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Full-Text Articles in Engineering
Ignition And Extinction Behavior Of Fuels In A Microcombustor, Pawan Sharma
Ignition And Extinction Behavior Of Fuels In A Microcombustor, Pawan Sharma
LSU Doctoral Dissertations
Conventional fuel testing device-CFR engine requires large quantities of fuels, which makes it unsuitable for research of small samples of fuels. This current study seeks to address this limitation by using an externally heated microcombustor as an alternative fuel testing device. Mainly three combustion behaviors have been observed inside a microcombustor: strong flames at higher flow rates, Flames with Repetitive Extinction and Ignition (FREI) at intermediate flow rates, and weak flames at marginal flow rates. In previous studies, weak combustion behavior has been proven suitable to study fuel properties from small samples of fuels. Microcombustor experiments typically rely on flame …
A Multi-Scale Approach For Modeling Shock Ignition And Burn Of Granular Hmx, Pratap Thamanna Rao
A Multi-Scale Approach For Modeling Shock Ignition And Burn Of Granular Hmx, Pratap Thamanna Rao
LSU Doctoral Dissertations
Deflagration-to-detonation transition (DDT) in confined, low-density granular HMX (65%-85% Theoretical Maximum Density, TMD) occurs by a complex mechanism that involves compaction shock interactions within the material. Piston driven DDT experiments indicate that detonation is abruptly triggered by the interaction of a strong burn-supported secondary shock and a piston-supported primary (input) shock, where the nature of the interaction depends on initial packing density and primary shock strength. These interactions influence transition by affecting hot-spot formation within the micro-structure during pore collapse. In this study, meso-scale simulations of hot-spot formation in shock loaded granular HMX are used to guide the development of …
Tomographic Imaging Of Combustion Zones Using Tunable Diode Laser Absorption Spectroscopy (Tdlas), Avishek Guha
Tomographic Imaging Of Combustion Zones Using Tunable Diode Laser Absorption Spectroscopy (Tdlas), Avishek Guha
LSU Doctoral Dissertations
This work concentrates on enabling the usage of a specific variant of tunable diode laser absorption spectroscopy (abbr. TDLAS) for tomogaphically reconstructing spatially varying temperature and concentrations of gases with as few reconstruction artifacts as possible. The specific variant of TDLAS used here is known as wavelength modulation with second harmonic detection (abbr. WMS-2f) which uses the wavelength dependent absorbance information of two different spectroscopic transitions to determine temperature and concentration values. Traditionally, WMS-2f has generally been applied to domains where temperature although unknown, was spatially largely invariant while concentration was constant and known to a reasonable approximation (_x0006_+/- 10% …
Energetic Nanoparticles As Fuel Additives For Enhanced Performance In Propulsion Systems, Srinibas Karmakar
Energetic Nanoparticles As Fuel Additives For Enhanced Performance In Propulsion Systems, Srinibas Karmakar
LSU Doctoral Dissertations
Biofuels are currently being explored as a carbon-neutral fuel alternative to petroleum-based fuels. However, biofuels such as ethanol has lower energy density (~27MJ/kg) relative to petroleum fuels (~ 45 MJ/kg). Adding high-energy density particles (such as boron with heating value of ~ 58.5 MJ/kg) to biofuels can generate fuel slurry with higher energy density than the base fuel, and represents a potential strategy toward making biofuels more viable. However, the combustion of boron is inhibited (specifically, the ignition is delayed) by the initial presence of an oxide layer, and its high evaporation and boiling temperatures. The present study investigates the …
Micro Injection Fuel/Air Premixer/Combustion, Jian Zhang
Micro Injection Fuel/Air Premixer/Combustion, Jian Zhang
LSU Doctoral Dissertations
Lean premixed (LP) combustion has become the dominant industrial approach to reduce NOx emissions. Homogeneous mixing of lean fuel and air mixtures prevents the presence of undesirable localized regions of near-stoichiometric fuel/air mixtures, thereby allowing a reduction in thermal NOx. A new concept, a multi-point micro injection premixer, is presented in this dissertation. The multi-point micro injection premixer is a porous plate that provides a simple but extremely effective method to mix air and fuel. An array of fuel jets is injected in a direction perpendicular to the plane of the premixer plate into an oncoming counterflow stream of air. …