Huvudämnet i denna avhandling är användningen av prediktiva modeller för att styra randvillkori en encylindrig motor. Encylindriga motorer används i utvecklingen av nya motorer för att studeraförbränningskoncept. De utgör en modulär plattform för utveckling av bland annat nyaventilkoncept, förbränningsmetoder, bränsleinsprutningsmetoder och portkonstruktioner. I enproduktionsmotor representeras turboaggregatet och motorn av ett kopplat dynamiskt system därmotorns driftspunkt bestämmer avgasmottryck och insugstryck. Det är nödvändigt att utföraexperiment på encylindriga motorer med rätt insug- och avgasmottryck för att studierna ska vararealistiska. Dessa encylindriga motorer har dock oberoende ventilstyrda insug- och avgassystemdär driftspunkten för en produktionsfärdig flercylindrig motor simuleras. Därför finns det ett behovav att använda modellbaserade tekniker för att styra inlopps- och utloppstryck. I denna avhandling har en metod utvecklats för att förutsäga randvillkor med hjälp av en skaladversion av den encylindriga modellen tillsammans med en modell av ett turboaggregat. Endetaljerad 1D modell av en encylindrig provcell skapades i AVL Boost. Modellen har sedanvaliderats med hjälp av mätdata och skalats till en flercylindermodell. En 0D Simulinkmodell harutvecklats utöver 1D modellen för att jämföra deras användning i en realtidsapplikation. Samtidigttas det hänsyn till de avvikelser från verkliga processer som sker i båda modellerna. 0D modellenrepresenterar en enkel motormodell för att förutsäga stationär prestanda genom att förutsätta kvasistationär strömning. Motivationen bakom att använda en sådan modell är att de förutsagdamedelvärden av inlopps- och utloppstryckspår ger en mer realistisk referensparameter som kananvändas för att styra randvillkoren på en encylindermotor. Avgasturbinen har också modellerats i syfte att studera volutets dämpande effekt på det pulserandeavgasflödet. Olika extrapoleringsmetoder för turbinmappar studerades där fysiskt baseradealgoritmer användes för att extrapolera turbindata. Turbinvolutet och dess effekter påturbinprestanda har diskuterats tillsammans med uppskattning av effektiviteten hos turbinen underostadiga flödesförhållanden. Dessa modeller har sedan kalibrerats och validerats motvevaxelupplösta cylindertryck och cykelmedelvärderade parametrar från mätdata som erhållitsfrån den encylindriga provmotorn. De fel och avvikelser mellan 0D- och 1D modellerna ochmätdata identifierades och diskuterades. En styralgoritm baserad på den encylindriga 1D Boostsimuleringen utvecklades för att reglera insug- och avgastryck och jämfördes sedan mellan 0D-och 1D modellerna för att utvärdera prestanda och noggrannhet. / The main topic of study in this thesis is the use of predictive models to control the boundaryconditions of a single cylinder engine. Single cylinder engines are used to study combustionconcepts in the development cycle of new engines. They provide a modular research platform todevelop new valve train concepts, combustion methods, fuel injection methods, port designsamong other things. In a production engine the turbocharger and engine represents a coupleddynamic system where the operating point of the engine sets the cylinder exhaust back pressureand the inlet pressure. Hence, it is necessary to provide single cylinder engines with correctcharged air input and exhaust back pressure for the studies to be realistic. These single cylinderengines however have independent charging systems and valves to simulate the operating point ofa production multi cylinder engine. Therefore, there is a need to use model-based techniques tocontrol the inlet and outlet pressure. In this thesis a method was developed to predict the boundary conditions of the single cylinder testengine using a scaled version of the single cylinder model along with a turbocharger model. Adetailed 1D model of the single cylinder test cell was created using AVL Boost. This model wasthen validated using measured data and scaled to a multi cylinder model. A 0D model, in theSimulink environment, was also developed together with the 1D model in order to compare theiruse in real time application. The 0D model represents a simple approach to engine modelling inorder to provide steady state performance prediction, assuming quasi-steady flow. The motivationbehind using such a model is that the predicted mean values of inlet and outlet pressure tracesprovide a more realistic reference parameter that can be used to control the boundary conditionsin the single cylinder engine. The turbine volute was also modelled in order to capture the dampening effect it has on thepulsating flow. Different turbine map extrapolation methods were also studied and physics basedalgorithms were used to extrapolate the turbine data. The turbine volute and its effects on theturbine performance have been discussed along with some thoughts on estimating the efficiencyof the turbine during unsteady flow conditions. These models were then calibrated and validatedagainst crank angle resolved cylinder pressures and cycle averaged parameters from measured dataobtained from the single cylinder test engine. The errors and deviations between the 0D and 1Dmodel as well as from the measured data were identified and discussed. A control algorithm usingthe Single cylinder 1D Boost simulation, as the plant model, was developed in order to control theinlet and exhaust pressures. The algorithms were then compared between 0D model and 1D modelfor evaluating the performance and accuracy.

<p>QC 20150611</p>

Due to growing concerns regarding global energy security and environmental sustainability it is becoming increasingly important to increase the energy efficiency of the transport sector. The internal combustion engine will probably continue to be the main propulsion system for road transportation for many years to come. Hence, much effort must be put in reducing the fuel consumption of the internal combustion engine to prolong a future decline in fossil fuel production and to reduce greenhouse gas emissions. Turbocharging and variable valve actuation applied to any engine has shown great benefits to engine efficiency and performance. However, using a turbocharger on an engine gives some drawbacks. In an attempt to solve some of these issues and increase engine efficiency further this thesis deals with the investigation of a novel gas exchange concept called divided exhaust period (DEP). The core idea of the DEP concept is to utilize variable valve timing technology on the exhaust side in combination with turbocharging. The principle of the concept is to let the initial high energy blow-down pulse feed the turbocharger, but bypass the turbine during the latter part of the exhaust stroke when back pressure dominates the pumping work. The exhaust flow from the cylinder is divided between two exhaust manifolds of which one is connected to the turbine, and one bypasses the turbine. The flow split between the manifolds is controlled with a variable valve train system. The DEP concept has been studied through simulations on three heavy-duty diesel engines; one without exhaust gas recirculation (EGR), one with short route EGR and one with long route EGR. Simulations show a potential improvement to pumping work, due to reduced backpressure, with increased overall engine efficiency as a result. Although, the efficiency improvement is highly dependent on exhaust valve size and configuration due to issues with choked flow in the exhaust valves. The EGR system of choice also proves to have a high impact on the working principle of the DEP application. Furthermore, the DEP concept allows better control of the boost pressure and allows the turbine to operate at higher efficiency across the whole load and speed range. The option of discarding both wastegate and variable geometry turbine is apparent, and there is little need for a twin-entry type turbine since pulse interference between cylinders is less of an issue. / <p>QC 20130108</p>

En konceptanalys för en tvärbalk med integrerad tryckluftstank byggd i fiberkomposit för en lastbil har tagits fram. Syftet har varit att reducera vikt samt spara utrymme. Arbetet har beställts av Scania och utförts som ett kandidatexamensarbete i Lättkonstruktioner vid KTH. De mekaniska, geometriska och funktionella kraven på balken har undersökts och definierats. För att uppnå krav på intern tryckluftsvolym och samtidigt klara de geometriska begräsningarna krävds ett elliptiskt tvärsnitt på balken. Ett koncept för förbandet mellan kompositmaterialet och lastbilens befintliga stålstruktur har tagits fram. Konceptet bygger på ett limförband där en ihålig kompositbalk med öppna ändar limmas mot en stålplatta via ett lim-flänsförband. Stålplattan i sin tur är skruvad mot lastbilens ramsidobalk. Trycktvärbalken har tryckluftsanslutning och möjlighet till dränering vid balkens kortsidor. För fiberkompositen har vinylester valts som matrismaterial tack vare dess mekaniska, termiska och ekonomiska fördelar. Kolfiber har valts som förstärkningsmaterial utifrån sin mycket höga specifika styvhet. Tillverknings-metoden för kompositdelen föreslås för små volymer vara filament winding och för större volymer pullwinding. Balkens ändstycken tillverkas förslagsvis genom gjutning. En FEM-analys på balken har gjorts för att verifiera att de mekaniska kraven är uppfyllda. Balken dimensioneras av sin torsionsstyvhet. Utmattningsberäkningar har inte genomförts. För att ta fram materialdata har provningar på en kolfiberskomposits mekaniska och kemiska egenskaper genomförts. Även hållsfasthetsprovning av strukturlim har genomförts. Slutgiltig totalvikt beräknas till 28,6kg, vilket ger en viktbesparing på 46% gentemot den befintliga stålbalken och trycktanken som idag har en totalvikt på 53kg. Trycktvärbalken har en intern luftvolym om 31 liter och kan därmed ersätta en 30 liters tryckluftstank. / A feasibility study of a cross-beam with an integrated pressure vessel built in fiber composite for a truck has been developed in order to reduce weight and save space. The project is commissioned by Scania. The mechanical, geometrical and functional requirements have been defined. To achieve the requirements of internal air volume and the geometrical limitations an elliptic cross-section of the beam is required. A concept for the joint between the composite material and the truck's existing steel structure frame has been developed. The concept is based on an adhesive joint where the hollow composite beam with open ends is glued in a flange joint to a steel plate. The steel plate is then bolted to the truck’s frame side. The beam has connections for compressed air and drainage located on the sides. Vinyl ester was chosen as matrix material because of its good mechanical, thermal properties and economical advantages. Carbon fiber was chosen as reinforcement material because of its strong specific mechanical properties. For smaller production volumes filament winding is proposed as manufacturing process for the composite part and for larger volumes pullwinding is proposed. The recommended manufacturing process for the steel plates is casting. A FEM analysis of the beam has been made to verify that the mechanical requirements are met. The beam is dimensioned according to its torsional stiffness. Fatigue calculations have not been performed. To obtain material data, a number of tests of the carbon fiber composite’s mechanical and chemical properties were carried out. Testing of adhesives has also been performed. The final total weight was calculated to 28.6 kg, resulting in a weight reduction of 46% compared to the current steel beam and pressure vessel with a total weight of 53kg. The pressure beam has an internal air volume of 31 liters and a 30 liter pressure vessel can be replaced.

No description available.

No description available.

Welding as high productive joining method is widely employed in automotive, aerospace and shipbuilding industries. In practice, welding distortion brings about undesirable effects on production accuracy, appearance and strength of welded components. Thus, in order to increase the productivity and decrease the cost of the product, prediction and analysis of welding deformation are key factors in industrial context. Distortion of a structure can be measured experimentally; whilst in case of large or complex structures it is expensive and also time consuming. Numerical analysis is then performed using finite element method (FEM) that reduces the cost; however, in case of large welded structure and considering extremely nonlinear mechanical behavior of welding the computational expense incurred which must be cut through elastic analysis. In this sense, the residual plastic strain, namely inherent strain as a source of residual stress and welding distortion should be analyzed. The purpose of this study is to detail the prediction procedure of deformation in welded structure by elastic finite element modeling using inherent strain method. As a matter of fact inherent strain as an inelastic permanent strain or residual plastic strain, which exists in vicinity of fusion zone, is responsible for welding deformation and residual stresses. Comparing with elastic plastic analysis, inherent strain method has less computing time however the state of welding may be not investigated in detail; Furthermore, appropriate assumption of inherent strain region and determining the accurate values of inherent deformations in each typical joint bring about some limitations. On the other hand, just the elastic modulus and Poisson’s ratio at room temperature is used in elastic FEM, and there is no need for temperature material properties. So, at the present time, thermal elastic plastic finite element method can be used to predict residual stresses and welding deformations in small or medium structures but for large components elastic FEM is promising method.

Extreme value behavior of a moored semi-submersible vessel is investigated. There is a need for alternative methods other than the Rayleigh peak model when investigating non-Gaussian processes. In this context the Rayleigh peak model will generally underestimate extreme values. Four methods are investigated in this study with data from 1000 seeds. They are; construction of an empirical cumulative distribution function, mean of maximas, a LF/WF spectral partition and peak distribution tail tting. In turn six peak distributions are investigated. It was found that global motions are more sensitive than point accelerations to estimation errors, and the more accurate methods should be applied to global motions. A tted Weibull peak distribution proved to be the most conservative for both MPM value and 90 th percentile estimations. It was also found that a mean of 10 maxima was a good estimation of a MPM value. Longer seeds than three hours are recommended in order to include higher maxima and lower minima. Further comparison studies are recommended.

The focus of today’s automotive industry is to reduce emissions and fuel consumption of all vehicles. Concentrating on the truck industry, the last 20 years have focused largely on cutting emissions of particulate matter and nitrogen oxides. For the future, attention will be focused on fuel consumption and emissions of carbon dioxide. Waste heat recovery appears to be a very promising concept for fuel economy on long haul heavy duty Diesel trucks. After a general introduction on the concept of waste heat recovery and the Rankine cycle, this thesis work shows how to model and calibrate a cooling system circuit for a heavy duty Diesel engine equipped with a waste heat recovery system. Then an overview of the current transmission systems that are suitable to transfer energy from the waste heat recovery expander to the engine shaft is presented. For all transmission architectures, input speed range, speed ratio range, transmission efficiency as well as weight and size are detailed and compared to each other. Finally, these systems are modeled and integrated to a complete vehicle Simulink simulation platform and simulations are run on two highway driving cycles. Resulting average recovered powers and fuel consumptions are compared and the analysis finally shows that a gear train transmission has the best performance for this kind of driving cycle.

It is the objective of this thesis project to understand the physics behind the different modes of bird flight and to do numerical two dimensional simulations of pure plunging, pure pitching and combined pitch-plunging motion of an aerofoil. First, the different physical models used to understand the generation of thrust are explained. Then the numerical model used for the simulation is explained briefly. Then the results and analysis of the numerical simulations are presented.