<p>The objective with this thesis is to build a Black-Box model of the tank pressurization system in JAS 39 Gripen. This model is intended to be used in an existing diagnosis system for the security control in the tank pressurization system. The tank pressurization system is a MIMO system. This makes the identification process more complicated when the best model is to be chosen. In this master's thesis the identification procedure for a MIMO system can be followed. Testing of the diagnosis system with the created Black-Box model shows that the model seems to be good enough. The diagnosis system takes the right decisions in the performed simulations. This shows that system identification might be a good alternative to physical modelling for a real-time model. The disadvantage with the Black-Box model is that it is less accurate in steady-state than the physical model used before is. The advantage is that it is faster than the physical model. The diagnosis system and the model developed in this thesis are not directly applicable on the real system today. The model has to be redesigned on the real system, this is also the case for the diagnosis system. The diagnosis system also has to be redesigned, so general flight cases, not only the security control can be supervised. However, experiences and choices like input and output signals, and choice of sample interval can be reused from this thesis when a new model might be developed.</p>

This thesis is a result of the increased requirements on availability and costs of the aircraft Jas 39 Gripen. The work has been to specify demands and to find methods suitable for development of a decision support system for the fault isolation of the aircraft. The work has also been to implement the chosen method. Two different methods are presented and a detailed comparison is performed with the demands as a starting point. The chosen method handle multiple faults in O(N2)-time where N is the number of components. The implementation shows how all demands are fulfilled and how new tests can be added during execution. Since the thesis covers the development of a prototype no practical evaluation with compare of manually isolation is done.

Master’s thesis deals with comparsion and rating the compressed natural gas as an aircraft piston engine fuel. An information search of conventional fuels and differences of the fuel systems for AVGAS and CNG is included. Next part describes the aircraft and its engine on which is the mathematic model based. After that perfomance and consumption data are calculated for both fuels and the results are then compared. At the end of the thesis, a design of the CNG fuel system with components selection is described.

The fuel system is a very important part of the vehicle and the engine. The main function is to deliver the fuel- air mixture into the engine cylinder. This thesis describes the design of the Formula student car fuel system. The first part is an introduction to Formula Student competitions. The next section describes the options of the fuel systems structure and options for individual components. Those rules limit the possibilities for us FSAE that in the next chapter. The following parts are major chapters dealing with the actual design of the fuel system and analysis of selected components. The last part are chapters that deal with the production possibilities of parts and subsequent incorporation into the fuel system of the car.

With increasing demands for lowering emissions from diesel engines, bio fuel has been introduced to the fuel mixture. This fuel is based on vegetable oil with a much smaller carbon footprint than fossil fuel. The chemical composition of bio fuel has lead to deposits forming inside the fuel injector in diesel engines, these deposits are usually denoted as Internal Diesel Injector Deposits (IDID). At Scania CV AB an injector test rig is designed with the goal of creating and investigating IDID. This project has made a theoretical investigation of how IDID are formed and how this affects the mechanics inside the injector. It has also analysed injector components from a worst case scenario perspective in order to find a testing method for creating IDID in the test rig. By analysing performance changes from a build-up perspective, where IDID decreases the tolerances inside the injector, as well as friction, formed when deposits cause injector mechanics to stick together, it has been found that injector performance does hardly change from build-up and that performance changes only occur when friction is introduced. From the injector component analysis it is found that the limiting factors in rig testing come from fuel system components rather than the injector itself. This is the base for a rig running test method presented.

Fuel Optimization Unit (FOU) is part of an new system for the low pressure fuel circuit (LPFC) designed for Scania’s combustion engines. The system replaces engine mounted, mechanically driven, fuel feed pump and pre filter. One FOU variant (Type 1) pushes fuel through the pre filter using an additional electrical fuel pump and utilizes a small volume of fuel as a buffer, mainly to increase water separation performance. The second variant (Type 3) is similar to a conventional LPFC but uses an electric feed pump. The thesis investigate prerequisites and possible limitations when introducing FOU in Scania’s bus program. The investigation also compare Type 1 with Type 3 to determine if any technology is preferable. Among others, the investigation finds: • Type 1 is because of its size more difficult to house but is because of design less sensitive for placement in the chassis compared to Type 3. • CAN communication with electric fuel pumps risks disturbances due to potentially long cables. • Pressure drop in fuel lines is not identifies as an limitation for Type 1 but length is recommended to minimize on the low pressure side of the feed pump for Type 3. • There is an risk that fuel return temperature decrease between engine and fuel tank causing clogging of pre filter due to wax formation at low temperatures. • Number of start/stops and operating hours is a potential limitation for electrical fuel pumps. • Drainage of engine mounted main filter to the catch tank in FOU Type 1 may work non satisfactory if the fuel lines are routed badly. • The air conducted sound level caused by electrical fuel pumps is not identified as a problem. However, structural conducted sound may cause disturbance for passengers if the attachment is carelessly designed. Comparison between the variants indicates that Type 1 is preferable. Type 1 catch points mainly due to the use of catch tank but loses points mainly related to size, mass and complexity which results in a presumably high cost. Type 3 is similar to present LPFC but holds a number of advantages shared with Type 1. Both Type 1 and Type 3 are identified as clear improvements compared with current LPFC. / Fuel Optimization Unit (FOU) är en del av ett nytt lågtrycksbränslesystem avsett för Scanias förbränningsmotorer. Systemet ersätter motormonterad, mekaniskt driven, matarpump och förfilter. FOU utvecklas i två varianter som har gemensamt en chassimonterad elektrisk matarpump och förfilter. Den ena varianten (Typ 1) trycker bränsle genom förfiltret med hjälp av en ytterligare elektrisk bränslepump och utnyttjar en mindre volym bränsle som buffert bl.a. för att förbättra vattenseparering. Den andra varianten (Typ 3) liknar till stor del ett konventionellt lågtrycksbränslesystem men med elektriskt driven matarpump. Examensarbetet utreder förutsättningar och möjliga hinder att introducera FOU på Scanias bussar. I utredningen jämförs även Typ 1 med Typ 3 för att avgöra om någon teknik är att föredra. Utredningen finner bl.a. att:• Typ 1 är pga. sin storlek svårare att bereda plats för men pga. sin konstruktion mindre känslig för placering jämfört Typ 3. • CAN-kommunikation med elektriska pumpar riskerar störningar pga. potentiellt långa ledningslängder. • Tryckfall i bränsleledningar utgör ingen hinder hos Typ 1 men ledningslängderna bör minimeras på matarpumpens sugsida hos Typ 3. • Det föreligger en risk att returbränsletemperaturen svalnar såpass mycket mellan motor och FOU att förfiltret sätts igen av paraffinering vid kall väderlek. • Antal start/stopp och drifttimmar utgör möjligen en begränsning för elektriska pumpar. • Dränering av finfiltret på motorn till catch-tanken i FOU Typ 1 riskerar att fungera otillfredsställande om bränsleledningarna dras ogynnsamt. • Den luftburna ljudnivån från de elektriska bränslepumparna bedöms inte vara oroväckande hög men är beroende på infästning då strukturburet ljud kan vara störande för passagerare. Jämförelse mellan varianterna indikerar att Typ 1 är att föredra. Typ 1 får många pluspoäng i huvudsak förknippade med förekomsten av bufferttank men också med en hel del minuspoäng i huvudsak relaterade till storlek, vikt och komplexitet vilket också resulterar i ett förmodat högt pris. Typ 3 liknar till stor del befintligt lågtrycksbränslesystem men innehar en del tydliga fördelar som den till stor del delar med Typ 1. Både FOU Typ 1 och Typ 3 identifieras som tydliga förbättringar gentemot befintligt lågtrycksbränslesystem.

The process of flying fighter jets naturally comes with tough environments and manoeu-vres where temperatures, pressures and forces all have a large impact on the aircraft. Part degeneration and general wear and tear greatly affects functionalities of the aircraft, and it is of importance to carefully monitor the well being of an aircraft in order to avoid catastrophic accidents. Therefore, this project aims to investigate various ways to improve anomaly detection of selected signals in the Gripen E fuel system. The methodology in this project was to compare collected flight data with generated data of a simulation model. The method was conducted for three selected signals with different properties, namely the transfer pump outlet pressure and flow, as well as the fuel mass in tank 2. A neural network was trained to generate predictions of the residual between measured and simulated flight data, together with a RandomForestRegressor to create a confidence interval of said signal. This made it possible to detect signal abnormalities when the gathered flight data heavily deviated from the generated machine learning algorithm predictions, thus alarming for anomalies. Investigated methods to improve anomaly detection includes feature selection, adding ar-tificial signals to facilitate machine learning algorithm training and filtering. A large part was also to see how an improved simulation model, and thus more accurate simulation data would affect the anomaly detection. A lot of effort was put into improving the simulation model, and investigating this area. In addition to this, the data balancing and features to balance the data on was revised. A significant challenge to tackle in this project was to map the modelling difficulties due to differences in signal properties. A by-productof improving the anomaly detection was that a general method was obtained to create a anomaly detection model of an arbitrarily chosen signal in the fuel system, regardless of the signal properties. Results show that the anomaly detection model was improved, with the main improvement area shown to be the choice of features. Improving the simulation model did not improve the anomaly detection in the transfer pump outlet pressure and flow, but it did however slightly facilitate anomaly detection of the fuel mass in tank 2 signal. It is also concluded that the signal properties can greatly affect the anomaly detection models, as accumulated effects in a signal can complicate anomaly detection. Remaining improvement areas such as filtering and addition of artificial signals can be helpful but needs to be looked into for each signal. It was also concluded that a stochastic behaviour was seen in the data balancing process, that could skew results if not handled properly. Over all the three selected signals, only one flight was misclassified as an anomaly, which can be seen as great results.

A key factor for driving the shift towards sustainable transportation systems is alternative fuels, where compressed natural gas (CNG) is a beneficial alternative to the conventional fossil fuels with respect to greenhouse gas emissions. A fuel system is needed for heavy-duty natural gas vehicles, in order to transport the highly pressurized gas from the fuel tanks to the internal combustion engine. The fuel system can be contaminated from several different sources – carry-over compressor oil from refuelling stations, water already present in the gas, manufacturing residuals and road dust entering the fuel system via the receptacle valve. The contaminants can induce fuel system failure modes, leading to poor engine performance, increased emissions or gas pressures above component pressure ratings. The objective of this thesis was to develop an accelerated test method to evaluate CNG fuel system robustness against contamination, to be able to prevent CNG fuel system failures and to ensure a high-quality product. The experimental setup was developed to be installed on a truck in order to utilize already present surrounding systems. The setup enables performance testing of six out of nine components belonging to the fuel system, which can be tested individually or combined in an arbitrary way. The setup induces premature failure modes primarily through excessive contamination in a controlled manner. An experimental procedure has been developed as a complement. Validation of metrics through testing is needed before the test method can be considered finalized. / En nyckelfaktor för att driva omställning mot hållbara transportsystem är alternativa bränslen, varpå naturgas (CNG) är ett slagkraftigt alternativ till konventionella fossila bränslen med avseende på utsläpp av växthusgaser. För att kunna transportera den högt trycksatta gasen från bränsletankarna till förbränningsmotorn krävs ett bränslesystem för tunga naturgasfordon. Bränslesystemet kan kontamineras genom ett flertal olika källor – överförd kompressorolja från tankstationer, vatten som redan finns i gasen, tillverkningsrester och vägdamm eller grus som tar sig in i systemet genom bränslepåfyllningsventilen. Kontamineringen kan ge upphov till felmoder i bränslesystemet, vilket leder till låg motorpresentanda, ökade utsläpp eller övertryck i systemet. Syftet med examensarbetet var att utveckla en accelererad testmetod för att utvärdera CNG-bränslesystems robusthet mot kontaminering, för att kunna förebygga systemfel och säkerställa en högkvalitativ produkt. Den experimentella uppställningen utvecklades för att monteras på lastbil, för att på så vis nyttja de kringliggande befintliga systemen. Uppställningen möjliggör prestandaprovning av sex av nio komponenter som tillhör bränslesystemet, som kan testas individuellt eller kombineras på ett godtyckligt sätt. Uppställningen framkallar tidiga felmoder, huvudsakligen genom excessiv kontaminering på ett kontrollerat vis. En metodbeskrivning har utvecklats som ett komplement till den experimentella uppställningen. Validering av metrik genom testning är nödvändigt för att finna testmetoden färdigställd.

Made available in DSpace on 2014-12-17T14:58:22Z (GMT). No. of bitstreams: 1 ValdicleideSM_DISSERT.PDF: 4448803 bytes, checksum: fa349b3064555b231f574c1ef787342f (MD5) Previous issue date: 2013-02-04 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The biodiesel use has become important due to its renewable character and to reduce environmental impacts during the fuel burning. Theses benefit will be valid if the fuel shows good performance, chemistry stability and compatibility with engines. Biodiesel is a good fuel to diesel engines due to its lubricity. Then, the aimed of this study was to verify the physicalchemistry properties of biodiesel and their correlations with possible elastomers damage after biodiesel be used as fuel in an injection system. The methodology was divided in three steps: biodiesels synthesis by transesterification of three vegetable oil (soybean, palm and sunflower) and their physical-chemistry characterization (viscosity, oxidative stability, flash point, acidity, humidity and density); pressurized test of compatibility between elastomers (NBR and VITON) and biodiesel, and the last one, analyze of biodiesels lubricity by tribological test ball-plan( HFRR). Also, the effect of mixture of biodiesel and diesel in different concentrations was evaluated. The results showed that VITON showed better compatibility with all biodiesel blends in relation to NBR, however when VITON had contact with sunflower biodiesel and its blends the swelling degree suffer higher influences due to biodiesel humidity. For others biodiesels and theirs blends, this elastomer kept its mechanical properties constant. The better tribological performance was observed for blends with high biodiesel concentration, lower friction coefficient was obtained when palm biodiesel was used. The main mechanisms observed during the HFRR tests were abrasive and oxidative wear / O uso do biodiesel tem ganhado for?a por seu car?ter renov?vel e por diminuir o impacto ambiental causado pela queima dos combust?veis f?sseis. Estes benef?cios valer?o a pena se o combust?vel apresentar bom desempenho, estabilidade qu?mica favor?vel e que n?o comprometa a integridade do sistema no qual venha a atuar. A sua aplica??o nos motores diesel tem sido indicada por apresentar maior lubricidade, que ? desej?vel para este sistema em raz?o do funcionamento da bomba. Desse modo, este trabalho teve como objetivo verificar o papel das propriedades f?sico-qu?micas do biodiesel e correlaciona-las com os poss?veis danos causados com o seu uso aos elast?meros aplicados no sistema de inje??o dos motores diesel. A metodologia foi dividida em tr?s etapas: s?ntese dos biodieseis por metan?lise a partir de tr?s oleaginosas (soja, dend? e girassol) e caracteriza??o f?sico-qu?mica (viscosidade, estabilidade oxidativa, ponto de fulgor, acidez, umidade e densidade); ensaio pressurizado de compatibilidade dos biodieseis com os elast?meros (NBR e VITON) e por fim, an?lise da lubricidade dos biodieseis atrav?s de ensaio tribol?gico esfera-plano( HFRR). Tamb?m foi avaliado o efeito da mistura do biodiesel ao diesel em diferentes propor??es, que limitam a deteriora??o dos materiais em contato com este combust?vel. O VITON apresentou maior compatibilidade com todos os combust?veis em rela??o ao NBR, no entanto para o contato com o biodiesel de Girassol e suas blendas o grau de inchamento sofreu maiores influ?ncias devido a este biodiesel apresentar maior umidade. Para as demais blendas e combust?veis analisados, este elast?mero manteve suas propriedades mec?nicas praticamente constantes. Em rela??o aos combust?veis estudados e suas blendas, os melhores desempenhos tribol?gicos foram observados para as maiores concentra??es dos biodieseis, com coeficientes de atrito menores para o biodiesel de dend?. Os principais mecanismos de desgaste observados foram abrasivo e oxidativo

This master’s thesis describes the area of operational suitability data that is established as part of the aircraft type certificate. The thesis first chapters are describing OSD, its origin and implementation. The thesis also analyzes all regulations that are connected with this matter and are focusing on the training of maintenance certifying staff. A part of this thesis deals with the description of aircraft Evektor EV-55 Outback, for which is created the educational material, and a description of its fuel system. The concept of educational material for maintenance certifying staff theoretical type rating training and an example of final test are at the end of the thesis.