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ID 113

LIF/Mie planar droplet sizing in IC engine sprays using single-droplet calibration data

Matthias Koegl
University of Erlangen Nuernberg
Germany

Yogeshwar Nath Mishra
Lund University
Sweden

Bernhard Hofbeck
University of Erlangen Nuernberg
Germany

Kevin Baderschneider
University of Erlangen Nuernberg
Germany

Jonas Pracht
University of Erlangen Nuernberg
Germany

Edouard Berrocal
Lund University
Sweden

Stefan Will
University of Erlangen Nuernberg
Germany

Lars Zigan
University of Erlangen Nuernberg
Germany

 

Abstract:

This paper presents an improved method for planar measurement of the droplet size distribution of sprays, which is applied to an ethanol multi-jet DISI (direct-injection spark-ignition) spray studied in an injection chamber. The method is based on simultaneous detection of Mie-scattering and liquid Laser-Induced Fluorescence (LIF) using two sCMOS-cameras. Two-phase SLIPI (Structured Laser Illumination Planar Imaging) is applied for both techniques for suppression of multiple light scattering. As fluorescent tracer, the organic luminescence dye Eosin-Y is added to the liquid fuel, which is excited at 532 nm using a Nd:YAG laser. From the instantaneous LIF/Mie ratio images, quantitative planar measurements of the droplet Sauter Mean Diameter (SMD) are conducted using calibration data from single spherical droplets. For this purpose, a droplet generator was employed, which produces a droplet chain with a wide range of droplet sizes relevant for DISI-sprays. A high-resolution microscopic setup was used for calibration of the LIF/Mie ratio as a function of SMD. Effects of liquid fuel temperature, laser power and dye concentration on the LIF/Mie ratio are studied in detail. The calibration data is used to quantify the droplet size distribution of the DISI spray, which was studied for an injection pressure of 8 MPa and ambient conditions of 0.2 MPa and 298K. The spray evolution and structure were analyzed in various planes in terms of SMD. From these measurements, a complete 3-dimensional spray data set has been generated.