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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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Optical aerodynamic measurements of hypersonic free-flight using Bayesian state estimation

Optical aerodynamic measurements of hypersonic free-flight u...

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AIAA Aviation Forum

作者： Lock, Andrew Armstrong, Gerard Hack, Flynn Birch, Byrenn Buttsworth, David Jahn, Ingo Univ Southern Queensland Darling Heights Qld Australia

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

Free-flight aerodynamic measurements via optical tracking have recently gained popularity due to model simplicity, unconstrained body motion, and lack of flow interference from supporting stings. However, the signal to noise ratio of high-speed optical aerodynamic measurements is unfavourable, requiring significant data smoothing for meaningful results. This work presents a new method of optical six-degree-of-freedom aerodynamic measurements founded on Bayesian state estimation. A sigma-point Kalman filter and Rauch-Tung-Striebel smoother computes the state estimate at each time using images from two high-speed camera images and a kinematic process model. The pixel location of markers detected in camera images are each treated as individual measurements, and are related to the body position and pose in local coordinates using calibrated camera models. This new method allows aerodynamic measurements using two un-synchronised cameras at arbitrary positions. As a demonstration, this work measures aerodynamics of a cube in Mach 6 flow in the University of Southern Queensland's TUSQ wind tunnel. Images are taken with an existing z-type schlieren camera assembly and one additional standard high-speed camera over approximately 30 ms. During three tests the cube has low initial rotation;in a fourth run we rotate the cube to approximately 600 RPM prior to release in the flow. Measured force and moment coefficients are compared to simulations using compressible flow computational fluid dynamics conduced as part of this work. The two result sets show strong agreement, and high tracking accuracy is demonstrated by superimposing the body motion over camera images. This new method may allow wind tunnels to conduct optical aerodynamic measurements with less modification and equipment than traditional stereoscopic methods. Moreover, the use of Bayesian state estimation algorithms is shown to be effective at reducing otherwise-large measurement noise.

关键词： State Estimation Aerodynamic Coefficients Extended Kalman Filter Compressible Flow Hypersonic Wind Tunnels Rauch Tung Striebel Smoother Optical Tracking Six Degree of Freedom computational fluid dynamics simulation Data Smoothing

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Implicit Large Eddy simulations of Crossflow Instabilities on a Slotted, Natural-Laminar-Flow Airfoil

Implicit Large Eddy Simulations of Crossflow Instabilities o...

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AIAA Aviation Forum

作者： Gosin, Samuel A. Coder, James G. Penn State Univ Dept Aerosp Engn State Coll PA 16802 USA

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

A low-speed, slotted, natural-laminar-flow airfoil has been tested in the Klebanoff-Saric Wind Tunnel at Texas A&M University. The instigation of crossflow instabilities was the primary focus of the experiment, most notably the wing configurations of Lambda = 35 degrees and alpha = -5.5 degrees, 2.25 degrees. Computations were also conducted using DEKAF to study the linear growth of disturbances measured by integrating the Linear Parabolized Stability Equations (LPSE). N-factor envelopes were established for each instability mechanism. The present work seeks to replicate and validate these results using high-fidelity computational fluid dynamics simulations. The experiments employ the use of both discrete roughness elements on the leading edge, as well as acoustic noise. The OVERFLOW 2.4b overset grid computational fluid dynamics solver is used, with a transitional Reynolds-averaged Navier-Stokes simulation, as well as a time accurate, implicit large eddy simulation. The effect of the crossflow instability on boundary-layer transition is also investigated.

关键词： Natural Laminar Flow Airfoil computational fluid dynamics simulation Reynolds Averaged Navier Stokes Leading Edges Acoustic Noise Klebanoff Saric Wind Tunnel Laminar to Turbulent Transition Parabolized Stability Equations Wing Configurations

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Towards Mixed-Fidelity Aero-Structural-Acoustic Optimization for Urban Air Mobility Vehicle Design

Towards Mixed-Fidelity Aero-Structural-Acoustic Optimization...

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AIAA Aviation Forum

作者： Pacini, Bernardo Prajapati, Malhar Duraisamy, Karthik Martins, Joaquim R. R. A. He, Ping Univ Michigan Dept Mech Engn Ann Arbor MI USA Univ Michigan Dept Aerosp Engn Ann Arbor MI USA Univ Michigan Aerosp Engn Ann Arbor MI USA Iowa State Univ Dept Aerosp Engn Ames IA USA

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

Many urban air mobility vehicle designs feature propellers integrated with fuselage, wings, and other appendages. These vehicle designs are based on complex configurations with novel propulsion systems and flight technology. The tightly coupled nature of the systems in these vehicles and the novel technologies within them create opportunities for vehicle analysis and optimization. Furthermore, the geometries being developed are unique, utilizing advanced materials for integral components. Aerodynamic, structural, and acoustic analysis and optimization can provide insight into their performance, and how the propellers, structures, and lifting surfaces can be designed to further improve vehicle efficiency considering operational constraints. This work details an aero-structural-acoustic optimization toolchain built with the MACH and OpenMDAO tools, embedded within the modeling and optimization framework called MPhys. This analysis and optimization framework utilizes multiple model fidelities, including hybrid blade element momentum theory, computational fluid dynamics, finite-element modeling, and an aeroacoustic analogy. With this toolchain, this work presents gradientbased aero-structural-acoustic optimization, minimizing required flight power while ensuring structural integrity and respecting acoustic considerations. The toolchain is applied to the NASA tiltwing concept vehicle to optimize the wing and propeller designs, yielding a 17.8% reduction in required power for cruise flight while considering aerodynamic, structural, and acoustic constraints. This aero-structural-acoustic optimization framework can help make vehicle designs more efficient, lighter, and quieter.

关键词： Urban Air Mobility Propeller Performance computational fluid dynamics simulation Finite Element Analysis Tractor Configuration Blade Element Momentum Theory Flight Technology Ffowcs Williams Hawkings Equation NASA OpenMDAO

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Inverse estimation of the Kentucky Re-entry Universal Payload System (KRUPS) flight trajectory

Inverse estimation of the Kentucky Re-entry Universal Payloa...

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AIAA Aviation Forum

作者： Tacchi, Bruno Stoffel, Tyler D. Martin, Alexandre Poovathingal, Savio J. Univ Kentucky Dept Mech & Aerosp Engn Lexington KY 40506 USA

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

The Kentucky Re-entry Universal Payload System (KRUPS) is a small spacecraft developed to provide flight data during atmospheric re-entry. The KRUPS capsules made a historic re-entry to the Earth's atmosphere in 2021, and this work details the reconstruction of the flight trajectories by inverse estimation based on the flight data. A trajectory modeling program is used with a one-dimensional material response solver to generate a prediction of the stagnation wall temperature of the KRUPS capsule during the Kentucky Re-Entry Probe Experiment, the orbital flight launched from the International Space Station. These temperature results are compared to the temperature data obtained during the mission, and the initial parameters of the trajectory simulation are optimized to find the best estimated trajectories. The inverse estimation is performed in three ways;by assuming radiative equilibrium at the wall, by estimating the wall temperature after the trajectory simulations are first performed, and by coupling the trajectory and one-dimensional material response solver. Finally, the best estimated trajectories are compared against simulations performed using a computational fluid dynamics and a three-dimensional material response solver, the Kentucky Aerodynamics and Thermal-response System fluid dynamics and Material Response modules, and comparing the thermal response to flight data. It is observed that all approaches converge to a possible ejection of the KRUPS capsule into the Earth's atmosphere in the range of 35 to 40 km.

关键词： Flight Trajectory Payload System Wall Temperature computational fluid dynamics simulation Stagnation Temperature Drag Coefficient Flight Software Thermal Response International Space Station Earth Atmosphere

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The role of design parameters on the performance of diffuse ceiling ventilation systems - thermal comfort analyses for indoor environment

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ADVANCES IN BUILDING ENERGY RESEARCH 2022年第6期16卷 806-824页

作者： Sadeghian, Parastoo Rahnama, Samira Afshari, Alireza Sadrizadeh, Sasan KTH Royal Inst Technol Dept Civil & Architectural Engn Brinellvagen 23 SE-10044 Stockholm Sweden Aalborg Univ Dept Built Environm Copenhagen Denmark Malardalen Univ Sch Business Soc & Engn Vasteras Sweden

Thermal comfort conditions profoundly affect the occupants' health and productivity. A diffuse ceiling ventilation system is an air distribution system in which the air is supplied to the occupied zone with relatively a low velocity through the perforated panels installed in the ceiling. The current study evaluated the impact of diffuse ceiling design parameters, i.e. diffuse panel configurations and heat load distributions, on the thermal comfort condition of the occupants. In this regard, the computational fluid dynamics technique was used to evaluate thermal comfort conditions in a waiting room, meeting room and office. The central and dispersal configuration of active diffuse panels was considered. The PMV-PPD model was applied to evaluate the overall occupants' comfort, while the draft rate was considered to assess local thermal comfort. The model validation was performed by comparing the collected laboratory measurement data. Overall, the results indicated that the central active diffuse panel configuration had a better thermal comfort than the dispersed one. The evaluation of dispersed configuration in realist scenarios, including office and waiting room, had the highest dissatisfaction, with a PPD value of 9%. Local thermal comfort assessment revealed that dispersed configuration had the highest draft rate of 14% in the office.

关键词： Diffuse ceiling ventilation thermal comfort PMV-PPD model draft rate computational fluid dynamics simulation

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Effect of the air supply angle of swirling diffusers on the air diffusion performance index in a vehicle assembly workshop

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INDOOR AND BUILT ENVIRONMENT 2022年第7期31卷 1918-1931页

作者： Li, Can Zi, Huali Wei, Xiaoqing Xiong, Jiayuan Hunan Univ Technol Coll Civil Engn Taishan West Rd 88 Zhuzhou 412007 Peoples R China

Airflow improvement in a large industrial building is one of the most effective ways to improve the thermal comfort of workers. Air Diffusion Performance Indices (ADPI) of an industrial workshop area under different air supply angles (15 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees and 90 degrees in summer and 90 degrees in winter) of the ceiling-mounted swirling diffusers were evaluated by on-site measurements and computational fluid dynamics (CFD) modelling. The measurement data was used to verify the CFD numerical model. The temperature and velocity field of the working area were simulated and analysed under seven operating conditions of swirling diffusers. The findings showed that in summer, the increase of the swirling air supply angle would increase the air velocity. When the air supply angle was larger than 75 degrees, a draughty wind speed (>0.3 m/s) in the local working area, was produced. When the air supply angle was 30 degrees-75 degrees, the indoor design comfortable temperature range (26 degrees C-28 degrees C) was produced. The ADPIs of the workshop were 100% with the air supply angles of 45 degrees and 60 degrees in summer and 90 degrees in winter, respectively. The research findings should provide a reference for improving the airflow organization in the working area of a tall factory building.

关键词： Swirling air diffuser large industrial building computational fluid dynamics simulation air diffusion performance index air supply angles

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Coupled High Pressure-Temperature Effects on Performance of Dielectric Barrier Discharge Actuators

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AIAA JOURNAL 2022年第6期60卷 3917-3922页

作者： Dammak, Hassen Versailles, Philippe Duc Vo, Huu Polytech Montreal Dept Mech Engn Montreal PQ Canada

A study is conducted to provide a quantitative assessment of the combined effect of high pressures and temperatures on the thrust induced by a dielectric barrier discharge (DBD) plasma actuator. The device was installed in an enclosure capable of operating with dry air from standard sea level atmospheric conditions to 6 atm and 200°C, and its thrust measured by means of particle image velocimetry (PIV). The configuration of the DBD plasma actuator used for the tests consists of 0.003-in.-thick copper electrodes placed on both sides of a 0.25-in.-thick fused-glass silica dielectric that can withstand high temperatures without degradation of its dielectric strength. Strips of 0.006-in.-thick polyimide tape are used to cover the hidden electrode and the upstream part of the exposed electrode to prevent the formation of parasitic plasma. The results show that the thrust drops very rapidly with increasing pressure becoming negligible beyond 3.04 atm, which is consistent with the measured flowfield and observed plasma extent.

关键词： Plasma Actuator Dielectric Barrier Discharge Temperature Effects Particle Image Velocimetry Atmospheric Conditions Thermocouples Aero Engine Boundary Layer Separation Charge Coupled Device computational fluid dynamics simulation

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The Hollow Porous Sphere Cell Carrier for the Dynamic Three-Dimensional Cell Culture

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TISSUE ENGINEERING PART C-METHODS 2022年第11期28卷 610-622页

作者： Gao, Weidong Xiao, Lan Wang, Jiaqiu Mu, Yuqing Mendhi, Jayanti Gao, Wendong Li, Zhiyong Yarlagadda, Prasad Wu, Chengtie Xiao, Yin Queensland Univ Technol Ctr Biomed Technol Brisbane Qld Australia Australia China Ctr Tissue Engn & Regenerat Med A Brisbane Qld Australia Queensland Univ Technol Sch Mech Med & Proc Engn Brisbane Qld Australia Chinese Acad Sci Shanghai Inst Ceram Shanghai Peoples R China Griffith Univ Sch Med & Dent Gold Coast Qld 4222 Australia

Large-scale mammalian cell culture is essential in cell therapy, vaccine production, and the manufacturing of therapeutic protein drugs. Due to the adherent growth characteristic of most mammalian cell types, the combination of cell carrier and bioreactor is a common choice in large-scale mammalian cell culture. Current cell carriers developed by polymer crosslinking, lithography, or emulsion drops are unable to obtain a structure with uniformed porous structure and porous interior design, which results in an inhomogeneous culture condition for cells and therefore cannot ensure an optimal dynamic culture condition for cell proliferation, matrix production, and cell differentiation. In addition, the fluidic shear stress (a standard mechanical stimulation in bioreactor culture) and inner-carrier velocity (to ensure nutrient transport and waste exchange), which influence cell viability and growth, are not well-controlled/analyzed due to an irregular porous structure with these traditionally synthesized cell carriers. To solve these problems, we designed four types of hollow porous spheres (HPS, 1.0 cm diameter) with different porous structures. To investigate the impacts of porous structure on surface shear stress and inner velocity, computational fluid dynamics (CFD) simulations were conducted to analyze the liquid flow behavior in HPSs, based on which an optimal structure with minimal surface shear stress and best inner velocity was obtained and fabricated using fused deposition modeling three-dimensional (3D) printing technology. Inspired by the industrial large-scale culture system, a novel 3D dynamic culture system was then established using HPSs to seed the cells, which were then placed in a mini bioreactor on a tube roller. CFD analysis showed that under 0.1 m/s water flow, the shear stress at most surface areas from four HPSs was lower than 20 dynes/cm(2), which suggests that the HPSs should provide protection against physical stress to the cells living on the

关键词： 3D printing 3D cell culture dynamic cell culture computational fluid dynamics simulation cellular viability porous hollow spheres cell carrier bioreactor

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Powered Low-speed Experimental Aerodynamic Investigation of an Over-wing Mounted Nacelle Configuration

Powered Low-speed Experimental Aerodynamic Investigation of ...

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AIAA Aviation Forum

作者： Silva, Vinicius T. Lundbladh, Anders Xisto, Carlos Milten, Petter Jonsson, Isak Chalmers Univ Technol Mech & Maritime Sci Horsalsvagen 7A S-41258 Gothenburg Sweden GKN Aerosp S-46181 Trollhattan Sweden GKN Aerosp Engine Syst Flygmotorvagen 1 S-46181 Trollhattan Sweden

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

Over-wing integration of ultra-high bypass turbofan engines can be a solution for next-generation commercial transport aircraft, since it eliminates the ground clearance issue, and it has the potential to reduce ground noise due to acoustic shielding. Moreover, a unique characteristic of this installation type is the powered lift benefit at low-speed flight conditions. This paper aims to experimentally investigate the effect of the engine power setting on the low-speed aerodynamic performance of an over-wing mounted nacelle configuration comprising a conventional tube-and-wing layout. Thus, low-speed wind tunnel tests were performed for a half-span powered scale model of the aforementioned configuration. The effect of the engine power setting on the wing lift and spanwise pressure distributions was investigated. The experiments were carried out for angles-of-attack varying from 0 degrees to 6 degrees and inlet mass flow ratios up to 2.4. The results were used to validate computational fluid dynamics simulations conducted for the same wind tunnel conditions. It has been shown that a significant powered lift benefit can be achieved for the studied configuration, without a penalty in the net propulsive force, and that the lift increases linearly with the inlet mass flow ratio. Furthermore, it was observed that the engine power setting largely influences the pressure distributions along the wing, especially at the spanwise sections closer to the nacelle. The low momentum zone created upstream of the engine at high power settings reduces the pressure at the wing's upper surface, which is the main factor responsible for the increased lift. By taking advantage of such behavior, drag can potentially be reduced at takeoff and climb due to a lower flap setting required for the same lift.

关键词： Landing Gear Powered Lift computational fluid dynamics simulation Low Speed Wind Tunnel Aerodynamic Performance Mass Flow Transonic Aircraft Ultra High Bypass Turbofan Freestream Conditions Reynolds Averaged Navier Stokes

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