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

Abstract

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% ??-methyl-naphthalene and 1% TMPD and the other 88% decane, 10% ??-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. ?? 2013 Elsevier Inc. All rights reserved

Velocity field analysis of the high density, high pressure diesel spray

“…Solutions to recent and ever increasing concerns of fuel efficiency and pollutant emissions are, therefore, closely linked to a better understanding of this mixing process. Because of this, the diesel spray development has been extensively studied, and the characteristics of liquid phase (Bardi et al, 2012;Herfatmanesh et al, 2013;Naber and Siebers, 1996;Payri et al, 2012;Payri et al, 2013a) and vapor penetration (Bardi et al, 2012;Herfatmanesh et al, 2013;Pastor et al, 2012;Payri et al, 2013b) are now quite well known. These experiments have enabled the development of very useful 1D spray models (Desantes et al, 2009;Desantes et al, 2007;Musculus and Kattke, 2009;Pastor et al, 2008;Pickett et al, 2011)] that allow for fast and reliable predictions that effectively reduce testing times and costs necessary for new developments to comply with efficiency standards, emission regulations, etc.…”