Date of Award

6-2012

Document Type

Open Access

Degree Name

Bachelor of Science

Department

Mechanical Engineering

First Advisor

Bradford Bruno

Language

English

Keywords

combustion, instabilities, fuel, flow, volume

Abstract

Combustion instability is characterized by periodic fluctuations during the combustion process. Such instabilities can cause a reduction in engine performance and damage to engine components. In liquid fueled combustion, some types of combustion instability may be driven by changes in fuel droplet size distribution. The fuel droplet size distribution can be changed if the original or “primary” fuel droplets are broken apart by the flow. This is called secondary droplet breakup. The smaller drops that are created during breakup are consumed more rapidly and increase the energy release rate, which may act as a sustaining force of the instability. Currently, experimental and computational results exist for secondary droplet breakup caused by steady aerodynamic flows. However neither experimental nor computational results exist for droplets broken up by high frequency periodic flows. This study utilized a computational fluid dynamics program called STAR-CCM+ to model secondary droplet breakup in a periodic flow. By incorporating the volume of fluid multiphase flow model and varying boundary conditions, the behavior of the droplet in a sinusoidal flow was simulated at different ratios of the drop’s natural frequency to the flow’s oscillation frequency. This investigation tested predictions of the droplet response at different flow frequencies and made conclusions about fundamental droplet behavior.

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