Characteristics Of Airfoil Research Articles

Quasi-stationary modeling of the DBD plasma flow control around airfoil

This paper presents the results of numerical simulation of a dielectric barrier discharge (DBD) plasma actuator and shows its effectiveness to control air flow around the NACA(National Advisory Committee for Aeronautics)0015 airfoil. The actuator consists of two tape electrodes separated by a dielectric layer, and it is mounted on the suction side of the airfoil at 18% of the chord length. An alternating voltage with 20 kV magnitude and 10 kHz frequency is applied between both electrodes. The physical model of the DBD includes the drift of two ionic species, positive and negative, and the Poisson equation for the electric potential distribution. The spatio-temporal distribution of the electric field, the space charge density in the ambient air, and the surface charge density on the dielectric layer have been determined. The time average electric body force was entered into the air flow model, which was solved using the Spalart–Allmaras turbulence technique. The simulation of the air flow was performed for the free-stream velocities between 5 m/s and 20 m/s (Reynolds numbers 1.65 × 105–6.61 × 105 based on the chord length). The results of computations show the effect of the electrohydrodynamic actuation on the flow pattern, the lift and drag coefficients, the pressure coefficient, and the flow fluctuation near the airfoil. The ability of the DBD actuation to effectively control the aerodynamic airfoil characteristics has been confirmed, and its limitations for the discussed case have been determined.

Research on aerodynamic characteristics of wind turbine airfoil and blade in sand‐wind environment

Research on aerodynamic characteristics of wind turbine airfoil and blade in sand‐wind environment

Investigation on the aerodynamics characteristics of dimple patterns on the aircraft wing

Airfoil plays an important role in the efficiency of aircraft. Modification in the shape of the airfoil is also important in aircraft. In this paper, airfoil characteristics specified by many researchers were premeditated and in the interim, the surfaces of airfoils were adapted. Variation on the surface of airfoil elasticities substantial changes in the result without consuming much amount of fuel in aircraft, drag can be diminished with simple modification on the airfoil surface. The present work describes the change in aerodynamic characteristics of an airfoil by applying certain surface modifications in the form of dimples. It is aimed to delay the flow separation and improve the lift enhancement by the use of dimples in the airfoil structures of NACA 2412 designation, which in turn improves maneuverability, and performance of an aircraft by flow manipulation over the airfoil. The computational fluid dynamics CFD is done using K-ε turbulence model. The experimental work is also made and the results are compared. The wing with Square dimple shows higher lift when compared to the other configurations.

Numerical Analysis of the Aerodynamic Characteristics of NACA-4312 Airfoil

The aim of the work is to investigate the aerodynamic characteristics such as lift coefficient, drag coefficient, pressure distribution over a surface of an airfoil of NACA-4312. A commercial software ANSYS Fluent was used for these numerical simulations to calculate the aerodynamic characteristics of 2-D NACA-4312 airfoil at different angles of attack (α) at fixed Reynolds number (Re), equal to 5×10^5 . These simulations were solved using two different turbulence models, one was the Standard k-ε model with enhanced wall treatment and other was the SST k-ω model. Numerical results demonstrate that both models can produce similar results with little deviations. It was observed that both lift and drag coefficient increase at higher angles of attack, however lift coefficient starts to reduce at α =13° which is known as stalling condition. Numerical results also show that flow separations start at rare edge when the angle of attack is higher than 13° due to the reduction of lift coefficient.

Numerical and experimental study of the laminar separation bubble over SS007 airfoil for micro aerial vehicles

PurposeThis paper aims to deal with the numerical investigation of laminar separation bubble (LSB) characteristics (length and height of the bubble) of SS007 airfoil at the chord Reynolds number of Rec = 0.68 × 105 to 10.28 × 105.Design/methodology/approachThe numerical simulations of the flow around SS007 airfoil were carried out by using the commercial fluid dynamics (CFD) software, ANalysis system (ANSYS) 15. To solve the governing equations of the flow, a cell-centred control volume space discretisation approach is used. Wind tunnel experiments were conducted at the chord-based Reynolds number of Rec = 1.6 × 105 to validate the aerodynamic characteristics over SS007 airfoil.FindingsThe numerical results revealed that the LSB characteristics of a SS007 airfoil, and the aerodynamic performances are validated with experimental results. The lift and drag coefficients for both numerical and experimental results show very good correlation at Reynolds number 1.6 × 105. The lift coefficient linearly increases with the increasing angle of attack (AOA) is relatively small. The corresponding drag coefficient was found to be very small. After the formation of LSB which leads to burst to cause airfoil stall, the lift coefficient decreases and increases the drag coefficient.Practical implicationsLow Reynolds number and LSB characteristics concept in aerodynamics is predominant for both civilian and military applications. These include high altitude devices, wind turbines, human powered vehicles, remotely piloted vehicles, sailplanes, unmanned aerial vehicle and micro aerial vehicle. In this paper, the micro aerial vehicle flight conditions considered and investigated the LSB characteristics for different Reynolds number. To have better aerodynamic performances, it is strongly recommended to micro aerial vehicle (MAV) design engineers that the MAV is to fly at 12 m/s (cruise speed).Social implicationsMAVs and unmanned aerial vehicles seem to give some of the technical challenges of nature conservation monitoring and law enforcement a versatile, reliable and inexpensive solution.Originality/valueThe SS007 airfoil delays the flow separation and improves the aerodynamic efficiency by increasing the lift and decreasing the drag. The maximum increase in aerodynamic efficiency is 12.5% at stall angle of attack compared to the reference airfoil at Re = 2 × 105. The results are encouraging and this airfoil could have better aerodynamic performance for the development of MAV.

Numerical simulation and analysis of aerodynamic characteristics of fan-wing airfoil with leading edge winglet

Numerical simulation and analysis of aerodynamic characteristics of fan-wing airfoil with leading edge winglet

A numerical approach for assessing flow compressibility and transonic effect on airfoil aerodynamics

For free Mach numbers M∞ < 0.65, the standard methods for subsonic potential flows break down when the flow becomes supersonic locally. The transition of the potential equation from elliptic to hyperbolic indicates that the flow changes from a diffusive character to a propagation behavior. The elliptic numerical operators for the subsonic flow will not be able to correctly simulate the propagation properties of supersonic flow regions, which are governed by the equation of hyperbolic type. The presence of local supersonic regions significantly influences the aerodynamic characteristics of airfoil when compared to the predicted results using the standard methods for subsonic flows. To evaluate this transonic effect, the paper presents a method of solving the full potential equation using central and backward finite difference schemes corresponding to the subsonic and supersonic regions. The rotated difference scheme consists in differencing all the derivatives in the normal direction centrally, while the derivatives in the local flow direction are upwind differenced at supersonic points. The transonic effects on airfoil aerodynamics depending on the free Mach number, incidence angle and airfoil geometry were evaluated.

Experimental and computational study of ice accretion effects on aerodynamic performance

Purpose The purpose of this paper is to analyse an actual representation of ice accretions, which are important during the certification process. Design/methodology/approach Ice accretion experiments are conducted in a low-speed subsonic wind tunnel testing facility to evaluate the influence of various ice shapes around the airfoil sections. Ice accumulation changes the shapes of local airfoil sections and thereby affects the aerodynamic performance characteristics of the considered NACA 23012 profile. The ice profiles are impregnated using balsa wood with glace, horn and mixed ice accretion cases for the detailed experimental investigation. Findings Computational fluid dynamics analysis is done to compute the influence of different ice shapes on the aerodynamic coefficients (Cl and Cd) while ice accretion occurs at the leading edge of the airfoil sections. It is observed that the Cl and Cd modified immediately more than 40% as compared to the clean wing configuration. In the same fashion, the skin friction coefficient also abruptly changes for different ice shapes that have the potential to induce flutter at the critical speed of the airplane. The computational solutions are further validated through wind tunnel experiments and recent literature concerning certification for flight in icing conditions. Social implications The ice accretion study on the aerodynamic surfaces can also be extended for wind turbine blades installed at different cold regions around the globe. Further, the propeller icing influences the entire rotorcraft aerodynamics at low temperature conditions and the findings of this study are strongly connected with such problems. Originality/value The aerodynamic characteristics of the baseline airfoil are greatly affected by the ice accretion problem. Although flight through icing condition endures for a short duration, the takeoff path and decision speed are determined based on airplane drag as per federal aviation regulations. Hence, the proposed study is focussed on a cost-effective approach to predict the effect of ice accretion to achieve optimum performance.

Performance Analysis of High Wing for a Micro Class Unmanned Aerial Vehicle.

The paper deals with the design and performance analysis of high wing of a Micro Class Unmanned Aerial Vehicle. The wing design involves its initial considerations like and weight of the aircraft, planform selection, selection of airfoil, area of the wing and wing loading characteristics. The design is done based on the calculated values and performance analysis is done to show airfoil characteristics, and performance of the wing with the help of XFLR5 software. The objective of this project is to compare the results obtained for different wing planforms, different angle of attack over a range of speeds. From the results we will conclude which wing configuration meets the payload lifting goals. Selection of wing configuration is an iterative process. The iterative process allows us to accommodate other design criteria such as catering storage, systems installations (high lift devices, attachment of motors and the main undercarriage) which may or may not be directly related to the goals of the mission. The result of iterative optimization is typically a compromise in a configuration which best satisfies the overall needs of the mission. The final decision upon configuration will represent a compromise based on design priorities.

Analysis of the Influence of Camber on Hydrodynamic Characteristics of Airfoil Based on FLUENT

Based on hydraulic machinery blades airfoil design, numerical simulation was carried out for the hydrodynamics force of airfoil with different camber at Re = 107. Firstly, the numerical simulation of airfoil was performed with structured grid and the Reynolds-averaged Navier-stokes-method, which coupled with the k – ε turbulence model. Secondly, the drag and lift characteristics of airfoil with different camber were analysed. Finally, the flow field and pressure distribution of the airfoil was discussed. The result shows that as camber increases, drag, lift and lift-to-drag ratio increase, while the attack angle corresponding to maximum lift-to-drag ratio decreases. The results are useful for understanding the hydrodynamic performance of the airfoil, and provide an important theoretical basis for the design, selection and development of the airfoil in hydraulic machine.

Numerical Investigation of Flatback Airfoils Drag and Noise Reduction by a Splitter Plate

In this paper the aerodynamic and aeroacoustic characteristics of a wind turbine airfoil have been numerically investigated. The modified versions of TU Delft DU97-W-300 airfoil with a flatback trailing edge and a splitter plate were selected. IDDES method was introduced and provided good results compared with the experimental data with regard to the lift. Aeroacoustic analysis focused on the amplitude and frequency of noise associated with the vortex-shedding tone from the trailing edge wake. The results showed that wake flows were significantly effected by the addition of a splitter plate to the flatback trailing edge, and lead to reduction on both drag and noise.

Unsteady Aerodynamic Characteristics Simulations of Rotor Airfoil under Oscillating Freestream Velocity

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 actual dynamic stall characteristics of rotor airfoil in forward flight more accurately. By comparing the simulated results of OA209 airfoil under coupled freestream velocity/pitching oscillation conditions, it is indicated that the dynamic stall characteristics of airfoil associate with the critical value of Cp peaks (i.e., the dynamic stall characteristics of OA209 airfoil would be enhanced when the maximum negative pressure is larger than −1.08, and suppressed when this value is smaller than −1.08). By comparing the characteristics of vortices under different oscillating velocities, it indicates that the dissipation rate of leading edge vortex presents as exponent characteristics, and it is not sensitive to different oscillating velocities.

CFD Analysis of Controlling the Airflow over Airfoils using Dimples: Technical Note

The main objective of this work is to improve the aerodynamic characteristics and manoeuvrability of the aircraft. The reduction in drag and stall phenomena will automatically enhance the aerodynamic characteristics. This project is an effort to enhance the aerodynamic characteristics of airfoil by introducing surface modifications in the form of dimples. The shape of the dimples we selected is circular shaped dimple. We placed 12 dimples in both the surfaces in appropriate places so that they could delay the boundary layer formation. The dimple generally creates turbulence by creating vortices which in turn delays the boundary layer formation. With the effects of dimple, pressure drag gets reduced and also the acoustic effects get reduced. This project includes the computational analysis of dimple effect on aircraft wing using NACA 0018 symmetric airfoil with uniform cross section throughout the length of airfoil. Subsonic flows are considered for this analysis. The analyses were done under the inlet velocities of 30m/s and 60m/s at different angle of attack such as 0, 5, 10 and 15 degrees. The models were designed using CATIA V5 and simulated using ANSYS CFX software.

Aerodynamic Characteristics of Different Airfoils under Varied Turbulence Intensities at Low Reynolds Numbers

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 the numerical method. Then, the effects of varied low Reynolds numbers and turbulence intensities on the aerodynamic performance of NACA0012 and SD7037 were investigated. The results show that higher turbulence intensity or Reynolds number leads to more stable airfoil aerodynamic performance, larger stalling angle, and earlier transition with a different mechanism. The generation and evolution of the laminar separation bubble (LSB) are closely related to Reynolds number, and it would change the effective shape of the airfoil, having a big influence on the airfoil’s aerodynamic characteristics. Compared with the symmetrical airfoil, the low-Reynolds-number airfoil can delay the occurrence of flow separation and produce more lift in the same conditions, which provides guidance for further airfoil design under TeDP jet flow.

Flow characteristics of slat cove fillers

Experimental measurements using Particle Image Velocimetry were carried out to understand the flow characteristics of a 30P30N high-lift airfoil with and without slat cove fillers. The tests were carried out for the 30P30N airfoil with a retracted chord of c=0.35, at angles of attack of α=6∘ and 12∘, and for a chord-based Reynolds number of Rec=7.0×105. The wall pressure fluctuation results show that the use of slat cove fillers eliminates the slat tonal noise component. The results of the mean flow fields such as the normalized mean velocity, Reynolds stress components, and turbulent kinetic energy are presented for the baseline, half-slat cove filler, and slat cove filler configurations. The velocity contour results with streamlines showed a recirculation region within the slat cavity. The use of the half-slat cove filler reduced the size of the recirculation region and the use of the slat cove filler eliminated the recirculation region. The mean velocity and turbulent kinetic energy profiles at the slat wake showed insignificant difference between the three tested configurations. The Particle Image Velocimetry results were further analyzed using Proper Orthogonal Decomposition. The results showed that the first two eigenmodes of the vorticity with the highest energy were contained within the slat shear layer and vortex shedding emanating from the slat cusp for the baseline case. The energy levels were distributed over the slat shear layer for the half-slat cove filler and slat cove filler configurations as the vortex shedding is suppressed by the use of the slat cove fillers.

A simple improvement of a tip loss model for actuator disc simulations

AbstractThe loading of a wind turbine decreases towards the blade tip because of the velocities induced by the tip vortex. This tip loss effect has to be taken into account when performing actuator disc simulations, where the single blades of the turbine are not modeled. A widely used method applies a factor on the axial and tangential loading of the turbine. This factor decreases when approaching the blade tip. It has been shown that the factor should be different for the axial and tangential loading of the turbine to model the rotation of the resulting force vector at the airfoil sections caused by the induced velocity. The present article contains the derivation of a simple correction for the tangential load factor that takes this rotation into account. The correction does not need any additional curve fitting but just depends on the local airfoil characteristics and angle of attack. Actuator disc computations with the modified tip loss correction show improved agreement with results from actuator line, free wake lifting line, and blade element momentum simulations.

Study on Influence of Environmental Parameters on Dynamic Stall Characteristics of Wind Turbine Blades

Wind turbines in complex environments could encounter dynamic loads that deviate from design values, while the dynamic stall problem could reduce the reliability and safety of wind turbines. In order to accurately evaluate the aerodynamic characteristics of wind turbine blades, the influence on the dynamic stall characteristics of wind turbine airfoil under complex wind farm environmental factors is studied. The variation law of lift coefficient under different working conditions is obtained, and the pressure coefficient and flow field distribution with times are given. The evolution characteristics of vortex on airfoil surface are analyzed. The results show that when the unsteady effect is significant, the closed-loop area of the blades lift coefficient is gradually larger, and the angle of attack for the maximum lift is proportional to it; when the oscillation angle becomes larger, the upper and lower extreme values of the lift force increase, and the lift curve is more obvious in the shape of the oblique “$$\infty$$.” When the blade appears to be in dynamic stall, the lift coefficient increases quickly and has a hysteresis effect. The maximum increase is up to 46.15%, and the hysteresis effect occurs. The instability of the shear layer, the formation and quenching of the trailing edge vortex are the main causes of the hysteresis effect for the blade lift coefficient. Reasonable evaluation of its value is of great significance for wind turbine blade design in complex wind farm environment.

Low-Speed Aerodynamic Characteristics of Supercritical Airfoil with Small High-Lift Devices from Flow Pattern Measurements

In this paper, the lift coefficients of SC-0414 airfoil are estimated by applying modified Yamana’s method to the flow visualization results, which are obtained by utilizing the smoke tunnel. The application of the modified Yamana’s method is evaluated with two calculation methods. Additionally, the lift estimation, wake measurements, and numerical simulations are performed to clarify the low-speed aerodynamic characteristics of the SC airfoil with flaps. The angle of attack was varied from −5° to 8°. The flow velocity was 12 m/s and the Reynolds number was 1.6 × 105. As a result, the estimated lift coefficients show a good agreement with the results from reference data and numerical simulations. In clean condition, the lift coefficients calculated from the two methods show quantitative agreement, and no significant difference could be confirmed. However, the slope of the lifts calculated from ys is higher and closer to the reference data than those obtained from sc, where ys denotes the height where the distance from the streamline to the reference line is the largest, and sc denotes the displacement of the center of pressure from the origin of the coordinate, respectively. In the case of flaps, the GFs have an observable effect on the aerodynamic performance of the SC-0414 airfoil. When the height of the flap was increased, the lift and drag coefficients increased. The installation of a GF with a height equal to 1% of the chord length of the airfoil significantly improved the low-speed aerodynamic performance of SC airfoils.

Unsteady Aerodynamic Characteristics of NACA0012 Airfoil Undergoing Constant-Pitch-Rate Motions at Low Reynolds Numbers

Unsteady Aerodynamic Characteristics of NACA0012 Airfoil Undergoing Constant-Pitch-Rate Motions at Low Reynolds Numbers

Aerodynamic Characteristics of Airfoil with Thin Leading-Edge at Low Reynolds Numbers

Aerodynamic Characteristics of Airfoil with Thin Leading-Edge at Low Reynolds Numbers