University of Beira Interior
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Twenty-Five Years of Portuguese Aviation Events at Amadora
No full textFrom 1912 to 1938, the Amadora became the central location for several of Portugal's most significant aviation events. After a Kite-Flying Competition (1912), Flying Demonstrations (1913), and the 1st Air Festival in Portugal (1917), in 1919, the village became selected to host the Military Aviation Squadron GEAR - Grupo de Esquadrilhas de Aviação «República.» As WWI ended, Aviation shifted its vision to new dimensions of international civil transport. With their minds set on developing Portuguese Civil Aviation, the GEAR pilots started using military aircraft for civilian flight purposes. Thus, between 1920 and 1936, memorable and significant flights departed from Amadora to the most varied Portuguese territories worldwide; 1) Amadora – Madeira Flight Attempt (1920); 2) First Aerial Raid from Portugal to Macau (1924); 3) Amadora – Guinea (1925); 4) A Trailblazing Flight for Portuguese Overseas Commercial Air Route (1928); 5) Amadora – Portuguese India (1930); 6) Round trip Flight Amadora – Guinea – Angola (1930/31); 7) Aerial Journey from Portugal to East Timor, Macau, India, and Return (1934); and 8) Portuguese Empire Mission Amadora – Angola – Mozambique (1935/36). Furthermore, in 1934 and 1935, Amadora received the two firsts International Air Festivals in Portugal. Finally, after nearly Twenty-Five Years of Portuguese Aviation Events in Amadora, Military Aeronautics ended Amadora's connection to national aviation in 1938, thus dictating the end of the Portuguese Pioneer Flights. Organizational reasons, in addition to the smallness and deficiencies of the dirt runway track, determined the extinction of the Grupo de Aviação de Informação n.º 1 [as the GEAR was renamed], whose personnel and material would be later transferred to Tancos.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
History of Aeronautics Engineering Course at UBI
No full textIn 1991/92, the University of Beira Interior (UBI) established Portugal's first permanent and official civilian Aeronautics program, a 5-year Licenciatura Degree in Aeronautics Engineering. In addition, a Doctorate Degree in Aeronautics Engineering was established in 1993/94, and a Master's Degree in Aerospace Systems Engineering in 1999/2000. By 2007/08, a European intergovernmental reform (Bologna Process) was implemented to achieve the European Higher Education Area to allow students, graduates, and specialized staff working in higher education to benefit from mobility and equal access to high-quality higher education without obstacles. The essential bases are mutual recognition of degrees, transparency (readable and comparable degrees organized in a 3-Cycle structure), and European quality assurance cooperation, emphasizing competency development over knowledge transmission. The degree system was made official in Portugal by Decree-Law nº. 74/2006. According to the expressed perspective, the reformulation of Aeronautical Engineering Studies at UBI followed the adoption of formal structures, corresponding to 6 Semesters for Licenciatura (180 ECTS = 1st Cycle); 4 Semesters for Master's (120 ECTS = 2nd Cycle), and 6 Semesters for Doctorate (180 ECTS = 3rd Cycle). After its implementation, the requirements to accomplish the reformulation created significant national difficulties leading to successive adaptations exposed in six amendments to Decree-Law nº. 74/2006. A Master's and Doctorate Degree in Portugal legally requires the support of an R&D Unit with a minimum classification of Very Good or Excellent in an evaluation process carried out by foreign experts, with concepts and procedures recognized by the international scientific community. The Aeronautics and Astronautics Research Center (AEROG) is a member of the Associated Laboratory for Energy, Transport, and Aeronautics (LAETA). LAETA received an Excellent Overall Quality Grade from the International Evaluation Panel.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
Leading-Edge Parametric Study of the NACA0012-IK30 Airfoil
No full textIn many research areas, such as rotor dynamics and biomimetics, the dynamics of oscillating airfoils are of great interest. The findings of this study provide great insight into the importance of the leading edge regarding the propulsive characteristics of flapping airfoils. The main objective of the present work is to analyze the influence of the leading-edge pitching amplitude of the NACA0012-IK30 airfoil at a Reynolds number of 1.4x10^4, constant Strouhal number of 0.15 with three different (k,h) combinations and five leading-edge pitching amplitudes (A_alpha=0º,5º,10º,15º,20º). Using a RANS approach with the turbulence model k-omega SST coupled with the Intermittency Transition Model, results show that changing the leading-edge pitching amplitude has great impact on thrust enhancement, although presenting a small influence when it comes to lower nondimensional amplitudes. The required power coefficient is typically reduced while increasing the leading-edge pitching amplitude which, in some cases, provides an increase up to 211% in propulsive efficiency.Fundação para a Ciência e a Tecnologia; Brazilian’s National Council for Scientific and Technological Development; São Paulo State Research Foundation.The present work was performed under the scope of the Aeronautics and Astronautics Research Center (AEROG)
of the Laboratório Associado em Energia, Transportes e Aeronáutica (LAETA) activities and it was supported by
Fundação para a Ciência e Tecnologia (FCT) through the project number UIDB/50022/2020 and the grant sponsored
by Fundação para a Ciência e a Tecnologia 2020.04648.BD. F. Marques acknowledges the financial support of the
Brazilian’s National Council for Scientific and Technological Development (CNPq grant #306824/2019-1), and the São
Paulo State Research Foundation (FAPESP grant #2017/02926-9).info:eu-repo/semantics/publishedVersio
Computational Analysis of High-Pressure Nitrogen Jets from Transcritical to Supercritical Gas-Like Conditions
No full textA fluid is considered to be in a supercritical state if its pressure and temperature are above their critical point values, which can be regarded as identifiers of pure fluid. However, in the thrust chamber of liquid rocket engines, the propellant mixture is a reality, which albeit being injected at supercritical conditions, can lead to local transcritical behavior, meaning that the mixture temperature can have values below its critical point condition. As such, an accurate numerical solver aiming at characterizing the flow inside the combustion chamber of liquid rocket engines needs to replicate transcritical behavior. The present study is focused on the analysis of nitrogen jets under transcritical and supercritical conditions. While a greater approximation to the experiments is obtained for the tested supercritical conditions, insights are obtained into transcritical behavior and the transition between transcritical and supercritical jet behavior.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
Laser-Doppler Analysis of the Separation Zone of the Ground Vortex Flow
No full textLaser Doppler measurements are presented for a highly curved flow generated by the collision of plane wall turbulent jet with a low-velocity boundary layer. The experiments were performed for a wall jet-to-boundary layer velocity ratio of 2, and include mean and turbulent velocity characteristics along the two normal directions contained in planes parallel to the nozzle axis. The results, which have relevance to flows encountered by powered-lift aircraft operating in ground effect, quantify the structure of the complex ground vortex flow resulting from the collision of a wall jet with a boundary layer. The results revealed the existence of a very low-frequency instability. The source of this low frequency unsteadiness is probably associated with a small vortex located near the separation point. In the central zone of the upwash flow where the maximum values of the vertical velocity component occurs, additional distinct high frequency peaks were also identified.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
Pressure Based Comparison of Different Gas Turbine Ground Vortex Flows
No full textThe present paper has the previous work of Barata et al in mind and has the purpose of analyzing the behavior of ground vortex flows through several values of height of the engine axis above the ground, diameter of engine intake and inlet airflow velocity using pressure on the ground and in a 3D scale for that.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
Development of a New Dynamic Liquid Film Extension and Integration into a Spray Impingement Model
No full textThis paper is concerned with the improvement of macroscopic spray impingement simulations, for which a sub-model has been proposed for the formation of the liquid film over the impingement wall due to the deposition of particles. This computational extension deals with the interaction and spreading of the liquid between adjacent nodes due to the dynamic motion induced by the film inertia and crossflow velocity, as well as, the exchange of mass between incident drops, secondary droplets and liquid film. Moreover, an empirical correlation deduced from experimental data is used to define the relative liquid film thickness. Experimental data are used to validate the numerical model. Good agreement is obtained between numerical and experimental results for the test cases performed. The distribution of the relative liquid film thickness for two cases of crossflow velocities are also illustrated, as well as, its temporal evolution from start of injection. The dynamic behavior of the layer proved to be in concordance with the observations reported in experimental investigations available in the literature.info:eu-repo/semantics/publishedVersio
Flow Characteristics of Twin Impinging Jets
No full textThis work is devoted to the visualization and characterization of a twin jet flow when impinging vertically to a solid surface, which is of primary importance to the understanding of the phenomena relevant to V/STOL type of aircraft performance and stability when operating in ground vicinity, during short take-off and landing. The visualization of a distinctive fan-shaped flow that is formed in the collision zone (or fountain formation zone) is the major concern in this work. Variables analyzed in this work are the separation distance, height and diameter of the jets. It was found that the fountain flow involves complex flow structures, quite sensitive to small imbalances between the jets. It was also observed that significant changes in the flow pattern and properties in the fountain formation zone occur with according changes in the parameters studied.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
Numerical and Experimental Study of Two Impinging Jets in a Row through a Crossflow
No full textAn experimental and numerical study is carried out to investigate the flowfield created by twin impinging jets aligned with a low velocity crossflow. The mean velocity, velocity fluctuation and visualization in the impingement region were obtained for a Reynolds number based on the jet exit conditions of Rej=4.3x104, an impingement height of 20.1 diameter and for a velocity ratios between the jet exit and the crossflow VR=Vj/Uo of 22.5, 33.7 and 43.8 with interject spacing, S of 6D. The experimental results show a large penetration of the first (upstream) impinging jet, giving rise to a ground vortex due to the collision of the radial wall jet and the crossflow that wraps around the impinging point like a scarf. The second jet (located downstream) it is not so affected by the crossflow in terms of deflection, but it does not reach the ground due to the downstream wall jet that flows radially from the impinging point of the first jet along the ground. The results indicate a new flow pattern not yet reported so far, in which a VSTOL aircraft operating in ground vicinity with front wind or small forward movement may result in enhanced negative pressures in the underside of the aircraft causing a pitching moment and a suction down force towards the ground. To extend the experimental results, the flow was also numerically simulated using a Reynolds Averaged Navier-Stokes formulation with the "k-ε" turbulence model.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
Does liquid film temperature affects single drop impact dynamics?
No full textThe effect of liquid film dynamics in the hydrodynamics of an isolated drop impact is a complex phenomenon and not fully understood. Therefore, in this work, an experimental setup built to characterize the impact of an isolated droplet on heated and unheated liquid films consists of a heating element made of an aluminum block with resistances to produce several impact conditions. The parametric studies include the drop impact velocity and size for different fluids to evaluate their properties effect on the phenomena. The results were compared with existing thresholds in the literature to evaluate their validity and applicability range. This comparison allows us to assess if temperature causes the limits of the thresholds to change drastically or if its influence is negligible. Regarding IC engines, thresholds like splashing and bubble encapsulation are significant since they influence the atomization of the mixture and, consequently, the pollutant emissions.Fundação para a Ciência e a Tecnologia (FCT)info:eu-repo/semantics/publishedVersio