Since the outbreak of the economic crisis in 2009 and the explosion of the nuclear power plant in Japan in 2011, the price and needs of fossil fuel have gradually decreased, and environmental problems, e.g. greenhouse gas, have directed the world’s attention to other energy resources, so-called green energy. However, not only are oil reserves many in the world, but also a boom of shale gas, which the US has triggered, plays an important role in developing relevant technologies and has the possibility of making tectonic shifts in energy initiative. Moreover, although many kinds of electric cars have been released by major companies, a massive number of vehicles are still equipped with internal combustion engines, and power plants involving the combustion of fossil fuels are also used to produce electricity. It is certain that the technologies relevant to the combustion of fossil fuels are still essential and should exist for a fairly long time. The ultimate goal of combustion research is enhancing the understanding of the mechanism of combustion, fuel efficiency, and so forth, of which practical results end up helping us control combustion process safely and efficiently. Among such research subjects, the measurement of burning velocities about laminar and turbulent flames have been studied and discussed in the last decades. Regrettably, there is still doubt on how a variety of factors affect the burning rate. Especially, cellular flame structures that appear in a certain condition require more considerable observation and research to investigate their characteristics.
The aim of this research is to examine the characteristics of cellular flame. In order to observe the flame, LUPOE-2D, Leeds University Ported Optical Engine version 2 with Disc-head, was used and an optical-accessible engine. In order to measure flame propagation speed, unburned gas velocity, burning velocity, and others, the research engine was modified, and the appropriate diagnostic system was installed. Hydrogen, methane, and propane were employed as fuels in this research. In the case of hydrogen, many researchers and major companies have paid much attention to it as a clean energy source to alleviate the global warming. And methane and propane have been widely used in the industrial fields. Using these three fuels, the experiment was carried out, and it was investigated how their cellular flames were locally changed.
