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AIAA Aviation Forum

作者： Schmeling, Daniel Dehne, Tobias Lange, Sven Schiepel, Daniel Shishkin, Andrei German Aerosp Ctr DLR Inst Aerodynam & Flow Technol Dept Ground Vehicles Bunsenstr 10 D-37073 Gottingen Germany Volkswagen AG Dev Aerodynam Postbox 1787 D-38436 Wolfsburg Germany

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

The ventilation of passenger aircraft cabins as a subsystem of the environmental control system directly affects the (thermal) passenger comfort and the air quality in the cabin. Additionally, the energy efficiency of the ventilation concept is the third major evaluation parameter. Within the triangle of 'air quality', 'thermal comfort' and 'energy efficiency' the optimal configuration for the specific cabin geometries has to be determined addressing all of the mentioned parameters. Furthermore, the robustness, the capability of integration and the possibility to implement modularization processes are additional evaluation parameters. In the present study, we introduce the Do728 passenger aircraft cabin as potential common research model. Moreover, we present the results of numerical and experimental investigations of two different ventilation concepts within this cabin geometry: mixing ventilation, which is state-of-the-art in all modern passenger aircraft, and cabin displacement ventilation as an alternative concept. The results are discussed in terms of temperature and velocity distributions as well as with regard to the aerosol dispersion in the cabin.

关键词： Aircraft Cabin Common Research Model Energy Efficiency Environmental Control System computational fluid dynamics simulation Reynolds Averaged Navier Stokes Particle Image Velocimetry Digital Twins German Aerospace Center Thermal Convection

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Anisotropic Mach Cone Aligned Mesh Adaptation for Low Boom simulations

Anisotropic Mach Cone Aligned Mesh Adaptation for Low Boom S...

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AIAA Aviation Forum

作者： Ashby, Chase P. Housman, Jeffrey A. Duensing, Jared NASA Computat Aerosci Branch Ames Res Ctr M-S 258-2 Moffett Field CA 94035 USA

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

An automated off-body Mach cone aligned structured curvilinear grid generation procedure is presented for near-field computational fluid dynamics simulations. This procedure combines output-based indicators and mesh redistribution to perform anisotropic mesh adaptation while maintaining Mach cone alignment. Automation is achieved through a novel direction-based adaptation indicator formulation. The adaptation procedure is demonstrated on the JAXA Wing Body geometry and X-59 C608 demonstrator model from the Second and Third AIAA Sonic Boom Prediction Workshops, respectively. It is demonstrated that anisotropic mesh adaptation may result in a greater than fifty percent reduction in the resource usage required to achieve the same level of accuracy as uniform and user constructed Mach cone aligned grids for near-field pressure signatures, ground-level overpressure signatures, and loudness metrics.

关键词： Sonic Booms computational fluid dynamics simulation Compressible Flow Aerodynamics Aspect Ratio Euler Equations Angle of Attack Environmental Control System Nonlinear Systems Richardson Extrapolation

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Uncertainty Quantification in Flows with Discontinuities: A Probabilistic Approach on Nonlinear Manifolds

Uncertainty Quantification in Flows with Discontinuities: A ...

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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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Implementation and Verification of the SST-γ and SA-AFT Transition Models in FUN3D

Implementation and Verification of the SST-γ and SA-AFT Tra...

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AIAA Aviation Forum

作者： Hildebrand, Nathaniel Choudhari, Meelan M. Venkatachari, Balaji S. NASA Langley Res Ctr Computat AeroSci Branch Hampton VA 23681 USA Natl Inst Aerosp Computat AeroSci Branch Hampton VA 23666 USA

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

The transition modeling capability in the NASA unstructured FUN3D suite of codes has been augmented by incorporating two additional transport-equation-based transition models, namely, the gamma transition model coupled with Menter's 2003 Shear-Stress Transport (SST) turbulence model and Coder's Amplification Factor Transport (AFT) transition model combined with the Spalart-Allmaras (SA) turbulence model. Both of these models, SST-gamma and SA-AFT, are used to compute transition characteristics of several test cases from the literature. The selected test cases cover a range of transition scenarios including bypass transition over a flat plate (ERCOFTAC T3A and T3A- flow configurations), transition in the presence of separation bubbles (NLF-0416 airfoil at selected angles of attack), and natural transition due to Tollmien-Schlichting instabilities (flat-plate experiment by Schubauer and Klebanoff). To address the urgent need for model verification as highlighted in recent workshops on transition modeling, the drag, lift, surface pressure, and skin-friction coefficients from the FUN3D solutions for a sequence of meshes are compared with the results obtained with the same models implemented in the NASA structured grid flow solver OVERFLOW. Comparisons between the local and global surface coefficients from the FUN3D and OVERFLOW solvers for all test cases resulted in good agreement for the finest meshes.

关键词： FUN3D Skin Friction Coefficient Lift Coefficient Freestream Mach Number Airfoil Spalart Allmaras Turbulence Model NASA Shear Stress Reynolds Averaged Navier Stokes computational fluid dynamics simulation

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Thermal Environment of Launch Pads During Rocket Launching

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JOURNAL OF SPACECRAFT AND ROCKETS 2022年第2期59卷 489-496页

作者： Lu, Chenyu Zhou, Zhitan Liang, Xiaoyang Le, Guigao Nanjing Univ Sci & Technol Dept Mech Engn Nanjing 210094 Peoples R China Nanchang Hangkong Univ Dept Aircraft Engn Nanchang 330063 Jiangxi Peoples R China

This paper investigates the thermal environment of launch pads during rocket takeoff. The rocket plume model is set up using the three-dimensional Navier-Stokes equations and realizable k - epsilon turbulence model. The aluminium oxide particles in the plume are considered by the Eulerian dispersed phase model. Comparing with the experimental data, the accuracy of the numerical model can be verified. On this basis, in total 16 numerical cases are performed to analyze the influence of the rocket flight altitude and lateral drift on the temperature of the launch pad. The results show that the launch pad has a more severe thermal environment at the flight altitudes from 3 to 20m. Because of the rocket drift, a high-temperature gas flow layer is formed on the launch pad, which results in a dramatic increase in the temperature of the cross beam. At this location, the maximum temperature can reach up to 3900 K, 30% higher than the value without rocket drift. The method in this paper can provide an effective way to evaluate the thermal environment of the launch pad during rocket launching and have a great value on the thermal protection system design.

关键词： Rocket Launch Launch Pad Rockets Flight Altitude Numerical Modeling Thermal Protection System Solid Rocket Motor Navier Stokes Equations computational fluid dynamics simulation Reynolds Averaged Navier Stokes

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Understanding the influence of hydraulic conditions on colloidal fouling development by using the micro-patterned nanofiltration membrane: Experiments and numerical simulation

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JOURNAL OF MEMBRANE SCIENCE 2022年 654卷

作者： Shang, Wentao Yang, Songwen Liu, Wenjie Wong, Pak Wai Wang, Rui Li, Xiaoyan Sheng, Guoping Lau, Woonming An, Alicia Kyoungjin Sun, Feiyun Harbin Inst Technol Shenzhen Sch Civil & Environm Engn Shenzhen Key Lab Water Resource Applicat & Environ Shenzhen 518055 Peoples R China Univ Hong Kong Environm Engn Res Ctr Dept Civil Engn Hong Kong Peoples R China City Univ Hong Kong Sch Energy & Environm SEE Kowloon Hong Kong Peoples R China Univ Sci & Technol Beijing Shunde Grad Sch Foshan Peoples R China Univ Sci & Technol Beijing Ctr Green Innovat Sch Math & Phys Beijing Peoples R China Univ Sci & Technol China Dept Environm Sci & Engn CAS Key Lab Urban Pollutant Convers Hefei 230026 Peoples R China

Surface patterning has emerged as a promising method to control membrane fouling by disturbing the flow field on the membrane surface. In this study, fouling development was non-destructively characterized by optical coherence tomography (OCT), while the micro hydraulic conditions and particle migration trajectories were investigated by using computational fluid dynamics (CFD). Preliminary results demonstrated remarkable antifouling performance of the MNF membrane, and CFD simulation revealed that the local flow velocity on the apex area of patterns was greatly accelerated and the vortex among the valley regions was continuously generated. These hydraulic characteristics resulted in the enhancement of the hydrodynamic lift force (fL) and decrease of the permeation drag (fD) enforced on the retained foulants by the MNF membrane. Moreover, particle trajectories simulation integrated with comprehensive forces allowed to understand the influence mechanism of the flow field around MNF membrane surface on particle deposition. This study presents a new understanding of the antifouling mechanism of the MNF membranes and provides new insights into the design of self-cleaning membranes.

关键词： Micro-patterned nanofiltration membranes Anti-fouling Hydraulic conditions computational fluid dynamics simulation

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Effects of geometric and operational uncertainties on aerodynamic performance of centrifugal compressor stage

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART A-JOURNAL OF POWER AND ENERGY 2022年第3期236卷 490-505页

作者： Zhu, Rui Ju, Yaping Zhang, Chuhua Xi An Jiao Tong Univ Sch Energy & Power Engn Dept Fluid Machinery & Engn 28 West Xianning Rd Xian Shaanxi Peoples R China

No real centrifugal compressor can exactly conform to its design geometry and expected operating conditions due to the uncertainties existing in the manufacturing and operational processes. Such uncertainties have been increasingly recognised to be detrimental to compressor performance. However, quite few studies have focused on the combined effects of geometric and operational uncertainties on compressor performance, and the underlying flow mechanism even remains unclear. In this context, we here present an uncertainty analysis of a centrifugal compressor stage, with both geometric and operational uncertainties taken into account. With the combination of CFD simulation and nonintrusive sparse grid based stochastic collocation methods, the combined and individual effects of total inlet temperature, total inlet pressure, outlet mass flow, impeller tip clearance and hub fillet radius on the stage/impeller performance are quantified and analysed. Particular attention is paid to elucidating the compressor performance variations through flow field and energy decomposition analyses. Results show that the considered uncertainties exert more influence on the compressor stage performance rather than on the impeller performance. Amongst the examined uncertainties, the impeller tip clearance contributes the most to the stage performance. The underlying mechanism lies in that the wake of impeller tip clearance produces distorted flow downstream towards the diffuser, which causes complicated vortex structures and less conversion of kinetic energy to pressure rise in the diffuser passage. The present study lays a theoretical foundation for the further uncertainty quantification and robust design of centrifugal compressors against various sources of uncertainties.

关键词： Centrifugal compressor uncertainty quantification geometric and operational uncertainties computational fluid dynamics simulation

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Comparison of the airflow characteristics and yarn properties between conventional and dual-feed-opening rotor spinning units

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TEXTILE RESEARCH JOURNAL 2022年第5-6期92卷 660-674页

作者： Shi, Qianqian Wang, Jiang Zhang, Yuze Ding, Qian Akankwasa, Nicholus Tayari Lin, Huiting Wang, Jun Donghua Univ Coll Text Shanghai Peoples R China Donghua Univ Coll Text Key Lab Text Sci & Technol Minist Educ Shanghai 201620 Peoples R China Quanzhou Normal Univ Coll Text & Fash Shanghai Peoples R China

In order to explore the differences between conventional and dual-feed-opening rotor spinning units (RSUs), this work compares the airflow characteristics of two RSU models utilizing a computational fluid dynamics simulation model with the accuracy verified by airflow behavior observation and air pressure measurement. The effect of two different opening roller speeds on the airflow field distribution of a dual-feed-opening model is also investigated. In addition, the yarn properties of six pure and blended yarns corresponding to the two RSU models are evaluated. The results reveal that the distributions of airflow velocity vector and air pressure in the two RSU models show a strong similarity under the same boundary conditions. However, the dual-feed-opening model possesses a centrosymmetric and more balanced airflow field distribution compared to the conventional model. In addition, the dual-feed-opening yarns show a superior performance in comparison to the conventional yarns. Furthermore, for the dual-feed-opening model, there are equivalent contributions of two separated opening and fiber transmission systems to the airflow field distribution and yarn formation. Compared to the configuration with the same two opening roller speeds, the dual-feed-opening model configured with two different opening roller speeds obtains an improved blended yarn performance with having few effects on the airflow characteristics. This strength of the dual-feed-opening RSU could facilitate the production of blended and fancy yarns employing the fibers with diverse properties. This study could provide some guidelines for the manufacture of rotor-spun yarns and the future design of RSUs.

关键词： Dual-feed-opening rotor spinning unit airflow field computational fluid dynamics simulation rotor-spun yarn

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Double-blade structured triboelectric-electromagnetic hybrid generator with aerodynamic enhancement for breeze energy harvesting

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APPLIED ENERGY 2022年 326卷

作者： Zhu, Mingkang Zhang, Jiacheng Wang, Zhaohui Yu, Xin Zhang, Yuejun Zhu, Jianyang Wang, Zhong Lin Cheng, Tinghai Wuhan Univ Sci & Technol Key Lab Met Equipment Control Technol Minist Educ Wuhan 430081 Hubei Peoples R China Chinese Acad Sci Beijing Inst Nanoenergy & Nanosyst Beijing 101400 Peoples R China Ningbo Univ Inst Circuits & Syst 818 Fenghua Rd Ningbo 315211 Peoples R China Georgia Inst Technol Sch Mat Sci & Engn Atlanta GA 30332 USA

Wind energy is a form of renewable energy with excellent development prospects. However, low-speed wind energy has not been effectively explored and utilized. To this end, a double-blade structured triboelectric-electromagnetic hybrid generator (DB-TEHG) is designed in this paper, which can efficiently harvest breeze energy by using double-blade structured design to improve the aerodynamic performance of the device. The improved blade structures directly drive the triboelectric nanogenerator (TENG) and electromagnetic generator (EMG) without requiring additional transmission systems. The blade parameters are simulated and optimized using computational fluid dynamics to enhance the wind energy harvesting capability of the device. The minimum starting wind speed of DB-TEHG is found to be 2 m/s. The output performance of a single TENG unit is 910 V, 45 mu A, 280 nC, and the peak power is 4 mW, and that of the EMG is 236 V, 24.2 mA, and a peak power of 0.5 W, when the wind speed is 5 m/s. It is also found that at this wind speed the DB-TEHG can convert wind energy into electricity output with an efficiency of 20.88%. The demonstration results prove that the proposed DB-TEHG can power a wireless thermometer by harvesting outdoor natural wind energy. This paper

关键词： Triboelectric nanogenerator Triboelectric -electromagnetic hybrid generator Breeze energy harvesting computational fluid dynamics simulation

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Improvement of optimization methods in indoor time-variant source parameters estimation combining unsteady adjoint equations and flow field information

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BUILDING AND ENVIRONMENT 2022年 226卷

作者： Wang, Fuyu Zhou, Xuanyi Kikumoto, Hideki Tongji Univ State Key Lab Disaster Reduct Civil Engn Shanghai 200092 Peoples R China Univ Tokyo Inst Ind Sci Tokyo Japan

When hazardous gas leaks, accurate and prompt identification of leakage location and leakage rate is essential for ensuring indoor air quality and environmental safety. In the process of source parameters estimation, precise establishment of source-detector relationship is critical. Although computational fluid dynamics (CFD) simula-tion has high accuracy, it demands massive computing time. Prior studies mainly concentrate on estimating constant release sources, and few of them focus on time-variant sources peculiarly under indoor complex flow. Therefore, this paper further develops optimization methods based on fixed-detector networks by combining unsteady adjoint equations and flow field information. With only three fixed detectors, the effectiveness of proposed method is tested by estimating three time-variant source parameters under complex indoor flow. The results indicate that the application of unsteady adjoint equations not only saves a huge amount of computation but also preserves the high accuracy of CFD simulation, making it possible to estimate time-variant sources promptly and accurately under indoor complex flow. For the convenience of practical application, performances of five commonly used optimization methods and three common cost functions are compared carefully. The results show that the cost function gradient determines their different estimation performances. In addition, the reason for the formation of local optimal areas is analyzed and the flow field information is utilized to avoid the problem that optimization methods may converge to local optimal values, which improves the accuracy of estimated results significantly.

关键词： Source parameters estimation Adjoint equation Optimization method Time -variant source computational fluid dynamics simulation

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