Presentation on theme: "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."— Presentation transcript:
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 = m/s V y,up = 8.21 m/s V x,down = m/s V y,down = 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 (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.