Keywords

Direct Numerical Simulation, Volume of Fluid, Droplet Combustion, Droplet Evaporation, Aluminum Droplet

Abstract

This thesis focuses on the direct numerical simulation of the combustion of a single aluminum droplet with phase change. For this purpose, the Volume of Fluid (VOF) method is employed for the direct numerical simulation of two distinct phases. To model the droplet combustion, the phase change (evaporation) and chemical reactions are modeled by setting source terms for each governing equation. This work proposes a new form of species source term by phase change, derived using the local instant formulation of two-phase flow.

The Stefan problem is used to verify the modified source term. Evaporation fluxes calculated with both modified and conventional sources are compared, demonstrating that the modified species source term yielded mass flow rates closer to theoretical values, with an error rate of less than 20%. The instabilities of source terms in the droplet case are also analyzed, revealing that surface tension and chemical reactions cause numerical errors arising from the sharp discontinuities at the interfacial cells.

The model’s validation includes a comparison with a benchmark case, assessing the temporal evolution of droplet diameter change and temperature fields. While the diameter change aligns reasonably with the benchmark, the temperature fields do not reach the benchmark’s flame temperature due to numerical diffusions. Furthermore, the molar fraction of aluminum gas at the interface closely matches experimental values, although the overall spatial distribution of molar fraction of species does not align with the benchmark.

Completion Date

2024

Semester

Summer

Committee Chair

Kinzel, Michael

Degree

Master of Science (M.S.)

College

College of Engineering and Computer Science

Department

Mechanical and Aerospace Engineering

Degree Program

Aerospace Engineering

Format

application/pdf

Release Date

8-15-2024

Length of Campus-only Access

None

Access Status

Masters Thesis (Open Access)

Campus Location

Orlando (Main) Campus

Accessibility Status

Meets minimum standards for ETDs/HUTs

Download

Share

COinS