Digital Commons Network^™

Direct Simulation And Reduced-Order Modeling Of Premixed Flame Response To Acoustic Modulation, Zheng Qiao

Theses and Dissertations

This dissertation introduces a general, predictive and cost-efficient reduced-order modeling (ROM) technique for characterization of flame response under acoustic modulation. The model is built upon the kinematic flame model–G-equation to describe the flame topology and dynamics, and the novelties of the ROM lie in i) a procedure to create the compatible base flow that can reproduce the correct flame geometry and ii) the use of a physically-consistent acoustic modulation field for the characterization of flame response. This ROM addresses the significant limitations of the classical kinematic model, which is only applicable to simple flame configurations and relies on ad-hoc models …

Nonwovens Of Ceramic Decorated Cellulose Based Fine Fibers For Leaded Water Purification, Alejandro J. Castillo

Theses and Dissertations

Fine fibers of cellulose acetate were Forcespun and used to make nonwoven mats of cellulose. Nonwovens were activated using a solution combustion synthesis which deposited iron nitride onto fibers. Cellulose and cellulose composite mats were tested as adsorbents for lead ion in water. Cellulose showed slightly higher adsorption capacities (mg/g) up to 1300 mg/g lead loading. Adsorption data were further analyzed using several isotherms, of which the Dubinin-Raduskevich gave the best fits.

Examination Of Flow Dynamics And Passive Cooling In An Ultra Compact Combustor, Tylor C. Rathsack

Theses and Dissertations

The Ultra Compact Combustor (UCC) promises to greatly reduce the size of a gas turbine engine’s combustor by altering the manner in which fuel is burnt. Differing from the common axial flow combustor, the UCC utilizes a rotating flow, coaxial to the engine’s primary axis, in an outboard circumferential cavity as the primary combustion zone. The present study investigates two key UCC facets required to further this combustor design. The first area of investigation is cooling of the Hybrid Guide Vane (HGV). This UCC specific hardware acts as a combustor center body that alters the exit flow angle and acts …

Reconstruction Of The 3d Temperature And Species Concentration Spatial Distribution Of A Jet Engine Exhaust Plume Using An Infrared Fourier Transform Spectrometer Hyperspectral Imager, Mason D. Paulec

Theses and Dissertations

The measurement of combustion byproducts is useful for determining pollution of any fuel burning application, efficiency of combustion, and determining detectability of aircraft exhausts. Both intrusive and non-intrusive techniques have been utilized to measure these quantities. For the majority of the non-intrusive techniques, the absorption and emission spectra of the gases are utilized for measurements. For this research, the use of the Telops Infrared Fourier Transform Spectrometer (IFTS) Hyperspectral Imager (HSI) was explored within the scope of combustion diagnostic methods, as an option for remote measurements of a jet turbine to determine concentration of species and temperature of the combustion …

Alkyne Combustion: Experimental And Computational Studies Of Formyl Radical Production, Matthew Charles Drummer

Theses and Dissertations

The United States consumed a total of 97.4 trillion BTUs of energy in 2016 with over 80% of that energy consumption source being fossil fuel combustion. Before a combustion reactions reaches its end products, a number of intermediate products form and may react with other abundant atmospheric species to form aerosol particles and acid rain, both of which have potentially negative impacts on both human-made structures and the natural environment.

In an effort to counteract the consequences of fossil fuel combustion, scientists are interested in understanding the reaction mechanisms of hydrocarbon combustion reactions to understand which intermediate products form and …

Development And Characterization Of A High Speed Mid-Ir Tunable Diode Laser Absorption Spectrometer For Co And Co2 Detection In Detonation Events, Stephen D. Wakefield

Theses and Dissertations

A tunable diode laser absorption spectroscopy system, capable of collecting data at a 10 kHz repetition rate near 4.5 microns. This system was made feasible in recent years due to the development of quantum cascade lasers active in the 4.5 microns region of the spectrum. Reaching into the mid-IR region of the electromagnetic spectrum allowed for an analysis of the fundamental absorption bands for both CO and CO₂. The spectral absorption was measured for ethylene, methane, ethane, and propane across a variety of equivalence ratios, at various heights above a Hencken Burner surface. For each fuel, the concentration …

Spectral Stability Of Weak Detonations In The Majda Model, Jeffrey James Hendricks

Theses and Dissertations

Using analytical and numerical Evans-function techniques, we examine the spectral stability of weak-detonation-wave solutions of Majda's scalar model for a reacting gas mixture. We provide a proof of monotonicity of solutions. Using monotonicity we obtain a bound on possible unstable eigenvalues for weak-detonation-wave solutions that improves on the more general bound given by Humpherys, Lyng, and Zumbrun. We use a numerical approximation of the Evans function to search for possible unstable eigenvalues in the bounded region obtained by the energy estimate. For the parameter values tested, our results combined with the result of Lyng, Raoofi, Texier, and Zumbrun demonstrate that …

Stability For Traveling Waves, Joshua W. Lytle

Theses and Dissertations

In this work we present some of the general theory of shock waves and their stability properties. We examine the concepts of nonlinear stability and spectral stability, noting that for certain classes of equations the study of nonlinear stability is reduced to the analysis of the spectra of the linearized eigenvalue problem. A useful tool in the study of spectral stability is the Evans function, an analytic function whose zeros correspond to the eigenvalues of the linearized eigenvalue problem. We discuss techniques for numerical Evans function computation that ensure analyticity, allowing standard winding number arguments and rootfinding methods to be …

Midwave Infrared Imaging Fourier Transform Spectrometry Of Combustion Plumes, Kenneth C. Bradley

Theses and Dissertations

A midwave infrared (MWIR) imaging Fourier transform spectrometer (IFTS) was used to successfully capture and analyze hyperspectral imagery of combustion plumes. Jet engine exhaust data from a small turbojet engine burning diesel fuel at a flow rate of 300 cm³/min was collected at 1 cm⁻¹ resolution from a side-plume vantage point on a 200x64 pixel window at a range of 11.2 meters. Spectral features of water, CO, and CO² were present, and showed spatial variability within the plume structure. An array of thermocouple probes was positioned within the plume to aid in temperature analysis. A single-temperature …