The current generation of Airbus long-range civil transport aircraft actively control the centre of gravity of the aircraft by adjusting the fuel distribution between the horizontal tail surface and the forward tanks in order to minimise cruise drag. Here, it is proposed that the current on-off control method could be replaced by a variable flow rate, provided by a variable speed centrifugal pump. The impacts of this at the aircraftlevelintermsof cruisefuelburnreduction,valveoperationcycle reductionand power consumption are investigated here using an extension to an existing fuel system simulationpackage and ageneric aircraftfuel systemdefinition. Itis shownthat using such a control system reduces fuel burn and the number of valve cycles, which could translate into a reduction in operating costs. The benefit of changing the controller to use tailplane trim angle directly rather than inferred centre of gravity position is assessed, and is shown to further reduce the fuel burn. It is suggested that such centre of gravity could provide significant benefits over the existing method. Steady-state anddynamic models ofcentrifugalpumps,ACinductiondrives andtypical aircraft fuel system pipework components are developed. These are validated against experimentaldatafrom a test rig of a representative system. Test rig simulation results areshowntoagreewell with thosefromexperimentation. Anewsecondary noisesource is developed for the dynamic analysis of the centrifugal pump, and a new acoustic experimental method is developed for the prediction of fluid inductance in pipework components. The results are compared against an existing CFD based method and showgood agreement. Thenewmethod representsamuch simplerexperimental means of determining the effects of fluid inertia than the existing secondary source method. Itisdemonstrated thatthedynamicbehaviourof thecentrifugalpumpis, asexpected, insignificant when considering systems containing long pipes, and that steady-state pump models are sufficient for analysing their behaviour. Thepumpmodels aregeneralisedby non-dimensionalisation,in order to maximise their applicability to analysis of aircraftfuel systems. They are applied to ageneric aircraft fuel system simulation, in order to model the behaviour of the system during a trim transfer. Thisisused todemonstratethe application of theproposed variable flowrate trim control system. The results of these simulations agree well with those used to demonstratethebenefitsof thecontrol systemattheaircraftlevel. Conceptsof system health monitoring tools are discussed with reference to the system simulations.

O presente trabalho avalia o impacto da utilização de misturas de álcool e gasohol no desgaste e corrosão de bombas elétricas de combustível. / Assessement of alcohol and gasohol fuel blends impact on wear and corrosion of electric fuel pumps.

O presente trabalho avalia o impacto da utilização de misturas de álcool e gasohol no desgaste e corrosão de bombas elétricas de combustível. / Assessement of alcohol and gasohol fuel blends impact on wear and corrosion of electric fuel pumps.

Bränsle är en viktig substans för fordon och utan bränsle så är de flesta fordon inte funktionella. I de allra flesta instruktionsböcker för fordon så rekommenderas det att bränslet inte får nå en kritisk låg nivå av bränsle. Då man talar om den kritiska bränslenivån så handlar det om ¼ kvarliggande bränsle. Då bränslet når den kritiska nivån i bränsletanken så kan problem ske och dessa problem är direkt kopplade till bränsletanken och pumpen.     Syftet med denna kandidat examensarbete är att undersöka problemet och det befintliga bränslesystemets konstruktion för att sedan generera en eller fler lösningar till problemet. Då information för detta arbete är begränsad över nätverket så skedde en del intervjuer med verkstan och fordons företag och fabriker såsom Volvo och Scania för att få en bra mängd information som sedan användes som utgångspunkt till arbetet.   För att generera lösningar till problemet med informationen som erhållits av intervjuer och andra källor så användes vissa verktyg och metoder. Då arbetet var begränsad att utföra praktiskt så utfördes den teoretiskt med hjälp av kunskaper från materiallära, hållfasthetsberäkningar, simulations program såsom AutoCAD, NASTRAN, fysik och en mängd andra ingenjörs baserat litteratur för att åstadkomma goda resultat.   Resultat blev en enkel konstruktion som är anpassat för tillverkningen av bränsletankar och som både funkar för cylindriska och rektangulära bränsletankar.   I denna rapport så presenteras resultatet i form av några förslags modeller av ett koncept som anses vara en lämplig lösning för problemet och resultat utfört med konceptet som då visar att konceptet uppfyller en fungerande lösning för det presenterade problemet. Storlek för konstruktionen presenteras i en form av enkla beräknings steg där man utgår ifrån bränsletanks modellen man vill tillämpa konceptet i. / The fuel is an important substance for vehicles and without fuel the most vehicles are not functional. In other words, they cannot move. In all instruction manuals, it is recommended that the fuel should not attain a low level in the fuel tank itself because it could lead to many consequences and these consequences are directly linked to the fuel pump and the engine itself.   The purpose of this bachelor's thesis is to investigate the issues and the existing fuel system design, then generate concepts to solve the problem. The information about the problem is limited on the world wide web, therefore we have been in contact with various truck workshops, vehicle companies and been visiting some of them. Volvo and Scania were at the top of the list. The reason was to get good and reliable information about the fuel tanks and then use it as a starting point.   Using information from interviews and sources helped very much to generate different concepts and solutions to the problem. Also, some tools and methods were very useful to build, chose and evolve the concepts. Note that some work was not performed practically because of limitations, therefore it was theoretically done with help of knowledge from different courses like materials theory, strength of materials calculations, physics, simulation programs like AutoCAD, NASTRAN and other engineering literature to achieve good results.   The result was a simple design adapted for the production of fuel tanks for the manufacture of fuel tanks, which works for both cylindrical and rectangular fuel tanks. In this report, the results are presented in the form of some proposal models and results performed with the concept, which then shows that the concept satisfies a solution to the presented problem. / <p><strong>Presentationerna genomfördes på distans med zoom</strong></p>