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Date of Award

2017

Document Type

Campus Access Master's Report

Degree Name

Master of Science in Mechanical Engineering (MS)

Administrative Home Department

Department of Mechanical Engineering-Engineering Mechanics

Advisor 1

Scott A. Miers

Committee Member 1

Jeffrey D. Naber

Committee Member 2

Antonio Gauchia

Committee Member 3

David Wanless

Abstract

This is an MSc report to develop a turbulent combustion model and couple it with engine simulation software to improve its predictive capability. For liquid or gaseous fuels one of the most important quantities is the velocity at which the flame front propagates normal to itself and relative to the flow into the unburned mixture. In a non-turbulent mixture, flame propagation is laminar and the flame has smooth surface. However, in a turbulent flow field, the flame front is no longer smooth and the reaction zone is thicker than that in laminar case. According to Damkohler theory, the increase in flame front area due to turbulence causes to increase the flame speed. However, recent studies show that the ratio of turbulent to laminar flame speed (ST/SL) depends on both the relative increase in flame surface area as a result of turbulence, and the relative drop in local flame speed as a result of stretching. The proposed research will empirically study the effect of stretching on flame speed under engine-like conditions and develop a model for flame speed base on that. For this reason, flame surface area and speed will be found by processing high speed images which are taken from flame inside cylinder. Then, the developed combustion model will be coupled with GT-Power engine simulation software in order to, first, evaluate the developed model and then, improve the GT-Power predictive combustion capability. To specify initial conditions correctly, the initial swirl and tumble values will be measured by using the steady-flow-rig method. Finally, to verify the simulation and developed turbulent combustion model, a V-twin, four-stroke, air cooled, ECH 749 Kohler engine will be used.

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