Spelling suggestions: "subject:"combustion,"" "subject:"ombustion,""
901 |
Numerical solution of axial-mode instability problems in solid propellant rocket motorsKooker, Douglas Edward 12 1900 (has links)
No description available.
|
902 |
Large-Eddy simulation of combustion dynamics in swirling flowsStone, Christopher 05 1900 (has links)
No description available.
|
903 |
Measurement of solid propellant burning rates during rapid depressurizationClary, Albert Thurston 12 1900 (has links)
No description available.
|
904 |
Effects of turbulence on radiation induced ignition of solid fuelsCoffin, Derrick Brian 05 1900 (has links)
No description available.
|
905 |
Temperature measurements of a coal particle laden turbulent flame by the Sodium D-line reversal techniqueBaltar, James Yerger 12 1900 (has links)
No description available.
|
906 |
Concentration and composition effects in combustion chemical vapor deposited yttria-zirconiaGodfrey, Shelli Heather 05 1900 (has links)
No description available.
|
907 |
Physico-chemical characterisation and molecular modelling study of lubricant dispersantsTomlinson, Angela January 1998 (has links)
No description available.
|
908 |
Etude cinétique de l'oxydation de constituants de biocarburants et composés modèles : formation de polluantsTogbe, Casimir 27 October 2010 (has links) (PDF)
Pour faire face à l'épuisement des combustibles fossiles conventionnels et aux préoccupationsenvironnementales dont le réchauffement climatique, de nouveaux carburants issus de la biomasse sontutilisés purs ou comme co-carburants ; d'autres sont envisagés pour le futur. Une meilleure connaissance dela cinétique chimique d'oxydation des composés présents dans ces carburants alternatifs est indispensable.L'objectif de cette thèse est donc d'obtenir de nouvelles bases de données expérimentales et d'élaborer desmécanismes cinétiques d'oxydation des constituants de ces nouveaux carburants. Des molécules de deuxfamilles chimiques, à savoir les esters méthyliques et les alcools, ont été sélectionnées. L'oxydation de cescomposés purs ou en mélanges a été étudiée en réacteur auto-agité à haute pression (10 atm) et dans un largedomaine de températures (530-1250 K) et de richesses (ca. 0,3-4). Les profils de concentration des réactifs,produits et principaux intermédiaires stables ont été obtenus par spectroscopie d'absorption infrarouge àtransformée de Fourier (IRTF) et chromatographie en phase gazeuse (GC-FID-TCD-MS). Les résultatsobtenus ont permis de proposer des modèles cinétiques permettant de simuler avec un bon accord une grandepartie des résultats expérimentaux obtenus au cours de cette thèse. Les analyses cinétiques ont permis dedéterminer les principales voies de consommation de ces composés (principalement des mécanismes deperoxydation-isomérisation à basse température et de métathèse puis décomposition par β-scission à hautetempérature). Elles ont permis d'identifier les réactions les plus influentes (réactions de métathèse etréactions impliquant particulièrement les composés de la base C0-C2).
|
909 |
Numerical study of helicopter combustor and exhaust emissions using large eddy simulationDumrongsak, Janthanee 02 1900 (has links)
Although Large Eddy Simulation (LES) has demonstrated its potential for
modelling the reaction in simple academic combustors, it is more
computationally expensive than Reynolds Averaged Navier-Stokes (RANS)
which has been used widely for industrial cases. The aim of this research is to
employ LES at minimal grid resolution and computational resource
requirements to capture the main characteristics of the reacting flows in a
helicopter combustor and exhaust plume with the focus on NOx emissions.
Test cases have been carried out to validate the current LES code for non-
reacting jet, non-premixed combustion and unstructured grids. Despite the
moderate grid refinement and simple chemistry models employed, the findings
from these test cases have demonstrated good capabilities of the current LES
to capture the mixing, flame and flow characteristics. In a farther test case, a
key gas-phase chemical reaction selected for the helicopter exhaust plume
modelling has also been tested.
The validated LES code is then employed in the numerical study of the reaction
in the helicopter combustor. The LES predictions in terms of the temperature
and EINOx agree generally well with the combustor design, analytical solutions,
previous LES and test measurements. Subsequently, the potential application
of LES for the calibration of simpler models has been assessed for the generic
and helicopter combustors. The results obtained from LES are compared with
those from a one-dimensional combustor performance and emissions code,
HEPHAESTUS, developed within the Cranfield University Power and
Propulsion Department. The discrepancies between the results are found to be
primarily due to specific simplification and assumptions established in the
HEPHAESTUS model which can be addressed.
Finally, LES has been employed to model the transformation of NO to NO2 in
the helicopter exhaust plume. The findings from this research have
demonstrated that, even without the implementation of highly dense mesh or
advanced reaction model, LES is able to provide results with an acceptable
level of fidelity at relatively low computational costs. These advantages make it
a powerful predictive tool for future design and emissions optimisation
investigations, and calibration of other simpler modelling approaches.
|
910 |
Stress analysis of overlapped crankshaftsSime, Anthony P. January 1998 (has links)
The crankshaft is a complex component, and as such, the influence of its geometric parameters on stresses seen under service loads is not well understood. The objectives of this work are to investigate the effects of a wide range of geometric parameters on stresses in overlapped crankshafts, to find correlation between results and to formulate simple methods of predicting peak stress levels: It is intended to achieve this by use of the Finite Element (FE) and Boundary Element (BE) methods. Individual crankthrows are loaded under the important load cases of bending and torsion. Stress concentration factors are determined by normalising peak stresses with respect to the nominal stress occurring in the most appropriate section in the neck between the fillets. Analyses are carried out in 2D and 3D, making use of symmetry as far as possible. Many of the governing dimensions of the crankthrow are included in the analyses; crankpin and journal diameters, crankpin and journal overlap, and web thickness. Variations in SCF are plotted over a wide range for each of these parameters. Additionally, features such as fillet size and shape, bore-holes, dimples, cut-back webs and oil holes are investigated. It is found that the effects on stress of individual parameter changes can be superimposed to accurately predict the effect of combining various parameter changes in one model. The crankpin and journal fillet radii and the length of the minimum section between the fillets are shown to be the critical parameters in determining the peak stress levels in the crankshaft. SCFs obtained from the range of analyses performed show good agreement with the classical theory of SCFs in notched bars. Bore-holes and dimples are found to offer significant benefits in terms of peak stress reduction, in addition to their common usage of reducing the out of balance crankpin mass. The FE and BE methods give accurate results for stress analysis of crankshafts and offer several advantages over traditional experimental techniques; they are ideally suited to parametric analyses, can be carried out relatively quickly, results are repeatable because boundary conditions can be exactly defined, and the cost of analysis is significantly reduced.
|
Page generated in 0.0681 seconds