Simultaneous imaging of diesel spray atomisation and evaporation processes in a single-cylinder CR diesel engine

This document is the Accepted Manuscript version of the following article: Mohammad Reza Herfatmanesh, Mohammadreza Anbari Attar, and Hua Zhao, ‘Simultaneous imaging of diesel spray atomisation and evaporation processes in a single-cylinder CR diesel engine’, Experimental Thermal and Fluid Science, Vol. 50, pp. 10-20, October 2013. © 2013 Elsevier Inc. This manuscript version is made available under the terms of the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/. The Version of Record is available online at DOI: https://doi.org/10.1016/j.expthermflusci.2013.04.019 :In direct injection diesel engines, combustion and formation of pollutants are directly influenced by the spatial and temporal distributions of the injected fuel. In this study mixture formation during the pre-combustion phase of a diesel engine was investigated using the laser-induced exciplex fluorescence (LIEF) technique. The main purpose of this investigation was to develop an experimental setup capable of providing the full-field view of both liquid and vapour phases of evaporating diesel sprays during the fuel injection process inside the combustion chamber of a diesel engine with optical access. An expanded laser beam was employed for full combustion chamber visualisation. In this study two model fuels were tested; one consisted of 89% decane, 10% α-methyl-naphthalene and 1% TMPD and the other 88% decane, 10% α-methyl-naphthalene and 2% TMPD. The spray atomisation and evaporation processes during the pre-combustion phase of a diesel engine were measured at an injection pressure of 1200 bar and the engine speed of 1500 rpm. The results demonstrated the capability of the full-field LIEF technique in simultaneous imaging of liquid fraction and fuel vapour distribution during high pressure fuel injection process. It also highlighted the effect of dopant concentration on the fluorescence intensity of liquid and vapour signals. The exciplex system containing 1% TMPD produced better visualisation of the liquid phase, though the crosstalk in the vapour phase precluded accurate detection of the vapour phase signal. In contrast, the exciplex system containing 2% TMPD resulted in satisfactory visualisation of the vapour phase; however the intensity of the liquid phase was compromised as a result. This was presumed to be mainly due to the spectral shift of the exciplex species and/or TMPD decomposition at elevated temperatures and pressures.Peer reviewedFinal Accepted Versio

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

This is the Accepted Manuscript version of the following article: M. A. Attar, H. Zhao, M. R. Herfatmanesh, and A. Cairns, “Turbulent flame boundary and structure detection in an optical DISI engine using tracer-based two-line PLIF technique”, Experimental Thermal and Fluid Science, Vol. 68: 545-558, November 2015. The final published version is available at: https://doi.org/10.1016/j.expthermflusci.2015.06.015 © 2015 Elsevier Inc. All rights reserved.Design and development of new combustion system for Spark Ignition Direct Injection (DISI) engines requires thorough understanding of the flame as it develops from electric discharge and propagates across the combustion chamber. The main purpose of this work was to develop an experimental setup capable of investigating premixed and partially-premixed turbulent flame boundary and structure inside 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 photophysical models of dopant tracer, a specially designed Constant Volume Chamber (CVC) was utilized for quasi in situ calibration measurements. 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 employed to detect flame boundary and structure during combustion process in the 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 accurate means for flame segmentation. The proposed technique has the potential to be utilized for study of turbulent flames in non-homogeneously mixed systems.Peer reviewedFinal Accepted Versio