Effects of Injection Strategies on Fluid Flow and Turbulence in Partially Premixed Combustion (PPC) in a Light Duty Engine

Slavey Tanov*, Zhenkan Wang, Hua Wang, Mattias Richter, Bengt Johansson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Partially premixed combustion (PPC) is used to meet the increasing demands of emission legislation and to improve fuel efficiency. With gasoline fuels, PPC has the advantage of a longer premixed duration of the fuel/air mixture, which prevents soot formation. In addition, the overall combustion stability can be increased with a longer ignition delay, providing proper fuel injection strategies. In this work, the effects of multiple injections on the generation of in-cylinder turbulence at a single swirl ratio are investigated. High-speed particle image velocimetry (PIV) is conducted in an optical direct-injection (DI) engine to obtain the turbulence structure during fired conditions. Primary reference fuel (PRF) 70 (30% n-heptane and 70% iso-octane) is used as the PPC fuel. In order to maintain the in-cylinder flow as similarly as possible to the flow that would exist in a production engine, the quartz piston retains a realistic bowl geometry. The distortion caused by the complex shape of the optical piston is corrected by an advanced image-dewarping algorithm. The in-cylinder charge motion is evaluated and investigated over a range of crank angles in the compression and expansion strokes in order to understand the turbulence level, especially the late-cycle turbulence. The results show the spatial and temporal development of the flow-field structures in the piston bowl. The PIV data, obtained in the vertical plan, are used to calculate the ensemble average velocity turbulent kinetic energy (TKE), cycle-resolved turbulence, and mean velocity of the instantaneous fluid motion.

Original languageEnglish (US)
JournalSAE Technical Papers
Volume2015
DOIs
StatePublished - Sep 6 2015

ASJC Scopus subject areas

  • Automotive Engineering
  • Safety, Risk, Reliability and Quality
  • Pollution
  • Industrial and Manufacturing Engineering

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