Aviation industry is continuously growing especially for very long distance flights due to the globalisation of local economies around the world and the explosive economic growth in Asia. Reducing the time of intercontinental flights from 16-20 hours to 4 hours or less would therefore make the, already booming, ultra-long distance aviation sector even more attractive. To accomplish this drastic travel time reduction for civil transport, hypersonic cruise aircraft are considered as a potential cost-effective solution. Such vehicles should also be fuelled by liquid hydrogen, which is identified as the only viable propellant to achieve antipodal hypersonic flight with low environmental impact. Despite considerable research on hypersonic aircraft and hydrogen fuel, several major challenges should still be addressed before such airliner becomes reality. The current thesis is therefore motivated by the potential benefit of hydrogen-fuelled hypersonic cruise vehicles associated with their limited state-of-the-art.Hypersonic cruise aircraft require innovative structural configurations and thermal management solutions due to the extremely harsh flight environment, while the uncommon physical properties of liquid hydrogen, combined with high and long-term heat fluxes, introduce complex design and technological storage issues. Achieving hypersonic cruise vehicles is also complicated by the multidisciplinary nature of their design. In the scope of the present research, appropriate methodologies are developed to assess, design and optimize the thermo-structural model and the cryogenic fuel tanks of long-range hydrogen-fuelled hypersonic civil aircraft. Two notional vehicles, cruising at Mach 5 and Mach 8, are then investigated with the implemented methodologies. The design analysis of light yet highly insulated liquid hydrogen tanks for hypersonic cruise vehicles indicates an optimal gravimetric efficiency of 70-75% depending on insulation system, tank wall material, tank diameter, and flight profile. A combination of foam and load-bearing aerogel blanket leads to the lightest cryogenic tank for both the Mach 5 and the Mach 8 aircraft. If the aerogel blanket cannot be strengthened sufficiently so that it can bear the full load, then a combination of foam and fibrous insulation materials gives the best solution for both vehicles. The aero-thermal and structural design analysis of the Mach 5 cruiser shows that the lightest hot-structure is a titanium alloy construction made of honeycomb sandwich panels. This concept leads to a wing-body weight of 143.9 t, of which 36% accounts for the wing, 32% for the fuselage, and 32% for the cryogenic tanks. As expected, hypersonic thermal loads lead to important weight penalties (of more than 35%). The design of the insulated cold structure, however, demonstrates that the long-term high-speed flight of the airliner requires a substantial thermal protection system, such that the best configuration (obtained by load-bearing aerogel blanket) leads to a titanium cold design of only 4% lighter than the hot structure. Using aluminium 7075 rather than titanium offers a further weight saving of about 2%, resulting in a 135.4 t wing-body weight (with a contribution of 23%, 25%, 18% and 34% from the TPS, the wing, the fuselage, and the cryogenic tanks respectively). Given the design hypotheses, the difference in weight is not significant enough to make a decisive choice between hot and cold concepts. This requires the current methodologies to be further elaborated by relaxing the simplifications. Investigation of the thermal protection must be extended from one single point to different regions of the vehicle, and the TPS thickness and weight should be considered in the structural sizing of the cold design. More generally, the design process should be matured by including additional (static, dynamic and transient) loads, special structural concepts, multi-material configurations and other parameters such as cost and safety aspects. / Doctorat en Sciences de l'ingénieur et technologie / This thesis was conducted in co-tutelle between University of Sydney and Université Libre de Bruxelles.Professor Dries Verstraete was my supervisor at the University of Sydney (so as a member of SydneyUni), but is automatically registered here as a member of ULB because he worked at ULB almost ten years ago.Ben Thornber is also a member of the University of Sydney but the application does not save it for an unknown reason. / info:eu-repo/semantics/nonPublished

A porous silica –silica composite was processed with varying fiber diameters using the slurry moulding technique. The advantage of the process was that the density of the composite could be processed to the required levels. The reinforcements used were fibers obtained by leaching E-glass cloth, imported silica fibers with diameter <1.8µ and hollow silica fibers processed using sol-gel method. All the properties depend on the density of the composite. The compressive strength was measured in the perpendicular and parallel directions. Strength was high when the load axis was along the fiber direction. The composite with fine fibers (< 1.8 µ pure silica fibers) showed higher strength compared to the leached silica fibers. The thermal conductivity measurement on these composites showed an increase with temperature owing to the domination of radiation at high temperatures. As the vacuum level was approached, the thermal conductivity showed a decrease due to the absence of the convective part of the thermal transfer process. For use as a thermal protection system, it is important to measure the thermal response of these tiles in a simulated re-entry environment. Tests were done to measure this response for a given heat flux conditions at 38W/cm2 to 75W/cm2 and the backwall temperature was measured for various types of silica -silica composites. The role of impurities like sodium and B2O3 was also studied with respect to the conversion from amorphous to crystalline forms of SiO2. The severe increase in the coefficient of thermal expansion when SiO2 converted from amorphous to α– crystoballite was also measured. CSZP CSZP which belongs to the NZP family was processed using the co-precipitation technique. The influence of substituting the ‘P’ site with ‘Si’ atom was studied for its influence on thermal expansion – both at the bulk level by dilatometry and at the intrinsic level using high temperature XRD. For many anisotropic materials micro-cracking is a serious issue while cooling from the sintering temperature. It has been previously proved that this extent of micro-cracking depends on the particle size. Smaller the particle size is therefore preferred. One of the significant results obtained in this study was the successful use of microwaves to process crack free CSZP with fine grain size. CSZP with 95% density having a grain size as small as 1µ have been processed using microwave sintering. Dielectric property evaluation namely dielectric constant, dielectric loss and temperature coefficient of resonant frequency which are vital parameters required if this material is to be used as a candidate TPS have also been measured. The thermal conductivity of the sample was measured using Laser flash apparatus and was found to be 0.9 W/mk which provides an indication that this material can be used as a successful material for TPS. Finally a composite consisting of silica fiber with CSZP as matrix was processed and tested for heat flux. The low back wall temperature indicates that this material is a potential replacement for silica tile.

Les travaux de cette thèse portent sur l'intégration dans le réseau électrique du limiteur supraconducteur de courant (SCFCL). Un modèle du ruban supraconducteur ont été développé et validé grâce à une comparaison avec des tests expérimentaux. Premièrement, ce modèle a permis le dimensionnement du SCFCL du projet Eoccoflow (projet européen). Dans un deuxième temps, le modèle de SCFCL est intégré dans différents types de réseau. D'une part, l'intégration du SCFCL dans les réseaux haute tension continu maillés rend vraisemblable la protection de tels réseaux. D'autre part, grâce au SCFCL de nouvelles architectures du réseau de distribution sont proposées permettant l'intégration massive de génération distribuée. Cette thèse se clot sur le dimensionnement et les tests d'un SCFCL pour un réseau à taille réduite. / This PhD deals with superconducting fault current limiter (SCFCL) network integration. A model of a superconducting tape had been developed and validated in comparison with experimental quench tests. This SCFCL model allowed us to design the SCFCL of the european project Eccoflow. Using this SCFCL model, SCFCLs are integrated in various types of networks. On one hand, SCFCL benefits are first studied in case of meshed HVDC networks. Indeed, the SCFCL makes realistic the protection of such networks. On the other hand, thanks to the SCFCL some new distribution network topologies are suggested in order to increase the distributed generation integration capacity. This PhD ends with the design and the test of a SCFCL in a downsize scale network.

Made available in DSpace on 2014-06-11T19:22:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-18Bitstream added on 2014-06-13T19:08:07Z : No. of bitstreams: 1 fabianespinoza_rg_me_ilha.pdf: 869619 bytes, checksum: 3c82572569bc2349669cb3765fb65c95 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Ensino Pesquisa e Extensão de Ilha Solteira (FEPISA) / Neste trabalho apresenta-se uma metodologia para obter um ambiente interativo de simulação com ferramentas que permitam fazer análises de sistemas de proteção como estudos de coordenação e analises pós falta. As ferramentas estão baseadas no programa de simulação de transitórios eletro- magnéticos EMTP/ATP e na linguagem de programação ANSI C, sobre a plataforma de software livre GNU/Linux. Esta metodologia pode ser implementada, da mesma forma, em qualquer plataforma Windows sobre a qual possa funcionar o EMTP/ATP e o pacote ATP/MingW. Assim, implementou- se um relé de distância numérico através de modelos externos (“foreign models”). Ilustra-se também como usar arquivos no formato COMTRADE na análise com EMTP/ATP. Dessa forma foi possível analisar o comportamento do relé implementado tendo como entradas os sinais de tensões e correntes correspondentes aos eventos reais. Os sinais de disparo, assim como os demais componentes do relé, foram testados usando um sistema teste de referência do Power System Relaying Committee da PES-IEEE e os sinais de faltas reais do Sistema Elétrico Interligado da Colômbia. Por fim, foi feito um estudo de coordenação. Os resultados são apresentados e discutidos. A metodologia proposta pode ser usada para desenvolver qualquer componente ou elemento de controle dentro de um sistema elétrico, onde haja a necessidade de usar o EMTP/ATP para simular condições específicas de operação do sistema elétrico, complementando a simplicidade da linguagem MODELS com a portabilidade e potencialidade da linguagem C / This work presents the methodology to obtain an environment of interactive simulation with tools to perform analysis of protection systems, coordination studies and analysis post fault. These tools are based on the program for electromagnetic transients EMTP/ATP and in ANSI C programming language used in the free GNU/Linux software platform. The same methodology can be followed to be used on any Windows Operating System that can run EMTP/ATP and the package ATP/MingW. Then, for this, a numerical distance relay was implemented by means of foreign models using C programming language. It also shows how to use COMTRADE files in analysis with EMTP / ATP. Thus it was possible to analyze the behavior of the implemented relay with voltage and current signals of real events as inputs. The trip signals, like the other components of the relay, were tested using a testing reference system of Power System Relaying Committee of PES-IEEE and the signals of real faults of Inter- connected Electric System of Colombia. Finally, a coordination study was made. The results are presented and discussed. This methodology could also be used to develop any component or control element within an electrical system that one may need for a particular use; therefore, compensating the simplicity of the language MODELS with the flexibility and portability of C programming language

Les travaux présentés dans cette thèse CIFRE financée par AIRBUS Defence & Space s’intègrent dans une problématique de développement de nouveaux Systèmes de Protection Thermique (TPS) pour l’entrée atmosphérique. Ils se focalisent sur l’étude du transfert radiatif dans la zone d’ablation du TPS et son couplage avec le transfert conductif au travers de la matrice fibreuse de faible densité. Pour réaliser cette étude, il a été nécessaire d’évaluer les propriétés thermiques de ces matériaux, notamment les propriétés radiatives qui, contrairement aux conductivités thermiques, demeurent mal connues. La première étape de cette étude a donc visé à caractériser les propriétés optiques et radiatives de certains matériaux fournis par AIRBUS Defence & Space et par le CREE Saint-Gobain. Pour réaliser ces caractérisations, nous avons développé une méthode originale d’identification des propriétés radiatives basée sur des mesures de l’émission propre. Les spectres d’émission à haute température, réalisés sur des échantillons en fibre de silice ou en feutre de carbone nécessaires à l’identification, sont obtenus sur un banc de spectrométrie FTIR développé lors de ces travaux. Les échantillons sont chauffés à haute température à l’aide d’un laser CO2 et un montage optique permet de choisir entre la mesure du flux émis par l’échantillon ou un corps noir servant à l’étalonnage du banc. L’identification des propriétés repose sur la modélisation des facteurs de distribution du rayonnement calculés à l’aide d’une méthode de lancé de rayons Monte Carlo utilisant la théorie de Mie pour un cylindre infini pour le calcul des propriétés radiatives. Les températures identifiées sont comparées aux températures mesurées par pyrométrie au point de Christiansen dans le cas de la silice et montrent un bon accord avec ces dernières. Enfin la dernière partie de ce document est consacrée au couplage conduction-rayonnement dans ce type de milieu. Les échantillons ayant une très forte extinction, le modèle utilisé repose sur la définition d’une conductivité équivalente de Rosseland pour traiter les transferts radiatifs volumiques et ainsi simuler les champs de température au sein des échantillons dans les conditions de chauffage utilisées lors de l’identification. Dans le cas de la silice, cependant, les températures prédites par le modèle utilisant la conductivité équivalente de Rosseland, sont nettement supérieures à celles obtenues par identification ou par pyrométrie au point de Christiansen. Le fait que la conductivité équivalente de Rosseland ne fasse pas la distinction entre une forte extinction due à la diffusion ou à l’absorption est probablement la cause de cette différence. / The work presented in this thesis has been financed by AIRBUS Defence and Space. It is part of the development strategy of new Thermal Protection Systems (TPS) for atmospheric reentry purposes. The aim is to study the radiative transfer in the ablation zone of the TPS as well as the coupling of the radiative and conductive heat transfer in the low density fibrous matrix. To this end, radiative properties of the materials have to be evaluated since they are not well known. The first step of this study is therefore to characterize the optical and radiative properties of sample provided by AIRBUS Defence and Space and the CREE Stain-Gobain laboratory. Thus, an original identification method based on radiative emission measurement was developed to obtain the radiative properties. The needed emission spectra are measured on silica or carbon samples at high temperature with an experimental setup based on Fourrier Transformed InfraRed spectrometry. The samples are heated using a CO2 laser. An optical setup allows us to measure emission spectra on the sample or a black body used to calibrate the experiment. The identification process is based on the modeling of the radiative distribution factor computed by a Monte Carlo ray-tracing method. It uses Mie theory for infinite cylinder to compute the radiative properties. Temperature are also identified and, for silica, compared to the one measured by a Christiansen pyrometry technique. The last part of this study focuses on the coupled radiative/conductive heat transfer modeling in low density fibrous media. Samples being greatly absorbing, we used the Rosseland equivalent conductivity to model the radiative transfer in volume and obtain the thermal response of the samples in the conditions of the experimental setup used for the identification. For silica, predicted temperatures are superior to the identified ones or those measured with the Christiansen pyrometry technique. This is probably because the Rosseland equivalent conductivity makes no difference between extinction due to absorption and extinction due to scattering.

The Master´s thesis describes continuous automatic train protection system and its functional properties, principally the transmission of special encoded signal between stationary part and rail vehicle. There is also summarized some important information about the gear rotational speed sensors and its communication with other onboard peripherals. Depends by analysed parameters of electrical signals, the general suggestion of portable electronic device is outlined. Portable electronic device or TESTER will be used to in phase of testing mobile part of automatic train protection system mounted onboard of rail vehicle. Tester will generate equivalent electrical signals to signals in system automatic train protection and the real system response will be possible to evaluate. The generator block allows to model real electrical signals in automatic train protection technology type LS or type EVM and signals rail vehicle odometry.

In dieser Arbeit wird ein Motorschutzsystem vorgestellt, das die Temperaturen in Asynchronmotoren während des Betriebes zuverlässig und sensorarm berechnet und dabei leicht auf andere Motoren übertragbar ist. Neben dem Schutz vor unzulässiger Erwärmung können die auftretenden Wicklungsverluste für eine wirkungsgradoptimale Ansteuerung genauer ermittelt werden. Basis ist ein thermisches 9-Körper-Modell, das die Temperaturverläufe wesentlicher Maschinenteile abbilden kann. Der vorgeschlagene Identifikationsalgorithmus sorgt für eine hohe Übereinstimmung der Temperaturverläufe. Fehler im thermischen Modell oder der Verlustleistungsberechnung können durch die Rückführung eines einzelnen Temperatursensors und eines verbesserten Schätzers der Läuferwicklungstemperatur korrigiert werden. Das Überschreiten definierter Temperaturgrenzen kann mit der vorgeschlagenen Abschaltzeitprognose auch im Fehlerfall frühzeitig erkannt werden.

Vid byggnation av tunnlar och bergrum används bergförstärkning för att exempelvis säkra mot nedfallande lösa block och uppsprickning av berg. En vanlig förekommande förstärkning är bergbultar i kombination med sprutbetong. Vid installation av bultar borras hål i bergväggen som sedan fylls med cementbruk. Bultar som redan är försedd med bricka, halvkula, och mutter trycks sedan in i borrhålen av manuell kraft. Understoppningen görs i samband med att den sista biten av bulten trycks in i borrhålet. Då förses brickans undersida med cementbruk innan den skruvas åt med mutter mot den sprutbetongtäckta bergväggen. Denna rapport syftar till att ta reda på om momentet understoppning av bergbultsbricka vid montering av kamstålsbultar vid konventionell tunneldrivning är möjlig att utesluta. Idag råder det delade meningar mellan beställare, entreprenörer och specialister kring momentets betydelse för bergförstärkningen av tunnlar då vissa menar att det är nödvändigt och andra menar att det kan uteslutas. Däremot är det ofta angett i tekniska beskrivningar att momentet ska utföras då det står med i AMA Anläggning 20, vilket innebär att momentet inte kan uteslutas vid installation av kamstålsbultar. Med denna bakgrund ämnar föreliggande studie till att ta reda på grunderna till varför och när kravet på understoppning av bergbultsbrickor lades till, samt huruvida det fortfarande finns belägg för att ha kvar kravet. I denna studie har ingen tidigare forskning hittats om själva syftet med understoppning som kan visa på anledningar till varför man utför momentet samt varför det har lagts till som ett krav. Metoden har därför utförts genom att inhämta information och sökta svar från litteraturstudier inom ämnet samt via intervju- och enkätstudier. En teoretisk livslängdsberäkning för rostskyddssystemet har utförts för att få svar på om det uppfyller Trafikverkets krav på en teknisk livslängd på 120 år. Att utföra experimentella tester för att svara på studiens syfte diskuterades under studiens gång men var inte möjligt att genomföra med tillhandahållen tidsram och resurser. Resultatet visade att understoppningens huvudsakliga syfte är för att skydda bergbulten mot korrosion och mot genomstansning av brickan i sprutbetongen. Studien visade dock att det saknas bakgrund och konkreta bevis som säkerställer att understoppning motverkar detta. Litteraturstudien visade att varmförzinkade och epoxilackerade bultar har hög beständighet mot korrosion men att tunnelmiljön troligtvis har en betydande faktor för bultens livslängd. Litteraturstudien visade även att brickans betydelse för bärsystemet är odefinierad. Detta då vissa studier fastställer att brickan endast har en liten inverkan och andra visar att brickans styvhet har betydelse för genomstansning. Resultatet visade även att momentet innebär en ogynnsam arbetsmiljö för yrkesarbetare samt att en eventuell uteslutning skulle innebära förmodade vinster för inblandade parter. En annan fråga som belysts är huruvida den omfattning av bergsförstärkning som utförs idag verkligen är nödvändig. Om bergförstärkningen skulle kunna ske mer sparsamt skulle det möjliggöra en besparing av statliga medel och naturresurser. Denna studie har inte gett svar på om kravet på bärighet och beständighet uppfylls utan understoppning. Förslag på vidare studier för att besvara den frågan har därför redovisats. / When building tunnels, rock reinforcement is used. E.g., to secure against falling loose blocks and cracking of rock. A common reinforcement is rock bolts in combination with shotcrete. When installing bolts, holes are drilled into the rock wall, which are then filled with cement mortar. Bolts already provided with plate, hemisphere, and nut are then pushed into the boreholes by manual force. The underfilling of the plate is done in connection with the last part of the bolt being pushed into the borehole. Then the underside of the plate is provided with cement mortar before it is screwed on against the shotcrete-covered rock wall with a nut. The purpose of this report is to evaluate whether it is possible to exclude underfilling of rock bolt plates when installing rebar bolts during conventional tunnelling. Today, there are divided opinions between customers, contractors and specialists about the importance of underfilling for the rock reinforcement. I.e., there is a lack of consensus if underfilling of rock bolt plates is necessary or can be excluded. On the other hand, it is often stated in the technical descriptions that the task must be fulfilled then it is included in AMA Anläggning 20, which means that it cannot be excluded when installing rebar bolts. With this background, this study aims to find out the reasons why and when the requirement for underfilling of rock bolt plates was added, and whether there is still evidence to maintain the requirement. No previous research has investigated applicable reasons of why it is performed and why it has been added as a requirement. The method has therefore been performed by obtaining information from literature studies in the subject as well as via interview and survey studies. A theoretical lifetime calculation for the corrosion protection system has been performed to answer whether it achieves the requirement of a technical lifetime of 120 years issued by the Swedish Transport Administration. Performing experimental tests to answer the purpose of this study was discussed but was not possible to perform with the resources provided. The result showed that the main purpose of underfilling is to protect the rock bolt against corrosion and punching of the plate into the shotcrete. However, the study showed that there is a lack of background and actual evidence that proves that underfilling counteracts this. The literature study showed that hot galvanized and epoxy-painted bolts have high resistance against corrosion, but that the tunnel environment probably is a significant factor for the bolt's lifetime. The literature study also showed that the importance of the plate for the support system is undefined. Some studies demonstrate that the plate only has a small impact and others shows that the stiffness of the plate has a high impact for shear punching. The results also showed that the task causes an unfavourable working environment for professional workers and that a possible exclusion would mean presumed profits for involved parties. Another question that is highlighted is whether the extent of rock reinforcement that is carried out today is really necessary. If the rock reinforcement could be done more sparingly, it would make it possible to save state funds and natural resources. This study has not been able to answer whether the requirement for bearing capacity and durability is achieved without underfilling of rock bolt plates. Suggestions for further studies to answer this question have therefore been presented.

Projektet behandlar utvecklingen av ett handledsskydd anpassat för snowboardåkare. Den primäramålsättningen är att med hjälp av optimerad design för komfort och användarvänlighet kunnaerbjuda ett högkvalitativt och funktionellt skydd. Det senare uppnås med hjälp av material som medhänsyn till skadebilden hos utövarna här anses vara den bästa lösningen. Val av material gjordes efteren ingående litteraturstudie över handledsskyddets funktion och mekanismerna bakomhandledsskador. Studien, i kombination med en rad andra metoder för informationsinhämtning, lågäven till grund för designprocessen och den slutgiltiga produkten.Lösningar på befintliga problem hos existerande handledsskydd har applicerats på slutprodukten.Användarvänlighet och passform har tillgodosetts genom att frångå det traditionella systemet medkardborrelås, till produktanpassning av ett etablerat snörsystem. En ökad bekvämlighet tillgodosesgenom hela skyddets form, men även med utvalda material, då dessa tillåter luftgenomströmninggenom skyddet.Inom ramen för projektet besvaras också frågeställningar rörande varför så få utövare använderhandledsskydd, och vad som kan göras för att locka till användning. Handledsskydd är idagimpopulära hos utövarna, trots att frakturer på handled är den vanligaste skadan förknippad medsnowboard. Genom utveckling av bättre skydd kan skadestatistiken kraftigt förbättras. / The project aims to develop customized wrist guards for snowboarders. By using optimized design for comfort and ease of use, the primary aim is to offer the customer a functional and high-quality protection. This is achieved by using materials that, considering the injury status of the practitioners, herein are considered to best meet the demands of such a protection. The choice of materials was made after a comprehensive literature-based study on wrist guard function and mechanisms responsible for wrist injuries. This study, along with other collected data, has formed the basis for the design process and the final product. Solutions to current problems with existing wrist guards have been applied to the final product. Requirements on ease of use and accuracy of fit have been met by abandoning the traditional closure-system of Velcro, in favor for an established lacing system that has been adapted to the current product. The entire shape of the wrist guard, combined with the selected materials breathable qualities, offers the user an increased comfort. The complementary aim of the project is to understand why so few practitioners wear wrist guards, and bring forth solutions that attracts to the usage of such. Wrist guards are currently unpopular amongst snowboarders, despite wrist fracture being the most common injury associated with the sport. Through the development of better wrist guards the injury statistics can be greatly improved.

The re-entry space vehicles encounter high temperatures when they enter the earth atmosphere and the high temperature air in the shock layer around the body undergoes partial dissociation. Also, the gas molecules injected into the shock layer from the ablative thermal protection system (TPS) undergo pyrolysis which helps in reducing the net heat flux to the vehicle surface. The chemical species due to the pyrolysis add complexity to the stagnation flow chemistry (52 chemical reactions) models which include species like NOx, CO and hydrocarbons (HCs). Although the ablative TPS is responsible for the safety of re-entry space vehicle, the induced chemical species result in variety of adverse effects on environment such as global warming, acid rain, green house effect etc. The well known three-way-catalyst (TWC) involves simultaneous removal of all the three gases (i.e, NOx, CO, Hydrocarbons) present in the shock layer. Interaction of such three-way-catalyst on the heat shield materials or on the wall of the re-entry space vehicle is to reduce the heat flux and to remove the gases in the shock layer, which is an important issue. For the re-entry vehicle the maximum aerodynamic heating occurs at an altitude ranging about 68 to 45 km during which the vehicle is surrounded by high temperature dissociated air. Then the simplest real gas model of air is the five species model which is based on N2, O2, O, NO and N. This five species model assumes no ionization and no pyrolysis gases are emitted from the heat shield materials. The experimental research work presented in this thesis is directed towards the understanding of catalytic and non-catalytic surface reactions on high temperature materials in presence of strong shock heated test gas. We have also explored the possibility of using shock tube as a high enthalpy device for synthesis of new materials. In the first Chapter, we have presented an overview of re-entry space vehicles, thermal protection system (TPS) and importance of real gas effects in the shock layer. Literature survey on TPS, ablative materials and aerothermochemistry at the stagnation point of reentry capsule, in addition to catalytic and non-catalytic surface reactions between the wall and dissociated air in the shock layer are presented. In Chapters 2 and 3, we present the experimental techniques used to study surface reactions on high temperature materials. A brief description of HST2 shock tunnel is presented and this shock tunnel is capable of generating flow stagnation enthalpies ranging from 0.7 to 5 MJ/kg and has an effective test time of ~ 800 µs. High speed data acquisition system (National Instruments and Yokogawa) used to acquire data from shock tube experiments. The experimental methods like X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Raman and FTIR spectroscopy have been used to characterize the shock-exposed materials. Preliminary research work on surface nitridation of pure metals with shock heated nitrogen gas is discussed in Chapter 2. Surface nitridation of pure Al thin film with shock heated N2 is presented in Chapter 3. An XPS study shows that Al 2p peak at 74.2 eV is due to the formation AlN on the surface of Al thin film due to heterogeneous non-catalytic surface reaction. SEM results show changes in surface morphology of AlN film due to shock wave interaction. Thickness of AlN film on the surface increased with the increase in temperature of the shock heated nitrogen gas. However, HST2 did not produce sufficient temperature and pressure to carry out real conditions of re-entry. Therefore design and development of a new high enthalpy shock tunnel was taken up. In Chapter 4, we present the details of design and fabrication of free piston driven shock tunnel (FPST) to generate high enthalpy test gas along with the development of platinum (Pt) and thermocouple sensors for heat transfer measurement. A free piston driven shock tunnel consists of a high pressure gas reservoir, compression tube, shock tube, nozzle, test section and dump tank connected to a vacuum pumping system. Compression tube has a provision to fill helium gas and four ports, used to mount optical sensors to monitor the piston speed and pressure transducer to record pressure at the end of the compression tube when the piston is launched. Piston can attain a maximum speed of 150 m/s and compress the gas inside the compression tube. The compressed gas bursts the metal diaphragm and generates strong shock wave in the shock tube. This tunnel produces total pressure of about 300 bar and temperature of about 6000 K and is capable of producing a stagnation enthalpy up to 45 MJ/kg. The calibration of nozzle was carried out by measuring the pitot tube pressure in the dump tank. Experimentally recorded P5 pressure at end of the shock tube is compared with Numerical codes. Calibrated pressure P5 values are used to calculate the temperature T5 of the reflected shock waves. This high pressure and high temperature shock heated test gas interacts with the surface of the high temperature test materials. For the measurement of heat transfer rate, platinum thin film sensors are developed using DC magnetron sputtering unit. Hard protective layer of aluminum nitride (AlN) on Pt thin film was deposited by reactive DC magnetron sputtering to measure heat transfer rate in high enthalpy tunnel. After the calibration studies, FPST is used to study the heat transfer rate and to investigate catalytic/non-catalytic surface reaction on high temperature materials. In Chapter 5, an experimental investigation of non-catalytic surface reactions on pure carbon material is presented. The pure carbon C60 films and conducting carbon films are deposited on Macor substrate in the laboratory to perform shock tube experiments. These carbon films were exposed to strong shock heated N2 gas in the shock tube portion of the FPST tunnel. The typical shock Mach number obtained is about 7 with the corresponding pressure and temperature jumps of about 110 bar and 5400 K after reflection at end of the shock tube. Shock exposed carbon films were examined by different experimental techniques. XPS spectra of C(1s) peak at 285.8 eV is attributed to sp2 (C=N) and 287.3 eV peak is attributed to sp3 (C-N) bond in CNx due to carbon nitride. Similarly, N(1s) core level peak at 398.6 eV and 400.1 eV observed are attributed to sp3-C-N and sp2-C=N of carbon nitride, respectively. SEM study shows the formation of carbon nitride crystals. Carbon C60 had melted and undergone non-catalytic surface reaction with N2 while forming carbon nitride. Similar observations were made with conducting carbon films but the crystals were spherical in shape. Micro Raman and FTIR study gave further evidence on the formation of carbon nitride film. This experimental investigation confirms the formation of carbon nitride in presence of shock-heated nitrogen gas by non-catalytic surface reaction. In Chapters 6 and 7, we present a novel method to understand fully catalytic surface reactions after exposure to shock heated N2, O2 and Ar test gas with high temperature materials. We have employed nano ZrO2 and nano Ce0.5Zr0.5O2 ceramic high temperature materials to investigate surface catalytic reactions in presence of shock heated test gases. These nano crystalline oxides are synthesized by a single step solution combustion method. Catalytic reaction was confirmed for both powder and film samples of ZrO2. As per the theoretical model, it is known that the catalytic recombination reaction produces maximum heating on the surface of re-entry space vehicles. This was demonstrated in this experiment when a metastable cubic ZrO2 changed to stable monoclinic ZrO2 phase after exposure to shock waves. The change of crystal structure was seen using XRD studies and needle type monoclinic crystal growth with aspect ratio (L/D) more than 15 was confirmed by SEM studies. XPS of Zr(3d) core level spectra show no change in binding energy before and after exposure to shock waves, confirming that ZrO2 does not change its chemical nature, which is the signature of catalytic surface reaction. When a shock heated argon gas interacted with Ce0.5Zr0.5O2 compound, there was a change in colour from pale yellow to black due to reduction of the compound, which is the effect of heat transfer from the shock wave to the compound in presence of argon gas. The reduction reaction shows the release of oxygen from the compound due to high temperature interaction. The XPS of Ce(3d) and Zr(3d) spectra confirm the reduction of both Ce and Zr to lower valent states. The oxygen storage and release capacity of the Ce0.5Zr0.5O2 compound was confirmed by analyzing the reduction of Ce4+ and Zr4+ with high temperature gas interaction. When Ce0.5Zr0.5O2 (which is same as Ce2Zr2O8) in cubic fluorite structure was subjected to strong shock, it changed to pyrochlore (Ce2Zr2O7) structure by releasing oxygen and on further heating it changed to Ce2Zr2O6.3 which is also crystallized in pyrochlore structure by further releasing oxygen. If this heating is carried out in presence of argon test gas, fluorite structure can easily change to pyrochlore Ce2Zr2O6.3 structure, which is a good electrical conductor. Due to its oxygen storage capability (OSC) and redox (Ce4+/Ce3+) properties, Ce0.5Zr0.5O2 had been used as oxygen storage material in three-way-catalyst. Importance of these reactions is that the O2 gas released from the compound will react with gas released from the heat shield materials, like NOx, CO and hydrocarbon (HCs) species which results in reduction of temperature in the shock layer of the re-entry space vehicle. The compound Ce0.5Zr0.5O2 changes its crystal structure from fluorite to pyrochlore phase in presence of shock heated test gas. The results presented in these two Chapters are first of their kind, which demonstrates the surface catalytic reactions. In Chapter 8, we present preliminary results of the oxygen recombination on the surface of heat shield material procured from Indian Space Research Organization (ISRO) used as TPS in re-entry space capsule (Space capsule Recovery Experiment SRE-1) and on thin film SiO2 deposited on silicon substrate. The formation of SiO between the junctions of SiO2/Si was confirmed using XPS study when shock exposed oxygen reacted on these materials. The surface morphology of the ablated SiO2 film was studied using SEM. The damage induced due to impact of shock wave in presence of oxygen gas was analyzed using Focused Ion Beam (FIB) microscope. The results reveal the damage on the surface of SiO2 film and also in the cross-section of the film. We are further investigating use of FIB, particularly related to residual stress developed on thin films due to high pressure and high temperature shock wave interaction. In Chapter 9, conclusions on the performance of FPST, synthesis of high temperature materials, catalytic and non-catalytic surface reactions on the high temperature material due to shock-heated test gases are presented. Possible scope for future studies is also addressed in this Chapter.