87 research outputs found
The beginnings of geography teaching and research in the University of Glasgow: the impact of J.W. Gregory
J.W. Gregory arrived in Glasgow from Melbourne in 1904 to take up the post of foundation Professor of Geology in the University of Glasgow. Soon after his arrival in Glasgow he began to push for the setting up of teaching in Geography in Glasgow, which came to pass in 1909 with the appointment of a Lecturer in Geography. This lecturer was based in the Department of Geology in the University's East Quad. Gregory's active promotion of Geography in the University was matched by his extensive writing in the area, in textbooks, journal articles and popular books. His prodigious output across a wide range of subject areas is variably accepted today, with much of his geomorphological work being judged as misguided to varying degrees. His 'social science' publications - in the areas of race, migration, colonisation and economic development of Africa and Australia - espouse a viewpoint that is unacceptable in the twenty-first century. Nonetheless, that viewpoint sits squarely within the social and economic traditions of Gregory's era, and he was clearly a key 'Establishment' figure in natural and social sciences research in the first half of the twentieth century. The establishment of Geography in the University of Glasgow remains enduring testimony of J.W. Gregory's energy, dedication and foresight
Pressure-Gradient Tailoring Effects On The Turbulent Flame-Vortex Dynamics Of Bluff-Body Premixed Flames
This paper explores the effects of pressure-gradient tailoring on the turbulent flame and vorticity generation mechanisms of premixed flames. A turbulent premixed flame stabilized by a bluff-body in a high-speed combustor is used for the investigation. The combustor pressure gradient is altered using a variable-geometry test section. The turbulent flame-flow field is measured and characterized using simultaneous high-speed particle imaging velocimetry (PIV) and CH* chemiluminescence. A Lagrangian tracking technique is applied to analyze the details of the flame-vortex interactions from the experimental data. Lagrangian fluid elements are tracked as they evolve across the flame. The vorticity mechanisms are decomposed along the Lagrangian trajectories to determine their relative balance under various pressure gradient conditions. It is demonstrated that the induced pressure-gradient affects the relative magnitudes of combustion-generated dilatation and baroclinic torque, as well as the vortex stretching. An increase in the magnitudes of the vorticity mechanisms is shown with the largest gain in baroclinicity for the augmented pressure gradient relative to the attenuated
Velocity-Induced Flame Blowout Of Lean Premixed Bluff-Body Stabilized Flames
An improved understanding of lean turbulent combustion phenomena is critical for the development of the next generation of aerospace propulsion technology. Systems operating at lean conditions are uniquely susceptible to flame stabilization dynamics which induce frequent and continuous local extinction throughout the combustion region. These blowout events originate from the local fluid dynamics, which induce regions of heightened hydrodynamic strain throughout the flow-field. When in excess of the flame’s tolerance, extinction occurs. Much recent experimental work has demonstrated that repeated local blowout and reignition events of this nature are inevitably indicative of global extinction. Global extinction is a critical obstacle which must be overcome in order to improve lean turbulent combustion technology. This research is focused on understanding the physical mechanisms which drive flame extinction using a recently developed and currently improved physics-based model. The model has been used in previous work to understand the flame extinction mechanisms which dominate turbulent combustion systems operating at the lean limit. In the current work, modifications are made to the same Lagrangian vortex model, which is used to analyze the mode of flame extinction driven by increasing inflow velocity. This is a fundamentally different extinction mechanism, induced primarily by increased strain rate rather than decreased flame strain rate tolerance. Improved understanding of this blowout mechanism will increase overall knowledge of flame stabilization dynamics and extinction in turbulent propulsion systems
Lagrangian Mechanisms Of Flame Extinction For Lean Turbulent Premixed Flames
Flame extinction is a critical impediment invariably limiting the performance of modern turbulent combustion technology. Combustion systems operating at lean conditions are highly susceptible to dynamic flame stability induced by local flame extinction. This stimulates flame blow-out and inevitably termination of the combustion process. The present study focuses on understanding the driving mechanisms which lead to flame extinction. A Lagrangian flame-vortex model is developed and used to study the flame extinction mechanisms. The model dynamically simulates the turbulent reacting flow exploiting a Lagrangian vortex element scheme and detailed strained kinetics. This systematic modeling strategy effectively encapsulates the dynamics of premixed turbulent flames in terms of stability and extinction. Two extinction modes of flame blow-out are analyzed using the model, the first of which is induced by decreasing equivalence ratio primarily resulting in diminishing strain rate limit of the flame. The alternate mode is focused on inflow-velocity induced extinction which is caused principally by increased hydrodynamic strain in the flow-flame field. The mechanics of both modes are examined utilizing the model\u27s unique Lagrangian tracking capability for extinction-inducing fluid element clusters. This technique enables isolation and detailed analyses of flame and fluid properties leading to blow-out, demonstrating the crucial driving mechanisms of flame extinction
Miller's most important geological discovery’: Archibald Geikie (1835–1924) as pupil and memorialist of Hugh Miller (1802–56)
Hugh Miller, stonemason turned writer, newspaper editor and geologist, became the young Archibald Geikie’s friend and geological mentor, encouraged his first research and presentation to a learned society, and recommended him to the Geological Survey, thus laying the foundations for a career that reached the top of British science. Geikie was deeply distressed when Miller died by his own hand. He helped deal with Miller’s posthumous publications. He modelled his early writings on those of Miller and wrote attractive and muchquoted pen-portraits of Miller, which are valuable to this day, although also reflecting Geikie’s perspective in biography and historiography, now seen as flawed
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