1. 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 Ultrafast X-ray Study of Multi-Orifice Diesel Nozzle Spray : Flow Dynamics and Breakup in the Near-Field Advanced Photon Source, Argonne National Laboratory Motivation  Deficient information on near-nozzle flow dynamics and breakup of multi-orifice nozzle sprays for validation of conventional breakup models Objectives  Interpretation of near-field flow dynamics and breakup of multi-orifice nozzle spray  Provide the validation data for conventional and future breakup models Overall Flow Development Principle of X-ray Phase-Enhanced Imaging Polychromatic X-ray Beam  Branching Multi-Jet Flows  Wavy Instabilities and Membrane-Mediated Breakup Single-Exposed (Side-View) P inj = 30MPa, Fuel = Biodiesel Needle Lift = 350  m, Ambient Gas = N 2 Two-Orifice Diesel Nozzle Experiments (Setup in XOR 7ID-B, APS ANL) X-ray Pulses for Single- and Double-Exposure Imaging Features  Breakup Process of Multi-Jet-Flows Single-Exposed (Top-View) 1. Wavy Instabilities  Thin Membranes  Instability Frequency  Instability1 : 2.8 MHz  Instability2 : 4.2 MHz  Originated from different inter-nozzle flows Double-Exposed (Side-View) x=3.5 mm Dynamics of Thinned Membranes  C v  Membrane : 0.73  Downflow : 0.84  Air drag exerted on membranes 2. Breakup of Membranes Single-Exposed (Top-View) Membranes breakup earlier than cylindrical flows. 3. Breakup of Cylindrical Flows Single-Exposed (Side-View) Cylindrical flows breakup directly into ligaments.  Dynamics of Multi-Jet-Flows Double-Exposed (Side-View) P inj = 40MPa* Axial Location (x) = 2.5 mm C v (V/V ideal ) = 0.87 V x,up = 273.53 m/s V y,up = 8.21 m/s V x,down = 273.53 m/s V y,down = -10.94 m/s Autocorrelation Local branching flows have same axial velocity but different penetration directions.  Structure of Multi-Jet-Flows Single-Exposed Axial Location (x) = 3.5 mm Local cylindrical (1) & tubular (2) Flows 1 2  Elliptical Spray (56 %) : (a) + (d)  Stretch of spray up and down  Comprised of cylindrical flows Spray width  Hollow Spray (44 %) : (a) + (b)  Hollow region inside spray  Comprised of tubular and cylindrical flows Side View Top View Stable elliptical spray was observed from another nozzle with 700  m needle-lift. Full hollow-cone spray was observed with 50  m needle-lift. The sprays with 350  m needle-lift in this study are in transient stage of full hollow-cone to stable elliptical spray. Top Needle-Lift = 350  m 01236 (mm) Summary  Development and breakup of multi-orifice nozzle spray are dictated by branching multi-jet-flows induced by complex inter-nozzle flows.  In the near-field, branching jet-flows with same axial velocity and have cylindrical or tubular structures were observed and these formed ellipti cal spray in one case and hollow circular spray in another.  At downstream, wavy instabilities associated with branching jet-flows appear on the spray and develop into thin membranes. The thinned membranes breakup first into ligaments by aerodynamic drag and then cylindrical flows breakup later at farther downstream.