Turbulent flame boundary and structure detection in an optical DISI engine using tracer-based two-line PLIF technique

Abstract

"Turbulent flame boundary and structure detection in an optical DISI engine using tracer-based two-line PLIF technique", Experimental Thermal and Fluid Science, AbstractDesign and development of new combustion systems for Spark Ignition Direct Injection (DISI) engines requires thorough understanding of the combustion flame as it develops from the electric discharge and propagates across the combustion chamber. The main purpose of this work was to develop an experimental setup capable of investigating the premix turbulent flame boundary and structure inside the combustion chamber of a DISI engine. For this purpose the tracer-based two-line Planar Laser Induced Fluorescence (PLIF) technique was set up. In order to have a thermometry technique independent of the photophysical model of dopant tracer, a specially designed Constant Volume Chamber (CVC) was utilized for quasi in situ calibration measurement. The thermometry technique was evaluated by measurements of average in-cylinder charge temperature during compression stroke for both motoring and firing cycles and comparing the results with temperature values calculated from in-cylinder pressure data. The developed technique was successfully implemented to detect flame structure during combustion process in an optical engine. The present study demonstrated that as the two-line PLIF thermal images are independent of species concentration and flame luminosity they can be utilized as an accurate means for flame segmentation. The proposed technique has the potential to be utilized for study of premix flames in non-homogeneously mixed systems.

Flame Boundary Measurement Using an Electrostatic Sensor Array

“…A flame is the central reaction zone of a combustion process. The geometrical characteristics of a flame are essential for the determination of its structural properties and the estimation of its thermal impact (i.e., convection and radiation) to the surroundings [1]. There has been a long history of characterizing the geometrical features of a burner flame in combustion research [1][2][3][4], such as flame shape, boundary, length, width, tilt, surface area, structure, location and front thickness, etc.…”

Imaging of flame propagation and temperature distribution in an all-metal gasoline engine with endoscopic access via anisole fluorescence

“…Tracer-based laser-induced fluorescence (LIF) is a widely used optical diagnostic tool for quantitative measurement of fuel concentration, temperature, and fuel/air ratio in combustion applications (Schulz and Sick 2005;Deguchi et al 2002;Kuwahara and Ando 2000). LIF has also been used to detect the flame front via the "negative-LIF" technique (Bladh et al 2005;Attar et al 2015) (i.e., the disappearance of the tracer where the fuel is burned), to investigate the spray in a diesel marine engine (Hult and Mayer 2013) and formation and evaporation of piston fuel films (Alger et al 2001;Geiler et al 2017;Hochgreb 2001). Previously, toluene (methylbenzene, CH 3 C 6 H 5 , boiling point 111 °C) has been well investigated as a tracer for LIF applications (Düwel et al 2003;Koban et al 2005) and used for measurements in combustion engines, e.g., to image equivalence ratio and fuel distribution (Frieden and Sick 2003;Smith and Sick 2005;James and Smith 2005), to investigate fuel films in DISI engines (Geiler et al 2017;Schulz and Beyrau 2018;Schulz et al 2016), and to image the gas-phase temperature distribution via the ratio in single (Fuyuto et al 2006) and two spectral bands (Gessenhardt et al 2015;Luong et al 2008;Peterson et al 2013).…”