The aim of this thesis is to increase engine efficiency by studying the flow structures created in an engine cylinder during the intake phase and the effect of the subsequent compression. The invention of the combustion engine has enabled three centuries of economic growth fueled by energy stored as hydrocarbons. However, during the latter part of the twentieth century negative consequences on health and environment of the combustion engine were observed. In order to reduce emissions without increasing fuel consumption, improved knowledge of all physical processes occurring in the engine are necessary. The aim of this thesis is to increase the understanding of the flow prior to combustion, which can lead to reduced engine emissions and fuel consumption. Intake flow structures are studied using large eddy simulations and experiments on a steady swirl test rig. Flow acceleration was observed to reduce the swirl coefficient, and higher swirl coefficient was found during valve closing as compared to during valve opening. This implies that the rotation is stronger during the later part of the intake then what has been previously assumed. In addition, the computations show that the volume above the valves has a profound effect on the swirl created during the intake. To take this into account a novel way of calculating the swirl number was suggested. This approach gives a lower swirl number as compared to the commonly used Thien methodology. The effects of compression are studied using simulations of predefined flow structures undergoing compression. The peak turbulence levels were found to be increasing with tumble number and decreasing with swirl. It was noted that compression increased the turbulent fluctuations in the cylinder axis leading to anisotropic turbulence and that a small tilt angle was observed to have a significant effect on swirl homogeneity at top dead center.  In this thesis, a new methodology was proposed and validated for calculation of in-cylinder turbulence for a flat piston. The results of the thesis enhance the understanding of the dynamic effects encountered during intake as well recognizing that a small tumble component has a strong effect on the flow structures prior to combustion. These results can be used to improve the simplified computational methods used to optimize the engine. / <p>QC 20150420</p>

Traditional 2-D contour models, Physical Models, Computer-Aided Architectural Design (CAD), Virtual Reality models, Google SketchUp, and Building Information Modelling (BIM) have all greatly enhanced the design process by enabling designers to visualise buildings and the space within them prior to their construction. A recent development is Massively Multiplayer Online Games (MMOG) such as Second Life (SL). These offer users the opportunity to interact with other participants in real time, and so offer an excellent opportunity to experience the environment, layout and form of virtual buildings. However, the effectiveness of such applications to some extent depends upon how realistic the interactions of those using virtual spaces are in relation to interactions within the real world. This research examines the potential of this technology for enhancing and informing the early stage building design process. Initially, the tools currently used by architects at early stages of the RIBA Plan of Work were evaluated through interviewing architects. Then, the advantages of using MMOG over current tools at early-stage design were evaluated through interviews in SL. A virtual model was developed to examine how realistic the visualisation and interaction between end-users in an MMOG was. This was used to propose and validate guidance to incorporating MMOG into the early stages of the RIBA Plan of Work. It revealed that the virtual model created, the validated guidance and a successful example combining 2D sketches, Google SketchUp and MMOG at early-stage design can be used to guide architects to manage the complex decision making process in a simple, easy, cost-effective way, while effectively engaging both professional and non-professional stakeholders.

<p>One of the major challenges in the field of internal combustion engines is keeping up with the advancements in electrification and hybridization. Automakers are striving to design environment – friendly and highly efficient engines to meet stringent emission standards worldwide. Improving engine efficiency and reducing heat losses are critical aspects of this development. Therefore, accurate heat transfer prediction capabilities play a vital role in engine design process. Current methods rely on computationally intensive 3D numerical analyses, there is a growing interest in reliable simplified models. </p> <p>In this study, a 1D diesel engine model featuring predictive combustion was integrated with a detailed finite element thermal primitive based on the 3D meshing feature available in GT Suite. Coolant and oil hydraulic circuits were incorporated in the model. The model proves to be an effective means to assess the impact on heat rejection and engine heat distribution given by an engine calibration and operating conditions. </p> <p>This work also contributes to the advancement of virtual IC engine development methods by focusing on the design and tuning of complex engine system models using GT Power for accurate prediction of engine performance. The current processes in engine simulations are assessed to identify sources of errors and opportunities for improvements. The methods discussed in this work include isolated sub system level calibration and model evolution specifically address the issue of identifying noise factors and issues in smaller parts. Additionally, the study aims on improving the model’s trustworthiness by computing 1st law sanity checks, replicating real-life compressor map calculations and refining GT’s existing global convergence criteria. </p>