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A Chalmers University of Technology Conceptional Design Method for Propellers. An implementation of Drela method for minimum induced loss and Garrick and Watkins method for sound pressure level
(2025) Helaleh, George
The ongoing development of electric aircraft aims to make the aviation industry more sustainable, with a focus on reducing energy consumption and noise emissions. Propellers, as a key component of electric airplanes, play a critical role in achieving these goals. This study focuses on designing optimized propellers for electric aircraft that maximize efficiency while minimizing energy loss and sound pressure levels (SPL). By employing Drela’s propeller design methodology for aerodynamic optimization and Garrick and Watkins models for noise analysis.
The primary tool used in this study is OptoProp, a numerical simulation program developed in Python to optimize propeller efficiency. The methodology involves several key steps. First, the program is verified using a documented case to ensure its accuracy in predicting propeller performance. Following verification, a parameter sensitivity study is conducted to understand how critical design elements, such as blade count, diameter, and angular speed, influence efficiency and noise levels. The final step involves conducting noise simulations using the calculated aerodynamic data to analyze the relationship between propeller parameters and SPL, providing deeper insight into the effects of each parameter.
The results of the parameter study reveal several important trends. The propeller’s diameter and blade count are pivotal in determining its overall efficiency. A larger propeller size enhances efficiency by reducing the power required and lowering the generated torque, both of which are critical for achieving sustainable performance.
However, increasing the diameter also leads to a positive effect on SPL, as larger propellers tend to produce less noise due to their inverse relationship with the sound pressure level. While this trend offers a valuable approach to designing propellers with better performance and reduced noise levels, there is a threshold for both the diameter and blade count. Beyond this threshold, further increases in these parameters have detrimental effects on performance and can lead to suboptimal propeller designs. This suggests that simply increasing the size or number of blades does not always result in improved performance, and a balanced design is essential.
On the other hand, the effect of angular speed on propeller performance is also significant. Increasing the angular speed improves efficiency up to a certain optimal value, after which further increases yield diminishing returns. However, angular speed has a negative impact on SPL, meaning that higher speeds generate more noise. This introduces a critical trade-off between performance and noise, as designers must be cautious not to increase the angular speed beyond the optimal level if low noise levels are a priority. The sensitivity of noise to angular speed makes it an important factor in designing propellers for electric aircraft, where minimizing noise
pollution is a key concern.
In conclusion, the study provides valuable guidelines for designing electric aircraft propellers that balance high aerodynamic performance with low noise emissions. The findings suggest that an optimal propeller design must consider not only aerodynamic
efficiency but also the impact of various parameters on SPL. The balance between propeller size, blade count, and angular speed is crucial for achieving sustainable performance, with thresholds for each parameter that must be respected to avoid diminishing returns in both efficiency and noise reduction. These insights contribute to the development of electric aircraft technology and offer a pathway
toward more sustainable aviation solutions, where both environmental impact and noise pollution are minimized without compromising on performance.
Preparing BIM Models for Construction- Challenges and Requirements
(2025) Iséni, Leo; Rosina, Patrik
As the construction industry shifts toward increased digitalization, model-based design
delivery is gaining attention as an alternative to traditional 2D documentation. While drawings
remain the main form of design communication, a growing number of projects are beginning
to adopt model-based deliveries. This uncovers a research gap in focus on the design phase,
and how specifications, interoperability, and trust are understood and applied in model-based
practices, particularly when models lack the visual cues and scale typically found in 2D
drawings.
This thesis explores how the absence of scale and visual hierarchy in BIM models affects
stakeholder interpretation, whether detail and maturity specifications can help address these
issues, and why collaboration and adoption challenges persist even in digitally advanced
project environments. Further, it investigates how the absence of drawing scale and other visual
cues that typically indicate detail or reliability affects the way stakeholders interpret design
information in BIM models. This research also investigates barriers to model use on
construction sites, including legal constraints, inconsistent use of standards and specifications,
limited digital literacy, and lack of trust in model data.
Based on a literature review and twelve semi-structured interviews with professionals across
the AEC industry, the findings show that BIM can support more efficient design
communication, but these benefits are limited without clear indicators of maturity and
reliability. Specifications such as Level of Development and Model-Maturity Index show
potential for improving model readiness, but are inconsistently applied and rarely enforced
through contracts. By focusing on the design phase, this thesis contributes new insight into how
models can be better structured and communicated to support their reliable use in construction,
bridging the gap between model-based design delivery and its practical implementation.
Enhancing Client Value Through Digital Solutions in Construction Project Management- A Study of the Construction Phase
(2025) Granath, Ida; Ingesson, Tova
Despite a long history of construction, the industry continues to face challenges such
as high costs, low productivity, and difficulties in delivering affordable, high-quality
buildings to the clients. Digitalization offers solutions to many of these problems
by improving communication, coordination, and decision-making across the project
lifecycle. This master thesis investigates how digital solutions can be utilized by
construction project managers during the construction phase, to create value for
the client. An initial literature study was conducted to examine the current state
of digitalization in the construction industry. Based on this, a qualitative inter view study was held with construction project managers, clients, and digitalization
experts. Based on their experiences, recurring challenges such as communication,
coordination, model handling, and documentation during the production phase were
identified. The study analyzes how Common Data Environments (CDE:s) can ad dress these issues through targeted features and workflows. The master thesis also
focuses on the integration of complementary technologies, such as 360-degree cam eras, to enhance documentation and site monitoring. The findings highlight how
CDE:s can centralize project communication, reduce information loss, and improve
decision-making by clients. The use of Building Information Models (BIM) with sta tus codes facilitates accurate progress tracking and early detection of delays. Key
client benefits include fewer construction errors, minimized cost and time overruns,
and improved documentation for the operational phase. A high-quality BIM model
supports long-term facility management and sustainability efforts. For construction
project managers, digital platforms offer tools to manage issues, document site vis its, and monitor the time plan in real time. Despite these benefits, several barriers
to implementation remain, including organizational resistance, cost, licensing, and
training needs. The study concludes that digital platforms have the potential to in crease client value during the construction phase. However, full realization of these
benefits requires early and continuous digitalization from the design stage and active
involvement of all stakeholders.
A scaled axisymmetric finite element model for heat flow in ventilated brake rotors
(2025) Håland, Elias; Sparf, Erik
The aim of this thesis was to develop a finite element model of the heat flow in a ventilated disc brake that is both accurate and computationally efficient. The model is intended to be used during the early stages of development for brake components. It must capture the out-of-plane effects on the non-axisymmetric ventilation layer while remaining two dimensional to allow for fast simulations. To accomplish this an enriched two-dimensional model was developed where each edge and face are scaled based on their size in the out of plane direction. The scaling factor was acquired by doing a geometry mapping of each surface and volume on a three-dimensional model of the brake disc, using it to integrate the weak-form over the out of plane dimension. The scaled axisymmetric model was validated against the result of a high-fidelity three-dimensional model of the brake disc supplied by Volvo Car Corporation.
The difference between the simulation result of the scaled two-dimensional axisymmetric model and the three-dimensional model was only about 1% when considering heating of an insulated wheel. When adding boundary condition pertinent to the convection over all surfaces, the difference in simulation results becomes about 5%. In both simulation cases, the scaled two-dimensional axisymmetric model accurately captures the average temperature distribution of the three-dimensional model.
This accuracy is good considering the difference in computational cost between the models. The scaled two-dimensional model takes minutes to compute while the three-dimensional model takes several hours, which is a good trade off during the early development stages of a brake rotor.
Embedded control firmware optimization for power electronics
(2025) Shao, Zhuoer
Modern power converters face quicker input and load changes. With higher switching
frequency and smaller inductors or capacitors, there is less stored energy to
smooth disturbances. If the control reacts slowly, voltage or current overshoots or
undershoots will take longer to settle, resulting in energy waste and potential damage
to the device. Therefore, a faster response is needed in the power electronics system.
Embedded control firmware plays a key role in improving closed-loop speed and
system stability. In high-frequency DC-DC converters and automotive power electronics,
firmware execution performance directly affects control accuracy, energy efficiency,
and system robustness. In this thesis, we compare three automotive-grade
MCUs—TI F29H85x, TI AM263x, and Infineon AURIX TC4x—under a unified
closed-loop control framework. By dividing the control loop into stages such as ADC
sampling, PID calculation, and PWM output, and by analyzing differences in interrupt
systems, CPU architecture, peripheral interconnect, and compiler optimization,
we systematically show their impact on execution delay. Delay is measured using
GPIO toggling and interrupt timestamps, and platform-specific optimizations (such
as DMA acceleration, early interrupt mode, memory mapping, compiler tuning, and
CDSP/PPU offloading) are applied to explore the shortest possible execution time.
Results show that all three MCUs achieved significant improvements over their baselines,
with F29H85x reaching 710 ns, AM263x 793 ns, and TC4x 750 ns.
The contribution of this project is not only to compare real-time performance across
MCUs, but also to propose a unified cross-platform analysis method. By linking experimental
results with structural differences, we show how interrupt paths, CPU
pipelines, and peripheral interconnects determine real-time performance. This approach
goes beyond single-platform studies, providing a systematic framework for
analysis. It also offers practical guidance for MCU selection and firmware optimization
in industrial applications.