AEM Seminar: TODAY, February 28th - Prof R. Jason Hearst, Department of Energy & Process Engineering, Norwegian University of Science & Technology (NTNU)

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Molly Schmitz

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Feb 28, 2025, 9:00:44 AMFeb 28
to AEM Seminar, AEM Regular Faculty
University of Minnesota
Aerospace Engineering and Mechanics
Spring 2025 Seminar Series

Friday, February 28, 2025
209 Akerman Hall
2:30pm-4:30pm

AEM Seminar:  
The complex role of turbulence: Vanishing tip vortices, scattering waves, and enhanced gas transfer


Abstract:
We will discuss three areas where recent advances in experimental turbulence measurements have led to new insights. First, time-resolved volumetric measurements of the wake of a model wind turbine are used to investigate the often-observed phenomenon whereby ortices “vanish” rapidly downstream of a wind turbine. Moving to air-water interfacial flows, we investigate the interaction between surface waves and sub-surface turbulence, with a particular focus on enstrophy enhancement and wave scattering. Our results demonstrate that sub-surface turbulence can increase the rate of environmentally significant gas exchange (e.g., O₂, CO₂) across the air-water interface by up to 45%. The talk will also showcase recent advances in flow measurements, including the use of quantifiable laser-induced fluorescence to map O₂ concentration in water while simultaneously capturing the velocity field and surface topology. Additionally, we introduce a novel co-flowing air-water facility equipped with active turbulence grids in each phase, allowing for independent control of turbulence in the air and water.

 

Bio:

Jason Hearst is a Professor at the Norwegian University of Science and Technology (NTNU) in Trondheim, Norway. His primary research activities are centred around the generation of bespoke turbulent flows using active turbulence generating grids and investigating how turbulence influences other canonical and environmental fluids problems. His team is primarily funded via the European Research Council (Starting Grant, GLITR), Marie Skłodowska-Curie Actions (Post-doctoral fellow, Dr. Yi Hui Tee, InMyWaves) and the Research Council of Norway (FRIPRO, WallMix; Knowledge Building Project, reSail).  Jason Hearst earned his PhD in 2015 from the University of Toronto Institute for Aerospace Studies (Canada), and then worked as a post-doctoral researcher at the University of Southampton (UK) with Prof. Bharath Ganapathisubramani. He moved to NTNU in 2017 as an Associate Professor and was promoted to Professor in 2023. He has been on sabbatical since August 2024, first at the University of Oxford and now from January 2025 he is at the University of Toronto.



*Refreshments to follow 


Molly Schmitz (She/Her/Hers)
Graduate Program Coordinator & Executive Accounts Specialist
Department of Aerospace Engineering & Mechanics
University of Minnesota - Twin Cities

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Molly Schmitz

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Apr 14, 2025, 9:02:30 AMApr 14
to AEM Seminar, AEM Regular Faculty
University of Minnesota
Aerospace Engineering and Mechanics
Spring 2025 Seminar Series

Friday, April 18, 2025
209 Akerman Hall
2:30pm-4:30pm

AEM Seminar:

Novel Multiple Time Scale Adaptive Control for Uncertain Nonlinear Dynamical Systems

 

Abstract: Adaptive control is seeing some use in the aerospace domain but has been limited to a small set of systems such as air-to-ground missiles, and small UAS.  Two of the limiting assumptions of adaptive control that contribute to this limitation of use are that the parameters in the system must only change relatively slowly, and that the parameters all change at roughly the same speed.  These are difficult to successfully address in adaptive control in a rigorous theoretical manner and have challenged the control community for decades.  This seminar presents a new and novel approach for adaptive control of multiple time-scale systems called Kontrol of Adaptive Multiple Time-Scale Systems (KAMS).  KAMS is inspired by the theoretical foundations of nonlinear time-scale control theory, and permits adaptive control to not only adapt to different speeds of parameter changes in a vehicle model, but to also account for different speeds due to using a mix of slow and fast actuators.  An extra feature of the KAMS theory enables adaptive control to be used on non-minimum phase systems, which is inherent to most fixed-wing air vehicles in the pitch axis dynamics.  KAMS has the potential to enable air and space vehicles with new operational capabilities, and has been used to design controllers for orbital transfers, rotorcraft UAS, fixed-wing UAS, and inlet unstart of hypersonic flight vehicles. 

 

Bio: John Valasek is Professor and Drs. L. Diane '88 and John E. Hurtado '91 Professor of aerospace engineering, Thaman Professor of Undergraduate Teaching Excellence, and Director of the Vehicle Systems & Control Laboratory (https://vscl.tamu.edu) at Texas A&M University (TAMU).  He has been conducting autonomy and flight controls research of Manned and Unmanned Air Systems (UAS) in both Industry and Academia for 40 years, first as a Flight Control Engineer for the Northrop Corporation, Aircraft Division.  His research is focused on bridging the scientific gaps between traditional computer science topics and aerospace engineering topics, while achieving a high degree of closure between theory and experiment.  At TAMU since 1997, John holds two patents and is co-author/editor of four books, including Nonlinear Multiple Time Scale Systems in Standard and Non-Standard Forms: Analysis and Control, (SIAM, 2014).  John is a Fellow of AIAA for “Pioneering contributions and outstanding leadership in flight mechanics and control leading to new capabilities in autonomous air refueling, morphing flight, and flight safety,” and the recipient of the 2014 ASEE/AIAA John Leeland Atwood Award for national outstanding aerospace educator.  John is the TAMU Site Director for the NSF Center for Autonomous Air Mobility and Sensing (CAAMS) and has conducted more than 600 fixed-wing and rotorcraft UAS test flights over a 26 year period at TAMU.  John earned the B.S. degree in Aerospace Engineering from Cal Poly, Pomona in 1986 and the M.S. degree with honors and the Ph.D. in Aerospace Engineering from the University of Kansas, in 1990 and 1995 respectively. 



*Refreshments to follow 


Molly Schmitz (She/Her/Hers)
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