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Comparison of flash boiling resistance of two injector designs and the consequences on downsized gasoline engine emissions

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journal contribution
posted on 04.10.2019 by Changzhao Jiang, Matthew Parker, Daniel Butcher, Adrian Spencer, Colin Garner, Jerome Helie
This paper presents a comparative study of two injectors designed for the same Gasoline Turbocharged Direct Injection engine, one featuring 5 holes and one with 6 holes. Hole diameter and circumferential spacing also differed between the two injectors in order to optimise targeting while maintaining flow rate and drop size distribution. By comparing the macroscopic spray characteristics of the two injectors, this study investigated possible design features which may better maintain a spray's intended morphology under severe flash boiling conditions. The sprays of each injector were firstly investigated by imaging in a quiescent pressure vessel before also being imaged in an endoscopically accessed version of the target 3-cylinder downsized engine to understand the impact of the spray morphology on performance and emissions. Near field images from the pressure vessel indicated that the 5-hole injector could tolerate a greater superheated degree before experiencing spray collapse, maintain its intended morphology better and exhibited a wider plume and shorter penetration length than the 6-hole injector for a given condition. Endoscopic images from the engine indicated that the spray area of the 5-hole injector was always wider under a range of start of injection timings, leading to a better air-fuel mixture and the observation of less diffusive combustion. The PN (particulate) emissions of the 5-hole injector was also consistently lower than the 6-hole injector under different injection timings due to better mixing and less piston impingement, whilst also being less sensitive to changes of injection timing due to its ability to maintain its spray morphology.

Funding

Advanced Propulsion Centre (APC) undertaken as part of TSB/APC project number 113130

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Aeronautical and Automotive Engineering

Published in

Applied Energy

Volume

254

Publisher

Elsevier

Version

AM (Accepted Manuscript)

Rights holder

© Elsevier Ltd.

Publisher statement

This paper was accepted for publication in the journal Applied Energy and the definitive published version is available at https://doi.org/10.1016/j.apenergy.2019.113735.

Acceptance date

11/08/2019

Publication date

2019-08-20

Copyright date

2019

ISSN

0306-2619

Language

en

Depositor

Dr Daniel Butcher

Article number

113735

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