A combustion engine generates a lot of heat which need to be cooled to prevent damages to the engine and the surrounding parts. If the cooling system can not provide enough cooling to keep the engine in a well defined range of temperatures performance and durability will decrease and emissions increase. It is also important that the cooling system do not over-cool the engine, since this may result in rough running, increased engine friction and an overall negative performance. The aim of this thesis work is to create a complete 3D digital model of the cooling system for the first generation VED4 HP with CFD in STAR-CCM+. The simulated results are compared to available experimental data for validation. Today the entire system is being modeled with 1D CFD. One of the selected components in the cooling system being model in 3D at Volvo Cars is the water jacket. The 3D CFD model depends on the 1D CFD model for the boundary conditions which is an ineffective and time consuming process, sending data back and forth between the models when making changes. A 3D CFD model is not only more accurate than the 1D CFD model, since it capture the 3D flow phenomenas but it also allows parts or areas to be studied in detail. A study of four different turbulence models is conducted on the water jacket and on an arbitrary pipe in the cooling system. A mesh study is carried on the water jacket, the same arbitrary pipe and on the thermostat, both for the opened and closed thermostat. These studies are done with regard to pressure drop only. The study yields a low Reynolds model with the k-ε v2f turbulence model gave the best results. There is a discrepancy between the simulated results and the experiments. Main reasons to this may be the difference in the geometry used in this thesis for the digital model and the geometry used for the experiments together with the inaccuracies in the experimental data. The overall deviation is larger for a case with closed thermostat than for a case with an open thermostat. With the correct geometry and more accurate experimental data the simulations should be a close representation of reality.

The work presented in this dissertation was carried out at the Division ofMechanics, Department of Management and Engineering at Link¨oping University,between 2003 and 2008. It was supervised by Prof. Anders Klarbring,head of the division, and financially supported by the National GraduateSchool of Scientific Computing (NGSSC) and the Swedish Research Council(VR). There are many people to whom I would like to express my gratitude: firstand foremost I would like to thank my supervisor Prof. Anders Klarbring forhis help, support and endless patience during our discussions, and for alwayshaving time to read and comment on the numerous drafts that eventually ledto the research manuscripts presented in this thesis. I would also like to thankmy co–supervisor Dr. Thomas Borrvall for all his help regarding numericalissues, especially with the implementation of the models. Moreover, I wouldlike to thank present and former colleagues for their inspiration and assistanceduring my time as a graduate student at the division. Last but not least, I am very grateful for having a family that has alwaysbeen there to support me, and for all my friends who enrich my life outsidethe office walls in more ways then I can say.

More and more vehicles are being electrified. Mobile working machines and heavy trucks are not excluded, and these machines are often hydraulically intense. Electrification entails new requirements for the hydraulic system and its components, and these requirements must be taken into consideration. Hydraulic systems have looked similar for a long time, but now there is an opportunity to advance. Many things change when a diesel engine is replaced with an electric motor. For example, variable-speed control becomes more relevant, electric regeneration becomes possible, and the use of multiple prime movers becomes an attractive alternative. The noise from the hydraulic system will also be more noticeable when the diesel engine is gone. Furthermore, the introduction of batteries to the system makes the energy more valuable, since batteries are heavy and costly compared to a diesel tank. Therefore, it is commercially viable to invest in the hydraulic system. This thesis revolves around the heart of the hydraulic system, that also is the root of all evil. That is the pump. Traditionally, a pump has had either a fixed displacement or a continuously variable displacement. Here, the focus is on something in between, namely a pump with discrete displacement. The idea of discrete displacement is far from unique, but has not been investigated in detail in combination with variable speed before. In this thesis, a novel design for a quiet pump with discrete displacement is presented and analysed. The results show that discrete displacement is relevant from an energy perspective for machines working extensively at high pressure levels and with low flow rates, and that a few discrete values are enough to make a significant difference. However, for other cycles, the possible energy gains are very limited, but the discrete displacement can be a valuable feature if downsizing the electric machine is of interest.

With the increasing reliance and use of sensors to improve the capabilities of modern road vehicles, ensuring their functionality during different weather conditions has become an important design consideration. The sensing equipment is utilized for a multitude of tasks, ranging from aiding the user with parking to avoiding potentially dangerous situations. If the sensory equipment's functionality is compromised, these additional features might fail. Various solutions are used to ensure the integrity of the sensing equipment, primarily the location of the sensor is chosen to minimize contamination. However, in certain situations, exposure to contaminants cannot be avoided, and active cleaning systems are utilized to mitigate the issue. These systems often contain some sort of cleaning nozzle that sprays liquid onto the sensor in question.  At Volvo Cars Corporation (VCC), the group of Contamination & Core CFD is responsible for assessing the vehicle performance when exposed to contamination, such as rain, snow, or dust. This task is accomplished by employing tools such as computational fluid dynamics (CFD), and experiments. In the first part of this thesis, physical tests were conducted in the VCC wind tunnel to assess the performance of a cleaning nozzle mounted on a side-view mirror at different vehicle speeds. With the knowledge gained during the experiments, the second part of the thesis focused on the development of a cost-effective computational method that could be used to evaluate the cleaning performance virtually. The novel computational method utilized a hybrid approach, including volume of fluid simulations, discrete particle modeling, and Eulerian wall film modeling. Different analysis tools and approaches were used to extract quantitative information from the inherently qualitative data obtained from the experiments, which was then compared against the results from the computational method. The computational method was evaluated for different incoming wind velocities, and three metrics were compared to investigate if any could predict the cleaning performance seen in the experiments. At low incoming wind velocities, an accumulated film mass metric exhibited a good correlation with the experimental data. However, at higher wind speeds, an accumulated film momentum metric showed the closest correlation.

The turbomachinery related industry relies heavily on numerical tools for the design and development of modern turbomachines. In order to be competitive turbomachines ought to be highly efficient and robust. This has lead engineers to develop more aggressive designs, which often leads to lower margins of structural reliability.  One of the strongest threats to turbomachines are high cycle fatigue problems which arise from aeroelastic phenomena such as flutter. According to Kielb R. (2013) many of such problems are detected at developing testing stage. This implies that the prediction capabilities for aeroelastic phenomena are in need of further development and/or tuning. This is especially evident for unsteady flow phenomena at transonic regimes. A very important step for the improvement of unsteady aerodynamic solvers is the validation and comparison of such solvers. The present thesis concerns with the validation and comparison of a non-linear time marching (ANSYS CFX) and the GKN’s in-house linearised solvers used for flutter analysis. The former has recently implemented a new feature called Transient Blade Row TBR, which drastically reduces the simulation domain to a maximum of two blades.  In order to be included in the deign process, such tool need to be validated. In the same way, the recently launched in-house code LINNEA needs to be validated in order to be considered as a design tool. Experimental data from the aeroelastic standard configuration 4, and the FUTURE project were used for the validation purposes. The validation process showed that the solvers agreed very well between them for the standard configuration. Such agreement was less clear for the FUTURE compressor; nonetheless, the solutions still sit within the bulk of solutions provided from the different FUTURE partners. The validation showed that these tools provide with similar results as the state of the art tools from different companies. This indicates that they can be used in the design process. At the same time it was observed that there is room for improvement in the solvers, as these still present some considerable differences with the experimental results.

Material damping in a structure is well defined and documented. However, dissipation due to mechanical contact (surface contact) in a complex built-up structure is not as well represented, in particular in large scale noise and vibration simulations. The present work is dealing with the understanding of the physical behaviour of losses that take place at such complex interfaces. The objective is to investigate, if, these mechanical loss phenomena can be modelled using linear response simulation techniques and implemented using commercially available finite element software. In a first step, the losses at the interfaces were experimentally investigated using an experimental setup capable of in-vacuo conditions. Following this, the second step was aimed at different ways of representing the proposed boundary conditions in a linear response simulation of a built-up structure. Two different approaches were studied, one using a continuous surface approach and one using a discrete element method. / <p>QC 20120424</p>

The structural damping is of importance to suppress the vibration amplitude of compressor blades rotating at high angular velocity under a high cycle impact. To avoid the appearance of the high cycle fatigue (HCF), damping materials may be applied to the compressor blades. To quantify the effect while using damping materials, a numerical tool needs to be developed for the damping prediction of a dynamic rotating blade. This thesis is divided into two parts: Paper A develops a dynamic model of a rotating blade and Paper B a damping structure model including measurements. In Paper A, a dynamic rotating blade model is developed by using a plate model at an arbitrary stagger angle. Hamilton’s principle is applied to derive a system of equations of motion and the corresponding boundary conditions. Numerical simulation is implemented to perform eigenfrequency analysis by the Extended Galerkin method. In addition, parametric analysis is performed with respect to rotation speed and stagger angle, respectively. Results show a good agreement with those of the finite element method. Finally, forced response analysis is determined for two cases; a point force and a distribution force, using a proportional damping model. In Paper B, unconstrained and constrained damping techniques are applied to increase the structural damping of the blades, including measurement and modeling results. Two specimens, titanium and stainless steel, are treated by aluminum oxide and epoxy coating material. Measurement results show that both treatments give damping increase, where aluminum oxide is more effective for damping improvement than the corresponding epoxy treatment. The unconstrained damping layer model is used to predict the total material damping of the combined structure as well as the material damping of coating layer. Furthermore, the constrained-layer model is used to optimize the damping configuration. Two compressor blades in titanium and stainless steel are tested in air and vacuum. One reason is being that the radiation loss factor increases the total damping comparing with that under vacuum condition. The calculation of radiation loss factor is performed to match the measurement data. Finally, increased material damping decreases peak stress and therefore increases the life time of the compressor blades. / <p>QC 20110311</p>

The production processes of porous materials introduce an inherent geometric anisotropy in the material at micro scale, which influences the material properties at macro scale. In this thesis, the focus is turned to one of these macroscopic properties, the flow resistivity, which is a measure of the resistance felt by the sound pressure waves as they propagate through a porous space. In the current work, two different porous materials have been studied, a fibrous glass wool and a Melamine foam. The two materials are expected to show different degrees of anisotropy with respect to flow resistivity. Glass wool is assumed to be transversely isotropic, as a result of the stacking of layers of fibres. The level of anisotropy in Melamine foam is not as obvious, and might be related to production specific aspects, such as the rise-direction, and the position of the injection nozzles. The thesis begins by giving an introduction to porous materials in general, and to glass wool and Melamine foam in particular, followed by an introduction to flow resistivity, together with two methods to measure the flow resistivity. The full anisotropic flow resistivity of glass wool and Melamine foam samples is determined by means of measurements and inverse estimation. An eigenvalue and eigenvector decomposition of the flow resistivity tensor provides an insight into the connection between the directionality of the flow resistivity in each material, and its production process. A study of the homogeneity in density and flow resistivity for the two materials shows that these properties vary within the block of material. However, for each material, there seems to be no connection between the variation in the two properties, investigated at the macroscopic scale. / QC 20110311

Numerical modeling of cavitation using computational software is a highly pursued topic of research due to its impact in different industrial sectors. While some industrial applications such as wastewater treatment and mineral processing are known to advantageously use this phenomena, it remains an unwanted process in others where it is known to induce vibration, reduce performance and cause structural damage. The main objective of the current research study is to investigate the accuracy to which cavitating flow behavior inside oil-hydraulic systems can be computationally modeled, what limitations exist and how to improve numerical predictions. An experimental test-rig has been built in the preceding years with plexiglass tube to observed the vapor formations during cavitation and the pressure readings at three points have been recorded. The current study uses a computational model with the same geometry as the experimental test-rig, and uses the experimentally recorded pressure values for validating numerical results. Two main software are used to setup the simulation framework. The first is Hopsan, one open source simulation software for hydraulic systems developed by Link\"oping University and the second is ANSYS Fluent, a commercial software for modeling complex fluid flow applications. Four different orifices are used to create different outlet pressures. For orifices of diameter 2 mm, 3 mm, and 5 mm, good correlation between numerical and experimental results were observed. Further investigations into complex cavitating flow behavior of repetitive water hammers were also carried out. Different valve profile movements were used to investigate what the impact of having and not having vapor bubbles in the plexiglass tube would have on the pressure distribution when oil starts to re-circulate in the system. Furthermore, repetitive water hammer flow behavior for oscillations of 2, 3, and 4 water hammers were investigated. This investigation revealed several important findings.  The first is that if valve opens to the point that the flow starts to re-circulate in the system while vapor bubbles already exist in the plexiglass tube, massive pressure peaks, as high as 350 bar, will be created in the plexiglass pipe. The strength of this pressure surge will be dependent on the amount of vapor in the pipe when flow is re-introduced. The second is that if the valve starts to re-open (move backwards) while no vapor exists in the plexiglass tube, this movement will result in the formation of vapor. However, this vapor only lasts for a small duration and disappears before the valve reaches a point that allows flow move again. The third and final finding for repetitive water hammers was that the strength of the pressure surges will reduce with each sequential water hammer.

Internal combustion engines has been used for more than 100 years. The use of the abundant energy supply stored as hydrocarbon fueled unprecedented economic growth. The use of hydrocarbons increased the work output of human labor significantly, thus increasing the economy and prosperity. However, during the latter part of the twentieth century negative consequences of the internal combustion engine has been noticed. Initially the being emissions of local pollutants such as carbon monoxide, nitrogen oxides and unburnt hydrocarbons. These pollutants have to this day in the western world been reduced significantly and further reductions are under way. Thereafter, has the focus been shifted somewhat to global emissions such as carbon dioxide due to the effect on the climate. However, as the most accessible oil resources have been exhausted the price of oil has five folded since the turn of the century, straining the exponential economic growth enjoyed for two centuries. Heavy duty diesel engine efficiency is still below 50\%, there is thus a need and a possibility to further increase engine efficiency. In this thesis, work has been done to increase the understanding of the flow prior to combustion. A better knowledge of pre-combustion in-cylinder flow would increase the possibility to reduce engine emissions and fuel consumption, through better mixing and lower heat transfer. The work presented is ordered in such a way that the flow structures created during the intake is presented first. Thereafter, the effect of compression is investigated. Intake flow structures are studied using Large-Eddy Simulations (LES) and experiments on a steady swirl test rig. The effects of compression are studied using simulations of predefined flow structures undergoing compression. It is found that the flow structures created during intake is qualitatively different depending of intake valve lift. And that a single Swirl Number (SN) is an insufficient quantity to characterize the flow created at low valve lifts, due to high fluctuations. During compression it is found that a high swirl number suppress small scale turbulence while the compression has an increasing effect of axial fluctuations due to vorticity-dilation interaction. Additionally, it is shown that turbulent kinetic energy is introduced in the flow field by the piston in the absence of tumble breakdown. / <p>QC 20130704</p>