The work presented in thesis is part of the DANIELA project which aims to replace the current air data system on civil aircrafts with a flush mounted Air Data System (ADS) built around a 3 axis Doppler LIDAR function as the primary data channel. This thesis is focused on the comparison of different window materials and their optical clarity by means of theoretical and experimental analysis. Four different window materials including BK7, Sapphire, Germanium and ZnS are placed in a wind tunnel. The samples are each exposed to flows of air and water for specific periods of time during which temperature, pressure and air speed are recorded. Subsequently, each sample is carefully observed under the microscope. This is followed by the measurement of the amount of back scatter via detecting the change in the voltage once it is placed in the optical station. The optical tests reveal the amount of dust adhered to the samples which results in increased voltage. Review of these samples under the microscope matches the results obtained from the optical test. The two sets of data obtained from the two tests determined that some samples collected more dust in comparison to others. It was established that under identical test conditions i.e. flow, temperature and moisture, BK7 and Sapphire collect considerably less dust compared to ZnS. Moreover it was impossible to test Germanium sample optically, under a microscope as it is a dark opaque glass.

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Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xii, 99 p. : ill. Vita. Includes abstract. Includes bibliographical references (p. 79-82).

Computational investigations were carried out to evaluate the effectiveness and usability of hybrid RANS/LES techniques for predicting the unsteady separated flow over wings with ice accretion. RANS and hybrid RANS/LES computations were performed using the viscous flow solver CHEM with the SST turbulence model. Two configurations were considered during the study: an extruded wing with a glaze-ice shape and a swept wing with a simulated glaze-ice accretion. Hybrid RANS/LES results, in general, predict a less active shear layer ``roll up' than seen in the experimental data. Qualitative improvements are seen in the hybrid RANS/LES results over corresponding RANS results. The extruded wing results show that the CHEM hybrid RANS/LES results are similar to the AVUS DES results. The use of preconditioning and a different turbulent model in CHEM showed a slight improvement in results.

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In this thesis, development process of de-icing and anti-icing solutions and their flow instability characteristics are presented. In the beginning, the chemical additives in the solutions and their effects on the most critical physical properties of the solutions were investigated. Firstly, chemical additives were added to glycol and water mixtures at different weight ratios one by one in order to see their individual effects. Then, the changes in physical properties were observed when the chemicals were added to water-glycol mixture together. After that, study was focused on effect of polymer which makes the solution pseudoplastic. Further investigations on viscosity behavior of the solution at different pH values, glycol and water mixtures and surfactant weight ratios, which is used for surface tension reduction, were performed. For the investigation of flow instability characteristics of the solutions&rsquo / flows, linear stability analysis for two-layer flows is a basic tool. Firstly, the effects of main parameters on the stability of two-layer flows were observed with a parametric study. Then, the commercially available and developed de-icing and anti-icing solutions were compared according to the characteristics of unstable waves. According to the results, unstable waves on developed de-icing fluids are observed at a lower critical wind speed compared to the commercially available de-icing solution. Moreover, it flows off the wing faster due to a higher value of critical wave speed. Developed anti-icing solution has similar wave characteristics compared to commercially available anti-icing solution, except critical wave speed, which is significantly lower. However, this problem can be overcome by decreasing the viscosity of developed anti-icing solution at very low shear rates.

This thesis is done within the master program in energy systems engineering at Uppsala University and in cooperation with OX2. The aim was to compare the operation and performance of three different de- and anti-icing systems for wind turbines during the winter 2014/2015. The systems evaluated were de-icing with heating resistances, de-icing with warm air and anti-icing with heating resistances. Inconsistency in the operation of the wind turbines and the systems as well as lack of information made it hard to compare the efficiencies of the systems. The systems showed tendencies to improve the production. Especially examples during single ice events where the systems increased the power output were found, but the examples also showed possible improvements regarding the size of the systems and the duration of the de-or anti-icing cycles. Based on the approximated gain in production, during the studied time period, none of the systems could be determined to be profitable. The gain in production does however not have to be especially large for the systems to become profitable, and the results could be very different in a year with more ice, higher electricity prices or a more consistent operation of the systems. Important characteristics of the systems were found to be the duration of a cycle, the energy required for the operation of the system and the trigger-point for activation of the system. Additional benefits like for instance decreased loads, risk for standstill and ice throws could also be provided by the system.

The rise of the Environmentalism in every sector of the Industry has lead the aircraft and engine manufacturing companies to develop new generations of more environmentally friendly engines. The companies, encouraged to this purpose, are in a constant research for new manufacturing and production techniques, in order to improve their products, from the environmental point of view, by gaining efficiency in the manufacturing techniques and reduce the fuel consumption and emissions in-flight. Having in mind this scenario, the sponsor of this Project is interested in understanding how changing the materials of the blades, titanium alloys currently, for other lighter materials, such as composites, is going to have an effect in the overall gas turbine efficiency. In the particular case of this Project, it will be studied the influence of the Stiffness and coating Thickness of those non-metallic materials suitable to be employed as coatings on gas turbine fan blades, from the icing point of view. The work procedure will be based on a study of Linear Elastic Fracture Mechanics of bi-material junctions and will extrapolate the general problem to the ice-coatings case, by getting experimental data from tests carried out in an Icing Tunnel. It will be observed that the coating Stiffness has an influence on the Adhesion Level of ice to less stiff materials, if compared with the Adhesion Level of ice to metals. Besides, it will be described how a 0.5 millimetres thin polymeric coating placed over a metallic substrate is enough to reduce the Adhesion Level of ice, hiding any effect that the underneath materials might have on the Adhesion Level.

The rise of the Environmentalism in every sector of the Industry has lead the aircraft and engine manufacturing companies to develop new generations of more environmentally friendly engines. The companies, encouraged to this purpose, are in a constant research for new manufacturing and production techniques, in order to improve their products, from the environmental point of view, by gaining efficiency in the manufacturing techniques and reduce the fuel consumption and emissions in-flight. Having in mind this scenario, the sponsor of this Project is interested in understanding how changing the materials of the blades, titanium alloys currently, for other lighter materials, such as composites, is going to have an effect in the overall gas turbine efficiency. In the particular case of this Project, it will be studied the influence of the Stiffness and coating Thickness of those non-metallic materials suitable to be employed as coatings on gas turbine fan blades, from the icing point of view. The work procedure will be based on a study of Linear Elastic Fracture Mechanics of bi-material junctions and will extrapolate the general problem to the ice-coatings case, by getting experimental data from tests carried out in an Icing Tunnel. It will be observed that the coating Stiffness has an influence on the Adhesion Level of ice to less stiff materials, if compared with the Adhesion Level of ice to metals. Besides, it will be described how a 0.5 millimetres thin polymeric coating placed over a metallic substrate is enough to reduce the Adhesion Level of ice, hiding any effect that the underneath materials might have on the Adhesion Level.