Examensarbeten för masterexamen
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- PostAerodynamics investigations and optimization of a simplified pick-up truck with wind tunnel and CFD testing(2024) Yathiraj, Karthik; Chaithanya, Pavan; Chalmers tekniska högskola / Institutionen för mekanik och maritima vetenskaper; Chalmers University of Technology / Department of Mechanics and Maritime Sciences; Vdovin, Alexey; Vdovin, AlexeyThis master’s thesis presents a comprehensive study on the aerodynamics and optimization of a simplified generic pick-up truck model through combined wind tunnel testing and computational fluid dynamics (CFD) simulations in StarCCM+. The primary objective is to understand and investigate the aerodynamic behavior of the generic pickup truck and design new attachments for the pickup truck on the trailer. Based on existing knowledge, design optimization techniques were used to find design changes that could reduce aerodynamic drag. A flat underbody, a closed grill gap, and various rear attachments were among the changes made to the truck’s shape. A comprehensive study and cross-validation of the suggested aerodynamic improvements were made possible by the combination of wind tunnel testing and CFD. The ANSA software was used to optimize the CAD model. 3D printing was later used to create a 1/10 scaled-down model of the generic pickup truck, along with three distinct attachments called Flat back, Hatch back, and Fastback. Later tested the 3D printed model in Chalmers University of Technology’s wind tunnel in Sweden. Drag forces were captured with the aid of wind tunnel experiments. These experimental findings served as a standard by which to validate the CFD models. The airflow surrounding the vehicle was then simulated using extensive CFD analyses using the StarCCM+ software. The findings presented in this paper are the outcome of research and comprehension of the vehicle’s aerodynamic behavior. They also show enhancements in the pickup truck’s aerodynamic performance, with the quick back attachment lowering the drag coefficient. In addition to highlighting the potential for significant fuel and pollution reductions in pick-up trucks through aerodynamic optimization, this work shows how well experimental and computational methodologies may be used for aerodynamic investigations.
- PostAssessing the influence of show, don’t tell principle on external human-machine interfaces across cultures(2024) Saha, Shouvanik; Chalmers tekniska högskola / Institutionen för mekanik och maritima vetenskaper; Chalmers University of Technology / Department of Mechanics and Maritime Sciences; Benderius, Ola; Benderius, OlaTogether with the shift towards green renewable energy sources, the automotive industry is currently witnessing a rapid advancement in the context of autonomous vehicle technology. In this setting, the way in which the autonomous vehicle interacts with the vulnerable road users will be indispensable both in terms of safety and acceptance. Therefore, understanding the societal perceptions and cultural influences on the external human-machine interfaces (eHMIs) has become significant. This research investigates the intersection of social constructivism and the show, don’t tell principle within the context of eHMIs for autonomous vehicles. Grounded in the hypothesis of social constructivism and technological insights from the show, don’t tell principle, the study aims to analyse the alignment between the current theoretical frameworks and the practical design solutions. Specifically, it explores how cultural factors impact the acceptance and effectiveness of eHMIs among pedestrians. In order to achieve autonomous driving with minimal or zero human intervention, seamless integration of these vehicles into complex urban traffic is required. This research suggests that the development of culturally sensitive design solutions may facilitate the harmonious co-existence of autonomous vehicles and vulnerable road users in urban landscapes.
- PostA Method for Determining Feasibility of Electrification of Small Fishing Vessels: Developed Using Operational Data from Two Fishing Vessels in Kosterhavet National Park(2024) Barman, Aditya; Sörfeldt, Arvid; Chalmers tekniska högskola / Institutionen för mekanik och maritima vetenskaper; Chalmers University of Technology / Department of Mechanics and Maritime Sciences; Schreuder, Martin; Schreuder, Martin; Olsson, Fredrik; Sanchez-Heres, LuisAll European industries are facing a big shift away from their dependency on fossil fuels as a result of the European Green Deal. Currently, there is no clear plan available for small fishing vessels to make that shift. The purpose of this thesis was to develop a simple and intuitive method for stakeholders to evaluate the feasibility of electrifying small fishing vessels. It was developed using mostly publicly available operational data of two fishing vessels, combined with a regulatory, environmental, and economic analysis of the two vessels. The results of the analysis where compiled into a method implemented as an excel sheet. The resulting method is applicable to most small Swedish fishing vessels. Applying the method to the two case vessels, it was found that the technical and environmental aspects of feasibility are straight forward to evaluate and the chance of electrification being feasible is good. However, the regulatory and economic aspects are less straight forward and need more thought and effort put in by the user. Furthermore, it was found that being able to use grants from Klimatklivet to electrify small fishing vessels is unlikely. This is because the investment tends to become profitable before the environmental performance is good enough. Finally, it was concluded that electrification will play an important role in the transition away from the use of traditional fossil fuels in the fishing fleet.
- PostFluid-Structure Interaction of Human Upper Airways(2024) Papakarmezis, Leandros; Chalmers tekniska högskola / Institutionen för mekanik och maritima vetenskaper; Chalmers University of Technology / Department of Mechanics and Maritime Sciences; Yao, Huadong; Schickhofer, LukasThis thesis investigates the fluid-structure interaction (FSI) of a Starling Resistor to understand the mechanics behind wheezing, which is a common respiratory symptom. By using a combination of computational fluid dynamics (CFD) and structural analysis, the study applies a partitioned FSI approach to simulate the interaction between airflow and a Starling Resistor. The results of this study present the first valid FSI simulation that models wheezing. In addition, the research investigates how changes in the shape of airways, particularly narrowing in the middle part, affect the flow speed and distribution of pressure. The simulations show how air moves and how the structures change, capture the frequency of the onset of tube’s oscillations. The results suggest that the increase in pressure at the inlet of the tube in combination with the external pressure that act on the tube, is the primary mechanism causing the tube’s oscillations. This study provides valuable insights into how fluids and structures interact in collapsible airways and contributes to the broader field of respiratory mechanics, especially for wheezing. The results could help in developing better tools for diagnosis and strategies for treating respiratory conditions. Also, future work could focus on improving the simulation models by using more advanced mesh designs, models that account for turbulent flow, finer time steps to accurately capture the exact start and frequency of tube movement and an improvement of signal processing to analyze the tube oscillations with a wavelet process. These improvements could lead to more precise and predictive models, ultimately benefiting both clinical practice and patient diagnoses.
- PostDesign and Simulation of Acoustic Metamaterials for Noise Reduction in Open- Flow Systems(2024) Ji, Chenya; Reddy, Prajwal Sunil; Chalmers tekniska högskola / Institutionen för mekanik och maritima vetenskaper; Chalmers University of Technology / Department of Mechanics and Maritime Sciences; Yao, Huadong; Yao, Huadong; Na, Wei; Keulemans Westlin, ChristinaThe growing demand for larger and more efficient cooling systems in heavy-duty trucks has led to increased noise levels, particularly from cooling fans, which poses challenges to both environmental standards and user comfort. Conventional techniques for sound absorption typically restrict particle motion, which will also impede flow and increase temperature in a situation when fans are present. Acoustic metamaterial (AMM) solutions have been explored to address these problems. A systematic methodology for designing a single metamaterial cell is presented, encompassing four stages: specification of geometrical parameters, parametrization, parametric design, and optimization. Noise characterization of a vehicle’s cooling fan, based on Lu’s study[20], revealed broadband noise and tonal harmonics centred on the blade passing frequency (BPF). In response, a double-layer micro-perforated panel (DLMPP) structure was designed to reduce noise over a broad frequency range; a space-coiling structure was created to target specific tonal noise. Theoretical calculations show that both structures have excellent noise absorption performance. Simulations of the space-coiling cell with a flow field were then conducted. Although the absorption coefficients show slight deviations from theoretical calculations, the results remain promising for this study and warrant further investigation. A simulation of an under-cab environment was also studied by applying the acoustic impedance of DLMPP on target surfaces under conditions with and without flow. The results demonstrate that the present AMMs can significantly reduce cooling fan noise while maintaining thermal management efficiency.