Master Thesis Defense

Luis Hatashita

(Advisor: Prof. Suresh Menon)

"Turbulent jet mixing in a high temperature crossflow"

Friday, December 8

12:30 p.m

Montgomery Knight Building 325

and

Virtual:
Microsoft Teams Meeting
Meeting ID: 222 946 666 351
Passcode: g9iaHc

Abstract

Jet in crossflow (JICF) has been a subject of research for several decades due to its enhanced mixing properties, i.e. greater than free and coaxial jets. It is moreover encountered in nature in the form of volcano plumes, and in industrial applications. Fuel injection and dilution in jet engines or gas turbines are also of interest. Non iso-density ratio jet in a crossflow has only more recently been subject of studies. While jet mixtures are adjusted to alter the density ratio, fewer studies have been reported on varying temperature to achieve the same effect. The current work extends on previous studies to evaluate momentum ratio, crossflow temperature and jet molecular weight on mixing. High-fidelity numerical simulations are conducted and validated against experimental data, demonstrating the capability of the simulation to predict mixing.  Furthermore, the simulation data is evaluated to predict reduced order model decomposition. Results indicate that momentum ratio is the dominant parameter and the governing factor to control macroscopic features of the flow, such as jet penetration and concentration decay. Mixing is also enhanced for the set of fully developed turbulent jets. Crossflow temperature presents a non-negligible effect on mixing, despite not affecting overall flow geometry. Spatial probability density functions and integral mixing metrics corroborate this result. Turbulence time scales and instantaneous scalar concentration fields demonstrate how temperature affects mixing. Molecular weight (within the range studied) on the other hand is shown to be a minor parameter and does not demonstrate significant changes to the metrics. The influence of temperature on mixing is investigated through a reduced order model decomposition to extract and evaluate coherent structures. It is found that increase in temperature inhibits the formation of coherent structures such as wake vorticities.

Committee

• Prof. Suresh Menon – School of Aerospace Engineering (advisor)
• Prof. Joseph Oefelein – School of Aerospace Engineering
• Prof. Wenting Sun – School of Aerospace Engineering