Computational Modeling and Analysis of Heavy Fuel Feasibility in Direct Injection Spark Ignition Engine
Haibo Dong (Committee Chair), Andrew Hsu (Other), George Huang (Other), Greg Minickweicz (Committee Member), Hui Wan (Committee Member)
Master of Science in Engineering (MSEgr)
Direct Injection spark ignition (DISI) technology is helpful for the present day engine to increase the fuel efficiency. Power output and the choice of fuel as the demand and scarcity for fossil fuels are increasing. As a new technology DISI engines are employed in some commercial cars like the Pontiac Solstice using gasoline fuel. The advantages of DISI engines like use of different fuels, reduced compression ratio, reduced injection pressure and reduced operating pressures in DISI engines has not been widely tested. As a new technology DISI engines lack experimental results and combustion co-relations that can be directly used as in the case of conventional engines. The experimental analysis of this technique is very expensive as it involves large number of parameters to be changed each and every time the experiment is done. This makes the experimental analysis of DISI engine a costly and time consuming task. Computational fluid dynamics on the other hand can simulate the combustion process and let researches visualize the process of combustion inside the cylinder.
The ability of DISI engine to work on different fuels in the engine is successfully tested. Two engines, reciprocating and rotary, equipped with DISI technology is simulated in FLUENT. The engines are selected in such a way that they represent the major part of engine family to show that DISI technology is feasible in any type of IC engines. Because of unavailable experimental data on DISI diesel engines, the models used in the thesis are validated with a gasoline DISI reciprocating engine. The validated model is used for parametric study of diesel fuel in DISI engine. It was found that the engine parameters need to be tuned to avoid the undesired effects of diesel fuel. After several parametric changes, combustion and power output which is identical to the experimental validated case are obtained. Hence it has been proved that the diesel fuel can be successfully utilized in DISI engine. This technology is then applied to the rotary engine. Because of the change in geometry and many other specifications, the parameters used for reciprocating engine are not feasible for rotary engine. Therefore a parametric study on rotary engine is carried out to obtain a good combustion and power output.
It is proven successfully in this thesis that DISI technology can be applied to any engine and can use any kind of fuel. However, each and every engine needs to be tuned according to its specifications and geometrical constrains to obtain the maximum fuel to air mixture and therefore the maximum power output. The thesis explains the influence of parameters on the power output considering the important properties of fuel such as cold start ability, flash point detonation, volatility and density. The behavior of fuel and flow physics inside the cylinder is visually explained. The fuel air interaction, which is very important to have a good air fuel mixture formation, is extensively studied and the methods are developed to time the injector depending on the air turbulence inside the cylinder. The conclusions in this thesis demand the importance of further studies of this technology. The results of the thesis show that this technology can be used as a more energy efficient and echo friendly technology. However, further studies on this technology are essential to build a flawless more efficient technology in the field of IC engines.
Department or Program
Department of Mechanical and Materials Engineering
Year Degree Awarded
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