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First Aerial South Atlantic Night Crossing
No full textThe history of the transatlantic flights began in 1919 when Albert C. Read’s team flew an NC-4 flight between Newfoundland and Lisbon, Portugal with a stopover at Azores Islands, for fuel and repairs. The flight was made following a chain of 70 US warships in order to guide it along its route and provide assistance if needed. Two weeks later, John Alcock and Sir Arthur Whitten Brown made the first nonstop transatlantic flight from Newfoundland to County Galway, Ireland, covering more than 3000 km in just 16 hours of flight. Gago Coutinho and Sacadura Cabral crossed the South Atlantic Ocean by air in 1922, using only internal means of navigation: a modified sextant and a course corrector. For the first time in the aviation history a transatlantic flight was accomplished using exclusively astronomical and estimated navigation processes. Both devices proved its effectiveness. In 2 March 1927 and by following all the knowledge obtained by the First Cross of the South Atlantic, Sarmento de Beires, Jorge Castilho, Duvalle Portugal and Manuel Gouveia started a new mission that became known as the First Aerial South Atlantic Night Cross. During the night of 16 to 17 March 1927 a Portuguese crew flew 2595 km over the Atlantic Ocean from Guinea, Africa to Fernando de Noronha Island, Brazil. The flight was made only by astronomical processes navigation resources that proved again to be absolutely feasible and trustworthy, regardless day or night lighting conditions.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
Numerical Study of a Gas Turbine Engine Ground Vortex
No full textA computational method was used to predict and understand ground vortices forming between the ground and a 1/1th scale model intake of a engine. Calculations have been performed for the case of an irrotational crossflow mode of formation. Two different kinds of vortices appear around the intake: an inlet vortex and a trailing vortex. The computational method was found to describe all the main features of the flow for full scale geometry.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
Origins of Scientific Aircraft Navigation
No full textTwo Portuguese navigators crossed the South Atlantic in the beginning of the 20th century. They developed and used for the first time scientific methods of astronomic navigation when flying out of sight of land. A new model of sextant that could be used to measure the altitude of a star without the need of the sea horizon was developed. Another instrument called "path corrector" was introduced to calculate graphically the drift of an airplane and the direction of flight, taking into account the intensity and the direction of the winds. For the very first time in the history of the aviation the crossing of the South Atlantic had been achieved, and using an instrument that enabled an airplane's position to be precisely determined by astronomic navigation when flying out of sight of land.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
Numerical Study of Impinging Droplets Through a Crossflow
No full textThe present paper reports a numerical study of a spray impinging on a surface through a crossflow. This work is aimed to study the fundamental aspects of the spray impingement phenomena in a three-dimensional configuration, which is relevant to practical engines. The work describes a computational study of the flow produced by a spray stream injected through a crossflow. Different impinging models were tested, including a variant of the Grover and Assanis model developed in the present study, and the results are compared with measurements and predictions of other authors. The predicted results show in general reasonable agreement with the experimental data. The performance of droplet impinging models depends strongly on the conditions of pre-impingement.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
A Machine Learning Approach to Forecasting Turbofan Engine Health Using Real Flight Data
No full textThe modern gas turbine engine widely used for aircraft propulsion is a complex integrated system that undergoes deterioration during operation due to the degradation of its gas path components. Turbofan engine-related costs can account for as much as a third of the total aircraft maintenance costs, which have driven the industry to adopt on-condition monitoring. In this work an integrated condition monitoring platform is proposed and developed for performance analysis and prediction. Different machine learning approaches are compared with the application of predicting engine behavior aiming at finding the optimal time for engine removal. The selected models were OLS, ARIMA, NeuralProphet, and Cond-LSTM. Long operating and maintenance history of two mature CF6 turbofan engines were used for the analysis, which allowed for the identification of the impact of different factors on engine performance. These factors were also considered when training the ML models, which resulted in models capable of performing prediction under specified operation and flight conditions. The ML models provided forecasting of the EGT parameter at the take-off phase allowing for predicting gradual performance deterioration under specified operation type. Cond-LSTM is shown to be a reliable tool for forecasting engine EGT with a MAE under 5℃. In addition, forecasting engine performance parameters has shown to be useful for identifying the optimal time for performing important maintenance action, such as engine gas path cleaning. This work has shown that engine removal forecast can be more precise by using sophisticated trend monitoring and advanced ML methods.Fundação para a Ciência e Tecnologiainfo:eu-repo/semantics/publishedVersio
Aerial Journey from Portugal to Timor, Macau, India, and Return (1934)
No full textIn the 1920s and 1930s, a group of Portuguese Aviation Pioneers added the name of Portugal to the History of Aviation, essentially by performing Aerial Journeys to Portuguese Colonies. East Timor was an outlier until 1934. Thus, Humberto Amaral da Cruz conceived and designed an Aerial Journey from Portugal to East Timor, Macau, India, and return, with the primary purpose to highlight the country's relevance and consolidation as a colonial power as a demonstration of sovereignty over its most distant domains. With the help of a national public subscription, a government subsidy, and the support of some private entities, he purchases a De Havilland DH. 85 aircraft. Between October 25 and December 21, the pilot, and his mechanic, António Lobato, accomplish their Journey of 42,670 km in 268 hours and 25 minutes. The pilots' reception was apotheotic, with enormous national pride, followed by the feeling of dignity and expansion of the Portuguese Nation. The Journey had a global impact through the massive propaganda effort from distant countries in the Far East and a vast national influence through the rapprochement and consolidation of the Portuguese colonial empire in the most remote places in the World. Humberto da Cruz demonstrated his skills as a pilot, his skill as an officer, and the strength of his upstanding character. In particular, he praised aviation for developing a new era on earth, arguing that Portugal would have to adopt this form of communication between its overseas territories, Brazil, and the rest of the World.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
Experimental Study of the Collision Zone of a Boundary Layer with a Wall Jet
No full textLaser-Doppler measurements are presented for a highly curved flow resulting from the collision of plane turbulent wall jet with a boundary layer. This configuration can be found in the case of impinging jets of a V/STOL aircraft operating in ground vicinity. The experiments were carried out for boundary layer to wall jet velocity ratio of 0.5. The results include mean and turbulent velocity characteristics of the flow field as well as the characterization of the vorticity. The results revealed the existence of very small recirculation zones located upstream the separation point that co-exist and interact with the very well known VSTOL ground vortex. Copyright © 2009 by the American Institute of Aeronautics and Astronautics, Inc.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
Evaluation of Numerical Variable Density Approach to Cryogenic Jets
No full textThe present work is devoted to study cryogenic nitrogen jets in high subcritical conditions. Fuel injection is one of the great challenges in engineering of diesel engines, gas turbines and rocket engines, combining in the last one also the injection of oxidizer. It is widely known that the increase of operation pressures and temperatures increases engine efficiency and reduces fuel specific consumption. Thus, it is a general trend in modern engines the operation in increasingly higher pressures. However at higher chamber pressures the injected fluids may experience ambient conditions exceeding the critical values. Several authors stated that at these conditions the injected fluids suffers a change of its properties, and the traditional two-phase flow models cannot correctly predict the jet behavior at these conditions, thus new computational models are needed for these specific conditions. Barata et al. [18] performed a numerical investigation aimed to evaluate the applicability of an incompressible but variable density model in liquid jets under sub-to-supercritical conditions. The results achieved agree well with the experimental data but they only considered intermediate density ratios from 0.05 to 0.14. The objective of the present work was to extend the investigation of Ref. 18 to lower density ratios from 0.025 to 0.045 which correspond to cases with subcritical chamber pressures. The obtained results agree well with the experimental and numerical data of Chehroudi et al. presented in Ref. 18. It was also found in this work that the computational model does not offers valid results for density ratios lower than 0.025.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
An Experimental Study of Terrain-Induced Airflow at the LPPI Airport
No full textThe present paper reports a study of the airflow around Pico Island in the Azores and the problems it represents to the operation of aircraft at the island airport. A statistical study of the wind data collected at Pico and Faial Island was carried out to find discrepancies that can be attributed to the flow around Pico Mountain. A wind tunnel visualization of the flow around the Island was conducted, in order to identify some of the characteristics of the flow under different wind directions at the airport site. With this data, some assumptions of the best runway to use and where the most problematic phenomena should be encountered in the approach areas were made.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
Experimental Study of Spray Dispersion and Wall Interaction
No full textThe present paper reports experimental results of a monosized droplet spray impinging on a surface through a crossflow that can be used to assist the development of computational models. Different impinging models are presented and the experimental results are used to provide a first insight into their adequacy to the description of the physical phenomena. The transition criteria between spray impingement regimes presently available revealed important difficulties to predict the corresponding threshold. Presently available numerical models to predict this type of flows require a careful evaluation of their applicability to the particular case.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio