Resumo em Inglês:
Abstract An algorithm was developed to obtain the air chemical equilibrium composition. The air was considered to be composed of 79% N2 and 21% O2, and the models are 5 chemical species, N2, O2, NO, N, O, and 7 chemical species, N2, O2, NO, N, O, NO+, e-, respectively. The air chemical equilibrium composition is obtained through the equilibrium constants method and it was used the Absolute Newton method for convergence. The algorithm can be coupled as a subroutine into a Computational Fluid Dynamics code, given the flow field over an atmosphere reentry vehicle where, due to high velocities, dissociative chemical reactions and air ionization can occur. This work presents results of air chemical equilibrium composition for pressures of 1, 5, 10, 50 and 100 atm in a temperature range from 300 to 30000K.Resumo em Inglês:
Abstract This paper presents a research in the development of the 14-X hypersonic airspace vehicle at Institute for Advanced Studies (IEAv) from Department of Science and Aerospace Technology (DCTA) of the Brazilian Air Force (FAB). The 14-X project objective is to develop a higher efficient satellite launch alternative, using a Supersonic Combustion Ramjet (SCRAMJET) engine and waverider aerodynamics. For this development, the waverider technology is under investigation in Prof. Henry T. Nagamatsu Aerothermodynamics and Hypersonics Laboratory (LHTN), in IEAv/DCTA. The investigation has been conducted through ground test campaigns in Hypersonic Shock Tunnel T3. The 14-X Waverider Vehicle characteristic was verified in shock tunnel T3 where surface static pressures and pitot pressure for Mach number 10 were measured and, using Schlieren photographs Diagnostic Method, it was possible to identify a leading-edge attached shock wave in 14-X lower surface.Resumo em Inglês:
Abstract The work reported in the present paper was performed to honor the centennial of the flight by Alberto Santos Dumont with his 14-Bis aircraft. The paper describes results for a computational fluid dynamics (CFD) analysis of the 14-Bis aircraft aerodynamics and flight stability. The 14-Bis aircraft geometry was generated from historical sources and observations. CFD computations were performed using well-established commercial codes for calculation of the historical flight conditions. Simulations considered a Reynolds-averaged Navier-Stokes formulation, in which turbulence closure was achieved by using Menter's model. The flight conditions investigated were primarily concerned with historical observations regarding flight speeds and the need for a more powerful engine, as well as flight stability characteristics of the 14-Bis airplane, which are unknown up to the present day. The results led to qualitative agreement with historical reports, although quite interesting conclusions could be drawn with regard to the actual aerodynamic flight speeds and the aircraft stability parameters.Resumo em Inglês:
Abstract In the aircraft industry a great practical relevance is given to the extensive use of vibration dampers between fuselage and interior panels. The proper representation of these isolators in computer models is of vital importance for the accurate evaluation of the vibration transmission paths for interior noise prediction. In general, simplified models are not able to predict the component performance at mid and high frequencies, since they do not take into account the natural frequencies of the damper. Experimental tests are carried out to evaluate the dynamic stiffness and the identification of the material properties for a damper available in the market. Different approaches for its modeling are analyzed via FEA, resulting in distinct dynamic responses as function of frequency. The dynamic behavior, when the damper natural modes are considered jointly with the high modal density of the plate that represents the fuselage, required the averaging of results in the high frequency range. At this aim, the statistical energy analysis is then used to turn the comparison between models easier by considering the averaged energy parameters. From simulations, it is possible to conclude how the damper natural modes influence the dynamic response of aircraft interior panels for high frequencies.Resumo em Inglês:
Abstract The main objective of this work was to present the specification of an experimental firing test stand for liquid rocket engines (LRE) and develop a program for control and acquisition of data. It provides conditions to test rocket engines with thrust from 50 to 100 kgf. A methodology for laboratory work implementation using information technology, which will allow the automatic and remote functioning of the test stand, permits users to input the necessary data to conduct tests safely, achieve accurate measurements and obtain reliable results. The control of propellant mass flow rates by pressure regulators and other system valves, as well as the test stand data acquisition, are carried out automatically through LabVIEW commercial software. The test stand program is a readable, scalable and maintainable code. The test stand design and its development represent the state of art of experimental apparatus in LRE testing.Resumo em Português:
Resumo O presente estudo apresenta os resultados da investigação de um método de resfriamento amplamente utilizado em câmaras de combustão, denominado filme de resfriamento, que é aplicado a um motor-foguete à propulsão líquida. Esta utiliza como propelentes oxigênio líquido e querosene. Partindo de um motor cujo filme de resfriamento é formado por meio da introdução de combustível pelos injetores posicionados na periferia do sistema de injeção, analisou-se experimentalmente o filme formado pelo líquido que escoa pela parede interna da câmara de combustão. O parâmetro utilizado para validação e refinamento dos dados teóricos foi o comprimento do filme de resfriamento, pois esse parâmetro é de suma importância para que se obtenha uma proteção térmica eficiente internamente à câmara de combustão. Os ensaios a frio confirmaram um comprimento suficiente do filme de resfriamento para a câmara de combustão do motor estudado.Resumo em Inglês:
Abstract This study presents the results of the investigation of a cooling method widely used in the combustion chambers, which is called cooling film, and it is applied to a liquid rocket engine that uses as propellants liquid oxygen and kerosene. Starting from an engine cooling, whose film is formed through the fuel spray guns positioned on the periphery of the injection system, the film was experimentally examined, it is formed by liquid that seeped through the inner wall of the combustion chamber. The parameter used for validation and refinement of the theoretical penetration of the film was cooling, as this parameter is of paramount importance to obtain an efficient thermal protection inside the combustion chamber. Cold tests confirmed a penetrating cold enough cooling of the film for the length of the combustion chamber of the studied engine.Resumo em Inglês:
Abstract Despite the large use of differential scanning calorimetry (DSC) technique in advanced polymer materials characterization, the new methodology called DSC in high heating rates was developed. The heating rate during conventional DSC experiments varying from 10 to 20ºC.min-1, sample mass from 10 to 15mg and standard aluminum sample pan weighting, approximately, 27mg. In order to contribute to a better comprehension of DSC behavior in different heating rates, this work correlates as high heating rate influences to the thermal events in DSC experiments. Samples of metallic standard (In, Pb, Sn and Zn) with masses varying from 0.570mg to 20.9mg were analyzed in multiples sample heating rate from 4 to 324ºC. min-1. In order to make properly all those experiments, a precise and careful temperature and enthalpy calibrations were performed and deeply discussed. Thus, this work shows a DSC methodology able to generate good and reliable results on experiments under any researcher choice heating rates to characterize the advanced materials used, for example, for aerospace industry. Also it helps the DSC users to find in their available instruments, already installed, a better and more accurate DSC test results, improving in just one shot the analysis sensitivity and resolution. Polypropylene melting and enthalpy thermal events are also studied using both the conventional DSC method and high heating rate method.Resumo em Português:
Resumo A análise estatística do perfil de vento obtido junto à torre anemométrica do Centro de Lançamento de Alcântara foi realizada com base nos dados de vento (direção e velocidade), coletados no período de 1995 a 1999, obtidos em seis níveis diferentes: 6,0; 10,0; 16,3; 28,5; 43,0 e 70,0 m. Nesta análise, foram considerados os meses característicos das estações chuvosa (março) e seca (setembro), na região do Centro de Lançamento de Alcântara. O total de dados analisados para o período chuvoso (março) foi de 76.882 perfis do vento (intervalo de tempo de dez minutos) e para o período seco (setembro), foi de 109.809. Foram obtidos os valores médios da velocidade (ou intensidade) do vento, desvio padrão, mediana, moda e predominância da direção do vento. Obteve-se a como direção predominante NE com 33 e 40% de frequência de ocorrência para os períodos chuvoso e seco, respectivamente. Os valores médios da velocidade do vento apresentam dependência com a altura, sendo observado que os níveis mais elevados da torre anemométrica apresentam as maiores intensidades no período seco (8,2 ms-1). Os valores da velocidade média dos ventos observada foram de 6,4 ms-1 para o período seco e de 4,1 ms-1 para o chuvoso. Na análise das distribuições de dados, foram realizados ajustes para as distribuições estatísticas normal e Weibull. Os resultados mostram que a velocidade do vento está ajustada para um nível de significância de 95% (α=0,05) à distribuição estatística normal e Weibull. A distribuição de Weibull, para o período completo, apresentou ajuste para valores entre 3,0 e 9,0 ms -1 e a distribuição normal apresentou um bom ajuste para valores entre 4,0 e 9,0 ms-1.Resumo em Inglês:
Abstract Statistical analysis of the wind profile made at an anemometric tower installed at the Alcântara Launching Center was based on wind data (direction and wind speed) collected between 1995 up to 1999, which was carried out at six different levels: 6.0, 10.0, 16.3, 28.5, 43.0, and 70.0 m. This analysis was made for typical rainy months (March) and dry (September) season, in the Alcântara Launching Center area. The analyzed data total during the wet season (March) was 76,882 wind profiles (time interval of ten minutes) and during the dry season (September) was of 109,809 profiles. It was computed the mean wind speed (or intensity) of the wind, standard deviation, median, mode, and the prevailing wind direction. The predominant direction was from NE with 33 and 40% for wet and dry seasons, respectively. The average values of wind speed showed a dependency with height and it was observed that the highest levels of the anemometric tower have the strongest wind speed in the dry period (8.2 ms-1). The values of average wind speeds observed were 6.4 ms-1 for the dry season and 4.1 ms-1 during the wet one. The normal and Weibull statistical distributions were adjusted to the observed data set. Results show that the wind speed is adjusted to a 95% level (α=0.05) for the normal and Weibull statistical distributions. The Weibull distribution for the entire period presented and adjust to values between 3.0 and 9.0 ms-1, and the normal one showed a good fit for values between 4.0 and 9.0 ms-1.Resumo em Inglês:
ABSTRACT The paper aimed to identify and analyze the explanatory variables for airlines productivity during 2000 2005, by testing the Pearson correlation between the single factor productivity capital, energy and labor of a sample of 45 selected international airlines (4 Brazilian carriers among them) and their productivity explanatory variables like medium stage length, aircraft load factor, hours flown and cruise speed for selected routes besides aircraft seat configuration and airlines number of employees. The research demonstrated, that a set of variables can explain differences in productivity for passenger airlines, such as: investment in personnel training processes, automation, airplane seat density, occupation of aircraft, average flight stage length, density and extension of routes, among others.Resumo em Português:
Resumo Atualmente, as empresas têm interesse por adotar novas estratégias metodológicas, colocando em prática a cognição administrativa como ferramenta de crescente interesse para captar a natureza dos seus problemas. O presente trabalho teve como objetivo aplicar o mapa cognitivo como apoio à decisão a partir dos depoimentos extraídos do trabalho abordado por Silva (2008), aplicado a um problema de decisão em grupo da Força Aérea Brasileira (FAB) sobre quais ações adotar como prioritárias, inseridas no contexto entre comprar ou desenvolver tecnologias para o Setor Aeroespacial de Defesa do Brasil. O artigo tem como principal contribuição, a estruturação do problema do setor de Defesa Brasileiro, indicando os critérios mais importantes que devem ser considerados para avaliação das possíveis ações.Resumo em Inglês:
Abstract Currently, companies are interested in adopting new methodological strategies, using the administrative cognition as a tool of growing interest for grasping the nature of their problems. The present work aims to apply the cognitive map as decision support based on the statements taken from the work discussed by Silva (2008), applying to the Brazilian Air Force (FAB) group decision problem, about what actions to take as a priority, set in the context of either buying or developing technologies for the aerospace defense of Brazil. The contribution of this paper is a Brazilian defense industry problem structuring defining the relevant criteria that should be considered for the evaluation of possible actions to be taken by the Defense Sector in Brazil.