = 7 MPa
Droplet Sizes: 35 ~ 50 m
B. Opening – ‘Instability Waves’
Pinj = 2 MPa150 s ASOI
Pinj = 7 MPa120 s ASOI
Instability waves, an indicator of laminar to turbulence transition, appear on the sheet. The wavelengths are dependent to Re.
Wavelength: 40 m
Wavelength : 26 m
C. Steady – ‘Turbulent Flow from Strong Swirl’ D. Closing – ‘Streaks from Weakened Swirl’
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Re DependencyAnalyzed from
non-swirl hollow spray
Concluding Remarks Hollow-cone swirl spray showed four representative stages of flow development with time: (1) skirts and (2) instability waves during opening, (3) turbulent flow
from strong-swirl at steady-state and (4) streaks from weakened swirl during closing. Instability wavelengths, ligament and droplet sizes decrease and number of streaks increases with increase in injection pressure.
Pinj = 2 MPa
500 m 500 m
1 mm
Pinj = 2 MPa, 1.0 ms
Pinj = 5 MPa, 1.19 ms
Pinj = 7 MPa, 1.19 ms 2 MPa 5 MPa 7 MPa0
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Pinj = 7 MPa
Probability of Feature Size
Turbulent flow from nozzle exit from strong swirl flow Ligaments, droplets and bubbles at downstream Decrease in feature size at higher injection pressure Increase in feature density at higher injection pressure
Streaks with less turbulent flow from weakened swirl Increase in number of streaks at higher injection pressure Streaks are from hydrodynamic instability
500 m