The aerodynamic team at SCANIA has discovered the need to investigate the effect of the upstream turbulence conditions on the aerodynamics of the trucks. This need comes from the fact that there are differences between the drag coefficients obtained using computational fluid dynamics (CFD) and the on-road measurements. This difference can lead to wrong predictions of fuel consumption and emissions, which can cause incorrect evaluation of design changes. In this study the problem of modeling upstream turbulence in CFD simulations is addressed together with its effect on the aerodynamics of the trucks. To achieve this, representative values of turbulence intensity and length scale were found from the work of different researchers, who performed on-road measurements for various conditions. These values were then used in a method by Jakob Mann to generate a synthetic turbulence field. This field was then used to generate time varying velocity components, added to the mean velocity at the inlet of a CFD simulation. After the implementation of the method it was discovered that the conditions at the test section of the virtual wind tunnel were representative of the on-road measurements. The results showed drag increase and wake length decrease, similar to previous studies performed on simple geometries. It also showed that the higher mixing of the flow increases the drag by surface pressure increase of forward facing surfaces and pressure decrease at the base. These conclusions may be extended to other bluff body geometries and it shows the importance of good design around gaps. The comparison between two truck geometries showed that a truck with better aerodynamics in a smooth flow shows less drag increase with introduction of upstream turbulence.

A park lock mechanism is a device that is fitted to an automatic transmission on a vehicle. The mechanism lock up the transmission so that no rolling of the vehicle can be done when the vehicle is put in the park position. The aim of this thesis is to develop a method in order the evaluate designs on a Park Lock Mechanism (PLM) that can be found in a dual clutch transmission (DCT). A Computer Aided Engineering (CAE) tool to calculate the output that is required for an evaluation of a park lock mechanism design will be created. The CAE tool shall calculate static, dynamic, and snap torque on a ratchet wheel in a gradient, with or without a trailer, also the minimum and maximum coefficient of friction between the pawl and cone, pull out force, the maximum amount of rollback, torque needed from the return spring, preload force from actuator spring, and engagement speed. The CAE tool created uses an Excel Visual Basics for Applications (VBA) workbook for all calculations. The tool allows the user to choose different vehicles with the required specification to evaluate the values for that PLM. The CAE tool will save time and cost if lots of different PLM’s are going to be designed. The CAE tool has potential for future work when more calculations can be added that can be in use for the evaluation the PLM. The CAE tool developed by the master thesis student calculates all the required values for evaluation of a PLM design, executed in a fast, efficient, and easy to use program.

The main objective of this Master Thesis project is the development of a new methodology to perform Computational Fluid Dynamics (CFD) conjugate heat transfer simulations for internal combustion engines, at the Fluid and Combustion Simulations Department (NMGD) at Scania CV AB, Södertalje, Sweden. This new method allows to overcome the drawbacks identified in the former methodology, providing the ability to use the more advanced polyhedral mesh type to generate good quality grids in complex geometries like water cooling jackets, and integrating all the different components of the engine cylinder in one unique multi-material mesh. In the method developed, these advantages can be used while optimizing the process to perform the simulations, and obtaining improved accuracy in the temperature field of engine components surrounding the water cooling jacket when compared to the experimental data from Scania CV AB tests rigs. The present work exposes the limitations encountered within the former methodology and presents a theoretical background to explain the physics involved, describing the computational tools and procedures to solve these complex fluid and thermal problems in a practical and cost-effective way, by the use of CFD.A mesh sensitivity analysis performed during this study reveals that a mesh with low y+ values, close to 1 in the water cooling jacket, is needed to obtain an accurate temperature distribution along the cylinder head, as well as to accurately identify boiling regions in the coolant domain. Another advantage of the proposed methodology is that it provides new capabilities like the implementation of thermal contact resistance in periodical contact regions of the engine components, improving the accuracy of the results in terms of temperature profiles of parts like valves, seats and guides. The results from this project are satisfactory, providing a reliable new methodology for multi-material thermal simulations, improving the efficiency of the work to be performed in the NMGD department, with a better use of the available engineering and computational resources, simplifying all the stages of multi-material projects, from the geometry preparation and meshing, to the post-processing tasks.

The high demands on low fuel consumption and low emissions on the combustion engines of both today, and the future, is highly dependent on advanced control systems in order to fulfill these demands. The control systems and strategies are based on models which describe the physical system. The more accuratly the models describe the real world system, the more accurate the control will be, leading to better fuel economy and lower emissions. This master's thesis investigates and improves the mass flow model used for a compressible restriction, such as over the throttle valve, EGR valve, or the wastegate valve, for example. The standard model is evaluated and an improvement is proposed which does not assume isentropic flow. This seems to explain the deviation from the isentropic Psi-function shown in earlier research such as (Andersson:2005). Furthermore a throttle valve is analyzed in ANSYS in order to show the generation of entropy. The presence of pressure pulsations in a combustion engine is also evaluated, especially how they effect the otherwise assumed steady flow model. It is tested if a mean value pressure is sufficient or if one needs to take the pulsations in to account, and the result shows that a mean pressure is sufficient, at least for the throttle when typical intake manifold pulsations is present. A dynamic flow model is also derived which can be useful for pressure ratios close to one. The dynamic flow model is based on the standard equation but with an extra dynamic term, however it is not implemented and tested due to complexity and time limitation. The proposed new non-isentropic flow model has proven promising and can hopefully lead to lower emissions and better fuel economy.

Automotive manufacturers currently face a challenge with expeditious enhancement of the vibro-acoustic properties of their vehicles. A major reason for this setback is the limited design information available during initial development stages added with limited knowledge of damping within complex structures. It is now well established that CAE studies of vibration energy flow show good correlation between power flowing into trimmed body and the interior noise produced. Aim of the dissertation is to harness this "good" correlation between power input and interior noise, by learning about the changing behaviour of system in different suspension damping scenarios. It investigates how the mechanical power input to body from suspension, interior road noise produced, and their relation is affected by changing the way damping is modelled into suspension. This is being done to make stronger design decisions from NVH point of view during the concept phases of vehicle development. The investigation is for vehicle programs during early development phases, and hence a simplified vehicle CAE model was chosen, that contains a trimmed body with cavity fluid, and wheel suspension to capture all relevant effects of varying damping. Then, a detailed flowchart of suspension and trimmed body connections was prepared to understand how power flows into the trimmed body through suspension. Using results of power flow study, the most relevant paths and their frequency ranges were identified (to reduce the number of parts in study, yet results relevant and easily extrapolatable to a larger system). Lastly, responses are analyzed for various damping cases of suspension and trimmed body.  Results obtained show a reducing trend in mechanical input power and interior noise values with increasing damping in system. Whereas, for good correlation between power and noise, a great inclination towards structural damping localized into bushings is observed compared to other damping cases. Additionally, a strong dependency of noise, active power and reactive power is observed on trimmed body and cavity fluid damping. Active power is reduced when trimmed body damping is decreased to zero, and more so when cavity fluid damping is put to zero. On the other hand, noise and reactive power have an exact opposite correlation compared to active power and noise. These results suggest that although active mechanical input power is the cause of interior noise, their correlation starts to deteriorate with reducing damping within the system, and instead it is the reactive power that starts to correlate better at very low damping values. But, it is physically impossible to have no damping or very low damping, so a modelling of damping within suspension that provides relatively better correlation between (active) input power and noise is when structural damping is localized within connectors.

Fatigue failure is one of the most critical issues in industry nowadays as 60 to 90 percent of failures in metals are due to fatigue. Therefore, different methods and approaches are developed to estimate the fatigue life of metallic parts. In this research, a case-hardened steel splined shaft is studied to estimate the fatigue life that the shaft will withstand before failure. The purpose of the research is to develop an advanced fatigue prediction method for splines.A static experimental test was performed on the splined shaft for analyzing the load-strain behavior of the shaft and determining the suitable load cases of the study. A dynamic test of pure torsional load was carried out to collect experimental results for validating the generated fatigue methods and investigating the failure behavior of the shaft. Stress analysis was performed on the part for investigating critical areas and the effect of the different spline teeth designs on the resulting stress. Two finite element models were analyzed using two software, MSC Marc software with a geometry of straight spline teeth and Spline LDP with an involute spline teeth model. DIN 5466-1 spline standard’s analytical solution was used for verification purposes. Stress and strain-based approaches were used to estimate fatigue life. The most suitable method was evaluated against experimental test results.The research findings show that the most critical stress areas on the shaft are the spline root fillet and relief. When the part fails due to fatigue the crack initiates at the root fillet and propagates to the relief. It is also shown that involute teeth spline gives higher stress than straight teeth for the same load due to less contact area.The conclusion of the research could be summarized in: the stress-based method (Wöhler curve) is giving good accuracy and proved a reliable method. While among six different approaches used of strain-based methods, four-point correlation method is giving the best correlation to test results. Hence, it is recommended to use four-point correlation method for fatigue analysis for its accuracy and for considering both elastic and plastic behavior of the material.

The turbocharger is an important component of competitive environmentally friendly vehicles. Mathematical models are needed for controlling turbochargers in modern vehicles. The models are parameterized using data, gathered from turbocharger testing ingas stands (a flow bench for turbocharger, where the engine is replaced with a combustion chamber, so that the exhaust gases going to the turbocharger can be controlled with high accuracy). Collecting the necessary time averaged data is a time-consuming process. It can take more than 24 hours per turbocharger. To achieve a sufficient level of accuracy in the measurements, it is required to let the turbocharger system reach steady state after a change of operating point. The turbocharger material temperatures are especially slow to reach steady state. A hypothesis is that modern methods in control theory, such as numeric optimal control, can drastically reduce the wait time when changing operating point. The purpose of this thesis is to provide a method of time optimal testing of turbo chargers.  Models for the turbine, bearing house and compressor are parameterized. Well known models for heat transfer is used to describe the heat flows to and from exhaust gas and charge air, and turbocharger material, as well as internal energy flows between the turbocharger components. The models, mechanical and thermodynamic, are joined to form a complete turbocharger model, which is validated against measured step responses. Numeric optimal control is used to calculate optimal trajectories for the turbo charger input signals, so that steady state is reached as quickly as possible, fora given operating point. Direct collocation is a method where the optimal control problem is discretized, and a non-linear program solver is used. The results show that the wait time between operating points can be reduced by a factor of 23. When optimal trajectories between operating points can be found, the possibility of further gains, if finding an optimal sequence of trajectories, are investigated. The problem is equivalent to the open traveling salesman, a well studied problem, where no optimal solution can be guaranteed. A near optimal solution is found using a genetic algorithm. The developed method requires a turbocharger model to calculate input trajectories. The testing is done to acquire data, so that a model can be created, which is a catch-22 situation. It can be avoided by using system identification techniques. When the gas stand is warming up, the necessary model parameters are estimated, using no prior knowledge of the turbocharger.

Ship exhausts contain high levels of sulphur oxides, nitrogen oxides, carbon dioxide and particles dueto the heavy fuel oil, HFO, used for combustion and the combustion characteristics of the engine.As a result of upcoming stricter regulations for shipping pollution, as well as growing attentionto greenhouse gas emissions, air pollution and uncertainty of future petroleum oil supply, a shifttowards a cleaner burning fuel is needed.This work explores potential alternative fuels, both conventional and unconventional, and abatementtechnologies, to be used by tankers in the worldwide spot market to comply with upcomingenvironmental regulations in the near and coming future. As a reference the product tanker M/TGotland Marieann is used and recommendations for which fuel that shall be used by the referenceship in 2015 and 2020 are presented.The environmental assessment and evaluation of the fuels are done from a life cycle perspective usingresults from Life Cycle Assessment, LCA, studies.This study illustrates that, of the various alternatives, methanol appears to be the best candidatefor long-term, widespread replacement of petroleum-based fuels within tanker shipping. It does notemit any sulphur oxides nor particles and the nitrogen oxides are shown to be lower than those ofmarine gas oil, MGO. The global warming potential of the natural gas produced methanol is notlower than that of MGO, but when gradually switching to bio-methanol the greenhouse gas emissionsare decreasing and with methanol the vision of a carbon free society can be reached.For 2015 a switch towards methanol is not seen as realistic. Further research and establishment ofregulations and distribution systems are needed, however there are indications that a shift will bepossible sometime between 2015 and 2020. For 2015 a shift towards MGO is suggested as it involveslow investment costs and there is no need for infrastructure changes. As MGO is more expensivethan methanol, a shift is preferable as soon as the market, technology and infrastructure are ready.

In order to replace diesel energy in the transportation sector as well as to reduce the emission of green house gases (GHGs) and avoid air pollution for a sustainable future, electrification of vehicles is one of the most popular topics today. Plug-in hybrid electric vehicle (PHEV) technology is a promising technology for electrification of automobiles. It uses both internal combustion engine and electric motor for propulsion. The battery pack that propels the electric machine can be recharged from grid electricity and from kinetic energy converted from regenerative braking. In this thesis, field test data from a Volvo V70 prototype in a 2010 study by Volvo and Vattenfall (ETC, Volvo, Vattenfall, 2010) was analyzed with Matlab to give a better understanding of the usage of PHEVs and the performance of lithium-ion battery. Several conclusions were obtained in this thesis from the analyzed data. It was found that average and maximum driving speed in Diesel Mode is faster than that in Electric Mode. Different drivers had different preference of driving speed. Driving distance vary in different months; longer distance was running under Diesel Mode; A considerable number of 370 kg carbon dioxide emission was saved by using electric energy instead of diesel energy for the studied car during one year. Battery performance in cold temperature conditions needs to be considered and the vehicle was switched to Diesel Mode from Electric Mode when SOC falls below 30%.

This thesis presents the work done to implement new computational tools and methods dedicated to aircraft conceptual design sizing and optimization. These tools have been exercised on different aircraft concepts in order to validate them and assess their relevance and applicability to practical cases. First, a geometry construction protocol has been developed. It is indeed essential to have a geometry description that supports the derivation of all discretizations and idealizations used by the different analysis modules (aerodynamics, weights and balance, stability and control, etc.) for which an aircraft concept is evaluated. The geometry should also be intuitive to the user, general enough to describe a wide array of morphologies and suitable for optimization. All these conditions are fulfilled by an appropriate parameterization of the geometry. In addition, a tool named CADac (Computer Aided Design aircraft) has been created in order to produce automatically a closed and consistent CAD solid model of the designs under study. The produced CAD model is easily meshable and therefore high-fidelity Computational Fluid Dynamics (CFD) computations can be performed effortlessly without need for tedious and time-consuming post-CAD geometry repair.Second, an unsteady vortex-lattice method based on TORNADO has been implemented in order to enlarge to scope of flight conditions that can be analyzed. It has been validated satisfactorily for the sudden acceleration of a flat plate as well as for the static and dynamic derivatives of the Saab 105/SK 60.Finally, a methodology has been developed to compute quickly in a semi-empirical way the buffet envelope of new aircraft geometries at the conceptual stage. The parameters that demonstrate functional sensitivity to buffet onset have been identified and their relative effect quantified. The method uses a combination of simple sweep theory and fractional change theory as well as the buffet onset of a seed aircraft or a provided generic buffet onset to estimate the buffet envelope of any target geometry. The method proves to be flexible and robust enough to predict within mainly 5% (and in any case 9%) the buffet onset for a wide variety of aircrafts, from regional turboprop to long-haul wide body or high-speed business jets.This work was done within the 6th European framework project SimSAC (Simulating Stability And Control) whose task is to create a multidisciplinary simulation environment named CEASIOM (Computerized Environment for Aircraft Synthesis and Integrated Optimization Methods), oriented toward stability and control and specially suited for aircraft conceptual design sizing and optimization. / QC 20101104 / SimSAC