Spatially and Temporally Resolved Imaging of Primary Breakup in High-Pressure Fuel Sprays
Abstract
The overarching goal of the proposed research is to identify governing mechanisms of atomization in diesel fuel sprays to provide a clear view on the role of fuel properties and engine operating conditions on spray and fuel-air mixture formation. Towards this goal, the objectives of the proposed work are to: 1) Provide a clear description, supported by quantitative experimental imaging measurements, linking the initial growth of interfacial instabilities at the injector nozzle exit to droplet formation. The widely employed classical description of high-pressure spray atomization, characterized by a progression from interface instability growth, to primary breakup and secondary breakup, contains many gaps in physical understanding, but even this overall descriptive view has yet to be validated. Related scientific questions that will be addressed include: a) What types of initial perturbations are important in determining the length and time scales of primary atomization (e.g., liquid turbulence, cavitation, or gas inertial forces at the interface)?, and b) How do the length and time scales of droplet formation scale with these perturbation sources? 2) Clarify defining spray characteristics and mechanisms for the transition to the so-called Atomization regime, where practical fuel spray operating conditions typically occur. The classical Oh-Re map denoting the different breakup regimes has remained largely unchanged for the last three decades and deserves to be revisited. First, the regime definitions do not account for liquid-gas density ratio. Based on literature findings, the liquid-gas density ratio is known to strongly affect interfacial instabilities and should therefore play a role in determining breakup regimes. Second, the empirical characterization of the atomization regime as Òcomplete disintegrationÓ at the nozzle exit is inconsistent with a view of atomization based on surface instability growth at the liquid-gas interface.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 11, 2018
- Source ID
- W911NF1510500
Entities
People
- Caroline Genzale
Organizations
- Army Contracting Command
- Georgia Tech Research Corporation
- United States Army