Keywords

turbulence, propulsion, flame stability, vorticity dynamics

Abstract

The contributions of vortex stretching, dilatation, baroclinic torque, and viscous diffusion to vorticity transport are experimentally investigated in a high-Reynolds number cavity combustor using high-speed particle image velocimetry and broadband chemiluminescence. An adaptive wall geometry forming converging, diverging, and nominal configurations is implemented to study the effects of pressure gradient on local flow physics and vorticity dynamics. The spatial profiles of the local turbulence terms are conditioned on the mean flame front to characterize the influence of the pressure gradient field and exothermic heat release on vortex dynamics in the cavity. In addition to isolate the influence of combustion on the flow, a nonreacting analysis is performed and a correlation is made between combustor geometry and the turbulence transport processes. Vorticity transport through dilatation was found to be significant relative to the other transport terms across all the configurations studied. These results contrast with direct numerical simulations of high Reynolds number flows in homogeneous isentropic turbulence. In addition, a scaling is proposed to quantify the significance of the flow induced vorticity and pressure fields on dilatation and baroclinic torque vorticity production. Experimental studies of similar confined combustors show a similar trend to the numerical studies with baroclinic torque dominating the transport mechanisms, motivating this study to understand the dependence of vorticity transport on the underlying flow physics.

Completion Date

2023

Semester

Fall

Committee Chair

Ahmed, Kareem

Degree

Master of Science in Aerospace Engineering (M.S.A.E.)

College

College of Engineering and Computer Science

Department

Mechanical and Aerospace Engineering

Degree Program

Aerospace Engineering

Format

application/pdf

Identifier

DP0028094

URL

https://purls.library.ucf.edu/go/DP0028094

Language

English

Release Date

December 2028

Length of Campus-only Access

5 years

Access Status

Masters Thesis (Campus-only Access)

Campus Location

Orlando (Main) Campus

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Restricted to the UCF community until December 2028; it will then be open access.

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