Slotted Flap Research Articles

Validation Task for Solution of Optimal Slotted Flap Position Using Fluent Software

CFD solvers are commonly used in optimization problems in aerodynamics. Typical task is the search for optimal position of slotted flap. On the example is shown that the optimum predicted by CFD software can differ significantly from that found in the wind tunnel. Then the focus is on the optimal position of slotted flaps. It was examined with ANSYS Fluent CFD code with both 2D and 3D structured meshes and three different models of turbulence. Results from CFD and those of wind tunnel were compared with relevant disagreement found. Possible sources of the error are discussed and topics for further investigation in this field are suggested in conclusion.

STUDY OF THE INFLUENCE OF A GAP BETWEEN THE WING AND SLOTTED FLAP ON THE AERODYNAMIC CHARACTERISTICS OF ULTRA-LIGHT AIRCRAFT WING AIRFOIL

The purpose of the study is to assess what the influence of the distance of the gap is between the wing and slotted flap on the aerodynamic characteristics of ultra-light aircraft wing when the flap is retracted. It has been elected numerical approach to the study and it is been realized through applied numerical model of the wing airfoil NACA 2412 for three different lengths of slotted gap size, whose length is expressed as percentages of the airfoil chord. The code ANSYS FLUENT has been applied, as it has been determined RANS (Reynolds-averaged Navier-Stokes) equations and DES (detached-eddy simulation) turbulent model has been used.

Study the Influence of a Gap between the Wing and Slotted Flap over the Aerodynamic Characteristics of Ultra-Light Aircraft Wing Airfoil

Study the Influence of a Gap between the Wing and Slotted Flap over the Aerodynamic Characteristics of Ultra-Light Aircraft Wing Airfoil

CFD Analysis on MAV NACA 2412 Wing in High Lift Take-Off Configuration for Enhanced Lift Generation

In a high lift take off configuration an MAV wing utilizes partially extended flaps and slats. Slats and Flaps are high lift devices installed on a wing for the purpose of augmenting Coefficient of Lift (CL). While Slats are installed on the leading edge of a wing the Flaps may be installed on the trailing edge or the leading edge of a wing. In this paper the effect of Slot size created by the Slats in percentage of wing chord ‘c’ and Double Slotted Flaps on CL for a MAV NACA 2412 has been studied using CFD analysis at 2*105 Reynolds Number. It is found that the maximum value of CL achieved is 67.134% higher than the plain NACA 2412 wing at 4 degrees angle of attack when slats are extended at 1.7 percent of wing chord ‘c’. The Stall angle of the MAV NACA 2412 wing in high lift take-off configuration was found to be 54 degrees whereas the plain NACA 2412 wing stalled at 20 degrees angle of attack.

프로펠러와 고양력 장치와의 공력간섭에 대한 수치해석 연구

A rotating propeller of turboprop aircraft gives much effect on the aerodynamic characteristics of wing such as lift, moment and stall. Specially propeller effect on the wing surface is much more dominant when aircrafts are in landing or take-off conditions. In the present paper, three dimensional Navier-Stokes simulations for the interaction of propeller and wing were carried out for medium sized turboprop aircraft. For rotating propeller, unsteady sliding mesh method was used to simulate a relative motion between moving and static bodies. For the power effect analysis in landing and take off configurations, double slotted flap was also considered and the aerodynamic characteristics were investigated. It was shown that the propeller slipstream enhanced the lift slope including maximum lift by eliminating local flow separation region and this enhancement was more dominant with high lift device.

In-flight Ice Accretion Prediction Code

The phenomenon of in-flight icing may affect all types of aircraft. The paper deals with the development of the computational wing airfoil ice accretion prediction code Ice. Presented code versions enable computational rime ice and glaze ice accretion prediction on single and multi-element airfoils in acceptable time of solution. There are presented results of rime ice and glaze ice accretion predictions and compared with current ice accretion prediction codes. Various cases of predicted ice shapes are shown in dependence of air temperature. The latest Ice code version enables to solve system of several airfoils. The example of ice prediction on the wing airfoil with a slotted flap is shown for two angles of deflection.

Wind tunnel CESAR model

Wind tunnel CESAR model

Shape Adaptive Airfoil Actuated by a Shape Memory Alloy and its Aerodynamic Characteristics

The methodology to adaptively change the configuration of an airfoil using a shape memory alloy (SMA) thin film actuator to improve aerodynamic performance is numerically demonstrated. To predict the thermomechanical behaviors of an SMA thin film, a 2-D incremental formulation of the SMA constitutive model is developed. By implementing a numerical algorithm of the SMA thin film, the interactions between the airfoil structure and SMA thin film actuator are investigated. Airfoils with either a plain flap or a slotted flap are considered and their aerodynamic characteristics are compared with those of the airfoil actuated using the SMA thin film actuator. Furthermore, the effectiveness of the airfoil actuated by SMA thin film to enhance the aerodynamic performance is discussed.

Design of a High-Lift System with Droop Nose Device

T HE realization of wings with an extended portion of laminar flow, such as is being designed in the European project New Aircraft Concept Research (NACRE), imposes to use high-lift systems that preserve the smoothness of the wing as far downstream as possible. Our choice was to develop a system equipped with a single slotted trailing-edge flap and amorphing droop nose device. A similar concept was earlier presented by Morgan [1], and high-lift systems with a droop nose bending around a hinge line were also studied by Khodadoust and Washburn [2] and Khodadoust and Shmilovich [3]. In the next section we use a design of experiment (DOE) approach, starting from a general description of the high-lift airfoil consisting of 12 parameters. Five of them were selected and optimized by a response surfacemethod. The performance of the best candidate is analyzed in a third section and compared there with a high-lift system equipped with a vented Krueger leading-edge flap. In the fourth section a flow control system with vortex generators (VG) is investigated in order to improve the overall performance of the high-lift system with flexible droop nose device.

High-Lift Devices Performance Enhancement Using Mechanical and Air-Jet Vortex Generators

A growing number of advanced-research studies have recently examined the benefits of applying mechanical or fluidic separation control to leading-edge slats or trailing-edge flaps for high-lift geometries. In particular, the use of various control devices placed near the leading edge of a slotted flap mounted on a realistic three-element wing was successfully demonstrated in ONERA’s F1 wind tunnel (Le Fauga-Mauzac Center), in the scope of the Advanced Aerodynamic Flow Control UsingMicroelectromechanical Systems II European project. The present paper aims at assessing the prediction accuracy of steady computational fluid dynamics simulations for flow-control problems, through a detailed validation procedure and comparisons against pressuremeasurements and skin-friction patterns obtained during the aforementioned experiment. In all, very good agreement was observed between numerical and wind-tunnel results, thus demonstrating the capability of Reynolds-averaged Navier–Stokes solvers to accurately predict suchmultiscale cases and the encouraging efficiency of conventional andmodern actuators in strong adverse pressure gradients.

Active Separation Control on the Flap of a Two-Dimensional Generic High-Lift Configuration

The paper describes experimental results of controlling flow separation by periodic excitation on the flap of a generic high-lift configuration. The single slotted flap of the two-dimensional test model is equipped with a robust and reliable actuator system that fits inside the flap. The flow is excited using a pulsed wall jet that emanates from the upper surface near the flap's leading edge through a small spanwise-oriented slot By preventing the flow from separating or by reattaching the separated flow, lift and drag are substantially improved, resulting in a lift-to-drag ratio enhancement of 20-25 %. Because of the actuator assembly with spanwise individually addressable segments, the separated flow can be forced to attach only to certain parts of the flap. Local spanwise excitation is thus used to generate a rolling moment without the need to deflect an aileron.

Stall Hysteresis of an Airfoil with Slotted Flap

Stall hysteresis discovered in wind tunnel performance of GA(W)-2 airfoil with 25%chord slotted flap is examined further by using the data obtained for lift, pitching moment, surface pressure distribution and hot film velocity vector. Test cases include 30 and 40 deg flap deflections each having an optimum and narrow gap at chord Reynolds number of 2.2 million and Mach number of 0.13. The flap optimized to produce the highest Clmax for each flap angle apparently did not have a proper contour and nose location for the slot flow to function effectively at off-design conditions. It is shown that suction pressures over flap, suppressed by thickening wing wake at stall, are not reversible to their pre-stall values within the decreasing α side of loop. It is suggested that the flap design include the use of a new flap parameter called slot flow angle to describe the slot flow orientation and a pressure recovery factor to select a proper contour for flap upper surface.

Lift Enhancement of Ground-Effect Wing (3rd Report, Analysis of Aerodynamic Performance of Wing in Ground Effect)

In order to grasp the aerodynamic characteristics of wings in ground effect, theoretical calculations were made for the ground-effect wings of lift enhancement by the two dimensional panel method assuming that the free surface is rigid wall. Trend analysis and parametric studies on the ground effect have been conducted to evaluate the kind of wings and the modulated wings with the slotted slats and flaps. The tendencies of oscillating the aerodynamic performances of wings have happened cyclically through the growth of the swirls on the surface of airfoils even if in the ground effect. These oscillating frequencies have been shown to reduce through the strong ground effect. Through controlling the growth of the swirls by these wings with slotted slats and flaps there were attained the high tendencies of the lift-drag ratios and rather than less movement on the center of pressure.

High-Lift Devices for a Delta Wing Installed Around a Trailing-Edge

Three devices to improve the aerodynamic characteristics of a delta wing at low speeds and high angles of attack are computationally examined. These are two types of blowing at the trailing edge and a slotted flap. All three are commonly employed on rectangle wings. They all show favorable effects, namely, chordwise blowing increases the lift considerably. The effectiveness in strengthening the leading-edge vortex is higher for chordwise blowing than lateral blowing. It is observed that, although the jet slots are installed at a trailing edge, the blowing strengthens the leading-edge separation vortex over the delta wing. This motivated an investigation of the use of a slotted flap. The flap also increases the lift of the wing, as well as the total lift due to both the wing and the flap, but the effect on the leading-edge vortices is smaller than both types of blowing

445 プロペラ型風力タービンの実験的・理論的な基礎研究 : 風車ブレード NACA44 系翼に噴出しフラップを装着した場合

Aerodynamic performance characteristies of the HAWT were investigated theoretically by the combination analysis of momentum, energy, and blade element theory by using the strip element theory, and experimentally by a sub-scale model, by considering the angular rotation of working flow. IN this study, no twist rectangular blade with NACA44 series aerofoil were examined by the analytical results under the condition of open typed wind tunnels with wind stream 0.8∿4.5m/s and outlet ducts dia of 0.88mΦ. The aeronautical characteristics of the H. A. W. T. were cleared to the relationship between C_P, C_T, C_q and tip speed ratio λ, and the far wake flow velocity distribution, for the pitch angle as parameter. Particularly, slotted flap was considered to avoid a stall of the blade for a gust with vortex, therefore, the rectangular blade with a single-slotted flap was examined by experiment. Obtained results were discussed under the same condition as parameter of attack angle and flap angle acting as significant role.

Bubble Bursting and Laminar Separation Unsteadiness on a Multi-Element High Lift Configuration

The purpose of this work is to gain insight into the problem of the bursting of a laminar separation bubble in the nose region of a slotted flap on a multi-element airfoil configuration. The interest in bubble bursting, which, especially on multi-element configurations has not been thoroughly investigated yet, was raised by the experimental results obtained while testing a computer designed flap in the low speed low Turbulence wind tunnel of the Delft University of Technology. A sudden and dangerous stall was found to occur on the flap surface due to the bursting of a bubble in its nose region. CFD calculations, both laminar and RANS, were first performed on a single element configuration, namely the Eppler E387 airfoil (Re = 105) and then on the multi-element configuration tested in the wind tunnel (Re = 2 ·106). The results show that a strong vortex shedding can potentially originate from the separated shear layer, both on the flap and on the single element airfoil, suggesting a close connection between the two cases. The effect of transition on the structure of the bubble was investigated by imposing and then varying the transition point. The computational results suggest that the unsteady behavior of the laminar bubble has to be regarded as a major issue in order to find an effective bursting predictor method for airfoil design.

Aeroelastic Deformation Measurements of Flap, Gap, and Overhang on a Semispan Model

Single-camera, single-view videogrammetry has been used to determine static aeroelastic deformation of a slotted flap configuration on a semispan model at the National Transonic Facility (NTF). Deformation was determined by comparing wind-off to wind-on spatial data from targets placed on the main element, shroud, and flap of the model. Digitized video images from a camera were recorded and processed to automatically determine target image plane locations that were then corrected for sensor, lens, and frame grabber spatial errors. The videogrammetric technqiue has been established at NASA facilities as the technique of choice when high-volume static aeroelastic data with minimum impact on data taking is required. The primary measurement at the NTF with this technique in the past has been the measurement of static aeroelastic wing twist on full span models. The first results using the videogrammetric technique for measurement of component deformation during semispan testing at the NTF are presented.

Navier–Stokes analysis of lift-enhancing tabs on multi-element airfoils

The flow over multi-element airfoils with flat-plate lift-enhancing tabs was numerically investigated. Tabs ranging in height from 0.25 to 1.25% of the reference airfoil chord were studied near the trailing edge of the main element. The two-dimensional numerical simulation employed an incompressible Navier–Stokes solver using a structured, embedded grid topology. The effects of various tabs were studied at a constant Reynolds number on a two-element airfoil with a slotted flap. Both computed and measured results indicated that a tab in the main-element cove improved the maximum lift and lift-to-drag ratio relative to the baseline airfoil without a tab. Computed streamlines revealed that the additional turning caused by the tab may reduce the amount of separated flow on the flap. A three-element airfoil was also studied over a range of Reynolds numbers, with computed results shown to be in good agreement with experimental data.

Delay of airfoil stall by periodic excitation

It was recently demonstrated that oscillatory blowing can delay separation from a symmetrical airfoil much more effectively than the steady blowing used traditionally for this purpose. Experiments carried out on different airfoils revealed that this flow depends on many parameters such as, the location of the blowing slot, the steady and oscillatory momentum coefficients of the jet, the frequency of imposed oscillations, and the shape and incidence of the particular airfoil. In airfoils equipped with slotted flaps, the flow is also dependent on the geometry of the slot and on the Reynolds number in addition to the flap deflection that is considered as a part of the airfoil shape. The incremental improvements in single element airfoil characteristics are generally insensitive to a change in Reynolds number, provided the latter is sufficiently large. The imposed oscillations do not generate large oscillatory lift nor do they cause a periodic meander of the c.p. C* C D = dp Ct =

125 煙風洞を用いた航空機翼まわりの局所流れの可視化

In teaching fluid mechanics, we have been making researches of high lift devices of an airplane, flap and slat by using a smoke wind tunnel. In this experimental study, we used NACA4412 wing section, and searched the optimum shape of a slot between the main wing and the flap. By the partial flow visualization technique, we confirmed the slot shape that a smoke streak-line passing through the slot was attached to the upper surface of the flap and by the force measurement technique, we also confirmed that the slot shape mentioned above had brought maximum lift coefficient. In this paper, we refer to the partial flow visualization of slotted flap of 40% chord length.