Issue 1, December 2009

Optical Diagnostics of Flows

Role of Planar Laser-Induced Fluorescence in combustion research


F. Grisch, M. Orain

Laser diagnostics are now considered an indispensable tool in fluid dynamics research. Such measurements provide a deeper understanding of the inner physical and chemical processes, which is required to validate and improve computer-based simulations and to assist applied research in practical combustors. This paper presents an overview of the potential of planar laser-induced fluorescence (PLIF), which currently allows for the imaging of scalar properties such as species concentration, temperature, velocity, pressure and density over wide pressure and temperature ranges with high temporal and spatial resolution. Although a complete picture of the present research and PLIF applications to fluid mechanics is beyond the scope of this article, this overview focuses rather on the basic concepts underlying the technique and its application to various flowfields at Onera. These examples cover applications to primarily gas flows like mixing experiments under isothermal and isobaric conditions, fuel/air mixing and temperature measurements in heated jet flows, subsonic and supersonic flame structures and improvement of combustion processes using nanosecond pulsed discharges. Several examples of measurements of fuel concentration in multiphase flows, flame structure around isolated droplets and fuel/air mixing processes in kerosene/air combustion at high pressure are presented. The paper concludes with a section that addresses key issues that remain as challenges for continued research towards the improvement of quantitative PLIF measurements.


Al1-11.pdf1.55 MB

drop with flame


drop without flame


axial injection supersonic combustor


wall injection supersonic combustor




ignition OH