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34th Congress of the International Council of the Aeronautical Sciences, ICAS 2024

作者： Swannet, Kilian Varriale, Carmine Anh Khoa Doan, Nguyen Delft University of Technology HS Delft2629 Netherlands Department of Flow Physics and Technology Flight Performance and Propulsion section Netherlands Department of Flow Physics and Technology Aerodynamics section Netherlands

This paper introduces an approach for parameterizing airfoil geometries using a Variational Auto encoder (VAE)with a focus on achieving a low-dimensional and interpretable model. The primary focus is to facilitate efficient use in design optimization environments by capturing essential airfoil features in a minimal number of latent dimensions. To address the black-box nature of VAEs and enhance interpretability, a correlation analysis is performed to uncover the relationships between the airfoil properties and these inferred latent dimensions. Key to this research is the incorporation of both geometric and aerodynamic properties in this analysis, enabling the generation of air foils with desired aerodynamic characteristics through manual tuning of the latent vector by a designer. The method is evaluated using the extensive UIUC airfoil database, which includes a diverse range of airfoil categories. The VAE is trained on airfoil surface coordinate points, and the generated output geometries are refined using a composite Bezier curve to smooth out local imperfections. Results demonstrate that theVAE can successfully extract and parameterize key airfoil features using a limited number of interpretable latent parameters. These parameters show clear correlations with geometric and aerodynamic airfoil properties, providing a practical and understandable parameterization model that facilitates the intuitive generation of new airfoil designs through smooth interpolation of the training data. © 2024, International Council of the Aeronautical Sciences. All rights reserved.

关键词： Parameterization

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Impact of Quantum Coherence on Inelastic Thermoelectric Devices:From Diode to Transistor

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Chinese physics Letters 2024年第7期41卷 117-125页

作者：曹蓓韩崇泽郝翔王晨陆金成 Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application School of Physical Science and TechnologySuzhou University of Science and TechnologySuzhou 215009China Department of Physics Zhejiang Normal UniversityJinhua 321004China

We present a study on inelastic thermoelectric devices, wherein charge currents and electronic and phononic heat currents are intricately interconnected. The employment of double quantum dots in conjunction with a phonon reservoir positions them as promising candidates for quantum thermoelectric diodes and transistors. We illustrate that quantum coherence yields significant charge and Seebeck rectification effects. It is worth noting that, while the thermal transistor effect is observable in the linear response regime, especially when phononassisted inelastic processes dominate the transport, quantum coherence does not enhance thermal *** work may provide valuable insights for the optimization of inelastic thermoelectric devices.

关键词： quantum charge Quantum

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Impinging Shock Wave Boundary Layer Interactions Control with Shock Control Bumps

Impinging Shock Wave Boundary Layer Interactions Control wit...

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AIAA Aviation Forum and ASCEND, 2024

作者： Bulut, Jane Schrijer, Ferry Oudheusden, Bas van Delft University of Technology Aerodynamics Section Department of Flow Physics and Technology Delft2629 HS Netherlands

ISBN: (数字)9781624107160

ISBN: (纸本)9781624107160

In this experimental study, the effect of three-dimensional shock control bumps (SCBs) on impinging-reflecting shock wave/boundary layer interactions (SWBLI) is investigated as a passive control method. The aim is to develop an understanding of the influence of such devices on the interaction structure by studying the position of the bump with respect to the shock-impingement location. The experiments were conducted in the ST-15 wind-tunnel at the Delft University of technology for fully developed turbulent boundary layer conditions with Reθ of 21.8 × 103 and Mach number of 2. The effectiveness was assessed by examining the size of the separated flow region, as well as the downstream boundary layer velocity profile. Stereo-PIV was employed as the main diagnostic method to characterise the three-dimensional flow field. Additionally, the effect of shock impingement location on the unsteady interaction dynamics was examined by analyzing the separation size and reflected shock foot position in the instantaneous flow. The investigation revealed the significance of the shock impingement location in terms of control effectiveness. Nevertheless, placement of the bump in the interaction region substantially decreased the probability of flow separation even in off-design conditions when compared to the uncontrolled interaction. © 2024, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Wind tunnels

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Modulation of Steady-State Heat Transport in a Dissipative Multi-Mode Qubit-Photon System

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Chinese physics Letters 2023年第5期40卷 6-13页

作者：陈泽欢王菲宇陈华陆金成王晨 Department of Physics Zhejiang Normal UniversityJinhua 321004China Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application School of Physical Science and TechnologySuzhou University of Science and TechnologySuzhou 215009China

Quantum heat transport is considered as an indispensable branch of quantum thermodynamics to potentially improve performance of thermodynamic *** theoretically propose a dissipative qubit-photon system composed of multiple coupled resonators interacting with a single two-level qubit,to explore the steady-state heat transport by tuning both the inter-resonator photon hopping and the qubit-photon *** in the three-mode case,the dramatic enhancement and suppression of the heat current into the central resonator can be modulated by the corresponding frequency,compared to the currents into two edge ***,fruitful cycle current components are unraveled at weak qubit-photon coupling,which are crucial to exhibit the nonmonotonic feature with increase of the reservoir temperature *** the one-dimensional case under the mean-field framework,the influence of the photon hopping on heat transport is *** steady-state heat current is comparatively enhanced to the single-mode limit at weak qubit-photon coupling,stemming from the nonvanishing mean-field photon excitation parameter and the additional cycle current *** hope these obtained results may have possible applications in quantum thermodynamic manipulation and energy harvesting.

关键词： thermodynamic quantum thermodynamics

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Optimization of Tollmien-Schlichting waves control: comparison between a deep reinforcement learning and particle swarm optimization approach

Optimization of Tollmien-Schlichting waves control: comparis...

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AIAA Aviation Forum and ASCEND, 2024

作者： Mohammadikalakoo, B. Kotsonis, M. Doan, N.A.K. Department of Flow Physics and Technology Section of Aerodynamics Delft University of Technology Kluyverweg 1 Delft2629HS Netherlands

ISBN: (数字)9781624107160

ISBN: (纸本)9781624107160

This work focuses on the suppression of Tollmien-Schlichting (TS)waves in a two-dimensional laminar boundary layer using optimized unsteady suction and blowing jets as an Active flow Control (AFC) method. The suppression of TS waves via this AFC system is enabled through two artificial intelligence-based optimization methodologies: Single-Step Deep Reinforcement Learning (SDRL) and Particle Swarm Optimization (PSO). The primary aim of this research is to assess the performance of these methods in optimizing the AFC parameters with respect to convergence rate, computational efficiency, and ability to find an optimum control state. The findings demonstrate the success of both methods in finding appropriate control parameters resulting in TS wave attenuation by up to 40 dB in the maximum convective instability amplitude for the linear and nonlinear stages of development. The comparative study in this paper presents the effectiveness of the SDRL algorithm in optimizing the AFC system for TS waves’ suppression and demonstrates that it can outperform PSO in terms of convergence rate and computational efficiency alongside a better performance in finding an improved optimum for linear control cases. However, the advantage of the SDRL-based controller over the PSO-based one diminishes in multi-frequency nonlinear control cases where the controller is located downstream and attempting to control highly amplified multi-modal TS waves. © 2024, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Laminar boundary layer

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Elasto-inertial focusing and particle migration in high aspect ratio microchannels for highthroughput separation

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Microsystems & Nanoengineering 2024年第3期10卷 381-394页

作者： Selim Tanriverdi Javier Cruz Shahriar Habibi Kasra Amini Martim Costa Fredrik Lundell Gustaf Mårtensson Luca Brandt Outi Tammisola Aman Russom Division of Nanobiotechnology Department of Protein ScienceScience for Life LaboratoryKTH Royal Institute of TechnologySolna 17165Sweden Division of Microsystems Technology Department of Materials Science and EngineeringUppsala UniversityUppsala 75237Sweden FLOW and SeRC(Swedish e-Science Research Centre) Department of Engineering MechanicsRoyal Institute of TechnologyStockholm SE 10044Sweden FLOW and Fluid Physics Laboratory Department of Engineering MechanicsRoyal Institute of TechnologyStockholmSweden Wallenberg Wood Science Center Royal Institute of TechnologyStockholm SE 10044Sweden Department of Energy and Process Engineering Norwegian University of Science and Technology(NTNU)TrondheimNorway AIMES Center for the Advancement of Integrated Medical and Engineering Sciences at Karolinska Institutet and KTH Royal Institute of Technology StockholmSweden

The combination of flow elasticity and inertia has emerged as a viable tool for focusing and manipulating particles using *** there is considerable interest in the field of elasto-inertial microfluidics owing to its potential applications,research on particle focusing has been mostly limited to low Reynolds numbers(Re<1),and particle migration toward equilibrium positions has not been extensively *** this work,we thoroughly studied particle focusing on the dynamic range of flow rates and particle migration using straight microchannels with a single inlet high aspect *** initially explored several parameters that had an impact on particle focusing,such as the particle size,channel dimensions,concentration of viscoelastic fluid,and flow *** experimental work covered a wide range of dimensionless numbers(0.05flow at a throughput of 150μL/*** work elucidates the complex particle transport in elasto-inertial flows and has great potential for the development of high-throughput and high-resolution particle separation for biomedical and environmental applications.

关键词： particle separation straight

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Low-Cost Computational Modeling of Aeroacoustic Interactions between Adjacent Propellers 30

Low-Cost Computational Modeling of Aeroacoustic Interactions...

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30th AIAA/CEAS Aeroacoustics Conference, 2024

作者： Prenter, Frits de Zarri, Alessandro Casalino, Damiano Department of Flow Physics and Technology Delft University of Technology Delft Netherlands Aeronautics and Aerospace Department von Karman Institute for Fluid Dynamics Rhode-St-Genèse Belgium

ISBN: (数字)9781624107207

ISBN: (纸本)9781624107207

Distributed Electric Propulsion systems are an emerging technology. Aerodynamic interactions between propellers in close proximity can, however, cause periodic variations in the blade loading. Together with acoustic interference, these installation effects can form a dominant noise source in such systems. In this contribution, we investigate a low-cost computational modeling approach to predict the unsteady loading of the propeller blades, and thereby the interaction noise of an array of side-by-side propellers. To inform this low-cost model, a numerical campaign of scale-resolving Lattice Boltzmann/Very Large Eddy Simulations (LBM/VLES) has been performed on the Dutch National Supercomputer Snellius. The goal of this model development is to gain a better understanding of the blade-to-blade interaction mechanisms and to determine to which extent the model can be applied for purposes like preliminary design, uncertainty quantification, or control, for which the computational cost of high-fidelity simulations is prohibitive. As a practical example, the optimal relative phase angle in an array of propellers is determined and validated. © 2024, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Aeroacoustics

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OPTIMAL APPROACH AND DEPARTURE TRAJECTORIES WITH ACOUSTIC FOOTPRINT ASSESSMENT FOR AN AIR MOBILITY QUAD-ROTOR 34th

OPTIMAL APPROACH AND DEPARTURE TRAJECTORIES WITH ACOUSTIC FO...

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34th Congress of the International Council of the Aeronautical Sciences, ICAS 2024

作者： Varriale, Carmine Yunus, Furkat Snellen, Mirjam Delft University of Technology Faculty of Aerospace Engineering Netherlands Department of Flow Physics and Technology Flight Performance and Propulsion section Netherlands Department of Control and Operations Aircraft Noise and Climate Effects section Netherlands

Advanced Air Mobility (AAM) vehicles are usually capable to operate in both forward and vertical flight thanks to their design configurations featuring multiple (tilting) rotors. Such maneuvering agility can be leveraged to minimize their acoustic footprint during operations close to the ground. The present work compares the acoustic footprint of optimal trajectories of AAM aircraft using low-order aero-acoustic models. The methodology is applied to the case of an AAM quad-rotor aircraft, which is modelled as a rotating point-mass with three Degrees of Freedom and two input controls. The trajectories are globally optimal in the sense of standard mission objectives, such as maneuver time or traveled horizontal distance, and are subject to realistic performance constraints. Results show that minimum-time trajectories generate higher and more concentrated noise footprints compared to minimum-distance trajectories, which distribute noise levels more evenly and result in overall lower noise footprints. Departure trajectories exhibit lower noise levels than approach trajectories. Adopting minimum-distance trajectories can significantly reduce noise impacts for both approach and departure maneuvers. © 2024, International Council of the Aeronautical Sciences. All rights reserved.

关键词： Maneuverability

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Passive stabilization of crossflow instabilities by a reverse lift-up effect

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Physical Review Fluids 2024年第4期9卷 043903-043903页

作者： Jordi Casacuberta Stefan Hickel Marios Kotsonis Department of Flow Physics and Technology Faculty of Aerospace Engineering Delft University of Technology Kluyverweg 1 2629HS Delft The Netherlands

A novel mechanism is identified, through which a spanwise-invariant surface feature (a two-dimensional forward-facing step) significantly stabilizes the stationary crossflow instability of a three-dimensional boundary layer. The mechanism is termed here as reverse lift-up effect, inasmuch as it acts reversely to the classic lift-up effect; that is, kinetic energy of an already-existing shear-flow instability is transferred to the underlying laminar flow through the action of cross-stream perturbations. To characterize corresponding energy-transfer mechanisms, a theoretical framework is presented, which is applicable to generic three-dimensional flows and surface features of arbitrary shape with one invariant spatial direction. The identification of a passive geometry-induced effect responsible for dampening stationary crossflow vortices is a promising finding for laminar flow control applications.

关键词： Aerodynamics Boundary layers Drag reduction flow instability Instability control Transition to turbulence Direct numerical simulations Navier-Stokes equation

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Magnetic properties and critical behavior of quasi-2D layered Cr_(4)Te_(5)thin film

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Frontiers of physics 2023年第1期18卷 141-151页

作者： Hao Liu Jiyu Fan Huan Zheng Jing Wang Chunlan Ma Haiyan Wang Lei Zhang Caixia Wang Yan Zhu Hao Yang Department of Applied Physics College of PhysicsNanjing University of Aeronautics and AstronauticsNanjing 211106China Key Laboratory of Aerospace Information Materials and Physics(NUAA) MIITNanjing 211106China Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application School of Mathematics and PhysicsSuzhou University of Science and TechnologySuzhou 215009China School of Materials Engineering Purdue UniversityWest LafayetteIN 47907USA High Magnetic Field Laboratory Chinese Academy of SciencesHefei 230031China College of Physics Science and Technology Yangzhou UniversityYangzhou 225002China

Quasi-2D layered Cr4Te5 thin film has attracted great attention because it possesses the high Curie temperature close to room temperature and relatively large saturation ***,the magnetic interactions and the nature of magnetic phase transition in the Cr4Te5 film have not been explored *** this paper,we focused on the critical behavior of its magnetic phase transition through the epitaxial Cr4Te5 film fabricated by pulsed laser deposition(PLD).The final critical exponentsβ=0.359(2)andγ=1.54(2)were obtained by linear extrapolation together with ArrottNoakes equation of state,and their accuracy was confirmed by using the Widom scaling relation and scaling *** find that some magnetic disorders exist in the Cr4Te5 film system,which is related to Cr4Te5 critical behavior why its critical behavior is quite far from any conventional universality ***,we also determined that the Cr4Te5 film exhibits a quasi-2D long-range magnetic ***,the itinerant ferromagnets of Cr4Te5 films were confirmed by the Takahashi’s self-consistent renormalization theory of spin *** work provides a new idea for understanding the mechanism of magnetic interactions in similar 2D layered films.

关键词： interaction film critical

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