Date Approved

6-26-2026

Graduate Degree Type

Thesis

Degree Name

Engineering (M.S.E.)

Degree Program

School of Engineering

First Advisor

Dr. Jenna Stolzman

Second Advisor

Dr. Sanjivan Manoharan

Third Advisor

Dr. Karl Brakora

Academic Year

2025/2026

Abstract

Gas flaring is widely used in the oil and gas industry to dispose of excess waste gas, and improving flare efficiency is critical for reducing emissions. Flare performance depends strongly on turbulent mixing between the flare gas and surrounding crossflow. While previous studies have examined the effects of crossflow velocity and low turbulence levels, the combined effects of crossflow turbulence intensity and integral length scale on mixing remains insufficiently understood.

This study uses a non-reacting jet in crossflow (JICF) configuration to represent the mixing process between the flare and crossflow interaction. Using computational fluid dynamics (CFD), Reynolds-Averaged Navier-Stokes (RANS) simulations were performed in ANSYS Fluent. Crossflow velocity (Uc), turbulence intensity (TI), and integral length scale (Lx), were systematically varied at the crossflow inlet, and carbon dioxide (CO2) was used as a passive scalar to quantify downstream mixing behavior. Experimentally, the AEROLAB Educational Wind Tunnel was used with the addition of passive turbulence grids to set turbulence at the inlet across the test section. CO2 was used as the experimental jet gas to compare against the computational setup. The turbulence levels produced by the passive grids was measured, as well as the CO2 concentrations downstream to quantify the mixing and compare to CFD trends.

Results show that mixing is strongly region dependent. Computationally, in the near nozzle region, increasing crossflow velocity and TI reduces mixing, while Lx has minimal influence. In contrast, far-field mixing is less sensitive to crossflow velocity but becomes increasingly dependent on turbulent characteristics. At higher crossflow velocities, increasing Lx enhances downstream mixing. The same trends are verified experimentally.

These findings highlight the trade-off between near-nozzle and far-field mixing and demonstrate the importance of accurately specifying inlet turbulence properties for the modeling of flare systems.

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