Bibliografie tematiche / Airplanes Turbulence

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Letteratura scientifica selezionata sul tema "Airplanes Turbulence"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 9 febbraio 2022

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Articoli di riviste sul tema "Airplanes Turbulence"

Tulapurkara, E. G. "Turbulence models for the computation of flow past airplanes". Progress in Aerospace Sciences 33, n. 1-2 (gennaio 1997): 71–165. http://dx.doi.org/10.1016/s0376-0421(96)00002-4.

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Bäuerle, N., O. Engelhardt-Funke e M. Kolonko. "ROUTING OF AIRPLANES TO TWO RUNWAYS: MONOTONICITY OF OPTIMAL CONTROLS". Probability in the Engineering and Informational Sciences 18, n. 4 (ottobre 2004): 533–60. http://dx.doi.org/10.1017/s0269964804184088.

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We consider the problem of routing incoming airplanes to two runways of an airport. Due to air turbulence, the necessary separation time between two successive landing operations depends on the type of airplane. When viewed as a queuing problem, this means that we have dependent service times. The aim is to minimize the waiting times of aircrafts. We consider here a model in which arrivals form a stochastic process and the decision-maker does not know anything about future arrivals. We formulate this as a problem of stochastic dynamic programming and investigate the monotonicity of optimal routing strategies with respect to the workload of the runways, for example. We show that an optimal strategy is monotone (i.e., of switching type) only in a restricted case where decisions depend on the state of the runways only and not on the type of the arriving aircraft. Surprisingly, in the more realistic case where this type is also known to the decision-maker, monotonicity need not hold.

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Hariyadi, Setyo, Sutardi Sutardi, Wawan Aries Widodo e Bambang Juni Pitoyo. "Comparative Study of Forward Wingtip Fence and Rearward Wingtip Fence on Wing Airfoil Eppler E562". Journal of Energy, Mechanical, Material, and Manufacturing Engineering 5, n. 1 (31 maggio 2020): 25. http://dx.doi.org/10.22219/jemmme.v5i1.11968.

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The perfect wing is a dream that many airplanes has manufactured have been striving to achieve since the beginning of the airplane design. There are some aspect that most influence in aircraft design lift, drag, thrust, and weight. The combination of these aspects leads to a decrease in fuel consumption, which reduces pollution in our atmosphere and increase in economic revenue. One way to improve aircraft performance is to modify the tip of the wing geometry, which has become a common sight on today’s airplanes. With computational programs, the effects on drag due to wingtip devices can be previewed. This research was done numerically by using turbulence model k-ω SST. Reynolds number in this research was 2,34 x 10 4 with angle of attacks are 0o, 2o, 4o, 6o, 8o, 10o, 12o, 15o, 17o and 19o. The model specimen is wing airfoil Eppler 562 with winglets. Two types of wingtips are used: forward and rearward wingtip fence. From this study, it was found that wingtip fence reduced the strength of vorticity magnitude on the x axis compared to plain wings. The leakage of fluid flow effect at the leading edge corner of the wingtip, giving pressure gradient and slightly shifting towards the trailing edge. this occurs in the plain wing and rearward wingtip fence but does not occur in the forward wingtip fence..

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Aqilah, Farah, Mazharul Islam, Franjo Juretic, Joel Guerrero, David Wood e Farid Nasir Ani. "STUDY OF MESH QUALITY IMPROVEMENT FOR CFD ANALYSIS OF AN AIRFOIL". IIUM Engineering Journal 19, n. 2 (1 dicembre 2018): 203–12. http://dx.doi.org/10.31436/iiumej.v19i2.905.

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ABSTRACT: Airfoils generate lift in engineering applications such as for airplanes, wind turbines, automotive spoilers, etc. For accurate CFD analysis of airfoils, the quality of the mesh is of paramount importance, especially when dealing with turbulent flows commonly encountered in real life applications. Currently there are different tools that are available to improve the quality of the mesh required for CFD studies. This paper describes a study to assess the significant of the quality of the mesh on CFD analyses of NACA 23012 airfoil by using selected open source tools. The turbulence is modeled using the well-known k-Ï‰ Shear Stress Transport model. For validation, results have been compared with experimental datasets which were obtained from â€œTAG Stuttgart #1â€ tunnel. ABSTRAK: Sayap pesawat dapat menghasilkan daya angkat dalam aplikasi kejuruteraan seperti kapal terbang, turbin angin, spoiler automotif, dan sebagainya. Kualiti pada jaringan adalah amat penting bagi mendapatkan analisa CFD yang tepat pada sayap pesawat, terutamanya apabila berhadapan situasi aliran turbulen sebenar. Pada masa ini terdapat pelbagai perisian bagi meningkatkan mutu jaringan dalam kajian CFD. Kertas kerja ini membentangkan satu kajian bagi menilai kepentingan kualiti jaringan pada analisis CFD bagi sayap pesawat NACA 23012 dengan menggunakan sumber terpilih perisian terbuka. Model turbulen dibangunkan mengguna pakai model k-Ï‰ Shear Stress Transport (SST) yang terkenal. Bagi pengesahan, keputusan uji kaji telah dibandingkan dengan set data yang diperoleh dari terowong "TAG Stuttgart #1â€."

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Majka, Andrzej. "Flight Loads of Mini UAV". Solid State Phenomena 198 (marzo 2013): 194–99. http://dx.doi.org/10.4028/www.scientific.net/ssp.198.194.

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Designing and building of the unmanned aircraft, especially light and ultra light vehicles, is mainly performed using the experience gained when constructing the flying models. There have not been uniform principles of building and exploiting of the mini and micro UAV (Unmanned Aerial Vehicle) in the form of regulations similar to those for manned airplanes. The unmanned vehicles of these classes in terms of their abilities and attractive price are more frequently exploited using the same air area as manned airplanes performing missions over the inhabited areas. An urgent necessity arises to work out the norms of flight suitability of the mini and micro unmanned aerial vehicles. The work contains the analysis of suitability of the current aviation regulations to determine the requirements for the mini unmanned vehicles. The work concentrates on the phenomenon of determining the symmetrical loads from the maneuvers and the turbulence atmosphere. The result of this analysis is the Limit Maneuver Envelope, Limit Gust Envelope and Limit Combined Envelope for mini UAV. The analyzed flight states allowed selecting the so called design cases which can become a basis for determining the norms of loading of mini unmanned aerial vehicles which can constitute the beginning of the regulations for building of the unmanned aerial vehicles of this class.

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Xu, Xin, Da Wei Liu, De Hua Chen e Yuan Jing Wang. "Numerical Investigation on Shock-Induced Separation Structure of Supercritical Airfoil". Advanced Materials Research 756-759 (settembre 2013): 4502–5. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.4502.

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The supercritical airfoil has been widely applied to large airplanes for sake of high aerodynamic efficiency. But at transonic speeds, the complicated shock-induced separation on the upper surface of supercritical airfoil will change the aerodynamic characteristics. The transonic flows over a typical supercritical airfoil CH were numerically investigated in this paper, in order to analyses different shock-induced separation structure. The two-dimensional Navier-Stokes equations were solved with structure grids by utilizing the S-A turbulence model. The computation attack angles of CH airfoil varied from 0oto 4o, Mach numbers varied from 0.74 to 0.82 while Reynolds numbers varied from 3×106to 50×106per airfoil chord. It is shown that with the attack angle increases, the separation bubble occurred on the upper surface first, then the trailing-edge separation occurred, the trailing-edge would separate totally at last. The different separation structure would result in different pressure coefficient distribution and boundary layer thickness.

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Łapka, Piotr, Marije Bakker, Piotr Furmański e Hans van Tongeren. "Comparison of 1D and 3D thermal models of the nacelle ventilation system in a small airplane". Aircraft Engineering and Aerospace Technology 90, n. 1 (2 gennaio 2018): 114–25. http://dx.doi.org/10.1108/aeat-09-2015-0204.

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Purpose Insight in the temperature distribution on the internal and external surface of the nacelle is of great importance during the design phase of an aircraft. However, detailed information is not always needed. In a preliminary project stage or during parametric optimization, short analysis times are often more crucial than high accuracy. In such cases, the global insight in the temperature levels suffices to gain understanding of the relevance and influence of certain parameters. Nevertheless, estimating the maximum temperature for the most adverse conditions should also be done before a prototype is built. Therefore, this study aims to present and compare a simplified and an advanced methodology for the analysis of engine bay cooling and ventilation systems as well as heat transfer in the nacelle in a small airplane equipped with a turboprop engine in the tractor arrangement. Design/methodology/approach Both approaches included conductive, convective and radiative heat transfer in the engine bay of the small airplane I-23 as well as heat conduction in the nacelle made of material with anisotropic thermal conductivity. The one-dimensional (1D) model assumed that the nacelle with the air flow and engine was represented by a lumped thermal model in which heat was exchanged between the different lumped segments (the nodes) and the flowing air and engine. The three-dimensional (3D) model was based on the continuous control volume approach for heat, fluid flow and thermal radiation as well as on realizable k-ε turbulence model. Both models used commercial software. Findings The temperature distribution at the internal and external surface of the top nacelle was calculated. The 1D model predicted a temperature per node (per segment) while the 3D model was able to determine its values accurately and find the location of hot spots. Considering the complex geometry of the engine bay and nacelle and the assumed simplification, the obtained 1D and 3D results agreed quite well. Practical implications Both models will help in the development of new ventilation and cooling systems of the engine bay and nacelle as well as in the selection of materials for parts of the top cowling in the newly redesigned airplane I-23 equipped with a turboprop engine. In addition, the methodology presented in this paper might be applied in the development of other airplanes. Originality/value The 1D and 3D models of complex heat transfer inside the engine bay and in the nacelle of the newly re-designed airplane I-23 were elaborated and compared.

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Aylor, Donald E., Matthew T. Boehm e Elson J. Shields. "Quantifying Aerial Concentrations of Maize Pollen in the Atmospheric Surface Layer Using Remote-Piloted Airplanes and Lagrangian Stochastic Modeling". Journal of Applied Meteorology and Climatology 45, n. 7 (1 luglio 2006): 1003–15. http://dx.doi.org/10.1175/jam2381.1.

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Abstract The extensive adoption of genetically modified crops has led to a need to understand better the dispersal of pollen in the atmosphere because of the potential for unwanted movement of genetic traits via pollen flow in the environment. The aerial dispersal of maize pollen was studied by comparing the results of a Lagrangian stochastic (LS) model with pollen concentration measurements made over cornfields using a combination of tower-based rotorod samplers and airborne radio-controlled remote-piloted vehicles (RPVs) outfitted with remotely operated pollen samplers. The comparison between model and measurements was conducted in two steps. In the first step, the LS model was used in combination with the rotorod samplers to estimate the pollen release rate Q for each sampling period. In the second step, a modeled value for the concentration Cmodel, corresponding to each RPV measured value Cmeasure, was calculated by simulating the RPV flight path through the LS model pollen plume corresponding to the atmospheric conditions, field geometry, wind direction, and source strength. The geometric mean and geometric standard deviation of the ratio Cmodel/Cmeasure over all of the sampling periods, except those determined to be upwind of the field, were 1.42 and 4.53, respectively, and the lognormal distribution corresponding to these values was found to fit closely the PDF of Cmodel/Cmeasure. Model output was sensitive to the turbulence parameters, with a factor-of-100 difference in the average value of Cmodel over the range of values encountered during the experiment. In comparison with this large potential variability, it is concluded that the average factor of 1.4 between Cmodel and Cmeasure found here indicates that the LS model is capable of accurately predicting, on average, concentrations over a range of atmospheric conditions.

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Bruce Ralphin Rose, J., e Gr Jinu. "Gust Induced Aerodynamic Force Prediction on a Transport Wing Using Quasi-Steady Approximation". International Journal of Computational Methods 12, n. 06 (dicembre 2015): 1550034. http://dx.doi.org/10.1142/s0219876215500346.

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The atmospheric wind turbulence over a specified time period has a strong influence on the airplane performance characteristics. Forecasting of this unsteady aerodynamic phenomenon is complex one for designing the control systems to ensure the structural safety. A novel approach is developed to assess the influence of a gust structure on the aerodynamic coefficients of an airplane. The load factor enhancement because of the discrete gust is also quantified to ensure the safety margin. The Kussner’s function is used to determine the time varying increment of gust-dependent lift produced on an airplane wing entering a sharp-edged gust. A most general gust shape is assumed for the present study with quasi-steady approximation. The turbulent viscosity across the chord wise positions are quantified to calculate the velocity fluctuations because of eddies. Determining the gust influence on the fundamental lift and drag characteristics of a commercial airplane is focused in the present investigation. It is accomplished with the help of Wagner’s function in the time domain for the gust response-dependent lift. The outcome of the numerical simulation process is fully verified using the theoretical and experimental results. Solution convergence is attained for a range of input conditions and it shows that the proposed methodology is competent to assess the gust response for various airplane systems design.

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Ma, Tielin, Zhihua Wei, Haibing Chen e Xiangsheng Wang. "Simulation of the dynamic retrieval process of a towed target system under towing airplane’s wake and atmospheric turbulence". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, n. 9 (2 aprile 2020): 1518–30. http://dx.doi.org/10.1177/0954410020916292.

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This paper studies the dynamic retrieval process of a towed target system under perturbation by simulating the reel-in operation under the towing airplane’s wake and atmospheric turbulence. To settle the computational problem of cable tension, the constant-length method is proposed to transform this variable-mass problem into a constant-length problem based on a mass-spring model that discretizes the cable. A three-dimensional atmospheric turbulence field is built using a recursive function to model the complex perturbation field along the cable. A horseshoe vortex model is adopted to simulate the towing airplane’s wake. Simulation analysis shows that both the reel-in speed and turbulence significantly affect the retrieval deviation, whereas the airplane’s wake has little influence. The reel-in speed should be chosen in concert with the turbulence intensity to achieve a high retrieval success rate. Moreover, a higher reel-in speed is preferred to maintain cable strain and smoothen the process when the retrieval tolerance is satisfied.

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Tesi sul tema "Airplanes Turbulence"

Riaz, Jamshed. "A simulation model of atmospheric turbulence for rotorcraft applications". Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/12940.

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Wee, Teik Khoo. "Cold flow drag measurement and numerical performance prediction of a miniature ramjet at Mach 4". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Dec%5FWee.pdf.

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Thesis (M.S. in Engineering Science (Mechanical Engineering))--Naval Postgraduate School, December 2003.
Thesis advisor(s): Garth V. Hobson, Rayomnd P. Shreeve. Includes bibliographical references (p. 67). Also available online.

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Bowersox, Rodney Dale Welch. "Meanflow and turbulence measurements in the wake of a supersonic through-flow cascade". Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03122009-040531/.

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Davis, James Arthur. "Acoustic-vortical-combustion interaction in a solid fuel ramjet simulator". Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/12947.

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Miki, Kenji. "Simulation of magnetohydrodynamics turbulence with application to plasma-assisted supersonic combustion". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/26605.

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Thesis (Ph.D)--Aerospace Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Menon Suresh; Committee Co-Chair: Jagoda Jeff; Committee Member: Ruffin Stephen; Committee Member: Thorsten Stoesser; Committee Member: Walker Mitchell. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Dagenhart, J. Ray. "Crossflow stability and transition experiments in a swept-wing flow". Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/39084.

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Zarro, Sarah E. "Steady state and transient measurements within a compressor rotor during steam-induced stall at transonic operational speeds". Thesis, Monterey, California. Naval Postgraduate School, 2006. http://hdl.handle.net/10945/2528.

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Approved for public release, distribution unlimited
Steam leakage from an aircraft carrier catapult is sometimes ingested into the aircraft engines upon launch which may induce compressor stall. Investigation of this phenomenon is of particular interest to the Navy with its new F35C, the aircraft carrier variant of the joint strike fighter. The single engine configuration of the F-35C makes this aircraft particularly vunerable to steam-induced stall. The present study examined both throttle-induced stall and steam-induced stall in a compressor at 90% and 95% speed through the use of 9 Kulite and 2 hot-film pressure transducers. The use of Fast Fourier Transform waterfall plots of the transient data before and during stall proved invaluable in determining stall precursors as well as the mode of rotor stall. In addition, a new computational fluid dynamic model was designed using CFX-5 software to represent a single blade passage of the compressor rotor, in order to predict compressor performance. The computed results were compared to experimental results gathered at various throttle settings. An accurate model will enable researchers to predict compressor performance for various and multiple gases.
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Zaki, Mina Adel. "Physics based modeling of axial compressor stall". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31683.

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Thesis (Ph.D)--Aerospace Engineering, Georgia Institute of Technology, 2010.
Committee Chair: Dr. Lakshmi N. Sankar; Committee Member: Dr. Alex Stein; Committee Member: Dr. J.V. R. Prasad; Committee Member: Dr. Richard Gaeta; Committee Member: Dr. Suresh Menon. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Fleming, Jonathan Lee. "An experimental study of a turbulent wing-body junction and wake flow". Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-08222009-040300/.

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Mendoza, Jeffrey Michael. "Effects of cavity dimensions, boundary layer, and temperature on cavity noise generation and control". Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/11959.

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Libri sul tema "Airplanes Turbulence"

Turbulence: A new perspective for pilots. Englewood, CO: Jeppesen Sanderson Training Systems, 1993.

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Breitsamter, Christian. Turbulente Strömungsstrukturen an Flugzeugkonfigurationen mit Vorderkantenwirbeln. München: Utz, Wissenschaft, 1997.

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Board, United States National Transportation Safety. Aircraft incident report: In-flight turbulence encounter and loss of portions of the elevators, China Airlines flight CI-012, McDonnell Douglas MD-11-P, Taiwan Registration B-150 about 20 miles east of Japan, December 7, 1992. Washington, D.C: National Transportation Safety Board, 1994.

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Roberts, L. The generation of side force by distributed section. Moffett Field, Calif: National Aeronautics and Space Administration, Ames Research Center, 1993.

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United States. National Transportation Safety Board. In-flight turbulence encounter and loss of portions of the elevators: China Airlines flight CI-012, McDonnell Douglas MD-11-P, Taiwan Registration B-150 about 20 miles east of Japan, December 7, 1992. Washington, D.C: The Board, 1994.

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Tatnall, Christopher Rhoads. An investigation of candidate sensor-observable wake vortex strength parameters for the NASA Aircraft Vortex Spacing System (AVOSS). Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1998.

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United States. National Transportation Safety Board. In-flight engine separation, Japan Airlines, Inc. Flight 46E, Boeing 747-121, N47EV, Anchorage, Alaska, March 31, 1993. Washington, D.C: The Board, 1993.

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1962-, Breitsamter Christian, a cura di. New results in numerical and experimental fluid mechanics IV: Contributions to the 13th STAB/DGLR Symposium, München, Germany 2002. Berlin: Springer-Verlag, 2004.

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AG, STAB/DGLR Symposium (10th 1996 Braunschweig Germany). New results in numerical and experimental fluid mechanics: Contributions to the 10th AG STAB/DGLR Symposium, Braunschweig, Germany 1996. Braunschweig/Wiesbaden: Vieweg, 1997.

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Ing, Wagner Siegfried Dr, a cura di. New results in numerical and experimental fluid mechanics III: Contributions to the 12th STAB/DGLR symposium, Stuttgart, Germany, 2000. Berlin: Springer, 2002.

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Capitoli di libri sul tema "Airplanes Turbulence"

Brock, Fred V., e Scott J. Richardson. "Dynamic Performance Characteristics, Part 1". In Meteorological Measurement Systems. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780195134513.003.0008.

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When the input to a sensor is changing rapidly, we observe performance characteristics that are due to the change in input and are not related to static performance characteristics. In this chapter we will assume that a static calibration has been applied so that we can consider dynamic performance independently of static characteristics. The terms “linear” and “nonlinear” have been used in chap. 3 in the static sense. Now they are being used in the dynamic sense where “linear” connotes the applicability of the superposition property. A given sensor could be nonlinear in the static sense (e.g., a PRT is nonlinear in that is static sensitivity is not constant over the range) but could be linear in the dynamic sense (modeled by a linear differential equation). We use differential equations to model this dynamic performance while realizing the models can never be exact. If the dynamic behavior of physical systems can be described by linear differential equations with constant coefficients, the analysis is relatively easy because the solutions are well known. Such equations are always approximations to the actual performance of physical systems that are often nonlinear, vary with time, and have distributed parameters. The justification for the use of simple, readily solved models must be the quality of the fit of the solution to the actual system output and the usefulness of the resulting analysis. Dynamic performance characteristics define the way instruments react to measurand fluctuations. When a temperature sensor is mounted on an airplane these characteristics will indicate what the sensor “sees.” If the airplane flies through a cloud with a slow sensor (where time constant is large) it may not register change of temperature or humidity. That would not be tolerable if we wanted to measure the cloud. Similarly, if the airplane flies through turbulence we would like to measure changes in air speed. Variations in temperature and humidity would be vital in the flight of a radiosonde, so again the time constant of the sensors would be considered. Fluxes of heat, water vapor, and momentum near the ground require fast sensors (with small time constants).

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Fleming, James Rodger. "Introduction". In First Woman, 1–9. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198862734.003.0001.

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Joanne Simpson transformed the science of the tropical atmosphere and set a course in science for professional women to follow. She had a lifelong passion for clouds and severe storms, flying into and above them, measuring and modeling them, theorizing about the role of tropical clouds in the planetary circulation, and mentoring a generation of tropical meteorologists. In 1993, just shy of her seventieth birthday, Joanne commandeered a fully equipped NASA-owned DC8 research airplane during a field project to study El Niño, and flew several flights directly into tropical cyclone Oliver in the Coral Sea, some 500 km off the coast of Townsville, Australia. She and the crew did this on several consecutive days. The aircraft was equipped with radar being tested for use on a new satellite to measure tropical rainfall, and they wanted to use it to collect the best possible data on storm structure and dynamics. The third flight, directly into the storm, pushed the plane to its limits. The excessive humidity and turbulent shaking shorted out the experimental electronics and rendered the plane unusable for future missions. NASA was not pleased. Buffeted but invigorated by the successful but totally unauthorized flights, Joanne told the press that she felt fortunate to have seen meteorology develop from the “horse-and-buggy era” to the space age....

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Atti di convegni sul tema "Airplanes Turbulence"

Khamedov, Ruslan, Ruslan Baitlessov e Luis Rojas-Solórzano. "CFD Study of Effects of Boundary Layer Suction on Transonic SC(2)-0714 Airfoil Performance". In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-70848.

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The complete understanding of the aerodynamics of wings and blades under transonic conditions represents a substantial challenge in the design of modern airplanes and turbomachinery. Transonic flow over airfoils may result in appearance of shock waves, which lead to increase in drag if not properly considered during the design stage. Therefore, it is a major challenge to design transonic airfoils such that potential appearance of shock waves is foreseen and negative drag effects are minimized. This paper presents the computational study of the SC(2)-0714 airfoil, focusing on its aerodynamics characteristics at Reynolds number of 35 × 106 and angle of attack of 2 and 10 degrees which are the most common operational conditions of transonic wings using this airfoil. The study was undertaken at free-stream Mach 0.72. The numerical simulation was conducted using the finite volume method on platform ANSYS CFX™ and solving the Reynolds-Averaged Navier-Stokes, mass conservation and energy equations. Mesh verification and model validation are presented. The latter is developed by using two different isotropic turbulence models: k-ω and Shear Stress Transport (SST) and the comparison of results with NASA experimental data to determine the best among the treated models. Thereafter, effects of local boundary-layer suction on shock wave strength and characteristics during transonic speed are analyzed for the two aforementioned angles of attack. Two suction slots were placed along the airfoil contour to determine their control effectiveness when compared to standard closed-contour airfoil. Suction slots were placed at the leading edge and in the middle of the upper camber of the airfoil with inflow in the normal direction to the surface. The slot length was 2.5 % of the chord with inflow velocity of 30%, 40% and 50% of free-stream velocity. Effects of suction slots were assessed on the wake region and by computing the resulting lift-to-drag ratio. Concluding remarks on the turbulence model and global aerodynamics performance of the airfoil are presented.

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Zur, Malte, Frank Otremba, Alexander Klippel e Alfred Leder. "Numerical Simulation and Experimental Study of Cabin-Airflow and Transport of Gas-Mixtures in Aircraft Cargo Compartments: Model Validation". In ASME 2013 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fedsm2013-16622.

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Dangerous goods are transported as air freight in commercial aircrafts. Using plastic jerrycans or plastic containers, liquids or gases can escape by leakage or permeation effects. Prior research by the German Federal Institute for Materials Research and Testing (BAM) showed that the lower explosion limit can be reached when transporting dangerous goods in sea-freight containers under normal transportation situations. This motivated the presented study of the transportation situation of dangerous goods in cargo compartments of commercial airplanes. The scope of this paper is to present the experimental method used for validating a numerical model for CFD (Computational Fluid Dynamics) simulations. The CFD model will be used in a future study to evaluate the potential risk from transporting dangerous goods. The objective of this paper is to present the model mock-up of an aircraft cargo compartment and some examples of three dimensional velocity profiles of the air flow in the mock-up. The velocity profiles are calculated using numerical simulations and measured by Laser-Doppler-Anemometry (LDA) experiments. The mock-up is a generic model of a wide-body aircraft lower deck cargo compartment in a 1:10 scale. Geometry, air exchange rates and inlet as well as outlet flow conditions in the cargo compartment are modeled using realistic boundary conditions. The commercial CFD (Computational Fluid Dynamics) code ANSYS CFX 14 is used for numerical flow simulations applying RANS (Reynolds-Averaged-Navier-Stokes) equations and turbulence models. The turbulence models studied are the renormalization group k-ε-model (RNG), the Reynolds-Stress model by Launder, Reece and Rodi (LRR) and the SST-k-ω-model by Menter (SST). The flow measurement with LDA in the mock-up of a cargo compartment proves to be a feasible method for producing data to validate CFD simulations. Qualitative evaluation of the results shows a good overall agreement between numerical and experimental results. The experimental validation indicates that the implemented CFD model is capable of reproducing the flow situation in the model mock-up.

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Vadake, Kshitij, e Jie Cui. "Numerical and Experimental Study of Turbulent Flows Around Clark Y-14 Aerofoil". In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-50536.

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Experimental Fluid Dynamics (EFD) and Computational Fluid Dynamics (CFD) have been instrumental in Fluid Mechanics to help solve scientific and engineering problems. This research attempts to use both techniques to perform a parametric study of turbulence flow around airfoil ClarkY-14 at various velocity and angle of attack (AoA). Clark Y-14 airfoil was designed in the 1920’s. It demonstrated good overall performance at low and moderate Reynolds numbers. With the progress in the aviation field, its performance was sub-optimal for newer aircraft designs. However, with the advent of RC airplanes and model aircrafts, there is a renewed interest in this airfoil. Various research projects have been conducted using this airfoil, but there hasn’t been a combined EFD and CFD study of the performance characteristics of the airfoil itself, which still finds real world applications today. One important aspect of this research included the investigation of the effects of a Force Measurement Device/Sensor, which is typically used in scaled/full-size wind tunnels to mount the test model as well as measure the forces/moments acting on it during the testing. The presence of such a device could affect the quality of the data obtained from the wind tunnel testing when compared to a real world application scenario where the aforementioned device may not be present. To the best of the author’s knowledge, no detailed study has been published on the effects of such devices. In this study, the results with and without the measuring device were generated by using CFD simulations. The results were then compared to see to what extent the inclusion of these devices will affect the results. The methodology used for this research was experimental as well as computational. In the present research, a commercially available CFD software STAR-CCM+ was employed to simulate the flows around airfoil Clark Y-14. The experimental data was obtained from wind tunnel tests using AEROLAB Educational Wind Tunnel (EWT) and compared with the simulation data from the CFD. The two data sets were in good agreement. Both experimental and simulation results were used to understand the effects of the measurement device/sensor used in the scaled wind tunnel on the lift and drag coefficients of the airfoil. Two separate CFD simulation setups were designed to model the presence and absence of the measurement device/sensor. These setups replicated the wind tunnel setup. The airfoil was tested and simulated at different speeds as well as different AoA. The comparative study gave a useful insight on the accuracy of the CFD simulations in relation to the actual testing. The analysis of results concluded that the force measurement device/sensor had insignificant effects on the accuracy and quality of data collected through wind tunnel testing.

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Granichin, Oleg, Tatjana Khantuleva e Olga Granichina. "Local voting protocol for the adaptation of airplane's “feathers” in a turbulence flow". In 2017 American Control Conference (ACC). IEEE, 2017. http://dx.doi.org/10.23919/acc.2017.7963840.

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Kandil, Osama, Ihab Adam e Tin-Chee Wong. "Far-field turbulent vortex-wake/exhaust plume interaction for subsonic and HSCT airplanes". In Fluid Dynamics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1996. http://dx.doi.org/10.2514/6.1996-1962.

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Miller, Teresa S., e Mark J. Moeller. "Wall Pressure Phase Velocity Measurements in a Turbulent Boundary Layer". In ASME 2012 Noise Control and Acoustics Division Conference at InterNoise 2012. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ncad2012-0195.

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The turbulent boundary layer that forms on the outer surfaces of vehicles can be a significant source of interior noise. In automobiles this is known as wind noise, and at high speeds it dominates the interior noise. For airplanes the turbulent boundary is also a dominant noise source. Because of its importance as a noise source, it is desirable to have a model of the turbulent wall pressure fluctuations for interior noise prediction. One important parameter in building the wall pressure fluctuation model is the convection velocity. In this paper, the phase velocity was determined from the streamwise pressure measurements. The phase velocity was calculated for three separation distances ranging from 0.25 to 1.30 boundary layer thicknesses. These measurements were made for a Mach number range of 0.1 < M < 0.6. The phase velocity was shown to vary with sensor spacing and frequency. The data collapsed well on outer variable normalization. The phase velocities were fit and the group velocity was calculated from the curve fit. The group velocity was consistent with the array measured convection velocities. The group velocity was also estimated by a band limited cross correlation technique that used the Hilbert transform to find the energy delay. This result was consistent with the group velocity inferred from the phase velocities and the array measured convection velocity. From this research, it is suggested that the group velocity found in this study should be used to estimate the convection velocity in wall pressure fluctuation models.

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Inglezakis, Dimitrios A., Georgios N. Lygidakis e Ioannis K. Nikolos. "Flow Analysis of the M151 Aircraft Model Using the Academic CFD Code Galatea". In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-70208.

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CFD (Computational Fluid Dynamics) solvers have become nowadays an integral part of the aerospace manufacturing process and product design, as their implementation allows for the prediction of the aerodynamic behavior of an aircraft in a relatively short period of time. Such an in-house academic solver, named Galatea, is used in this study for the prediction of the flow over the ARA (Aircraft Research Association) M151/1 aircraft model. The proposed node-centered finite-volume solver employs the RANS (Reynolds-Averaged Navier-Stokes) equations, combined with appropriate turbulence models, to account for the simulation of compressible turbulent flows on three-dimensional hybrid unstructured grids, composed of tetrahedral, prisms, and pyramids. A brief description of Galatea’s methodology is included, while attention is mainly directed toward the accurate prediction of pressure distribution on the wings’ surfaces of the aforementioned airplane, an uncommon combat aircraft research model with forward swept wings and canards. In particular, two different configurations of M151/1 were examined, namely, with parallel and expanding fuselage, while the obtained results were compared with those extracted with the commercial CFD software ANSYS CFX. A very good agreement is reported, demonstrating the proposed solver’s potential to predict accurately such demanding flows over complex geometries.

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Perez, M., M. Ezzine, K. Billon, V. Clair, J. Mardjono e M. Collet. "Design and Optimization of Piezoelectric Actuators for Aeroacoustic Noises Control in a Turbofan". In ASME 2020 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/smasis2020-2436.

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Abstract This paper reports on the design and optimization of different types of piezoelectric actuators for aeroacoustic control applications. This study was carried out within the context of the European project CleanSky 2/InnoSTAT. The aim of our work is to reduce the aeroacoustic noises that appear in an airplane turbofan by adding an area of piezoelectric actuators on the Outlet Guide Vanes (OGV). These piezoelectric structures will subsequently be controlled with an active approach and tested in the open-jet anechoic wind tunnel at LMFE. The noise source which has to be reduce/control comes from vortices located in the turbulent flow (which can for example be created by the fan module) interacting with the stator blades. The predominant frequencies and the pressure fluctuations levels related to these vortices rely on the airflow speed and are fixed between 1000Hz and 2000Hz in our case. To reach the target, we plan to manufacture an area of piezoelectric actuators on the intrados and the extrados of the stator blades in order to control the response of the blade to the turbulence of the airflow responsible for the aeroacoustic noise. Several adjacent blades will be equipped with this type of transducers. This study outline the design and the optimization of each piezoelectric cell in order to achieve good results in the frequency range previously defined as well as an acceptable mechanical strength of the blade. A most detailed study on the active shunt will be investigate later on.

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Doh, Il, Il-Bum Kwon, Jiho Chang e Sejong Chun. "Development of a Surface Flow Sensor for Measuring Turbulent Drag Force". In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-4680.

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Abstract A surface flow sensor is needed if turbulent drag force is to be measured over a vehicle, such as a car, a ship, and an airplane. In case of automobile industry, there are no automobile manufacturers which measure surface flow velocity over a car for wind tunnel testing. Instead, they rely on particle image velocimetry (PIV), pressure sensitive paint (PSP), laser Doppler anemometry (LDA), pitot tubes, and tufts to get information regarding the turbulent drag force. Surface flow sensors have not devised yet. This study aims at developing a surface flow sensor for measuring turbulent drag force over a rigid body in a wind tunnel. Two sensing schemes were designed for the fiber-optic distributed sensor and the thermal mass flow sensor. These concepts are introduced in this paper. As the first attempt, a thermal mass flow sensor has been fabricated. It was flush-mounted on the surface of a test section in the wind tunnel to measure the surface flow velocity. The thermal mass flow sensor was operated by either constant current or constant resistance modes. Resistance ratio was changed as the electric current was increased by the constant current mode, while power ratio was saturated as the resistance was increased by the constant resistance mode. Either the resistance ratio or the power ratio was changed with the flow velocity measured by a Pitot tube, located at the center of test section.

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Obeid, Sohaib, Ratneshwar Jha e Goodarz Ahmadi. "Closed-Loop Feedback Control of Flow Over a Flapped Airfoil at High Angles of Attack Using Identified NARMAX Model". In ASME 2012 Fluids Engineering Division Summer Meeting collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/fedsm2012-72350.

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This study investigates closed-loop feedback control system design aimed at reduction of turbulent flow separation over a NACA 0015 airfoil having 30% integral type trailing edge flap and equipped with leading-edge and trailing edge synthetic jet actuators (SJAs). The multiple-input single-output controller employs system identification techniques based on Nonlinear Auto Regressive Moving Average with eXogenous inputs (NARMAX) method to model nonlinear dynamics of the flow. RANS FLUENT simulations for 2-D airfoil are used besides an analytical modeling for the set of synthetic actuators. The resulting closed loop response using NARMAX tracks the desired pressure value and significant improvement in the transient response over the open-loop system at high angles of attack is realized. Improvements in aerodynamic efficiency and maximum lift values through active flow control would lead to better performance characteristics of airplanes.

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