Aditya Raman

Graduation Semester and Year

2016

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Aerospace Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Brian Dennis

Abstract

Vortex generators have extensively been used over the past few decades for heat transfer applications. Their passive form of enhancement coupled with the ease of their implementation is the primary reason for their growing popularity. The streamwise counter rotating vortex pair (CVP) that is formed downstream of these vortex generators act as a source of energy that can set up stirring scales to enhance heat transfer and improve mixing. The CVP can be used to energize the boundary layer in the case of wall bounded flows, and as a consequence vortex generators have also been used to delay flow separation. Another means of heat and mass transfer enhancement that is often used is the jet in cross-flow. A jet issued into the cross-flow has distinct flow features along with a longitudinal CVP that serve as a means of enhancement. In contrast to the vortex generators, a jet in cross-flow is an active means of enhancement as it requires external power to pump the jet. The jet in cross-flow has numerous applications, mixing of air & fuel in a combustor, turbine blade film cooling, thrust vectoring etc. In this research, the effect of geometric and flow parameters of a passive delta winglet vortex generator like the vortex generator angle of attack, Reynolds number and the undisturbed boundary layer height on the heat transfer enhancement and vortex strength is studied. The time averaged effect of the vortex shedding on the heat transfer enhancement is quantified. The vorticity transport equation is used to identify the sinks of vorticity with a goal to gain a better understanding of the enhancement mechanism and the vortex interaction with the boundary layer. The mixing efficiencies of the vortex generator employed along with a jet in crossflow is compared to the baseline case without the vortex generator.

Keywords

Vortex generators, Jet in cross-flow, Heat transfer enhancement, Mixing enhancement, Vorticity transport, Vortex boundary layer interaction

Disciplines

Aerospace Engineering | Engineering | Mechanical Engineering

Comments

Degree granted by The University of Texas at Arlington

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