Title: The influence of intake flow and coolant temperature on gasoline spray morphology during early-injection DISI engine operation

Abstract

Multi-hole gasoline injectors operating at conditions spanning throttled early-intake stroke operation produce spray plumes that either remained separated or merge and collapse due to flash boiling. Flash boiling occurs due to the sudden expansion of gas bubbles in the liquid fuel at high fuel temperature and low ambient pressure. This study records high-speed images of spray-morphology changes due to in-cylinder flow, thereby revealing operating conditions that do and do not affect the self-induced morphology observed in quiescent vessels. Specifically, in a central-injection, four-valve, high-tumble engine, where the thermodynamic state and in-cylinder cross flow are dynamic. Additionally, motivated by cold start and hot restart operation, the fuel pressure, coolant temperature, in-cylinder air pressure, and engine rpm were systematically varied over relevant operating conditions, which bracketed the range from non- to flash-boiling sprays. The results reveal the operating conditions at which the in-cylinder cross flow disrupts the spray morphology as well as the extent of the disruption. At 650 rpm, the spray morphology was similar to that observed in quiescent vessels at nominally equivalent fuel temperature and in-cylinder pressure, indicating that the spray’s self-induced entrainment flow dominated the in-cylinder flow. However, for fuel temperature and ambient pressure near the transition between non-more » and flash-boiling, the intake cross flow at higher engine speed (1950 rpm) significantly disrupted the spray morphology. The high cross-flow velocity appears to induce plume merging and collapse, whereas none was evident at low rpm (650 rpm). This study led to the postulate that the spray merging and collapse are governed by the rate of atomization near the nozzle exit, presumed to be controlled by either or both aerodynamic atomization and flash-boiling intensity. It would then follow that spray modeling in CFD requires atomization models that blend the effects of both physical processes.« less

Authors:

Reuss, David L.  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-2269-5192"

Kim, Namho ^[1]; Sjöberg, Magnus  ^[1]

• Search DOE PAGES for author "Sjöberg, Magnus"
• Search DOE PAGES for ORCID "0000-0002-4288-5607"

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+ Show Author Affiliations

1. Sandia National Laboratories, Livermore, CA, USA

Publication Date:

Sun Jun 19 00:00:00 EDT 2022

Research Org.:

Sandia National Lab. (SNL-CA), Livermore, CA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Office of Sustainable Transportation. Vehicle Technologies Office (VTO)

OSTI Identifier:

1873038

Alternate Identifier(s):

OSTI ID: 1882609

Report Number(s):

SAND2022-10091J
Journal ID: ISSN 1468-0874

Grant/Contract Number:  

NA0003525

Resource Type:

Published Article

Journal Name:

International Journal of Engine Research

Additional Journal Information:

Journal Name: International Journal of Engine Research Journal Volume: 24 Journal Issue: 5; Journal ID: ISSN 1468-0874

Publisher:

SAGE Publications

Country of Publication:

United Kingdom

Language:

English

Subject:

42 ENGINEERING; direct-injection spark-ignition engine; cold-start; multi-hole injector; flash boiling; spray collapse; in-cylinder flow; spray morphology