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- Numerical simulation of an array of droplets through a crossflowPublication . Barata, Jorge M M; Cometti, A.; Mendes, António; Silva, AndréThis paper describes the application of a three-dimensional computational method based on the solution of the Reynolds-averaged Navier-Stokes equations and a SSF (stochastic separated flow) model to the problem of an array of droplets through a crossflow. The calculation method is first evaluated against measurements for two-phase axisymmetric jets, and then extended to the three-dimensional case. The influence of the droplet sizes on the dispersion phenomena is analyzed. The exchange of momentum and turbulence energy was shown to play a decisive role in the change of the gaseous flow velocities. The analysis of the source terms due to the droplets revealed a strong influence of the boundary layer near the injection point in the dispersion process.
- Origins of Scientific Aircraft NavigationPublication . Barata, Jorge M M; Mendes, António; Morgado, Cândido M. P.; Neves, Fernando M. S. P.; Silva, AndréTwo 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.
- The Advent of Scientific Aircraft NavigationPublication . Barata, Jorge M M; Mendes, António; Morgado, Cândido M. P.; Neves, Fernando M. S. P.; Silva, AndréTwo Portuguese aerial navigators, Gago Coutinho and Sacadura Cabral, crossed for the first time, from Europe to the South Atlantic in 1922; they developed and used for the first time scientific methods of astronomic navigation when flying out of sight of land: a path corrector and a precision sextant. Both navigation devices were tested during short flights from Lisbon to Madeira Island (1921) and the encouraging results obtained, allow the navigators to apply them with quite success into an intercontinental flight. The “path corrector” was invented by Sacadura Cabral and Gago Coutinho with the intent to calculate graphically the angle between the longitudinal axis of an airplane and the direction of flight, taking into account the intensity and the direction of the winds. The regular sextant used by the navy could not be applied to aviation due to the difficulty of the definition of the sky-line at a normal flight altitude. Gago Coutinho developed a new model of sextant that could be used to measure the altitude of a star without the need of the sea horizon; this new device was called “precision sextant” and was improved with an artificial horizon line defined with the help of a water bubble. This device was later improved with an internal illumination system to allow its use during night flights and was used along the First Aerial South Atlantic Night Crossing, in 1927, performed by Portuguese airmen Sarmento Beires, Jorge Castilho, Duvalle Portugal and Manuel Gouveia. An advanced version of this instrument started to be manufactured in Germany by C. Plath under the name of “System Admiral Gago Coutinho”.