An experimental study of the detailed flame transport in a SI engine using simultaneous dual-plane OH-LIF and stereoscopic PIV

Brian Peterson, Elias Baum, Andreas Dreizler, Benjamin Böhm

Research output: Contribution to journalArticlepeer-review

Abstract

Understanding the detailed flame transport in IC engines is important to accurately predict ignition and combustion phasing, rate of heat release and assess engine performance. This is particularly important for RANS and LES engine simulations, which often struggle to accurately predict flame propagation and heat release without first adjusting model parameters. Detailed measurements of flame transport in technical systems are required to guide model development and validation.
This work introduces an experimental dataset designed to study the detailed flame transport and flame/flow dynamics for spark-ignition engines. Simultaneous dual-plane OH-LIF and stereoscopic PIV is used to acquire 3D measurements of unburnt gas velocity (U ⃑_gas), flame displacement speed (S_D) and overall flame front velocity (U ⃑_Flame) during the early flame development. Experiments are performed in an optical engine operating at 800 and 1500 RPM with premixed, stoichiometric isooctane-air mixtures. Analysis reveals several distinctive flame/flow configurations that yield a positive or negative flame displacement for which the flame progresses towards the reactants or products, respectively. For the operating conditions utilized, S_D exhibits and inverse relationship with flame curvature and a strong correlation between negative S_D and convex flame contours is observed. Trends are consistent with thermo-diffusive flames, but have not been quantified in context of IC engines. Flame wrinkling is more severe at the higher RPM, which results in a broader S_D distribution towards higher positive and negative velocities. Spatially-resolved distributions of U ⃑_gas and S_D are presented to describe in-cylinder locations where either convection or thermal diffusion is the dominating mechanism contributing to flame transport. Findings are discussed in relation to common engine flow features, including flame transport near solid surfaces. Findings provide a first insight into the detailed flame transport within a technically relevant environment and are designed to support the development and validation of engine simulations.
Original languageEnglish
Article number202
Pages (from-to)16-32
JournalCombustion and Flame
Volume202
Early online date14 Jan 2019
DOIs
Publication statusPublished - Apr 2019

Keywords

  • Detailed flame transport
  • Stereoscopic PIV
  • OH-LIF
  • piston engine
  • IC engines

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