Disertación/Tesis

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2023
Disertaciones
1
  • MARCO ANTÔNIO VIEIRA DE REZENDE
  • Activities and Geopolitical Actions Aimed at Technical-Scientific Education in the Space Sector
  • Líder : GIULIANI PAULINELI GARBI
  • MIEMBROS DE LA BANCA :
  • DINO LINCOLN FIGUEIROA SANTOS
  • GIULIANI PAULINELI GARBI
  • JOSE HENRIQUE FERNANDEZ
  • MARCOS AURELIO FERREIRA DOS SANTOS
  • Data: 22-jun-2023


  • Resumen Espectáculo
  • The world has undergone economic, political and social changes in a more intense and accelerated way since the beginning of the globalization of communications, with the advent of artificial satellites. These changes directly reflected on the dynamism of education despite the class model still being quite prescriptive and dogmatic, not encouraging students to become protagonists in the learning process. Interest in Science and Technology, as well as space exploration, is often related to subcultures that adopt specific entertainment media rather than actual scientific research as a vocational incentive. With few young people pursuing careers in math and science, there is a shortage of qualified professionals working in aerospace S&T. However, there are strong indications that it is possible to reverse this situation through innovative educational initiatives, some of which are already being implemented around the world. Believing that betting on young people is creating alternatives for a different world, various entities, public or private, in different countries, turned to the search for motivational and low-cost projects. Ludic activities and the STEAM methodology (Science, Technology, Engineering, Arts and Mathematics) present an interesting tool to help reverse the current situation and bring these students closer to Exact and Earth Sciences courses, as well as space activities. This dissertation presents, at first, the analysis of interesting models used worldwide. The STEAM model, with an operational focus, addresses activities aimed at stimulating curiosity, based on a new learning approach, which value multidisciplinarity in the classroom, as well as use practices in workshops aimed at the focus of “hands-on” activity. ”. The MANAGEMENT models, as an essential tool after the 1988 Constitution, are presented as beacons for a more efficient administrative-financial management. In a second moment, we sought, in the available literature, successful vocational-educational initiatives that could add positively to improving the model chosen by the Brazilian initiative. Some historical spending data on S&T and formal-informal education was also shown, with the aim of comparing some priorities around the world and, mainly, in Brazil. As a result, actions were proposed to boost the Brazilian space vocational project, with short, medium and long-term activities that arouse students' interest in space science and related technologies, focused on astronomy and space exploration.

2
  • THAÍS MILLA SIMÃO ARAÚJO
  • Performance analysis of GMSK receivers for the Global Open Data Collector System (GOLDS)

  • Líder : FRANCISCO JOSÉ TARGINO VIDAL
  • MIEMBROS DE LA BANCA :
  • ANTONIO MACILIO PEREIRA DE LUCENA
  • FRANCISCO JOSÉ TARGINO VIDAL
  • GIULIANI PAULINELI GARBI
  • Data: 29-sep-2023


  • Resumen Espectáculo
  • The Global Open CoLlecting Data System (GOLDS) is a satellite environmental data collection system proposed as an evolution the Brazilian Environmental Data Collecting System (SBCDA). The SBCDA signal is modeled with Phase Shift Keying (PSK) modula- tion and without channel encoding. One of the main problems of the SBCDA is inter-user interference. As the available bandwidth for reception is small, it is recommended that the frequency band occupied by the signals from Data Collection Platforms (PCD) be compact. In this context, with the aim of improving the spectral efficiency of PCD signals, GOLDS proposes the use of Gaussian Minimum Shift Keying (GMSK) modulation. Hence, the objective of this work is to evaluate synchronization and demodulation techniques for GMSK signals used in the GOLDS system. Three signal models were evaluated, and syn- chronization and demodulation techniques were presented to compose the receiver, followed by simulations to verify the system’s performance. The results showed an improvement in signal detection since inter-signals interference was reduced with the implementation of GMSK modulation. The MSK-type linear demodulator for the pre-coded GMSK signal demonstrated satisfactory performance for the system. As for timing and phase synchro- nization, some methods available in the literature were evaluated. Joint phase and timing estimation for MSK signals showed better performance for the GOLDS system.

3
  • ALEXANDER ALBERTO CAMACHO SOLANO
  • scramjet vehicle conceptual design for ascendant flight from 21 km to 31 km into Earth's atmosphere

  • Líder : PAULO GILBERTO DE PAULA TORO
  • MIEMBROS DE LA BANCA :
  • DOUGLAS DO NASCIMENTO SILVA
  • GEORGE SANTOS MARINHO
  • HEIDI KORZENOWSKI
  • PAULO GILBERTO DE PAULA TORO
  • Data: 18-dic-2023


  • Resumen Espectáculo
  • This monograph presents a conceptual study, under development at the Universidade Federal do Rio Grande do Norte (UFRN), of a supersonic combustion demonstrator (scramjet technology), during atmospheric flight, in constant hypersonic velocity of 1950 m/s in the altitudes of 21 km, 26 km and 31 km. The analytical theories of the oblique shock wave, the heat addition in one-dimensional flow in the cross section with constant area and the area ratio were applied in the compression, combustion chamber and expansion, respectively, considering air as a perfect gas and without considering viscous effects. The compression section angles were determined by ensuring that the temperature (higher than the fuel ignition temperature) and the supersonic velocity of the atmospheric airflow provided the stoichiometric burning of atmospheric air and hydrogen fuel in the combustion chamber. Also, it was considered that the incident shock waves have the same intensity providing on-lip and on-corner shock conditions. The expansion section has been optimized considering the combustion products have the same pressure at the scramjet flight altitude. Finally, it was observed the combustion products, in the expansion section, were at a hypersonic velocity greater than the flight velocity of 1950 m/s, allowing the generation the not installed thrust.

2022
Disertaciones
1
  • WILLIAM HUMBERTO ÚSUGA GIRALDO
  • Mask technique for detecting space debris with ground telescope images acquired in static mode

  • Líder : JOSE DIAS DO NASCIMENTO JUNIOR
  • MIEMBROS DE LA BANCA :
  • JOSE DIAS DO NASCIMENTO JUNIOR
  • JEFFERSON SOARES DA COSTA
  • LEANDRO DE ALMEIDA
  • Data: 31-ene-2022


  • Resumen Espectáculo
  • Orbital debris of approximately 10 cm in size can be measured with ground-based telescopes. This debris threatens the functioning of satellites and has an impact on the economy and the global security of space activities. In the GEO orbit, where most of the economically active satellites are located, exists approximately 842 cataloged debris. On the other side, orbiting LEO exists approximately 13485 debris cataloged. In this context, the  ESA studies show that hundreds of millions of small objects over 1 mm are currently in the two orbits GEO and LEO above the Earth and have not yet been cataloged. In this study, we created a computational procedure to detect space debris in GEO orbit based on images obtained from ground-based telescopes on the static mode. In this mode,  the field sky stars appear as lines in the CCD images and the garbage in the form of dots.  CCD images of 2992 x 2092 pixels (high resolution) and with 5 degrees of field of view (FOV) and with 7 seconds of exposure used in this work were obtained with the PanEOS telescope (Panoramic Electro-Optical System), 750 mm aperture, and installed at the Picos dos Dias observatory of the National Astrophysics Laboratory (LNA). For this research, we adapted the Photoutils package written in Python to build a mask and separate stars from candidates for space debris. Our methodology consisted of first smoothing the images using a Gaussian Kernel filter, then each element was categorized into two categories, and finally, the stars were erased resulting only in space debris candidates. We tested combinations of flow to establish the detection limit and used the different points spread function (PSF) to determine the limit of the elongation of objects. Our methodology works with a single image at a time in a fast and efficient way.  This allows us to detect objects with different PSF and therefore requires low hardware capability. Our results in this validation phase identified 100% of the artificial training debris. In the real images of the PanEOS telescope, we detected a few real debris consistent with the  expected size. In the next steps, we must estimate the size of the object and characterize its orbit.

2
  • JULIANA JENIFFER FERNANDES DE SOUZA RÊGO
  • Ballistic armor design of the as-350 helicopter from numerical-experimental analyses.

  • Líder : DINO LINCOLN FIGUEIROA SANTOS
  • MIEMBROS DE LA BANCA :
  • DINO LINCOLN FIGUEIROA SANTOS
  • JOSE DANIEL DINIZ MELO
  • JOSÉ VIRGÍLIO GUEDES DE AVELLAR
  • VIVIANE MUNIZ FONSECA
  • Data: 14-feb-2022


  • Resumen Espectáculo
  • Helicopters used in public safety operations go through several risk situations involving ballistic projectiles, one of the safest solutions is armor, offering maximum protection combined with technology.

    The present work aims to project an armoring system for the AS-350 helicopter, using as material the polymer matrix composite reinforced with para-aramid fiber and glass fiber. Considering the airworthiness requirements and the restrictions determined by the manufacturer, an analytical method was used to study the effects of armor on the weight and balance of the aircraft. The project used the Aerospace Design Methodology in conducting the work.

    To verify the efficiency of the ballistic composite, the experimental tests were carried out in an open outdoor environment where the composite was exposed to the impact of projectiles with a caliber of 5.56x45 mm. The performance of the material was analyzed by the results obtained in the tests and, this provided the determination of the protection reliability of the ballistic system. 

    The armor design for the AS-350 proved to be safe to be installed on aircraft of this model, as a level III ballistic protection tool, without impairing its mobility.

3
  • ELDER SAMUEL TAVEIRA DA SILVA
  • PRELIMINARY DESIGN OF A NANOSATELLITE LAUNCH VEHICLE USING SCRAMJET TECHNOLOGY

  • Líder : DOUGLAS DO NASCIMENTO SILVA
  • MIEMBROS DE LA BANCA :
  • DOUGLAS DO NASCIMENTO SILVA
  • JOSE HENRIQUE FERNANDEZ
  • PAULO GILBERTO DE PAULA TORO
  • JOÃO FELIPE DE ARAÚJO MARTOS
  • Data: 17-feb-2022


  • Resumen Espectáculo
  • This Master's Dissertation presents a preliminary design of an aerospace vehicle, using hypersonic airbreathing propulsion based on supersonic combustion (scramjet technology), for atmospheric flight at 20 km altitude, at hypersonic speed, corresponding to Mach number 5.79. Scramjet is an aeronautical engine without moving parts, where the aerospace vehicle integrated with scramjet technology (propulsion system) must be coupled to a rocket engine. The current means of access to space is limited by the chemical propulsion system (solid and / or liquid fuel) carried onboard rockets. The technology of supersonic combustion (scramjet) is being studied as an airbreathing propulsion system, to be used in the dense layers of the Earth's atmosphere, to access space. A demonstrator is being designed to be coupled to the Sonda III rocket engine, to operate as a second stage, starting the operation at 20 km altitude. The theory of oblique shock waves, the theory of heat addition in one-dimensional flow (Rayleigh's theory) and the theory of expansion waves (by Prandtl-Meyer) coupled to the area ratio are applied in the design of the compression sections, of combustion and expansion, respectively, of the scramjet demonstrator with internal admission configuration. Steady state, one-dimensional flow and air under calorically perfect gas conditions will be considered. Thermodynamic properties (pressure, temperature, density, speed of sound) and flow velocity (Mach number) will be presented along the streamline from the leading edge to the trailing edge of the demonstrator, considering flow without and with boundary layer effects, for the conditions of no fuel burning (power-off) and fuel burning (power-on). Finally, the conceptual design and a brief approach to systems engineering in the development of a nanosatellite launch vehicle are presented.

4
  • MARCOS VINICIUS SABINO PEREIRA
  • Preliminary design of a scramjet to insert cubesat into orbit

  • Líder : SANDI ITAMAR SCHAFER DE SOUZA
  • MIEMBROS DE LA BANCA :
  • DOUGLAS DO NASCIMENTO SILVA
  • HEIDI KORZENOWSKI
  • PAULO GILBERTO DE PAULA TORO
  • SANDI ITAMAR SCHAFER DE SOUZA
  • Data: 19-feb-2022


  • Resumen Espectáculo
  • In order to access the space through the application of hypersonic airbreathing propulsion technology, this work proposes the development of a scramjet (supersonic combustion ramjet). The aerospace vehicle proposed in this work will have three stages, two stages of rocket engines with solid propulsion and a stage composed by a scramjet with four combustion chambers. The scramjet of this vehicle will operate in vertical flight in the Earth’s atmosphere, from 20 km to 60 km of altitude with hypersonic speed corresponding to approximately Mach number 5.8. Bearing in mind that the scramjet has no moving parts and needs a system that accelerates it, up to supersonic combustion conditions, it will be necessary to use the accelerator vehicle that is responsible for propelling the scramjet to the ideal operating conditions (Mach number, position, dynamic pressure). This aerospace vehicle will have the utility of accessing space and conducting drilling experiments, injecting CubeSat into orbit and training the specialized labor responsible for aerospace operations. For the preliminary development of this work, it is necessary to use the theories referring to the formation of shock waves and expansion waves, in addition to the theories related to the addition of heat and the formation of a boundary layer in flow with hypersonic velocity. Therefore, for this development the analytical theoretical methodology was applied and then with the results obtained it was possible to carry out, in the near future, the preliminary mechanical design that determines the necessary basic measures, in addition to the possible materials to be used in the vehicle. The preliminary results of this work indicate that the scramjet will be able to generate thrust and that when considering the existence of the boundary layer, a change in the geometry of the vehicle's inlet is necessary, so that it is possible to maintain the formation of shock-on-lip and shock-on -corner in the scramjet structure.

5
  • ARTHUR BANDEIRA LUZ DE LIMA
  • A study about the influence of the solar cycles in the atmospheric conditions over the Curitiba Flight Information Region

  • Líder : JOSE HENRIQUE FERNANDEZ
  • MIEMBROS DE LA BANCA :
  • DINO LINCOLN FIGUEIROA SANTOS
  • FILIPE EMANUEL VIEIRA TAVEIROS
  • JOSE HENRIQUE FERNANDEZ
  • Data: 21-feb-2022


  • Resumen Espectáculo
  • Atmospheric conditions are mostly driven by the Sun, which follows a cycle of activity whose duration is about 11 years. Since this cycle has been found out, researchers has brought up the hypothesis that it may have some influence at the lower atmosphere, taking as proxies the Carbon-14 and Berilium-10 concentration in tree rings and ice cores. Beside that, some manuscripts have shown that, during the Maunder Minimum, where the Sun were at minimum of activity, some regions over the globe experienced a tiny "Ice Age". Initially, it was believed that this influence was related to the Total Solar Irradiation variation during a cycle. Although, further studies have shown that such variations were a rather small to produce these variations on the lower atmosphere. So, they have created the hypothesis that these influence was related to the solar cycle on the Galactic Cosmic Rays (GCR) flux through the heliosphere. GCR work as a ionizing agent, favoring the aerosol synthesis, which acts as Condensation Nuclei, which favors clouds formation. So, the objective of the research was to find a correlation between the solar cycles and meteorological conditions in the region where the cities of Rio de Janeiro e São Paulo are located. In this region, a huge flux of aircraft is observed.

6
  • BENJAMIM MONTEIRO DA SILVA NETO
  • DEVELOPMENT A MOBILE PLATAFORM APP FOR THE RISK MANAGEMENT OF NANOSATELLITE PROJECTS

  • Líder : GIULIANI PAULINELI GARBI
  • MIEMBROS DE LA BANCA :
  • FRANCISCO JOSÉ TARGINO VIDAL
  • GIULIANI PAULINELI GARBI
  • MARCOS AURELIO FERREIRA DOS SANTOS
  • Data: 22-feb-2022


  • Resumen Espectáculo
  • Within Systems Engineering, risk management processes are mandatory requirements in satellite missions, being used on a large scale for large satellites. However, traditional approaches need adaptations to be applied, in a viable way, to missions with small satellites due to the costs and deadlines involved. This work aims to design, implement, and disseminate a risk management methodology adapted to small satellites. To this end, it is proposed to create an application to perform this management, using the necessary adaptations for application to this type of mission. The bibliographic research methodology was used to characterize small satellites, mostly the CubeSat platform, and the description of methods and risk management tools used worldwide, as well as their applications to small satellite projects. For the design of the application, the Java language will be used. The application’s functionalities were chosen to provide agility, ease, and integration with the risk management processes. The work is divided into five chapters. The first one consists of an introduction. The second presents a historical reinterpretation of small satellites, definitions of them, and their importance. The third chapter deals with systems engineering and risk management. The fourth chapter presents examples of risk management adapted for nanosatellites. And the fifth chapter presents the proposed solution to the problem raised.

7
  • RAFAEL ALVES FREIRE
  • Stellar Rotation Period Versus Energy Variation of Flares in TESS Stars of Spectral Types K and M

  • Líder : JOSE HENRIQUE FERNANDEZ
  • MIEMBROS DE LA BANCA :
  • JOSE HENRIQUE FERNANDEZ
  • DOUGLAS DO NASCIMENTO SILVA
  • JOSE RENAN DE MEDEIROS
  • ANTONIO CARLOS DA SILVA MIRANDA
  • Data: 24-feb-2022


  • Resumen Espectáculo
  • Under the development of new technologies, the Aerospace Engineering is increasingly
    improving its equipments in order to assist exploration that goes beyond our Heliopause.
    As an example of this we can cite the launch of the space artfact Transiting Exoplanet Survey Satellite
    (TESS) that has been contributing photometric data to Space Sciences, like Astrophysics,
    with the aim of study various physical phenomena. As an exemple, the magnetic activity
    of stars can be fundamental in forming the atmosphere of exoplanets and impact your
    habitability as well as, it can trigger life in the orbit of type K and M stars, which are
    considered to be cold and they are the most numerous in the main sequence phase in
    the Hertzsprung-Russell diagram. Based on these investigations and through statistical
    analysis of the behavior of stellar flares in relation to their classi cations, rotational periods
    and spectral subtype, this dissertation presents a study on the variation of energie
    of stellar flares as a function of their rotational period in a sample of 679 TESS stars of
    spectral type K and M. None of the stars in this sample showed a correlation between the
    energy of their surface stellar eruptions as a function of their rotational period. Finally
    we present four scenarios involving the stars and their stellar eruptions and theirs that
    can explain our results.

8
  • THIAGO FONSECA MESSIAS
  • Test of a UHF receiver to collect satellite sensor data

  • Líder : JOSÉ MARCELO LIMA DUARTE
  • MIEMBROS DE LA BANCA :
  • FRANCISCO DE ASSIS BRITO FILHO
  • FRANCISCO JOSÉ TARGINO VIDAL
  • JOSÉ MARCELO LIMA DUARTE
  • Data: 25-feb-2022


  • Resumen Espectáculo
  • This master’s thesis presents a test plan, the automation system for carrying out the
    experiments and the results obtained from the Environmental Data Collector (EDC), UHF
    receiver for collecting data from satellite sensors. The parameters tested were: bandwidth,
    linearity, spurious, noise figure and performance of the decoding the received signals.
    The EDC will act in the space segment of the Brazilian Environmental Data Collection
    System (SBCDA), a forwarding system for satellite message. For over twenty years, the
    SBCDA has provided data for various surveys. sas, however, the SBDCA needs an update
    to its space segment. The Institute National Space Research Institute is developing a
    constellation of nanosatellites from the CubeSat standard to replace the current SBCDA
    satellites. The EDC will be the payload of the new SBCDA nanosatellites. To validate
    the EDC, a test plan was prepared which aims to assess whether the prototype built is in
    accordance with the desired specifications. To carry out the tests, a bench equipped with a
    computer was built, equipped with testing software, a signal generator, a voltage source
    and a Arduino. A spectral analysis, from the digitized signal, was used for the tests. of the
    RF-Front-End and the Frame Error Rate calculation was used to validate the capacity of
    the EDC to decode incoming messages. The EDC prototype was approved with based on
    the results obtained, however, some corrections were suggested.

9
  • JOÃO BATISTA DOLVIM DANTAS
  • Antennas for the Long Distance Communication System for Unmanned Air Vehicle 

  • Líder : FRANCISCO JOSÉ TARGINO VIDAL
  • MIEMBROS DE LA BANCA :
  • FILIPE EMANUEL VIEIRA TAVEIROS
  • FRANCISCO JOSÉ TARGINO VIDAL
  • GIULIANI PAULINELI GARBI
  • JOSE PATROCINIO DA SILVA
  • Data: 29-ago-2022


  • Resumen Espectáculo
  • Brazilian Space Launch Centers employ conventional aircraft to monitor large maritime areas destined to the impact point of rockets or parts of them, and this has a high cost. The remotely piloted aircraft (RPAs) have shown to be a low cost solution for operations
    of this type, however, the short range of their conventional remote controls is a limiting factor for their employment in large distances.
    This paper proposes high-performance antennas for remotely piloted aircrafts (RPA) communication system, aiming control and image transmission from RPA operating at long distances. It was considered the case-study of the Brazilian Space Launch Centers,
    which plan to employ RPA in order to assist the surveillance of the restricted area for rocket impact. The proposed antennas were designed in order to maximize gain and lobe aperture for the ground station operation; whereas, for RPA operation, the antennas were tailored in order to provide optimal gain and omnidirectional transmission, even during RPA maneuvers, as well as to minimize weight, size and aerodynamic drag in the aircraft. It is minutely described the design and evaluation of the proposed antennas, by means of simulations and experimental verification. The radio link using the proposed antennas was evaluated in laboratory and verified able to perform data transmission at emulated distance of 110 km (59.4 NM)(68.35 M).

10
  • PAULO CÉSAR DE OLIVEIRA JÚNIOR
  • Conception, design and structural analysis of a supersonic combustion demonstrator

  • Líder : JOÃO CARLOS ARANTES COSTA JÚNIOR
  • MIEMBROS DE LA BANCA :
  • GEORGE SANTOS MARINHO
  • HEIDI KORZENOWSKI
  • JOÃO CARLOS ARANTES COSTA JÚNIOR
  • PAULO GILBERTO DE PAULA TORO
  • Data: 14-dic-2022


  • Resumen Espectáculo
  • ABSTRACT

    In the current scenario of the aerospace sector, there is a great limitation related to the payload that can be launched into orbit or beyond. Rocket engines, propulsive technology in operation, have a low specific impulse compared to systems with airbreathing propulsion (scramjet technology) that use atmospheric air as an oxidant. During hypersonic flight, aerospace vehicles with hypersonic airbreathing propulsion are subject to high aerodynamic and thermal loads. In this context, in the present work the main objective is to perform a structural analysis of a generic supersonic combustion demonstrator, under flight conditions at an altitude of 23 km and speed corresponding to Mach 5,8. To carry out the structural analysis, an aerodynamic and dimensional design of a generic scramjet was carried out, designed for coupling to the national rocket engines S30 and S31. Optimization criteria were applied to the compression section, aiming to achieve the required temperature and Mach number conditions at the entrance of the combustion chamber to spontaneously burn hydrogen. In the expansion section, the optimization criterion is based on checking the point at which the pressure condition is equivalent to that of free flow, defining the region where the coupling to the accelerator vehicle must be carried out. The aerodynamic load was defined from analytical and numerical aerodynamic analysis, considering air as a calorically perfect gas and neglecting viscous effects. The design and aerodynamic analysis evaluated the case without fuel burning (power-off) and with fuel burning (power-on), but in the structural analysis only power-on was considered. Numerical flow analysis and numerical structural analysis were respectively performed in the Fluent and Static Structural modules of the Ansys software. The aerodynamic analysis showed that flying at an altitude of 23 km with a speed of 1723 m/s, the scramjet with three compression ramps with deflection angles of 7,48°, 8,93° and 10,77° is capable of generating, at the entrance to the combustion chamber, speed corresponding to Mach number 1,709 and static temperature of 1071,255 K, demonstrating the possibility of burning hydrogen. At the trailing edge, the flow velocity is 1688,958 m/s without fuel burning and 1806,977 m/s with fuel burning, demonstrating that the scramjet is only capable of generating thrust with fuel ignition. For the numerical analysis of the flow, the unstructured mesh with triangular elements proved to be more suitable to capture the flow conditions after the oblique shock waves in the scramjet, considering atmospheric air as a calorically perfect gas and without viscous effects. In the aerodynamic analysis the numerical results showed good agreement with the analytical results. In the numerical structural analysis, the maximum von-Mises equivalent stress is 122,93 MPa and occurs at the leading edge of the fairing, close to contact with the side panel, due to the thickness of the wedge at the leading edge and the high pressures of the chamber of combustion. However, this value is lower than the yield stress of the materials used, so that strains and displacements in the structure occur in the elastic regime of the materials and are therefore recoverable.

     

     

     

     

11
  • WILLIAM HENRIQUE DE LIMA FIUZA
  • Conception, Design and Structural Analysis of an Academic Shock Tube

  • Líder : PAULO GILBERTO DE PAULA TORO
  • MIEMBROS DE LA BANCA :
  • DOUGLAS DO NASCIMENTO SILVA
  • GEORGE SANTOS MARINHO
  • PAULO CELSO GRECO JÚNIOR
  • PAULO GILBERTO DE PAULA TORO
  • Data: 22-dic-2022


  • Resumen Espectáculo
  • The shock tube is an equipment used in laboratory studies on supersonic flows, providing data on the flight conditions in which the aerospace vehicles will find themselves. The Federal University of Rio Grande do Norte (UFRN) has stainless steel tubes – donated by the Institute of Advanced Studies (IEAv) – intended for the construction of the Institution's first shock tube. The objective of the research carried out was to make the construction of the equipment technically feasible. The correct sizing of the components is a fundamental part of the project, being essential to prevent accidents and control measurement errors during the tests, since it is a device subjected to high pressures. Structural modeling through software allows reducing material waste and operational risks during the construction of prototypes. Boundary conditions and applied loads must be rigorously selected, to provide a good level of confidence to the research results and, thus, constitute a guide for the execution of the academic project in a technical way. For this, the following were carried out and are presented here: calculations of the flow conditions; modeling and structural analysis of the high pressure (driver) and low pressure (driven) sections of the academic shock tube, considering the dimensions of the stainless steel tubes available at UFRN; in addition to determining the efforts to which the tubes will be submitted when the equipment becomes operational. Analytical (Lamé Equations) and numerical (Ansys Mechanical) results of circumferential, radial and von Mises stresses were compared by means of their percentage variations. Autodesk Inventor was also used for simulations and comparisons with Ansys Mechanical results. Both the driver and the driven were analyzed considering their ends closed by means of flanges and thus treated as pressure vessels. Ansys Mechanical and Autodesk Inventor software were used in the analysis, with discretization of the models by mesh generation and application of the Finite Element Method. A pressure of 70 atm (7.09 MPa) was applied to the inner surface of the high pressure section during calculations and computer simulation, while other pressures generated in the flow were calculated and applied to the low pressure section. All pressures were also multiplied by four to assess the impact of this change in stresses. Based on the results obtained for von Mises stresses, circumferential stresses, and radial stresses, it was found that, considering the properties of stainless steel AISI 304 and steel SAE 4140, the available tubes will withstand the workloads within the operating range to which they will be subjected without implying any risk of damage, in view of the first stage of the UFRN academic shock tube construction project.

2021
Disertaciones
1
  • ISAMARA DE MENDONÇA SILVA
  • Investigating the teleconnection patterns associated with the rainy season and analyzing the homogeneity and the trend in extreme precipitation indices in the Northern of Northeast Brazil

  • Líder : DEUSDEDIT MONTEIRO MEDEIROS
  • MIEMBROS DE LA BANCA :
  • DAVID MENDES
  • DEUSDEDIT MONTEIRO MEDEIROS
  • MEIRY SAYURI SAKAMOTO
  • Data: 26-feb-2021


  • Resumen Espectáculo
  • A first study used the hidden Markov model in this dissertation to describe the daily rainfall occurrence and intensity at four meteorological stations in the Metropolitan Region of Fortaleza in the Northern Northeast Brazil (NNB) and the teleconnection patterns that influence precipitation regime during the rainy season (February, March, April, and May) from 1975 to 2013. A model with four hidden states was associated with climatic conditions: very rainy (1), rainy (2), less rainy (3), and dry (4), satisfactorily agreeing with the interannual variability of the rainy season in this region. State 2 was the only one that showed a statistical trend, indicating a probable decrease in the occurrence of precipitation in the rainy season. It was also shown that the meteorology associated with states 2 and 4 is strongly related to the El Niño-South Oscillation and the North Atlantic tripole and is intrinsically conditioned by the large-scale atmospheric patterns of the Northern Hemisphere. All of these mechanisms modulated the displacement of the Intertropical Convergence Zone (ITCZ) southward (state 2) or northward (state 4), affecting the occurrence of precipitation in the NNB. State 1 was distinguished by the influence of the Atlantic Meridional Mode and the ITCZ displacement further south, while state 3 was identified by the absence of teleconnection patterns. A second study investigated the homogeneity and trend of eleven extreme precipitation indices from a daily data set of 84 rain gauges in the state of Ceará, located in the NNB, from 1974 to 2018, on the annual and seasonal time scales. The data were initially submitted to the gap-filling and quality control processes. Most precipitation series were classified as "useful," and dry day precipitation indices were more susceptible to breaks than rainy day variables for homogeneity. The significant break years in the series agreed well with the El Niño and La Niña events, suggesting a further investigation of this possible connection. The precipitation indices for rainy and dry days presented mostly decreasing and increasing trends, respectively, indicating a decline in the rainfall regime in Ceará, mainly in the central-eastern, northwestern, and southern regions, in the annual and rainy seasons. The LOWESS curve showed changes in almost all series during the 1980s and 1990s, coinciding with the homogeneity breaks and the years of severe droughts in the region. The correlation coefficients were strong and significant between all precipitation indices and the other variables, seeming to induce changes in total rainfall.

2
  • ARTUR CRISTIANO PAULINO PEREIRA
  • Study of supersonic combustion in aerospace vehicle in atmospheric flight at Mach 5.8 and 20 km of altitude.
  • Líder : GEORGE SANTOS MARINHO
  • MIEMBROS DE LA BANCA :
  • DOUGLAS DO NASCIMENTO SILVA
  • GEORGE SANTOS MARINHO
  • JOÃO FELIPE DE ARAÚJO MARTOS
  • PAULO GILBERTO DE PAULA TORO
  • Data: 26-ago-2021


  • Resumen Espectáculo
  • In the present work, the thrust generation capacity of a scramjet integrated aerospace vehicle was evaluated from the combustion of hydrogen and atmospheric air at supersonic speed, for the flight of the scramjet vehicle at 20 km of altitude and speed of 1709.6 m/s, corresponding to Mach number of 5.79. A Theoretical-analytical method was used, considering the steady-state. The First Law of Thermodynamics, without and with reaction based on enthalpy of formation, was used to determine the properties. Correlations between the equivalence ratio with the mixture temperature, mixture speed, and exhausted gases temperature after combustion were obtained. The temperature and speed were also determined after the combustion gases expansion process. Mixing speed equal to 1152 m/s and exhaust gases temperature in the range of 2400 K to 2600 K was assumed, resulting in a fuel-air ratio in the range of 0.648 to 0.774 and mixing temperature of 875 K to 855 K. The temperature after the expansion varied from 865 K to 964 K, and the speed varied from 2425 m/s to 2532 m/s. A mean specific impulse equal to 4049.7 s was obtained, and positive non-installed thrust ranging from 760.8 N to 879.3 N.

3
  • PEDRO PAULO BATISTA DE ARAÚJO
  • Supersonic combustion technology applied to the second stage of the nanoSats launch vehicle

  • Líder : PAULO GILBERTO DE PAULA TORO
  • MIEMBROS DE LA BANCA :
  • ROBERTO DA CUNHA FOLLADOR
  • DOUGLAS DO NASCIMENTO SILVA
  • PAULO CELSO GRECO JÚNIOR
  • PAULO GILBERTO DE PAULA TORO
  • SANDI ITAMAR SCHAFER DE SOUZA
  • Data: 15-oct-2021


  • Resumen Espectáculo
  • Current rocket engines have a low specific thrust compared to the airbreathing propulsion technologies. Airbreathing supersonic combustion engines/vehicles are an alternative to improve the efficiency of access to space in a flight through the dense Earth’s atmosphere, below 60 km of geometric altitude. In this work, aerodynamic analysis of the conceptual model of supersonic combustion engine/vehicle (scramjet) was carried out to operate as a second-stage propulsion engine of a nanoSats launch vehicle. Two engineering approaches, analytical and computational numerical methodology, were used to perform the preliminary analysis of the proposed scramjet model, coupled to the third propulsion stage, at an altitude of 20 km with flight speed equivalent to Mach 5.8. Atmospheric air was considered a calorically perfect gas, and the viscous effects were neglect in a preliminary analysis. Supersonic combustion was modeled as heat adding to the supersonic flow without fuel injection. Then, numerical simulations were carried out considering the effects of the boundary layer development to verify the aerodynamic feasibility of the model. Optimization of the compression angles at the scramjet compression section was used to minimize the entropy generation and increase the vehicle’s compression efficiency, aiming to reach the temperature and Mach number at the combustion chamber entrance. The temperature required at the combustion chamber entrance is estimated to self-ignite the air-fuel mixture. Korkegi limit was evaluated through oblique shock waves in the compression section and in the heat addition process. Using the Korkegi limit, in the preliminary analytical design, as an indication of unstart due to the separation of the boundary layer caused by the adverse pressure gradient, we investigated to identify in numerical simulations considering the viscous effects whether the unstart phenomenon would occur. Numerical simulations were performed using commercial software, ANSYS Fluent, using the turbulence model known as transition SST. We also performed mesh convergence tests, numerical experiment validation on top of numerical data validated by HyShot flight data. Both meshes used in the validation and the analysis of the present work have equivalent levels of refinement in the direction of the wall, satisfying the condition of the turbulence model (𝑦+ < 1). The analytical calculations showed good quantitative and qualitative consistency with the numerical simulation results considering the same simplifications adopted in the analytical. An adaptation of the analytical method is proposed to take into account the effects of the interaction of the expansion fan with the oblique shock wave incident on the compression section of the scramjet. The results of the viscous simulations indicated that should be made improvements in the geometry due to the low temperature at the combustion chamber entrance, as well as reduced mass flow captured by the combustor, as a consequence of solution used to prevent unstart.

4
  • IAGO VINICIUS MACEDO SANTOS
  • EVALUATION OF THE IMPACT OF DENSITY ON ROCKET FLIGHT
  • Líder : DOUGLAS DO NASCIMENTO SILVA
  • MIEMBROS DE LA BANCA :
  • CAMILA PACELLY BRANDÃO DE ARAÚJO
  • DOUGLAS DO NASCIMENTO SILVA
  • HEIDI KORZENOWSKI
  • Data: 19-nov-2021


  • Resumen Espectáculo
  • In this present work, the implementation of the ordinary differential equations developed in the literature and which govern the movement of a rocket is presented, with the chosen vehicle being the VS-30 rocket. The code, which is developed in Matlab, is designed so that it is possible to compare the Earth's atmosphere as one composed of ideal gas, that is, an atmosphere in which the gases obey the Ideal Gas Law, and in another scenario , like being a type of Van der Waals. The final aim is to verify whether or not there is a large impact on the flight phenomenon as a whole, applying the Euler method to the solution of the equations already mentioned above.

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