Publication Date


Document Type


Committee Members

Haibo Dong (Advisor), Hui Wan (Committee Member), Zifeng Yang (Committee Member)

Degree Name

Master of Science in Engineering (MSEgr)


A Gasoline Direct Injection (GDI) engine enables an increased fuel efficiency and higher power output than a conventional Port Fuel Injection (PFI) system. By injecting pressurized fuel straight into each cylinder of an internal-combustion engine, the degree of fuel atomization is increased, as well as the fuel vaporization rate. In order to further harness the effects of direct injection, ethanol is implemented as a fuel. The cooling effect of ethanol fuel droplets changing to vapor inside the combustion chamber facilitates a higher compression ratio, thus increasing engine power and efficiency. Three dimensional computational simulation is used to investigate the feasibility of ethanol and gasoline-ethanol mixtures as a fuel over varying compression ratios in a GDI engine. ANSYS Workbench is used to build a dynamic mesh of the varying compression ratio models, in conjunction with SolidWorks modeling software. To simulate flow physics, fuel injection, and combustion in the engine, ANSYS Fluent is employed. A parametric study of the effect of spark timing and compression ratio under ethanol operation at cruise RPM is performed. Additionally, a dual-injector gasoline-ethanol setup is implemented for the GDI engine and the effects of injection timing and mixture fraction of fuel is analyzed. Both ethanol and bi-fuel operation settings are found to provide significantly higher horsepower than the stock GDI engine. The dual-injector, bi-fuel operation is found to provide a specific fuel consumption comparable to the stock engine while providing substantially higher output. The results yield a promising fuel delivery strategy which can be appealing to many direct injection engine applications.

Page Count


Department or Program

Department of Mechanical and Materials Engineering

Year Degree Awarded