Spray and combustion characterization for internal combustion engines using optical measuring techniques – A review

The number of studies on spray and combustion characteristics in IC (internal combustion) engines using optical techniques has rapidly increased in the past few years due to an increase in the number of alternative fuels and stricter emission standard regulations. This study investigates better ways of controlling the combustion process, thus ensuring optimum performance and minimum emission levels produced during the combustion process. Alternative fuels such as CNG (compressed natural gas), biodiesel and hydrogen have been studied by many researchers due to their relative low environmental impact. Meanwhile, for conventional fuels such as gasoline and diesel, studies have focused on spray characteristics to provide better air/fuel mixtures in order to produce a cleaner combustion process. Few experimental works have investigated the effects of modifications to the injector itself, for example, varying the injection rate, injection pressure, etc. In order to provide a better understanding of spray and combustion characteristics, researchers have studied macroscopic and microscopic parameters using optical techniques. This paper presents the significance of spray and combustion study with optical techniques that have been reported by previous researchers in order to provide in depth knowledge as assistance to readers interested in this research area.

Research highlights
► The paper reviews about optical measurement techniques that were used in IC (internal combustion) engine, such as visualization, PIV (particle image velocimetry), LIF (laser induced fluorescence), and PDPA (phase Doppler particle anemometry).
► The experimental work that was done previously concentrated on macroscopic and microscopic spray and combustion characteristics of various type of fuel such as gasoline, diesel, biodiesel and oxygenated fuel.
► The review paper gives a short assessment of the presented methods and some proposals for the future research work.