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Journal articles on the topic 'Unsteady Airfoil'

Author: Grafiati

Published: 4 June 2021

Last updated: 5 February 2022

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1

Abdessemed, Chawki, Yufeng Yao, Abdessalem Bouferrouk, and Pritesh Narayan. "Morphing airfoils analysis using dynamic meshing." International Journal of Numerical Methods for Heat & Fluid Flow 28, no. 5 (2018): 1117–33. http://dx.doi.org/10.1108/hff-06-2017-0261.

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Purpose The purpose of this paper is to use dynamic meshing to perform CFD analyses of a NACA 0012 airfoil fitted with a morphing trailing edge (TE) flap when it undergoes static and time-dependent morphing. The steady CFD predictions of the original and morphing airfoils are validated against published data. The study also investigates an airfoil with a hinged TE flap for aerodynamic performance comparison. The study further extends to an unsteady CFD analysis of a dynamically morphing TE flap for proof-of-concept and also to realise its potential for future applications. Design/methodology/a

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2

Ho, WH, and TH New. "Unsteady numerical investigation of two different corrugated airfoils." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, no. 13 (2016): 2423–37. http://dx.doi.org/10.1177/0954410016682539.

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An unsteady, two-dimensional numerical study was conducted to investigate the aerodynamic and flow characteristics of two bio-inspired corrugated airfoils at Re = 14,000 and compared with those of a smooth NACA0010 airfoil. Mean aerodynamic results reveal that the corrugated airfoils have better lift performance compared to the NACA0010 airfoil but incur slightly higher drag penalty. Mean flow streamlines indicate that this favourable performance is due to the ability of the corrugated airfoils in mitigating large-scale flow separations and stall. Unsteady flow field results show persistent fo

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3

Buffum, D. H., and S. Fleeter. "Effect of Wind Tunnel Acoustic Modes on Linear Oscillating Cascade Aerodynamics." Journal of Turbomachinery 116, no. 3 (1994): 513–24. http://dx.doi.org/10.1115/1.2929440.

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The aerodynamics of a biconvex airfoil cascade oscillating in torsion is investigated using the unsteady aerodynamic influence coefficient technique. For subsonic flow and reduced frequencies as large as 0.9, airfoil surface unsteady pressures resulting from oscillation of one of the airfoils are measured using flush-mounted high-frequency-response pressure transducers. The influence coefficient data are examined in detail and then used to predict the unsteady aerodynamics of a cascade oscillating at various interblade phase angles. These results are correlated with experimental data obtained

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4

Zhu, Bao Li, Hui Pen Wu, and Tian Hang Xiao. "Study of Aerodynamic Interactions of Dual Flapping Airfoils in Tandem Configurations." Applied Mechanics and Materials 160 (March 2012): 301–6. http://dx.doi.org/10.4028/www.scientific.net/amm.160.301.

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The unsteady viscous flow fields of dual flapping airfoils in tandem configurations are simulated by a Navier-Stokes Solver based on dynamic deformable hybrid meshes. Aerodynamic interactions of three motion models are studied including flapping fore airfoil with fixed aft airfoil, two airfoils flapping in phase and out-of-phase. The results indicate that the aft airfoil in the wake of the flapping fore airfoil has great influence on the aerodynamic performance. When the fore airfoil flaps with a fixed aft airfoil, the thrust generation and thrust propulsive efficiency were enhanced by 65% and

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5

Atassi, H. M., J. Fang, and S. Patrick. "Direct Calculation of Sound Radiated From Bodies in Nonuniform Flows." Journal of Fluids Engineering 115, no. 4 (1993): 573–79. http://dx.doi.org/10.1115/1.2910182.

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Sound radiated from a single airfoil and a cascade of airfoils in three-dimensional gusts is directly calculated. Euler’s equations are linearized about the mean flow of the airfoil or cascade. The velocity field is split into a vortical part and a potential part. The latter is governed by a single nonconstant-coefficient convective wave equation. For a single airfoil, the radiated sound is calculated using Kirchhoff’s method from the mid field of the unsteady pressure obtained through the unsteady aerodynamic solver. The results indicate the importance of the contribution of the quadrupole ef

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6

Buffum, D. H., and S. Fleeter. "The Aerodynamics of an Oscillating Cascade in a Compressible Flow Field." Journal of Turbomachinery 112, no. 4 (1990): 759–67. http://dx.doi.org/10.1115/1.2927719.

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Fundamental experiments are performed in the NASA Lewis Research Center Transonic Oscillating Cascade Facility to investigate and quantify the aerodynamics of a cascade of bioconvex airfoils executing torsion mode oscillations at realistic reduced frequency values. Both steady and unsteady airfoil surface pressures are measured at two inlet Mach numbers, 0.65 and 0.80. and two incidence angles, 0 and 7 deg, with the harmonic torsional airfoil cascade oscillations at realistic high reduced frequency and unsteady data obtained at several interbladephase angle values. The time-variant pressures a

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7

Zhu, Chengyong, Tongguang Wang, and Jianghai Wu. "Numerical Investigation of Passive Vortex Generators on a Wind Turbine Airfoil Undergoing Pitch Oscillations." Energies 12, no. 4 (2019): 654. http://dx.doi.org/10.3390/en12040654.

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Passive vortex generators (VGs) are widely used to suppress the flow separation of wind turbine blades, and hence, to improve rotor performance. VGs have been extensively investigated on stationary airfoils; however, their influence on unsteady airfoil flow remains unclear. Thus, we evaluated the unsteady aerodynamic responses of the DU-97-W300 airfoil with and without VGs undergoing pitch oscillations, which is a typical motion of the turbine unsteady operating conditions. The airfoil flow is simulated by numerically solving the unsteady Reynolds-averaged Navier-Stokes equations with fully re

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8

Motta, Valentina, Alberto Guardone, and Giuseppe Quaranta. "Influence of airfoil thickness on unsteady aerodynamic loads on pitching airfoils." Journal of Fluid Mechanics 774 (June 11, 2015): 460–87. http://dx.doi.org/10.1017/jfm.2015.280.

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The influence of the airfoil thickness on aerodynamic loads is investigated numerically for harmonically pitching airfoils at low incidence, under the incompressible and inviscid flow approximation. Force coefficients obtained from finite-volume unsteady simulations of symmetrical 4-digit NACA airfoils are found to depart from the linear Theodorsen model of an oscillating flat plate. In particular, the value of the reduced frequency resulting in the inversion – from clockwise to counter-clockwise – of the lift/angle-of-attack hysteresis curve is found to increase with the airfoil thickness. Bo

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9

Henderson, G. H., and S. Fleeter. "Forcing Function Effects on Unsteady Aerodynamic Gust Response: Part 2—Low Solidity Airfoil Row Response." Journal of Turbomachinery 115, no. 4 (1993): 751–59. http://dx.doi.org/10.1115/1.2929310.

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The fundamental gust modeling assumption is investigated by means of a series of experiments performed in the Purdue Annular Cascade Research Facility. The unsteady periodic flow field is generated by rotating rows of perforated plates and airfoil cascades, with the resulting unsteady periodic chordwise pressure response of a downstream low-solidity stator row determined by miniature pressure transducers embedded within selected airfoils. When the forcing function exhibited the characteristics of a linear-theory vortical gust, as was the case for the perforated-plate wake generators, the resul

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10

Buffum, D. H., and S. Fleeter. "Wind Tunnel Wall Effects in a Linear Oscillating Cascade." Journal of Turbomachinery 115, no. 1 (1993): 147–56. http://dx.doi.org/10.1115/1.2929199.

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Experiments in a linear oscillating cascade reveal that the wind tunnel walls enclosing the airfoils have, in some cases, a detrimental effect on the oscillating cascade aerodynamics. In a subsonic flow field, biconvex airfoils are driven simultaneously in harmonic, torsion-mode oscillations for a range of interblade phase angle values. It is found that the cascade dynamic periodicity—the airfoil-to-airfoil variation in unsteady surface pressure—is good for some values of interblade phase angle but poor for others. Correlation of the unsteady pressure data with oscillating flat plate cascade p

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11

Zhao, Liangyu, and Shuxing Yang. "Influence of Thickness Variation on the Flapping Performance of Symmetric NACA Airfoils in Plunging Motion." Mathematical Problems in Engineering 2010 (2010): 1–19. http://dx.doi.org/10.1155/2010/675462.

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In order to investigate the impact of airfoil thickness on flapping performance, the unsteady flow fields of a family of airfoils from an NACA0002 airfoil to an NACA0020 airfoil in a pure plunging motion and a series of altered NACA0012 airfoils in a pure plunging motion were simulated using computational fluid dynamics techniques. The “class function/shape function transformation“ parametric method was employed to decide the coordinates of these altered NACA0012 airfoils. Under specified plunging kinematics, it is observed that the increase of an airfoil thickness can reduce the leading edge

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12

Li, Zhao, Guang-jun Yang, Xiao-yan Tong, and Feng Jiang. "A Parametric Design Method for Hybrid Airfoils for Icing Wind Tunnel Test." International Journal of Aerospace Engineering 2021 (April 20, 2021): 1–18. http://dx.doi.org/10.1155/2021/5594077.

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The size of aircraft models that can be tested in icing wind tunnels is limited by the dimensions of the facilities in present; it is an effective method to replace the large model with a hybrid airfoil to carry out the experiment. A design method of multiple control points for hybrid airfoil based on the similarity of flow field in the leading edge of airfoil is proposed. Aiming at generating the full-scale flow field and ice accretion on the leading edge, multiobjective genetic optimization algorithm is used to design the hybrid airfoil under different conditions by combining the airfoil par

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13

Shaw, L. M., D. R. Boldman, A. E. Buggele, and D. H. Buffum. "Unsteady Pressure Measurements on a Biconvex Airfoil in a Transonic Oscillating Cascade." Journal of Engineering for Gas Turbines and Power 108, no. 1 (1986): 53–59. http://dx.doi.org/10.1115/1.3239885.

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Flush-mounted dynamic pressure transducers were installed on the center airfoil of a transonic oscillating cascade to measure the unsteady aerodynamic response as nine airfoils were simultaneously driven to provide 1.2 deg of pitching motion about the midchord. Initial tests were performed at an incidence angle of 0.0 deg and a Mach number of 0.65 in order to obtain results in a shock-free compressible flow field. Subsequent tests were performed at an angle of attack of 7.0 deg and a Mach number of 0.80 in order to observe the surface pressure response with an oscillating shock near the leadin

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14

Nakagawa, T. "On unsteady airfoil-vortex interaction." Acta Mechanica 75, no. 1-4 (1988): 1–13. http://dx.doi.org/10.1007/bf01174624.

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15

Gao, Ji, Rui Shan Yuan, Ming Hui Zhang, and Yong Hui Xie. "Numerical Study on Thrust Generation Performance of Plunging Airfoils." Applied Mechanics and Materials 312 (February 2013): 235–38. http://dx.doi.org/10.4028/www.scientific.net/amm.312.235.

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In this paper, the effects of angle of attack, camber and camber location on propulsion performance of flapping airfoils undergoing plunging motion were numerically studied at Re=20000 and h=0.175. The unsteady incompressible viscous flow around four different airfoil sections was simulated applying the dynamic mesh. The results show that the time averaged thrust coefficient CTmean and propulsive efficiency η of the symmetric airfoil decrease with the increasing angle of attack, and the variation of CTmean is more obvious than that of CPmean. Both CTmean and η for NACA airfoils studied in this

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16

Zhang, Yang, Zhou Zhou, Kelei Wang, and Xu Li. "Aerodynamic Characteristics of Different Airfoils under Varied Turbulence Intensities at Low Reynolds Numbers." Applied Sciences 10, no. 5 (2020): 1706. http://dx.doi.org/10.3390/app10051706.

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A numerical study was conducted on the influence of turbulence intensity and Reynolds number on the mean topology and transition characteristics of flow separation to provide better understanding of the unsteady jet flow of turboelectric distributed propulsion (TeDP) aircraft. By solving unsteady Reynolds averaged Navier-Stokes (URANS) equation based on C-type structural mesh and γ - Re ˜ θ t transition model, the aerodynamic characteristics of the NACA0012 airfoil at different turbulence intensities was calculated and compared with the experimental results, which verifies the reliability of t

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17

Esfahanian, V., and M. Behbahani-nejad. "Reduced-Order Modeling of Unsteady Flows About Complex Configurations Using the Boundary Element Method." Journal of Fluids Engineering 124, no. 4 (2002): 988–93. http://dx.doi.org/10.1115/1.1511166.

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An approach to developing a general technique for constructing reduced-order models of unsteady flows about three-dimensional complex geometries is presented. The boundary element method along with the potential flow is used to analyze unsteady flows over two-dimensional airfoils, three-dimensional wings, and wing-body configurations. Eigenanalysis of unsteady flows over a NACA 0012 airfoil, a three-dimensional wing with the NACA 0012 section and a wing-body configuration is performed in time domain based on the unsteady boundary element formulation. Reduced-order models are constructed with a

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18

Tang, Hui, Yulong Lei, Xingzhong Li, and Yao Fu. "Numerical investigation of the aerodynamic characteristics and attitude stability of a bio-inspired corrugated airfoil for MAV or UAV applications." Energies 12, no. 20 (2019): 4021. http://dx.doi.org/10.3390/en12204021.

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In this study, two-dimensional (2D) and three-dimensional (3D) numerical calculations were conducted to investigate the aerodynamic characteristics, especially the unsteady aerodynamic characteristics and attitude stability of a bio-inspired corrugated airfoil compared with a smooth-surfaced airfoil (NACA2408 airfoil) at the chord Reynolds number of 4000 to explore the potential applications of non-traditional, corrugated dragonfly airfoils for micro air vehicles (MAVs) or micro-sized unmanned aerial vehicles (UAVs) designs. Two problem settings were applied to our numerical calculations. Firs

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19

Tatar, Massoud, Mojtaba Tahani, and Mehran Masdari. "Numerical study of boundary layer transition using intermittency model." Aircraft Engineering and Aerospace Technology 91, no. 8 (2019): 1156–68. http://dx.doi.org/10.1108/aeat-05-2018-0144.

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Purpose In this paper, the applicability of shear stress transport k-ω model along with the intermittency concept has been investigated over pitching airfoils to capture the laminar separation bubble (LSB) position and the boundary layer transition movement. The effect of reduced frequency of oscillations on boundary layer response is also examined. Design/methodology/approach A two-dimensional computational fluid dynamic code was developed to compute the effects of unsteadiness on LSB formation, transition point movement, pressure distribution and lift force over an oscillating airfoil using

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20

Feiereisen, J. M., M. D. Montgomery, and S. Fleeter. "Unsteady Aerodynamic Forcing Functions: A Comparison Between Linear Theory and Experiment." Journal of Turbomachinery 116, no. 4 (1994): 676–85. http://dx.doi.org/10.1115/1.2929460.

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The unsteady flow field generated by rotating rows of perforated plates and airfoil cascades is mathematically split into vortical and potential components using two methods, one relying entirely on velocity data and the other utilizing both velocity and unsteady static pressure data. The propagation and decay of these split flow perturbations are then examined and compared to linear theory predictions. The perforated plate gusts closely resemble linear theory vortical gusts. Both splitting methods indicate that they are dominantly vortical gusts with insignificant unsteady static pressure per

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21

Johnston, Christopher O., William H. Mason, and Cheolheui Han. "Unsteady thin airfoil theory revisited for a general deforming airfoil." Journal of Mechanical Science and Technology 24, no. 12 (2010): 2451–60. http://dx.doi.org/10.1007/s12206-010-0920-4.

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22

Klein, A., Th Lutz, E. Krämer, K. Richter, A. D. Gardner, and A. R. M. Altmikus. "Numerical Comparison of Dynamic Stall for Two-Dimensional Airfoils and an Airfoil Model in the DNW–TWG." Journal of the American Helicopter Society 57, no. 4 (2012): 1–13. http://dx.doi.org/10.4050/jahs.57.042007.

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The airfoil sections of helicopter rotors experience a wide range of flow conditions in forward flight from transonic flow on the advancing blade to subsonic flow and high angles of attack on the retreating blade. Most notably, the dynamic stall phenomenon has been a research topic for decades and various models have been introduced to predict the unsteady characteristics of the rotor blade undergoing unsteady separation. The objective of the present paper is to compare two-dimensional (2D) dynamic stall computations, suitable for airfoil design studies considering unsteady characteristics, wi

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23

Tobing, S. "Lift Generation of an Elliptical Airfoil at a Reynolds Number of 1000." International Journal of Automotive and Mechanical Engineering 16, no. 2 (2019): 6738–52. http://dx.doi.org/10.15282/ijame.16.2.2019.20.0507.

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Bumblebees cannot fly! That conclusion is likely to be drawn by scientists who analysed the insect using aerodynamics of stationary wings such as that of a passenger aircraft. Looking at the insect again using a newfound understanding of unsteady aerodynamics; it is clear why bumblebees can fly. Bumblebees utilise mechanisms behind unsteady aerodynamics such as leading-edge vortices (LEVs) formation, wake capture, and rapid end-of-stroke rotation to generate forces that enable the insect to fly. This study focuses on two-dimensional (2D) elliptical airfoil. Earlier works found the aerodynamic

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24

Yudin, V. A. "Airfoil cascade in unsteady eddy flow." Journal of Applied Mechanics and Technical Physics 35, no. 4 (1994): 563–68. http://dx.doi.org/10.1007/bf02369499.

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Howe, M. S. "On unsteady surface forces, and sound produced by the normal chopping of a rectilinear vortex." Journal of Fluid Mechanics 206 (September 1989): 131–53. http://dx.doi.org/10.1017/s0022112089002259.

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An investigation is made of the sound produced when a rectilinear vortex is cut at right angles to its axis by a non-lifting airfoil of symmetric section. The motions are at sufficiently low Mach number that the wavelength of the sound is large relative to the chord of the airfoil. In these circumstances the airfoil experiences no fluctuating lift during the interaction, and the radiation may be ascribed to an acoustic source of dipole type whose strength is equal to the unsteady drag. It is argued that previous analyses of the related problem of ‘unsteady thickness noise’ have ignored certain

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26

Wellenberg, Sören, Markus Marnett, Benedikt Roidl, Davis Kirkendall, Frederik Thönnißen, and Wolfgang Schröder. "Assessment of a numerical design tool for pitching airfoils." Wind Engineering 43, no. 6 (2019): 639–56. http://dx.doi.org/10.1177/0309524x18821883.

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The aim of this study was to assess the applicability of a numerical design tool for pitching airfoils; by evaluating their aerodynamic performance comparing experimental and numerical data at different levels of complexity. Experimental findings of non-harmonically pitching airfoil configurations in a water tunnel at medium Reynolds numbers are compared to solutions of a modified double-wake vortex-panel method with boundary-layer formulation and unsteady Reynolds-averaged Navier–Stokes simulations. For steady-state airfoil configurations at high angle of attack, large eddy simulation data ar

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27

Marques, Flávio D., Daniel A. Pereira, Mohamed Y. Zakaria, and Muhammad R. Hajj. "Power extraction from stall-induced oscillations of an airfoil." Journal of Intelligent Material Systems and Structures 29, no. 7 (2017): 1407–17. http://dx.doi.org/10.1177/1045389x17739161.

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Aerodynamic and structural nonlinearities of aeroelastic systems control different aspects of their limit cycle oscillations and bifurcations. One strong nonlinear unsteady aerodynamic effect that results in self-induced oscillations of airfoils is the dynamic stall. So, the concept of power extraction from stall-induced oscillations of a pitching airfoil is investigated. Experiments are performed to explore and enhance the conversion of the oscillations of a NACA0012 airfoil that is restrained elastically in pitching to electrical power. Wind tunnel tests are performed on an airfoil model con

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28

Wang, Qing, and Qijun Zhao. "Unsteady Aerodynamic Characteristics Simulations of Rotor Airfoil under Oscillating Freestream Velocity." Applied Sciences 10, no. 5 (2020): 1822. http://dx.doi.org/10.3390/app10051822.

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The dynamic stall characteristics of rotor airfoil are researched by employing unsteady Reynolds-Averaged Navier-Stokes (RANS) method under oscillating freestream velocity conditions. In order to simulate the oscillating freestream velocity of airfoil under dynamic stall conditions, the moving-embedded grid method is employed to simulate the oscillating velocity. By comparing the simulated dynamic stall characteristics of two-dimensional airfoil and three-dimensional rotor, it is indicated that the dynamic stall characteristics of airfoil under oscillating freestream velocity reflect the actua

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29

Ladopoulos, E. G. "Nonlinear unsteady flow problems by multidimensional singular integral representation analysis." International Journal of Mathematics and Mathematical Sciences 2003, no. 50 (2003): 3203–16. http://dx.doi.org/10.1155/s0161171203112318.

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A two-dimensional nonlinear aerodynamics representation analysis is proposed for the investigation of inviscid flowfields of unsteady airfoils. Such problems are reduced to the solution of a nonlinear multidimensional singular integral equation as the source and vortex strength distributions are dependent on the history of these distributions on the NACA airfoil surface. A turbulent boundary layer model is further investigated, based on the formulation of the unsteady behaviour of the momentum integral equation. An application is finally given to the determination of the velocity and pressure

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Xia, X., and K. Mohseni. "Unsteady aerodynamics and vortex-sheet formation of a two-dimensional airfoil." Journal of Fluid Mechanics 830 (October 2, 2017): 439–78. http://dx.doi.org/10.1017/jfm.2017.513.

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Unsteady inviscid flow models of wings and airfoils have been developed to study the aerodynamics of natural and man-made flyers. Vortex methods have been extensively applied to reduce the dimensionality of these aerodynamic models, based on the proper estimation of the strength and distribution of the vortices in the wake. In such modelling approaches, one of the most fundamental questions is how the vortex sheets are generated and released from sharp edges. To determine the formation of the trailing-edge vortex sheet, the classical steady Kutta condition can be extended to unsteady situation

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Yee, Kwanjung, Dong-Ho Lee, and Soogab Lee. "Unsteady Flowfield and Noise Propagation due to Transonic Airfoil-Airfoil Interaction." AIAA Journal 36, no. 5 (1998): 791–98. http://dx.doi.org/10.2514/2.438.

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Yee, Kwanjung, Dong-Ho Lee, and Soogab Lee. "Unsteady flowfield and noise propagation due to transonic airfoil-airfoil interaction." AIAA Journal 36 (January 1998): 791–98. http://dx.doi.org/10.2514/3.13893.

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Smith, T. E., and J. R. Kadambi. "The Effect of Steady Aerodynamic Loading on the Flutter Stability of Turbomachinery Blading." Journal of Turbomachinery 115, no. 1 (1993): 167–74. http://dx.doi.org/10.1115/1.2929201.

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An aeroelastic analysis is presented that accounts for the effect of steady aerodynamic loading on the aeroelastic stability of a cascade of compressor blades. The aeroelastic model is a two-degree-of-freedom model having bending and torsional displacements. A linearized unsteady potential flow theory is used to determine the unsteady aerodynamic response coefficients for the aeroelastic analysis. The steady aerodynamic loading was caused by the addition of (1) airfoil thickness and camber and (2) steady flow incidence. The importance of steady loading on the airfoil unsteady pressure distribu

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Zhong, Junwei, Jingyin Li, and Penghua Guo. "Effects of leading-edge rod on dynamic stall performance of a wind turbine airfoil." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 231, no. 8 (2017): 753–69. http://dx.doi.org/10.1177/0957650917718453.

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A cylindrical rod placed at the leading edge of the S809 airfoil is used as an alternative for the conventional vortex generators. In this paper, extensive numerical investigations have been conducted on the effects of the rod on the static and dynamic stall performance of the S809 airfoil. The flows around the stationary and sinusoidally oscillating S809 airfoils at Re = 106 are simulated by solving the unsteady two-dimensional Reynolds-averaged Navier–Stokes equations with the Shear Stress Transport k–ω model. For the stationary airfoil, the leading edge rod can effectively enhance the aerod

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Kamran, Ahmad, Zhi Gang Wu, and Muhammad Amjad Sohail. "CFD Analysis of Oscillating Airfoil during Pitch Cycle." Applied Mechanics and Materials 152-154 (January 2012): 906–11. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.906.

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This research paper presents the CFD analysis of oscillating airfoil during pitch cycle. Unsteady subsonic flow is simulated for pitching airfoil at Mach number 0.283 and Reynolds number 3.45 millions. Turbulent effects are also considered for this study by using K-ω SST turbulent model. Two-dimensional unsteady compressible Navier-Stokes code including two-equation turbulence model and PISO pressure velocity coupling is used. Pressure based implicit solver with first order implicit unsteady formulation is used. The simulated pitch cycle results are compared with the available experimental dat

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Lei, Peng-Fei, Jia-Zhong Zhang, Wei Kang, Sheng Ren, and Le Wang. "Unsteady Flow Separation and High Performance of Airfoil with Local Flexible Structure at Low Reynolds Number." Communications in Computational Physics 16, no. 3 (2014): 699–717. http://dx.doi.org/10.4208/cicp.111013.090514a.

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AbstractThe unsteady flow separation of airfoil with a local flexible structure (LFS) is studied numerically in Lagrangian frames in detail, in order to investigate the nature of its high aerodynamic performance. For such aeroelastic system, the characteristic-based split (CBS) scheme combined with arbitrary Lagrangian-Eulerian (ALE) framework is developed firstly for the numerical analysis of unsteady flow, and Galerkin method is used to approach the flexible structure. The local flexible skin of airfoil, which can lead to self-induced oscillations, is considered as unsteady perturbation to t

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Wolff, J. M., and S. Fleeter. "Nonlinear Separated Inviscid-Viscous Analysis of Oscillating Cascade Aerodynamics Using an Inverse Integral Method." Journal of Turbomachinery 121, no. 1 (1999): 134–44. http://dx.doi.org/10.1115/1.2841222.

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A mathematical model is developed to analyze the unsteady flow through an harmonically oscillating cascade of airfoils, including separated flow. The model incorporates an inverse integral boundary layer solution with the time-marching Euler analysis NPHASE. An embedded composite grid formulation is incorporated, specifically a deforming C-grid embedded in a Cartesian H-grid, thereby simplifying grid generation. To reduce computational requirements, Fourier series unsteady periodic boundary conditions are implemented. The integral turbulent boundary layer model is closed with steady correlatio

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38

Ardonceau, Pascal L. "Unsteady pressure distribution over a pitching airfoil." AIAA Journal 27, no. 5 (1989): 660–62. http://dx.doi.org/10.2514/3.10160.

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Leishman, J. G., and K. Q. Nguyen. "State-space representation of unsteady airfoil behavior." AIAA Journal 28, no. 5 (1990): 836–44. http://dx.doi.org/10.2514/3.25127.

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FUCHIWAKI, Masaki, and Kazuhiro Tanaka. "Vortex Flow behind an Unsteady Elastic Airfoil." Journal of the Visualization Society of Japan 28-1, no. 2 (2008): 1021. http://dx.doi.org/10.3154/jvs.28.1021.

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Gupta, Rohit, and Phillip J. Ansell. "Unsteady Flow Physics of Airfoil Dynamic Stall." AIAA Journal 57, no. 1 (2019): 165–75. http://dx.doi.org/10.2514/1.j057257.

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Alshabu, A., and H. Olivier. "Unsteady Wave Phenomena on a Supercritical Airfoil." AIAA Journal 46, no. 8 (2008): 2066–73. http://dx.doi.org/10.2514/1.35516.

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YANG, Chang, Akira SHIGEYOSHI, and Kazuhiro TANAKA. "The Vortex Flow of an Unsteady Airfoil." Proceedings of the JSME annual meeting 2003.2 (2003): 339–40. http://dx.doi.org/10.1299/jsmemecjo.2003.2.0_339.

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Chen, S. H., and C. M. Ho. "Near wake of an unsteady symmetric airfoil." Journal of Fluids and Structures 1, no. 2 (1987): 151–64. http://dx.doi.org/10.1016/s0889-9746(87)90315-x.

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Fuchiwaki, Masaki, and Kazuhiro Tanaka. "Vortex Structure and Scale on an Unsteady Air foil(Wing and Airfoil)." Proceedings of the International Conference on Jets, Wakes and Separated Flows (ICJWSF) 2005 (2005): 591–96. http://dx.doi.org/10.1299/jsmeicjwsf.2005.591.

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Meskell, Craig, and Alberto Pellegrino. "Vortex Shedding Lock-In due to Pitching Oscillation of a Wind Turbine Blade Section at High Angles of Attack." International Journal of Aerospace Engineering 2019 (March 11, 2019): 1–12. http://dx.doi.org/10.1155/2019/6919505.

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Abstract:

The unsteady flow around a pitching two-dimensional airfoil section (NREL S809) has been simulated using unsteady RANS with the transition SST turbulence model. This geometry is chosen to represent a wind turbine blade in a standstill configuration. The Reynolds number is Re=106 based on a chord length of 1 m. A prescribed sinusoidal pitching motion has been applied at a fixed amplitude of 7° for a range of high angles of attack 30°<α<150°. At these incidences, the airfoil will behave more like a bluff body and may experience periodic vortex shedding. It is well known that, in bluff body

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Abhari, R. S., and M. Giles. "A Navier–Stokes Analysis of Airfoils in Oscillating Transonic Cascades for the Prediction of Aerodynamic Damping." Journal of Turbomachinery 119, no. 1 (1997): 77–84. http://dx.doi.org/10.1115/1.2841013.

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An unsteady, compressible, two-dimensional, thin shear layer Navier–Stokes solver is modified to predict the motion-dependent unsteady flow around oscillating airfoils in a cascade. A quasi-three-dimensional formulations is used to account for the stream-wise variation of streamtube height. The code uses Ni’s Lax–Wendroff algorithm in the outer region, an implicit ADI method in the inner region, conservative coupling at the interface, and the Baldwin–Lomax turbulence model. The computational mesh consists of an O-grid around each blade plus an unstructured outer grid of quadrilateral or triang

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Qiao, Li Min, Xue Shan Liu, Yong Bo Yang, Yong Gang Jia, and Xiao Lin Quan. "Fluid Structure Interaction Simulation on the Seagull Airfoil of the Small Wind Turbine." Advanced Materials Research 546-547 (July 2012): 160–65. http://dx.doi.org/10.4028/www.scientific.net/amr.546-547.160.

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For the blades of the small wind turbine working under the conditions of Low-Reynolds, the air viscosity has relatively great influence on them. The design and calculation on thickness of airfoils were studied in order to raise its life and reduce weight. In the premise of strength, the lighter, the better. This paper studied the aerodynamic performance of the airfoil under the Low-Reynolds and analyzed fluid-structure interaction effect at Reynolds number 600,000 under three different attack angles. The numerical simulation approach addresses unsteady Reynolds-averaged N-S solutions and cover

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Gu, Ning, Zhiliang Lu, and Tongqing Guo. "Simulation of Viscous Flows Around A Moving Airfoil by Field Velocity Method with Viscous Flux Correction." Advances in Applied Mathematics and Mechanics 4, no. 03 (2012): 294–310. http://dx.doi.org/10.4208/aamm.10-m1167.

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AbstractBased on the field velocity method, a novel approach for simulating unsteady pitching and plunging motion of an airfoil is presented in this paper. Responses to pitching and plunging motions of the airfoil are simulated under different conditions. The obtained results are compared with those of moving grid method and good agreement is achieved. In the conventional field velocity method, the Euler solver is usually used to simulate the movement of the airfoil. However, when viscous effect is considered, unsteady Navier-Stokes equations have to be solved and the viscous flux correction m

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Rotaru, Constantin. "Nonlinear Characteristics of Helicopter Rotor Blade Airfoils: An Analytical Evaluation." Mathematical Problems in Engineering 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/503858.

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Some results are presented about the study of airloads of the helicopter rotor blades, the aerodynamic characteristics of airfoil sections, the physical features, and the techniques for modeling the unsteady effects found on airfoil operating under nominally attached flow conditions away from stall. The unsteady problem was approached on the basis of Theodorsen's theory, where the aerodynamic response (lift and pitching moment) is considered as a sum of noncirculatory and circulatory parts. The noncirculatory or apparent mass accounts for the pressure forces required to accelerate the fluid in

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