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Date of Award

2015

Document Type

Master's report

Degree Name

Master of Science in Mechanical Engineering (MS)

College, School or Department Name

Department of Mechanical Engineering-Engineering Mechanics

First Advisor

Jeffrey D. Naber

Abstract

Engine knock is a limitation towards higher efficiency and power output in spark ignited engines. Direct water injection into the combustion chamber is a potential solution to this problem by means of the ‘charge cooling’ effect of water. 1D Fluid Dynamic simulation tool GT-Power has been used to develop a test CFR S.I. engine model complete with direct water injection functionality. A GT-Power based Knock template, Kinetic Fit (KF) was selected, calibrated to experimentally known knock operating points and then used as a predictive tool to determine effect of Direct Water Injection on knock limit extension in the engine operation. Ideal cycle calculations were done to quantify the charge cooling effect of Direct Water Injection and compare it with the charge cooling potential of Ethanol-blends. Modeling of Direct Water Injection needs to take into account the evaporation mechanism to be able to accurately predict the effect on performance parameters. Two evaporation models, namely the Mass Diffusion controlled and the Convection/Diffusion controlled, were evaluated for predicting the in-cylinder water vaporization. Algorithms for integrating these models into GT-Power simulation were developed in MATLAB and Visual Fortran.

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