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AIAA Aviation Forum

作者： Iyengar, Nikhil Rajaram, Dushhyanth Mavris, Dimitri Georgia Inst Technol Georgia Tech Sch Aerosp Engn Atlanta GA 30332 USA Georgia Inst Technol Georgia Tech ASDL Atlanta GA 30332 USA

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

Uncertainty quantification (UQ) in transonic and supersonic flows is difficult due to the presence of strong nonlinearities and discontinuities. This challenge is further exacerbated by limited training data and the high cost of computational fluid dynamics simulations. This study presents a non-intrusive, nonlinear UQ method called proISOMAP to efficiently propagate uncertainty in problems with high-dimensionality and shockwaves. The objective is to identify a low-dimensional manifold that best captures the dynamics of the high-dimensional data and nonlinear features of the problem. This manifold is then parameterized by mapping the variations in the uncertain inputs to changes in the projected data in the latent space. Specifically, proISOMAP combines a data-driven global manifold learning procedure with an adaptive polynomial chaos expansion (PCE) to develop a probabilistic approach on manifolds for rapid UQ. The performance of the proposed methodology is compared to state-of-the-art linear and local manifold learning approaches for UQ on examples using wedges and nozzles under uncertain geometric and flow conditions. The accuracy and robustness of the method is assessed as polynomial chaos order and the number of training samples are varied. Several scalar and field-level error metrics are introduced to measure both global and local predictive performance.

关键词： Uncertainty Quantification computational fluid dynamics simulation High Speed Flows Lift Distribution Aerodynamic Performance Monte Carlo Analysis Artificial Neural Network Aircraft Design Process Computing Probability Density Functions

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Modelling of Transonic Buffet Alleviation via Spoilers

Modelling of Transonic Buffet Alleviation via Spoilers

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AIAA Aviation Forum

作者： Petrocchi, Andrea Barakos, George N. Univ Glasgow Sch Engn CFD Lab Glasgow G12 8QQ Lanark Scotland

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

In this work, computational fluid dynamics simulations are carried out to assess the ability of spoilers to alleviate transonic buffet. Spoilers are present on every commercial aircraft and can be used as shock and boundary-layer control devices. The difficulties to model slotted and deployable control surfaces have been overcome by adapting a formulation developped for modelling swinging Gurney flaps to wing spoilers. By adopting virtual spoilers, the separated region formed during buffet is divided. The shock is fixed to an upstream position, and the oscillations are stopped, or alleviated. The effectiveness of this buffet control method is first assessed using 2D computations around aerofoils with different sections and at different flow conditions. The sensitivity to the spoiler deployment angle is studied, and the optimum value based on the aerodynamic performance is determined. Then, computations on an OAT15A unswept wing are carried out to investigate the effect of the spoiler on the 3D buffet dynamics and flow topology.

关键词： Aerodynamic Coefficients Control Surfaces Aerofoil Aerodynamic Performance Buffeting Flows Commercial Aircraft Thickness to Chord Ratio Boundary Layer Control computational fluid dynamics simulation Gurney Flap

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Bayesian calibration of a low order aerodynamic model for the design of unconventional tail empennages

Bayesian calibration of a low order aerodynamic model for th...

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AIAA Aviation Forum

作者： Gori, Giulio Rausa, Andrea Zanotti, Alex Auteri, Franco Guardone, Alberto Politecn Milan Dept Aerosp Sci & Technol Via La Masa 34 I-20156 Milan Italy

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

In the frame of the MONNALISA Project of the Clean Sky 2 Joint Undertaking (CSJU), we develop a calibration framework for improving the prediction accuracy of a low-order aerodynamic model. The enhancement is sought with respect to a reference application case, an unconventional "Advanced Rear End" component for the forthcoming generation of ultra-efficient aircraft, which is a specific focus of the MONNALISA Project. The calibration framework develops upon a classical Bayesian inference approach providing not only optimal values for the model parameters, but also a probabilistic characterization in terms of their peculiar probability distribution within well defined bounds. The reference data include both numerical predictions from computational fluid dynamics simulations and experimental measurements collected at the large wind-tunnel facility (GVPM) at Politecnico di Milano.

关键词： Aircraft Configurations computational fluid dynamics simulation Wind Tunnel Models Reynolds Averaged Navier Stokes Aerodynamic Performance Aerodynamic Characteristics Wing Configurations computational Modeling Broyden Fletcher Goldfarb Shanno Swept Wing

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An experimental investigation of turbulent-boundary-layer trailing-edge noise from an aerofoil equipped with a flexible trailing edge

An experimental investigation of turbulent-boundary-layer tr...

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AIAA Aviation Forum

作者： Liu, Qian Liut, Yu Southern Univ Sci & Technol Dept Mech & Aerosp Engn Shenzhen 518055 Guangdong Peoples R China Hong Kong Univ Sci & Technol Dept Mech & Aerosp Engn Clear Water Bay Hong Kong Peoples R China

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

The acoustic characteristics of a symmetric NACA 0012 aerofoil with a flexible trailing edge (TE) and the deformation characteristics of the flexible TEare experimentally investigated. The acoustic measurement is conducted in an anechoic wind tunnel and the chord-based Reynolds number is ranging from 2.9 x 10(5) to 7.7 x 10(5). The aerofoil is at a zero angle of attack, and the boundary layer is tripped near the leading edge. The Polyethylene Terephthalate (PET) and Polypropylene (PP) strips are inserted into the slit along the chord line and extend out of the TE of the aerofoil, forming a flexible TE. Compared with the aerofoil without the flexible extension, the aerofoil with flexible PET and PP strips both reduce noise at medium frequencies approximately starting from 450 Hz. Besides, the upper limit of the frequency band of noise reduction increases with the free stream velocity U, following a scaling of f similar to U-1.4. However, peak noise increases are also noticeable, with similar frequencies at different free stream velocities. The strip deformation is captured using high-speed cameras and LaVision DAVIS 10.2 software. The result reveals that the vibration of the flexible strip contributes to the presence of noise peaks, which is consistent with the conclusion of previous numerical results [1]. The proper orthogonal decomposition (POD) analysis shows that the deformation consists of bending and torsional modes. Moreover, the results suggest that peak noise can be ascribed to the bending deformation at a low velocity of 20 m/s, while at high velocities, it is caused by a combination of bending and torsional modes.

关键词： Trailing Edges NACA 0012 Turbulent Boundary Layer Trailing Edge Noise computational fluid dynamics simulation Free Stream Velocity Angle of Attack Acoustic Measurement Wind Tunnels Chord Line

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Environmental co-benefits of urban design to mitigate urban heat island and PM2.5 pollution: considering prevailing wind's effects

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INDOOR AND BUILT ENVIRONMENT 2022年第7期31卷 1787-1805页

作者： Meng, Ming-Rui Xi, Chang Feng, Zhuangbo Cao, Shi-Jie Southeast Univ Sch Architecture 2 Sipailou Nanjing 21009 Peoples R China Guangzhou Univ Sch Civil Engn Acad Bldg Energy Efficiency Guangzhou Peoples R China

The impact of PM2.5 pollution and urban heat island (UHI) on sustainable urban development and human health has been a major concern for governments. Based on computational fluid dynamics (CFD) simulation and on-site monitoring, this study investigated the airflow velocity, PM2.5 concentration and urban heat island intensity (UHII) distribution in the urban area at different prevailing wind directions, from the perspective of urban design. In order to validate the accuracy of CFD simulation results, on-site monitoring of temperature and airflow velocity was conducted on the roof of a building. A low-dimensional model was adopted to improve the efficiency of CFD data analysis. Moreover, based on the results of the low-dimensional model, PM2.5 concentration and UHII in urban areas at different prevailing wind directions were assessed by clustering analysis. The findings showed that when alpha = 0 degrees and 90 degrees, the average PM2.5 concentration was 28.9-56.8% (8.76-27.66 mu g/m(3)) lower and the average UHII was 23.4-34.2% (0.8-1.15 degrees C) higher, compared to alpha = 30 degrees, 45 degrees and 60 degrees. Meanwhile, the downwind area suffers from more serious PM2.5 pollution and UHII than the upwind area. These findings could potentially provide a guide for future building/urban design to improve the urban environment from the perspective of building and road construction.

关键词： Urban design human health PM2 5 concentration urban heat island computational fluid dynamics simulation low-dimensional model cluster analysis

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Model-Guided Development of a Semi-Continuous Drying Process

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PHARMACEUTICAL RESEARCH 2022年第9期39卷 2005-2016页

作者： Grelier, Anthony Zadravec, Matej Remmelgas, Johan Forgber, Thomas Colacino, Franco Pilcer, Gabrielle Stauffer, Fanny Hoermann-Kincses, Theresa UCB Pharma SA Allee La Rech 60 B-1070 Brussels Belgium RCPE GmbH Inffeldgasse 13-2 A-8010 Graz Austria

Introduction With an increased adoption of continuous manufacturing for pharmaceutical production, the ConsiGma (R) CTL25 wet granulation and tableting line has reached widespread use. In addition to the continuous granulation step, the semi-continuous six-segmented fluid bed dryer is a key unit in the line. The dryer is expected to have an even distribution of the inlet air between the six drying cells. However, process observations during manufacturing runs showed a repeatable pattern in drying time, which suggests a variability in the drying performance between the different cells of the dryer. The aim of this work is to understand the root-cause of this variability. Materials and methods In a first step, the variability in the air temperature and air flow velocity between the dryer cells was measured on an empty dryer. In a second step, the experimental data were interpreted with the help of results from computational fluid dynamics (CFD) simulations to better understand the reasons for the observed variability. Results The CFD simulations were used to identify one cause of the measured difference in the air temperature, showing the impact of the air inlet design on the temperature distribution in the dryer. Conclusions Although the simulation could not predict the exact temperature, the trend was similar to the experimental observations, demonstrating the added value of this type of simulation to guide process development, engineering decisions and troubleshoot equipment performance variability.

关键词： computational fluid dynamics simulation process variability investigation semi-continuous fluid bed drying

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Application of Steady and Scale-Resolving computational fluid dynamics simulations to Assess Airfield Building Wake Impact on Operations

Application of Steady and Scale-Resolving Computational Flui...

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AIAA Aviation Forum

作者： Palmer, Timothy Pierce, Tyler Shah, Parthiv Alex, Nicholas ATA Engn Inc San Diego CA 92128 USA C&S Co San Diego CA 92108 USA

ISBN: (数字)9781624105982

ISBN: (纸本)9781624105982

Steady and time-accurate computational fluid dynamics (CFD) simulations were used in support of a planned aircraft hangar expansion at a regional airport. The goal of the computational analysis was to quantify the impact of the proposed expanded hangar's wake on the operation of landing aircraft on a nearby runway. Computed quantities of interest included generated wind deficits, wind shears, and turbulent velocity fluctuation magnitudes that aircraft may encounter when flying through the wake. Several approach trajectories were considered for a range of wind headings on the runway of interest. Steady Reynolds-averaged Navier-Stokes (RANS) CFD analysis provided the time-mean impact of the hangar and identified the worst-case direction for the approach velocity field. Scale-resolving, unsteady CFD analysis demonstrated generally similar time-mean wind velocity deficits as steady RANS, although instantaneous changes in velocity within the hangar wake obtained in scale-resolving simulations were significant relative to stall margin and allowable crosswind speeds. The larger hangar structure and closer dimensionless spacing from the runway were found to potentially exacerbate wake effects relative to the original structure. Methods are put forth to use data from scale-resolving simulations to quantify perceived changes in headwinds, crosswinds, and downwash for arriving aircraft under conventional and worst-case conditions.

关键词： computational fluid dynamics simulation Airfields Runways Reynolds Averaged Navier Stokes Aerodynamic simulation Wind Shear Aircraft Hangars Pilot Velocity Profiles Aircraft Landing

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Urban form study for wind potential development

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ENVIRONMENT AND PLANNING B-URBAN ANALYTICS AND CITY SCIENCE 2022年第1期49卷 76-91页

作者： Wang, Biao Geoffroy, Sandrine Bonhomme, Marion Soochow Univ Gold Mantis Sch Architecture Suzhou Peoples R China Univ Toulouse LMDC Lab Mat & Durabil Construct UPS INSA 135 Ave Rangueil F-31077 Toulouse France Univ Toulouse Dept Civil Engn Inst Natl Sci Appl Toulouse INSA Toulouse France

Wind energy development is helpful for realizing a green city. This work concentrates on the study of estimating urban wind energy with consideration of urban morphology. Fourteen typical urban forms in Beijing city were selected and analyzed with nine relevant urban morphology parameters. computational fluid dynamics numerical simulations were used to evaluate the wind energy potential of the urban forms. This work demonstrates that urban forms with higher plot ratio and mean aspect ratio usually have higher wind potential density by site area, an important indicator for neighborhood-scale wind potential development. Urban forms with higher average building height would have higher wind potential density by roof area, an important indicator for building-scale wind potential development. To promote wind potential over roofs, a layout of 45 degrees of building configuration with inlet wind direction and building forms with round-angle corners are suggested. Local wind distribution is important for wind energy evaluation of individual buildings and wind energy distribution over different directions;however, it has a substantially lesser effect on the general wind potential comparison among urban forms with different urban characteristics.

关键词： Urban wind energy urban morphology computational fluid dynamics simulation

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Framework for discovering porous materials: Structural hybridization and Bayesian optimization of conditional generative adversarial network

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DIGITAL CHEMICAL ENGINEERING 2022年 5卷

作者： Matsuda, Yosuke Ookawara, Shinichi Yasuda, Tomoki Yoshikawa, Shiro Matsumoto, Hideyuki Tokyo Inst Technol Dept Chem Sci & Engn 2-12-1 S1-26 OokayamaMeguro Ku Tokyo 1528552 Japan Egypt Japan Univ Sci & Technol Dept Energy Resources Engn POB 179-21934 New Borg El Arab City 21934 Alexandria Egypt

Although deep-learning-based materials discovery has attracted considerable research attention, the application of deep learning has been limited to discovery of materials within single material types such that the discovered materials are similar to existing ones. Thus, we developed an alternative approach for discovering porous materials. A materials discovery design space was configured using several key porous materials and a conditional generative adversarial network (CGAN), which structurally hybridizes them. Hybridization was controlled using a vector design variable input as a condition to the CGAN, and each design variable component represented a key porous material intensity, which was defined as a conceptual quantity for expressing materialness. Furthermore, by varying the vector latent variable input to the CGAN, any number of similar hybrid porous materials could be generated using the same design variable. The multiobjective Bayesian optimizer efficiently discovered hybrid porous materials constituting Pareto solutions in the objective function space of the material properties, which were mapped from the design space by the CGAN structural hybridization and computational fluid dynamics property evaluation. Tradeoff properties such as the pressure drop and filtration efficiency were multiobjectively optimized for key porous materials exhibiting random, packed-sphere, and sponge structures. By flexibly adopting their structural parameters depending on the required pressure drop and filtration efficiency, the discovered optimized hybrid porous materials outperformed the key porous ones. The results demonstrated the effectiveness of the proposed framework for discovering porous materials.

关键词： Porous material Permeability Filtration efficiency Conditional generative adversarial network computational fluid dynamics simulation Multiobjective Bayesian optimization

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JOURNAL OF SPACECRAFT AND ROCKETS 2021年第4期58卷 984-996页

作者： Gutsche, Kevin Marwege, Ansgar Guelhan, Ali DLR German Aerosp Ctr Inst Aerodynam & Flow Technol Superson & Hyperson Technol Dept D-51147 Cologne Germany

Retropropulsion, a deceleration technique where the thrust is directed along the flight path, is the driving technology for vertically landing, reusable launchers. Experiments, which are indispensable for the full comprehension of retropropulsion flows, pose serious challenges to the operability of wind tunnels and interpretation of these subscale experiments. The key factors to facilitate meaningful results of supersonic and hypersonic retropropulsion experiments are addressed in this study. Similarity parameters for subscale experiments are evaluated, the interaction of retropropulsion flows with the test facility is investigated, and condensation within these flows is analyzed. For this purpose, computational fluid dynamics simulations were performed;subsequently, cold gas experiments for a generic retropropulsion launcher configuration with a single central nozzle were carried out in the hypersonic wind tunnel Cologne H2K at the Supersonic and Hypersonic Technologies Department of the DLR, German Aerospace Center. Based on these data, an improved similarity parameter related to the exit condition of the engine exhaust flow is proposed, and a universally applicable scaling law for supersonic retropropulsion wind-tunnel models is derived and validated. Various condensation mitigation techniques for the conducted experiments are presented, and their varying effectiveness is highlighted.

关键词： Hypersonic Wind Tunnels Condensation computational fluid dynamics simulation Supersonic Retropropulsion German Aerospace Center

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