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ALICE (A Large Ion Collider Experiment) will be the detector dedicated to the study of nucleus-nucleus collisions at the LHC. The muon spectrometer of ALICE is dedicated to the measurement of heavy flavors in the muon channel. A brief description of the ALICE muon spectrometer and its physics program is reported. The expected performances for open and hidden charm and bottom measurements are presented. In this paper we show how a one dimensional fluid model can be used to interpret data obtained from an inclined Mach-probe or a Gundestrup probe. We use an analytical approximation of the solution of the differential equations describing the relation between the plasma flow and the measured ion saturation currents at the probe’s surface. The parameters of the approximate analytical solution are determined by comparison with the exact numerical solution of the equations. In this way we are able to measure the parallel as well as the perpendicular Mach numbers over the whole parameter range with a minimum accuracy of 90%. In this paper we show how a two dimensional fluid model can be used to interpret data obtained from an inclined Mach-probe or a Gundestrup probe. We use an analytical approximation of the solution of the differential equations describing the relation between the plasma flow and the measured ion saturation currents at the probe's surface. The parameters of this analytical solution are determined by comparison with the exact numerical solution of the equations. In this way we are able to measure the parallel as well as the perpendicular Mach numbers over the whole parameter range with a minimum accuracy of 90%.

Control of pollutants and emissions has become a major factor in the design of modern combustion systems. The “Liquid Hydrogen Fueled Aircraft - System Analysis” project funded in 2000 by the European Commission can be seen as such an initiative. Within the framework of this project, the Aachen University of Applied Sciences developed experimentally the “Micromix” hydrogen combustion principle and implemented it successfully in the Honeywell APU GTCP 36-300 gas turbine engine. Lowering the reaction temperature, eliminating hot spots from the reaction zone and keeping the time available for the formation of NOx to a minimum are the prime drivers towards NOx reduction. The “Micromix” hydrogen combustion principle meets those requirements by minimizing the flame temperature working at small equivalence ratios, improving the mixing by means of Jets In Cross-Flow and reducing the residence time in adopting a combustor geometry that provides a very large number of very small diffusion flames. In terms of pollutant emissions, compared to the unconverted APU, an essential reduction in emitted NOx was observed, stressing the potential of this innovative burning principle.The objective of this thesis is to investigate the “Micromix” hydrogen combustion principle with the ultimate goal of an improved prediction during the design process. Due to the complex interrelation of chemical kinetics and flow dynamics, the “Micromixing” was analyzed first. Stereoscopic Particle Image Velocimetry was used to provide insight into the mixing process. A “simplified” set-up, that allowed to investigate the flow characteristics in great detail while retaining the same local characteristics of its “real” counterparts, was considered. The driving vortical structures were identified. To further investigate the physics involved and to extend the experimental results, numerical computations were carried out on the same “simplified” set-up as on a literature test case. In general, a number of physical issues were clarified. In particular, the interaction between the different vortical structures was looked into, and a kinematically consistent vortex model is proposed. After demonstrating the development of the mixing, the “cold flow” study was extended to a single injector. The double backward-facing step injector geometry was addressed experimentally and numerically. At design geometry, the flow appeared to behave single backward-facing like, with respect to the first gradation. In terms of varying step configurations, the flow was seen to be dependent on the periodic perturbation arising from the graded series of backward-facing steps. During the second part of the investigation, the “hot flow” was analyzed. Considering combustor similar operating conditions, a test burner was experimented on an atmospheric test rig. NOx emissions were traced by exhaust gas analysis for different working conditions. Particular flame patterns, such as a regular attached flame as well as lifted flames were observed. In parallel with the experimental work, numerical computations on a pair of opposite injectors, permitted to classify the combustion regime and the main factors involved in the NOx formation. Accordingly, NOx emission enhancing design changes are proposed. Finally, the demanding computational effort, worthy of acceptance for academic purposes, is found not agreeable as future design tool and improvements to speed up the design process are projected., Doctorat en Sciences de l'ingénieur, info:eu-repo/semantics/nonPublished

Het ambitieuze ITER-tokamakproject is momenteel het toonaangevende onderwerp in het wereldwijde onderzoek naar magnetische fusie. In deze experimentele tokamak zullen brandstofmengsels van deuterium en tritium sterk verhit worden tot de vereiste fusietemperatuur van ongeveer 150 miljoen graden. Bij deze hoge temperaturen verkrijgt men een plasma. De prestaties van fusieplasmas zijn sterk afhankelijk van de interactie tussen het plasma en de reactorwandcomponenten. Een noodzakelijke methode om de gevolgen van de plasma-wand-interactie te controleren bestaat uit het optimaliseren van de staat van de reactorwandoppervlakken, namelijk wandconditionering, met behulp van specifieke plasma-ontladingen met lage temperaturen. De kwalificatie van routine wandconditioneringsontladingen toepasbaar in de tokamak ITER heeft een hoge prioriteit binnen het magnetische fusieonderzoek. Dit proefschrift kadert in het internationale R&D-programma rond de wandconditioneringstechniek “Ion Cyclotron Wall Conditioning” (ICWC) dat als doel heeft de ICWC-techniek te consolideren en de toepasbaarheid ervan op ITER te kwalificeren. Het omvat zowel experimenteel werk op vier Europese tokamaks, nl. TORE SUPRA, TEXTOR, ASDEX Upgrade en JET, waarbij de efficientie van ICWC voor specifieke conditioneringsdoelstellingen werd nagegaan en geoptimaliseerd, als het modeleren van de ICWC-conditioneringsplasmas en de plasma-wand-interactie tijdens ICWC. De toepasbaarheid van de techniek voor specifieke conditioneringsdoelstellingen op ITER werd aangetoond, en verdere onderzoeksdoelstellingen werden geïdentificeerd.