MEchanics GAthering -MEGA- Seminar: Talk 1 - The dynamic stall dilemma for vertical-axis wind turbines; Talk 2 - Mobile robots’ navigation in dense crowds and how to measure their performance
Event details
| Date | 04.11.2021 |
| Hour | 16:15 › 17:30 |
| Speaker | Sébastien Le Fouest (UNFoLD, EPFL) & David Julian Gonon (LASA, EPFL) |
| Location | Online |
| Category | Conferences - Seminars |
| Event Language | English |
Talk 1: The dynamic stall dilemma for vertical-axis wind turbines, by Sébastien Le Fouest (UNFoLD, EPFL)
Abstract Vertical-axis wind turbines are great candidates for wind energy diversification and could contribute to reaching a near-zero carbon emission electrical grid. The complex aerodynamics of vertical-axis wind turbines have challenged their development and integration into urban infrastructure. The blades of these turbine undergo periodic oscillations in inflow conditions, which continuously change the blade's effective angle of attack and flow velocity. These oscillations often lead to the formation of large-scale vortices and the occurrence of dynamic stall. These flow structures allow an increase in torque production, but also cause heavy load transients jeopardising the turbine's structural integrity and potentially leading to premature failure. This talk aims at presenting the dilemma vertical-axis wind turbines face over a wide operation envelope: generating torque while ensuring structural reliability. Time-resolved flow and load measurements were performed to characterise the occurrence of dynamic stall on a scaled-down vertical-axis wind turbine for a wide range of operating condition. The timescales of vortex formation and the corresponding impact on the unsteady load response are analysed. The torque generation and transient load fluctuation are systematically put on a balance. The goal is to lay the ground for flow control strategies that will aim at making vertical-axis wind turbines reliable and efficient.
Bio Sébastien completed his bachelor and master degree at Imperial College London, where he developed a strong interest for fluid mechanics applied to energy-related problems. He joined EPFL in 2018 to complete a doctoral thesis on the experimental investigation of dynamic stall on vertical-axis wind turbines.
Talk 2: Mobile robots’ navigation in dense crowds and how to measure their performance, by David Julian Gonon (LASA, EPFL)
Abstract Today’s mobile robots are able to sense objects’ shapes and motion and localize themselves in their environment. By continuously planning their own motion between obstacles and executing their current plan, they may navigate autonomously. Human crowds constitute particularly dynamic and therefore challenging environments from the perspective of motion planning. This talk reviews modern approaches to robots’ navigation in crowds and modeling dense crowds’ dynamics. Further, the speaker’s developments using the concept of Acceleration Obstacles for studying and enhancing navigation in dense crowds are presented. The preliminary technique’s evaluation in simulation and an outlook conclude the presentation.
Bio David is a doctoral student at the Learning Algorithms and Systems Laboratory (LASA-IMT-STI), EPFL, since 2018. Previously, he worked as a scientific staff member at the Institute of Structural Engineering, ETH Zürich. Gonon obtained his MSc degree in Robotics, Systems and Control in 2017 and his BSc degree in Mechanical Engineering in 2014, both from ETH Zürich. His scientific interests include robots’ motion planning and collision avoidance, control systems, computer vision, and computational geometry.
Abstract Vertical-axis wind turbines are great candidates for wind energy diversification and could contribute to reaching a near-zero carbon emission electrical grid. The complex aerodynamics of vertical-axis wind turbines have challenged their development and integration into urban infrastructure. The blades of these turbine undergo periodic oscillations in inflow conditions, which continuously change the blade's effective angle of attack and flow velocity. These oscillations often lead to the formation of large-scale vortices and the occurrence of dynamic stall. These flow structures allow an increase in torque production, but also cause heavy load transients jeopardising the turbine's structural integrity and potentially leading to premature failure. This talk aims at presenting the dilemma vertical-axis wind turbines face over a wide operation envelope: generating torque while ensuring structural reliability. Time-resolved flow and load measurements were performed to characterise the occurrence of dynamic stall on a scaled-down vertical-axis wind turbine for a wide range of operating condition. The timescales of vortex formation and the corresponding impact on the unsteady load response are analysed. The torque generation and transient load fluctuation are systematically put on a balance. The goal is to lay the ground for flow control strategies that will aim at making vertical-axis wind turbines reliable and efficient.
Bio Sébastien completed his bachelor and master degree at Imperial College London, where he developed a strong interest for fluid mechanics applied to energy-related problems. He joined EPFL in 2018 to complete a doctoral thesis on the experimental investigation of dynamic stall on vertical-axis wind turbines.
Talk 2: Mobile robots’ navigation in dense crowds and how to measure their performance, by David Julian Gonon (LASA, EPFL)
Abstract Today’s mobile robots are able to sense objects’ shapes and motion and localize themselves in their environment. By continuously planning their own motion between obstacles and executing their current plan, they may navigate autonomously. Human crowds constitute particularly dynamic and therefore challenging environments from the perspective of motion planning. This talk reviews modern approaches to robots’ navigation in crowds and modeling dense crowds’ dynamics. Further, the speaker’s developments using the concept of Acceleration Obstacles for studying and enhancing navigation in dense crowds are presented. The preliminary technique’s evaluation in simulation and an outlook conclude the presentation.
Bio David is a doctoral student at the Learning Algorithms and Systems Laboratory (LASA-IMT-STI), EPFL, since 2018. Previously, he worked as a scientific staff member at the Institute of Structural Engineering, ETH Zürich. Gonon obtained his MSc degree in Robotics, Systems and Control in 2017 and his BSc degree in Mechanical Engineering in 2014, both from ETH Zürich. His scientific interests include robots’ motion planning and collision avoidance, control systems, computer vision, and computational geometry.
Practical information
- General public
- Free
Organizer
- MEGA.Seminar Organizing Committee