Experiments in Fluids

, 59:59 | Cite as

Fuel film thickness measurements using refractive index matching in a stratified-charge SI engine operated on E30 and alkylate fuels

  • Carl-Philipp DingEmail author
  • Magnus Sjöberg
  • David Vuilleumier
  • David L. Reuss
  • Xu He
  • Benjamin Böhm
Research Article


This study shows fuel film measurements in a spark-ignited direct injection engine using refractive index matching (RIM). The RIM technique is applied to measure the fuel impingement of a high research octane number gasoline fuel with 30 vol% ethanol content at two intake pressures and coolant temperatures. Measurements are conducted for an alkylate fuel at one operating case, as well. It is shown that the fuel volume on the piston surface increases for lower intake pressure and lower coolant temperature and that the alkylate fuel shows very little spray impingement. The fuel films can be linked to increased soot emissions. A detailed description of the calibration technique is provided and measurement uncertainties are discussed. The dependency of the RIM signal on refractive index changes is measured. The RIM technique provides quantitative film thickness measurements up to 0.9 µm in this engine. For thicker films, semi-quantitative results of film thickness can be utilized to study the distribution of impinged fuel.



Carl-Philipp Ding performed these engine experiments during a research visit to Sandia. Carl-Philipp Ding and Benjamin Böhm gratefully acknowledge financial support by Deutsche Forschungsgemeinschaft (DFG) through SFB-Transregio 150. The engine experiments were conducted at the Combustion Research Facility, Sandia National Laboratories, Livermore, CA as part of the Co-Optimization of Fuels and Engines (Co-Optima) project sponsored by the U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies and Vehicle Technologies Offices. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. Xu He contributed to this study during a sabbatical visit to Sandia, which was supported financially by the China Scholarship Council under Grant no. 201506035029.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Fachgebiet Reaktive Strömungen und Messtechnik (RSM)Technische Universität DarmstadtDarmstadtGermany
  2. 2.Sandia National LaboratoriesLivermoreUSA
  3. 3.University of MichiganAnn ArborUSA
  4. 4.School of Mechanical EngineeringBeijing Institute of TechnologyBeijingChina

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