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- Technical and economic viability of the implementation of approach systems (radio aids) in regional airfields (Viseu airfield case study)Publication . Oliveira, Pedro Manuel Pimenta da Silva ; Silva, Jorge Miguel dos Reis; Soares, Paulo Alexandre Ramos de FigueiredoDespite all the efforts made by various institutions towards aeronautical safety, accidents and incidents are likely to happen at any time and under any circumstance. Around half of these accidents, at a commercial level, tend to occur during the approach and landing phases. Approach systems were developed with the main objective to improve the safety index in these flight phases, reducing the inherent risks of its complexity. This equipment can be categorised as precision providing course guidance and glidepath and non-precision providing course guidance only. When we talk about air transportation, it’s hard not to associate the theme to the big airports in the world. Despite of them representing a crucial part of all the aeronautical industry, regional airports and airfields can’t be ignored, because they also reach unmatchable levels of importance for the people and the regions they represent. The case study utilised was Viseu airfield, and to confirm its importance for the region, the biggest local companies were inquired. After 19 answers, it was possible to confirm the relevance the airfield has or could have, being the preferential choice compared to the international airports of Oporto and Lisbon. The main objective of this work was to demonstrate to what extent the implementation of one of those approach systems in the airfield is viable, and which one would be the better option for this case, from a technical and economic view. The systems analysed for this study were ILS and GBAS, both precision equipment. After a technical and economic analysis, revealing the technical characteristics of the airfield, as well as its revenue from the charged fees, allied with an 80% funded project with a six-year investment recovery forecast, it was concluded that GBAS would be the most suitable option. GLS approach charts were then elaborated, based on already existing GNSS charts in the airfield.
- Water-Emulsified Diesel Fuel in a CI Engine Tested for Aeronautical ApplicationsPublication . Oliveira, Pedro Manuel Pimenta da Silva ; Brójo, Francisco Miguel Ribeiro Proença; Serôdio, Rogério Pedro FernandesWater-in-diesel emulsions as an alternative fuel are emerging as a viable option to fight global fossil fuel consumption and emissions restrictions without the need for engine modifications. In an emulsion, two immiscible liquids are mixed with the help of surfactants, where droplets of one liquid are dispersed in a continuous flow. This thesis aims to compare water-emulsified diesel fuel with European commercially available diesel (EN590) when it comes to engine performance and emissions. The tests were performed in a single-cylinder, direct injection diesel engine (Hatz 1B40) using an eddy current dynamometer, an exhaust gas analyser, and an opacimeter. With the objective of testing the engine and the alternative fuels for operating conditions often found in aerial vehicles equipped with diesel engines (same operating principles), the tests were performed for idle settings (simulating the taxiing movement of an aircraft), 100% engine load (simulating the take-off and climbing manoeuvres), 50% engine load (representing the descent, approach, and landing phases), and 75% engine load (representing the cruise component of an aircraft's flight profile) at different engine speeds. Mixtures of EN590 diesel fuel, deionised water, and surfactants were performed in laboratory by mechanical homogenization to obtain the ideal concentrations of the different reagents to be later replicated on a bigger scale using a low-energy mixing method. The emulsions were developed to be optimised at the engine’s operating temperature and heated above the diesel fuel operating temperature to reach similar viscosities during the test procedures. The results suggest that adding water as a dispersed phase in the fuel allows to obtain overall better thermal efficiency and lower emissions of nitrogen oxides and smoke in some conditions when compared to traditional diesel. On the other hand, carbon monoxide, hydrocarbons, and carbon dioxide emissions have increased, possibly due to differences in the injection delay between the fuels. By focusing on performance over stability through the adoption of a hydrophilic emulsion formulation in line with the difficulty of further optimisation in general aviation gasoline engines and the widespread availability of diesel fuel, it can be concluded that water-in-diesel emulsions can be a viable alternative towards the goal of improving fuel consumption rates, lowering emissions, and reducing costs when optimised for specific operating conditions of diesel-powered aerial vehicles.