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The History of Aviation Education and Training

Publication . Barata, Jorge M M; Neves, Fernando M. S. P.

Aviation education and training began early in the 20th century just after the first successful powered flight of the Wright brothers. In the present paper, the types of aviation education and training around the world are reviewed. Its developments were distinct in many different countries, and in some cases evolved from the military needs while in others from the dedication of a few enthusiasts. In the 21st century aeronautical and aerospace engineering is taught at the most advanced engineering schools in the world providing skills and competences that integrate advanced disciplines.

2017-04-30Journal article

Open access

Aerodynamic Breakup of a Single Droplet due to a Crossflowed Airstream

Publication . Carrolo, Gabriel Alexandre da Costa; Ribeiro, Daniela; Barata, Jorge M M; Silva, A. R. R.

The main breakup regimes are visualized and studied with the help of a high-speed camera and a continuous jet of air, provided by a wind tunnel, is used to transition the droplet into the various stages of secondary atomization. The use of Jet Fuel and Biofuel mixtures is the focal point of this study. All the known regimes are encountered and each transitional We is calculated. The variation of We due to Oh is described, in addition to the comparison between We number thresholds and correlations existent in the literature for each regime transition. The influence of these numbers on the dimensionless characterization of time and later the maximum cross stream diameter is shown. Finally, a correlation for the temporal evolution of the drops’ cross stream diameter for all regimes, assuming its deformation is not a linear function of time, is proposed.

2019-01-06Conference object

Restricted access

Gyrostat Dynamics on a Circular Orbit: General Case of Equilibria Bifurcation and Analytical Expressions

Publication . Santos, Luís; Melício, Rui; Silva, A. R. R.

This paper is on the study of the Dynamics of a Gyrostat Satellite on a Circular Orbit, and the achievement of the analytical expressions which describes the bifurcation of equilibria. The attitude control of modern spacecraft's is essential to fulfil its missions. Every time that is necessary to point a camera or a scientific instrument the space platform must be perfectly balanced and stabilized. When a space platform loses its ability to be balanced and stabilized, which might be due to several factors, loses also its ability to carry out its mission. One approach to achieve such conditions is using Gyrostat configuration.

2018-06-20Conference object

Open access

Variable Density Approach for Modeling of Transcritical and Supercritical Jets

Publication . Antunes, Eduardo Luís Santos Farias; Silva, A. R. R.; Barata, Jorge M M

In order to study the high pressure and high temperature operating condition of a variety of internal combustion engines such as modern diesel engines, gas turbines and liquid fuel rocket engines, a cryogenic nitrogen jet injected into supercritical chamber conditions was simulated numerically. The favre averaged navier-stokes equations were employed together with a “k-ε” Turbulence Model and using instead of an ideal gas equation of state, the Amagat’s law in an approach originally conceived for gaseous turbulent jets with variable density. The present study describes the assessment of the capabilities of the approach by comparison against experimental data as well as numerical simulation performed by other researcher. The obtained results show an acceptable agreement with experiments for the axial density distribution, failing slightly in the prediction of the jet potential core. Good agreement is observed for radial density distribution as well as for the jet spreading rate.

2017Journal article

Open access

Modeling of Evaporating Sprays Impinging onto Solid Surfaces

Publication . Rodrigues, Christian; Barata, Jorge M M; Silva, A. R. R.

The present paper presents a numerical study on evaporating droplets impinging onto a solid surface through a crossflow. The characteristics of the initial spray are established by employing an empirical procedure that relies on a comprehensive set of free spray measurements. Distinct wall and crossflow temperatures are analyzed systematically to evaluate the influence of droplet evaporation on the final outcome of the simulation and, particularly, on the distribution of the thin liquid film that forms over the surface due to the deposition of incident droplets. The present computational model already has been proven to deliver accurate prediction results of the spray-wall interactions under different conditions. In this work, the conditions are extrapolated to a heated environment, which more adequately reproduces what is found in in-cylinder situations. The computational model is adapted to meet the new requirements and to perform within the range of conditions for which it is now being formulated. The analysis shows that higher temperatures lead to a decrease in the size of impinging droplets, an increase in the number of depositing droplets, a decrease in the fraction of mass of droplets contributing to the liquid film, and a more uniform distribution of the liquid layer over the surface.

2015-09-21Journal article

Restricted access