Abstract

The Tabulated Premixed Conditional Moment Closure (T-PCMC) method has been shown to provide the capability to predict turbulent, premixed methane flames with detailed chemistry and reasonable run times in a RANS/URANS adiabatic environment. Here the premixed T-PCMC method is extended in a Large Eddy Simulation (LES) framework for non-adiabatic premixed flames, allowing heat loss to occur in the mixture before, during and after combustion. It is proposed that the LES framework is a more suitable representation for both chemical and turbulent scales in premixed combustion. By resolving the high energy turbulent scales and modeling the small scale turbulence, it is expected that the resolution of the turbulence and transient effects are better captured in a LES framework leading to better predictions of the mixing rate and consequently the reaction rate, which is the main focus and source of error in combustion modeling. The LES T-PCMC model is implemented using the open source CFD software OpenFOAM for its open access to C++ source code and large library of turbulence and thermo-physical models. The proposed model validated with PIV and Raman measurements of a turbulent, enclosed reacting flame of a single jet and backward facing step geometry. The DLR data sets provide both unity (E.g.Methane) and non-unity (E.g. Hydrogen) Lewis number fuels, allowing for the proposed numerical model to be validated against both unity and non-unity Lewis # flames. Velocity, temperature and major/minor species are compared to the experimental data. Once validated, this model is intended to be useful for designing lean premixed combustors for gas turbines which operate primarily in the corrugated premixed combustion regime, where chemical and turbulent time scales are of the same order requiring adequate models for their interaction. LES results match the experimental data better than the Reynolds Averaged Navier-Stokes (RANS/URANS) solution and is able to better resolve the transient features of the flame with an increase in run time of only 50 %, when compared to URANS.

Notes

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Graduation Date

2015

Semester

Summer

Advisor

Vasu Sumathi, Subith

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Mechanical and Aerospace Engineering

Degree Program

Mechanical Engineering

Format

application/pdf

Identifier

CFE0006234

URL

http://purl.fcla.edu/fcla/etd/CFE0006234

Language

English

Release Date

February 2016

Length of Campus-only Access

None

Access Status

Doctoral Dissertation (Open Access)

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