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Mansfield, Andrew B.
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Effects of Engine Speed on Spray Behaviors of the Engine Combustion Network “Spray G” Gasoline Injector

Robert Bosch LLC-Mohammad Fatouraie
University of Melbourne-Joshua Lacey, Michael Brear
Published 2018-04-03 by SAE International in United States
Non-reacting spray behaviors of the Engine Combustion Network “Spray G” gasoline fuel injector were investigated at flash and non-flash boiling conditions in an optically accessible single cylinder engine and a constant volume spray chamber. High-speed Mie-scattering imaging was used to determine transient liquid-phase spray penetration distances and observe general spray behaviors. The standardized “G2” and “G3” test conditions recommended by the Engine Combustion Network were matched in this work and the fuel was pure iso-octane. Results from the constant volume chamber represented the zero (stationary piston) engine speed condition and single cylinder engine speeds ranged from 300 to 2,000 RPM. As expected, the present results indicated the general spray behaviors differed significantly between the spray chamber and engine. The differences must be thoughtfully considered when applying spray chamber results to guide spray model development for engine applications. Overall, increases in engine speed correlated well with enhanced vaporization, loss of distinct plume structure, and enhanced spray collapse which led to reductions in wetted-footprint area. Furthermore, while loss of distinct plume structures appeared to be strongly dependent…
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Impact of Fuel Octane Rating and Aromatic Content on Stochastic Pre-Ignition

GM Global Propulsion Systems-Andrew B. Mansfield, Elana Chapman, Kenneth Briscoe
Published 2016-04-05 by SAE International in United States
The effects of aromatic content and octane rating of gasoline fuels on stochastic pre-ignition (SPI) behaviors were investigated at typical operating conditions using a modern 2.0 L turbocharged engine. In-cylinder pressure time history measurements made during a speed-load test sequence designed to stimulate SPI were used to determine both the frequency of SPI occurrence and the in-cylinder peak pressure during such events. Six fuels were tested with varying levels of aromatic content (15 - 35% by vol.) and two octane rating levels (∼88 & 94 anti-knock index). The engine was operated using a production-intent calibration with equivalence ratio near one. Pressure and temperature in the intake manifold were held constant near two bar and 35°C respectively. Significant SPI activity was observed, with abnormal event frequencies up to ∼1 SPI event per 1,000 engine cycles and in-cylinder peak pressures up to ∼200 bar. Aromatic content correlated directly with frequency of SPI occurrence and had minimal effect on in-cylinder peak pressures; whereas, octane rating correlated inversely with in-cylinder peak pressures during SPI and had minimal effect on…
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