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Feed-water pumps. --- Outgassing (Low pressure environments)

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When doing in the off-gas purification business you will pretty soon register that you do not act in an isolated box. You have to make yourself familiar with the interplay of your emission problem and the environment, and you have to apply a broad view of the subject. We can hardly make a forecast on your first steps in this business, except that we want you to succeed. Therefore, we want to offer engineers and graduate students the basic tools for discussing air pollution problems and for deducing strategies for process and equipment design in off-gas purification, covering the whole span from the basics to dedusting, absorption, adsorption and redox processes. The didactic concept of the work is to attract students with a ‘learning by doing’ strategy. We discuss the problems, the solver strategies and the solvers. The problem solver proposals address a multitude of pollution control technologies. The work is a compact off-gas purification guide for practitioners and students by presenting basics as well as numerous applications with many examples and problems with solutions.

Outgassing (Low pressure environments) --- . --- Absorption. --- Adsorption. --- Air Pollution. --- Air Retension. --- Exhaust Gas Cleaning. --- Waste Air-Purification.

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With the customer’s increasing requirements on engine performance, the optimisation of every engine component is critical to maximize the performance. Therefore, the secondary effects have to be taken into account, to understand where the sources of losses come from and how reduce them. Among the many secondary effects that exist in compressors, leakage flows between stationary and rotating parts are one of the main sources of losses in turbomachinery. The standard method to take into account leakage flows relies on chimera grids of rectangular cavities at the bottom of which a mass flow and a flow direction are imposed. The evolution of the design methods gives rise to boosters geometries with ascending and descending flow path for which the method was not calibrated. Thus, a new advanced modelling of higher fidelity is needed to evaluate leakage flows and to analyse their behaviour.
The complete modelling of seal cavities has highlighted that the leakage flow rate was twice overestimated by the standard modelling. Moreover, the advanced modelling increases the compressor performance thanks to its higher fidelity. Near the stall conditions, the higher-fidelity results of the advanced modelling show that the flow behaviour at the stator foot is better than predicted by the standard modelling. However, this result does not allow to conclude if the stator is weaker on the foot or on the head. However, simulations based on the advanced modelling are costly compared to the standard modelling. Therefore, an analytical model based on the Stodola formula has been developed in order to approximate the leakage-flow rate and the windage heating. The calibration of the formula for two engines has shown that the discharge coefficient CD only depends on the geometric shape of the fin head.
Finally, a trade-off between the computation cost and the fidelity of the simulations is developed through a simplified modelling of cavities. This modelling was built for further optimisation of the corner-radius shape of the upstream cavity opening. The geometry of the upstream cavity seal is reproduced since it has a critical effect on the compressor performance. This simplified modelling gives faithful results compared to the advanced modelling on the compressor performance.

CFD modelling of leakage flows in low-pressure compressors --- Ingénierie, informatique & technologie > Ingénierie aérospatiale

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The transition of boundary layer from laminar to turbulent is more probable to happen across various components of a turbomachine. If narrowed down to a case of low-pressure turbine cascade, the transition of flow in boundary layer is due to separation induction. Due to this, blade losses are observed and it depends on various physical characteristics such as size and the length of the separation bubble. The physical characteristics can vary based on the variation of flow Reynolds number, expansion ration of the flow and the inlet flow turbulence intensity. Such characteristics can be studied using computational techniques, CFD analysis. Various computational techniques can be used for this scope of study, ranging from Reynolds Averaged Navier Stokes to Direct Numerical Simulation modelling, and each technique have its own set of advantages and disadvantages. 

The objective of this thesis is to present and acknowledge on how these separation bubble physical characteristics vary due to the variation of flow expansion ratio and variation of exit isentropic Reynolds number for a SPLEEN blade cascade. Direct Numerical Simulation technique will be adapted for this thesis, due to its ability to accurately predict separation bubble location and size but compromising to relatively high computational power requirement.

Low pressure turbine --- Flow separation bubble --- Boundary layer --- Flow transition --- Turbulence --- Reynolds stress --- Direct Numerical Simulation --- Discontinous Galerkin method --- Ingénierie, informatique & technologie > Ingénierie aérospatiale

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Pursuing a scalable production methodology for materials and advancing it from the laboratory to industry is beneficial to novel daily-life applications. From this perspective, chemical vapor deposition (CVD) offers a compromise between efficiency, controllability, tunability and excellent run-to-run repeatability in the coverage of monolayers on substrates. Hence, CVD meets all of the requirements for industrialization in basically all areas, including polymer coatings, metals, water-filtration systems, solar cells and so on. The Special Issue “Advances in Chemical Vapor Deposition” is dedicated to providing an overview of the latest experimental findings and identifying the growth parameters and characteristics of perovskites, TiO2, Al2O3, VO2 and V2O5 with desired qualities for potentially useful devices.

Technology: general issues --- APCVD --- VO2 --- processing parameters --- 2D --- chemical vapor deposition --- atomic layer deposition --- aluminum oxide --- aluminum tri-sec-butoxide --- thin film --- carbon nanotubes --- residual gas adsorption --- residual gas desorption --- field emission --- atmospheric pressure CVD --- low pressure CVD --- hybrid CVD --- aerosol assisted CVD --- pulsed CVD --- perovskite photovoltaic nanomaterials --- stabilization --- structural design --- performance optimization --- solar cells --- anatase single crystals --- process-induced nanostructures --- competitive growth --- pp-MOCVD --- vanadium pentoxide --- electrochromic --- spray pyrolysis --- ammonium metavanadate --- CVD --- electrochromism --- perovskite photovoltaic materials --- TiO2 --- Al2O3 --- V2O5 --- computational fluid dynamics