Mixture formation in a direct injection gas engine: Numerical study on nozzle type, injection pressure and injection timing effects

Research output: Contribution to journalArticleScientificpeer-review

Researchers

Research units

  • FPT Motorenforschung AG
  • Wärtsilä Finland

Abstract

DI (direct injection) gas engines aim at providing clean and efficient combustion. Mixture quality control and hydrocarbon emission reduction are key development challenges in such engines. Here, a CFD (computational fluid dynamics) study of the DI gas injection process is carried out. The aim is to provide knowledge that aids e.g. engine designers in i) extending the lean limit at part load conditions via stratified mixtures, ii) mitigating incomplete combustion by improving mixing and eliminating fuel crevice flow. We investigate the sensitivity of the mixture formation process to nozzle type, injection pressure and injection timing. First, the present CFD method is discussed in free gas jet computations. For reference, we utilize planar laser induced fluorescence measurements and large eddy simulation results. After this, a total of 12 DI cases in moving mesh engine conditions are simulated. The main findings and novel results are listed as follows: 1) injection timing has a considerable influence on mixing rate, 2) efficacy of mixing mechanisms is highly nozzle type dependent, 3) jet-piston interaction may be utilized in the generation of a confining toroidal vortex in the piston bowl, 4) phase space analysis reveals two highly case dependent stages of mixture evolution.

Details

Original languageEnglish
Pages (from-to)542-556
Number of pages15
JournalEnergy
Volume94
Publication statusPublished - 1 Jan 2016
MoE publication typeA1 Journal article-refereed

    Research areas

  • Direct injection, Gas engine, Hydrocarbon emissions, Mixing, Stratification

ID: 1658277