Examensarbeten för masterexamen


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  • Post
    Extra High Tensile Steel Applications for RoPax ferries
    (2024) Ribeiro Da Silva Mangas Pereira, Ana Carolina; Chalmers tekniska högskola / Institutionen för mekanik och maritima vetenskaper; Chalmers University of Technology / Department of Mechanics and Maritime Sciences; Li, Zhiyuan; Li, Zhiyuan
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    Iliac wing fracture from lap belt loading
    (2024) Bhat, Shreeraksha Umapathi; Chalmers tekniska högskola / Institutionen för mekanik och maritima vetenskaper; Chalmers University of Technology / Department of Mechanics and Maritime Sciences; Iraeus, Johan; Brynskog, Erik; Pipkorn, Bengt
    Autonomous cars are expected to increase in the near future and one of the features of those cars is to ride reclined as the driving task is managed by the vehicle. In the reclined posture the occupant will have a more horizontal torso position. With the current 3- point seatbelt it is more difficult to control torso body motion in reclined postures compared to upright postures and the risk of submarining may also increase. Submarining is an event where the pelvis slips under the lap belt and loads the abdomen instead of the pelvis. There are different techniques to avoid submarining and one of them is to increase the pre-tension force in the lap belt. This avoids the risk of submarining but instead, the risk of iliac wing fracture increases due to the higher pelvis load. Recently experiments on isolated iliac wings have been performed,with the intention to find the fracture load. In this thesis, these experiments were recreated in a simulation environment and with those simulation results, the injury risk functions are generated to estimate the probability of the iliac wing fracture. A conclusive single injury risk function suitable for practical application could not be determined.
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    Numerical study of condensation and conjugated heat transfer from flow in a heat exchanger
    (2024) Peyvandi, Ehsan; Chalmers tekniska högskola / Institutionen för mekanik och maritima vetenskaper; Chalmers University of Technology / Department of Mechanics and Maritime Sciences; Sasic, Srdjan; Johansson, Klas
    There are many industrial and nonindustrial fields where Plate heat exchangers, PHE, are utilized for their efficient heat transfer ability. Some fields in which PHEs are commonly used include HVAC (Heating, Ventilation, and Air Conditioning), Power Generation, and Refrigeration. The compact size, high heat transfer efficiency, ease of maintenance, and cleaning make them a popular option across various sectors. Hence, it is essential to study and understand the flow and heat transfer in plate heat exchangers to optimize the usage of these systems. Alfa Laval develops (design, analyze, and manufacture) a wide range of heat exchangers, including gasketed, brazed, and welded plate models. This Master’s thesis concentrated on investigating and laying the groundwork for conducting Computational Fluid Dynamics (CFD) simulations to study heat transfer during the phase change (condensation) process on the primary side, involving the full condensation of propane as it transitions from a gaseous to a liquid state. The procedure followed in this thesis is as follows: Initially, a Pipe flow, as a first test case, is simulated to gain an understanding of the various parameters involved in Computational fluid dynamics (CFD) analysis. Then, as a second test case, to develop and validate a multiphase flow modeling where a full condensation of the gaseous phase occurs, the Kuhn (1995) [12] experiment is adopted. The numerical simulation models were created using Ansys Discovery Modeling. Subsequently, the meshing and simulations were carried out using Ansys- Meshing and Fluent (2023R1). The hydrodynamics of the two-phase flow have been solved using both the Mixture- and Volume of Fluid (VoF) methods separately. Mass and heat transfer resulting from phase change (condensation) were handled through the Lee condensation model.
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    Minimize the aerodynamic effect of a strut on the wing
    (2023) Santor Blair, Andres Felipe; Utku, Mert; Chalmers tekniska högskola / Institutionen för mekanik och maritima vetenskaper; Chalmers University of Technology / Department of Mechanics and Maritime Sciences; Xisto, Carlos; Antunes, Alexandre
    The field of aircraft design is continuously advancing through the utilization of scientific techniques and empirical methods. The incorporation of computational methods has facilitated the design process of new and complex aircraft, enabling more efficient conceptual design and optimization. These advancements have the potential to significantly reduce fuel consumption and emissions, making a positive impact on the environment, a critical global concern. The development of battery-electric airplanes represents a significant step towards creating a more sustainable aviation sector. Among the various emerging concepts, the Strut-Braced Wing (SBW) has shown great promise in enhancing aerodynamic efficiency while reducing wing weight. However, the implementation of new concepts and technologies also presents new challenges and limitations that must be addressed, particularly the impact of aerodynamics on the aircraft’s range, which can impose limitations on its maximum travel distance. The primary objective of this thesis is to minimize the aerodynamiceffects of a strut and wing configuration by reducing total drag and increasing the Oswald efficiency of the Strut-Braced Wing during the conceptual design phase. To achieve this goal, Sequential Quadratic Programming (SQP) and Genetic Algorithm (GA) optimization algorithms are employed, utilizing low-fidelity Computational Fluid Dynamics (CFD) methods. The airfoil data utilized in the study is obtained from the XFOIL tool, which provides important viscous aerodynamic characteristics. By implementing these methodologies, it is anticipated that the aerodynamic performance of the Strut-Braced Wing configuration can be optimized, leading to improved efficiency and weight reduction. The results obtained from this research will contribute to the advancement of aircraft design and promote the development of more environmentally friendly and efficient aircraft during the conceptual design phase.
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    Torque vectoring using e-axle configuration for 4WD battery electric truck: Utilizing control allocation for motion control and steer by propulsion
    (2022) Fahlgren, Emil; Söderberg, Daniel; Chalmers tekniska högskola / Institutionen för mekanik och maritima vetenskaper; Chalmers University of Technology / Department of Mechanics and Maritime Sciences; Jonasson, Mats; Laine, Leo; Janardhanan, Sachin
    With the rise of electric drives in vehicle applications, configurations of new powertrain design are emerging. In recent years, this trend has shifted to include heavy vehicles as well. In this thesis, a concept 4x4 battery electric truck with a distributed powertrain is investigated. By using four individual motors on two separate e-axles, different coordination possibilities are available for motion control of the truck. This thesis focuses on using torque vectoring as a principle to allocate the requested global torque. Furthermore, a novel method mentioned to as steer by propulsion (SBP) is proposed, where the steering of the vehicle can be controlled solely by using the electric machines on the front axle. Investigations are conducted to explore the effectiveness of this method on vehicle performance and energy consumption. To distribute the control requests across the available actuators, control allocation (CA) is used. Here, the problem is formulated as a quadratic programming (QP) problem. High level controllers provide the requested global forces as an input to the control allocation, which in turn allocates torques to the separate wheel controllers. Furthermore, different formulations of the control allocator and motion controller are presented and compared. The control system is simulated with a vehicle model provided by Volvo, and the results indicate that steer by propulsion is able to follow a reference path with a lateral offset of a magnitude of an acceptable level. Furthermore, the simulations show that SBP can repeat this behavior at high speeds as well with an oscillatory behavior. Therefore, the method is recommended to use mainly at vehicle speeds below 50 km/h. Finally, simulations show that SBP increases the energy consumption by 2-4 %. Considering that the consumption is on par with using power steering, SBP will be viable for redundancy with some limitations.