Slotted Flap Research Articles

The influence of trailing edge flaps on the aerodynamic characteristics of S1223 aerofoil

The S1223 aerofoil is a low Reynolds number high lift aerofoil. Analysing the aerodynamic characteristics of this aerofoil can provide a theoretical basis for enhancing flight efficiency in the design of small unmanned aerial vehicles. This study employed the k--SST turbulence model in the fluid simulation software (ANSYS Fluent) to conduct two-dimensional numerical aerodynamic simulations on the original aerofoil and its modified versions, which included flaps (deflected 10 at 70% chord length) and slotted flaps (deflected 10 at 70% chord length with a slot width of 1.5% of the chord). The aerofoil's aerodynamic performance was confirmed by comparing lift and drag coefficients at different angles of attack under Reynolds number 5.0105, as well as by analysing the pressure and velocity gradients in the flow field. The results indicate that both the lower flap and the slotted flap can greatly enhance the lift-to-drag ratio. In contrast, slotted flaps delay boundary layer separation, providing greater lift at high angles of attack while reducing the impact on drag.

Numerical Simulation of Circulation Control for a Wing Section Using Coanda Jets

Large-eddy simulations were carried out to describe the subsonic flow over a wing section, using Coanda-jet circulation control to augment lift. The section geometry consists of a modified supercritical airfoil, with a jet that is blown over a one-quarter circular cylindrical trailing-edge Coanda surface. Because the configuration does not include a slotted trailing-edge flap, the mechanical complexity and weight may be reduced. The computations correspond to an experimental investigation, which provides data for comparison. High-fidelity solutions were obtained to the unsteady three-dimensional Navier–Stokes equations at a chord-based Reynolds number of 4.75×105 and freestream Mach number of 0.1. Several angles of attack were considered, and solutions were obtained both with and without circulation control. In the control cases, three different jet-mass flow rates were simulated at each angle of attack. A grid-resolution study was carried out to assure numerical accuracy. Comparisons are made between the respective cases and with the experimental data, and features of the flowfields are characterized. It was found that Coanda-jet control was able to augment lift in excess of factors of three with reasonable amounts of jet-mass flow.

Numerical Study on Single and Multi-Element NACA 43018 Wing Airfoil with Leading-Edge Slat and Slotted Flap

An optimal wing configuration is crucial for achieving the best performance during various flight phases, including take-off, cruising, and landing. Such configurations also contribute to maximizing the aircraft's cruising range. This study compares the aerodynamic performance of NACA 43018 wings under different conditions: without high-lift devices, with a slotted flap, and with a combination of a leading-edge slat and slotted flap. Numerical simulations were conducted using the k-ɛ Realizable turbulence model at twelve different angles of attack, with a flow speed of 120 m/s. The results demonstrate that multiple-element wings significantly improve aerodynamic performance, particularly at low angles of attack, by reducing the induced drag coefficient and delaying flow separation.

Aerodynamic design of a double slotted morphed flap airfoil– a numerical study

Introduction:The objective of this study is to develop and simulate a double slotted morphed flap with the intention of reducing drag and enhancing lift, thereby leading to a smaller flap size and reduced weight.Methods:A flap was meticulously designed to accommodate conditions at Mach 0.2 and Reynolds numbers of 4.7×106. To conduct the simulation, ANSYS FLUENT flow solver and POINTWISE grid generator were utilized. The morphing technique employed involved adjusting both flap mean camber and flap slots, ensuring minimal flow interferences. By discretizing the flap mean camber line, various flap geometries were achieved.Results and Discussions:The findings reveal a significant enhancement in the airfoil’s aerodynamic efficiency attributed to the implementation of the new flap design. The study shows that utilizing double-slotted morphing in the NACA 4412 airfoil at a 30° flap deflection angle increased the lift coefficient by 82% compared to the un-morphed state. A comparison of lift coefficients between this research and the NACA 4412 split flap at a 60° deflection angle indicates that the double-slotted morphing in the NACA 4412 airfoil at a smaller deflection angle of 30° results in a 14% higher maximum lift coefficient.

Análisis estructural de una aleta ranurada rediseñada con material compuesto

This research focuses on assessing the mechanical strength feasibility of utilizing composite materials in the design of slotted flaps as a replacement for isotropic materials. Modern computational capabilities and software tools enable the analysis of both anisotropic and isotropic materials. However, it is imperative to consider several factors to ensure that the computational model accurately mirrors real-world scenarios. In the context of composite materials, this necessitates the comprehensive integration of anisotropic properties such as Young's modulus in different orientations, Poisson's coefficients, fiber orientation, and ply stacking. Additionally, precise delineation of each boundary condition and exploration of various simulation conditions are vital to prevent biases. To validate the developed models, they are rigorously compared with laboratory tests, establishing a robust basis for the obtained results.

NumericalStudy of Turbulent Flows over a NACA 0012 Airfoil: Insights into Its Performance and the Addition of a Slotted Flap

This work provides a comprehensive overview of various aspects of airfoil CFD simulations. The airflow around a 2D NACA 0012 airfoil at various angles of attack is simulated using the RANS SST turbulent flow model and compared to experimental data. The airfoil is then modified with a slotted flap and additionally the angle of the flap is altered. The flow model is subsequently coupled to a heat transfer model to compare the isothermal versus non-isothermal performance. The airfoil with the slotted flap shows increased CL and CD values compared to the standard NACA 0012. Larger flap angles further increase the CL and CD. The lift and drag coefficients show no difference in the non-isothermal model compared to the isothermal model, indicating the isothermal model is sufficient for this system. The 3D model without wingtips shows a similar CL to the 2D model as it effectively has an infinite span. Adding a wingtip reduces the lift coefficient, as the air can flow around the wingtip, increasing the pressure on top of the wing. Overall, these results match the behavior expected from wing theory well, showing how CFD can be effectively applied in the development and optimization of wings, flaps, and wingtips.

Comparative Study and Aerodynamic Analysis of Rectangular Wing Using High-Lift Systems

High-lift systems are designed to expand the flight envelope and have a most important effect on the size of the wing, economy, and safety of many airliner configurations. Even a small increment of lift using a high-lift system can significantly impact an aircraft’s profitability. The effective design of the airfoil shape with the required aerodynamic performance is still difficult. In the early days, the designs of airfoils were randomly set up and tested in the flow section, and then, the Wright brothers emerged with a cambered section. NACA has provided an appropriate airfoil definition that supports us in making airfoil designs using formulas, not randomly. This paper describes the influence of aerodynamic analysis of wing with flaps at various deflection angles. Aerodynamic variables for the aircraft wing, which is made up of the NACA airfoil 6412 model with and without flaps, have been studied at various angle of attack (AOA) (i.e., -4, -2, 0, 2, 4, 6, 8, 10, 12, and 16) and different Mach number at 0.2, 0.3, and 0.4. Also, the analysis was done for the 15000 ft altitude to check the density effects for the real-time applications. The coefficients of lift and drag are gained by examining the pressure distribution over the surface of the wing. Lift increases as the approach ascends from a low to a high angle of attack, and the most extreme lift is produced at a specific point. After that, when the angle of attack increases further, the drag component increases, so the stall occurs at that point in time. The results showed that the NACA 6412 airfoil obtained the maximum lift at 14°, and the lift value started to decrease. The CFD computations are performed in Ansys Fluent by performing hybrid mesh using ICEM-CFD. The analysis is performed for various configurations of the wing section, and the effects of flow parameters like angle of attack, altitude, and the gap distance between the main wing and slotted flap were compared to identify the better configurations.

Performance enhancement of a vertical axis wind turbine using a slotted deflective flap at the trailing edge

Vertical axis wind turbines (VAWTs) exhibit dynamic stall under operational conditions which causes boundary layer separation from the surface of the blade. This hinders the turbine’s overall performance in which the turbine displays low efficiency, aerodynamic losses, and vibration and noise generation. The aim of this study is to optimize the performance of an H-type Darrieus VAWT by employing a single-slotted deflective flap at the trailing edge of the blade. To optimize the turbine’s performance, Computational Fluid Dynamics (CFD) and Design Of Experiments (DOE) methods are utilized simultaneously for time-saving purposes. The design parameters optimized for the NACA 0018 airfoil are the flap’s gap (Δy), overlap (Δx), and deflection angle (δf). The influence of each parameter on the performance of the VAWT are determined by DOE, which yields the optimum combination of design parameters for this H-rotor VAWT as Δx = 2 mm, Δy = 0.5 mm, and δf = 90 at TSR 3 where two-dimensional (2D) and three-dimensional (3D) CFD simulations yield turbine power increments of 27 % and 19 %, respectively. The flow characteristics of the 2D and 3D turbine models with slotted blades, developed using ANSYS Fluent R2020, demonstrated a delay in boundary layer separation and a reduction in vortices shedding due to the high-pressure flow through the slot, which in return reenergizes the boundary layer. The results from this study indicate an improved design of an H-rotor VAWT.

Delaying the Stall of A Low-Wing Aircraft Using A Novel Powerful Vortex Generator

In this study, a new aerodynamic surface concept is introduced, which is a powerful vortex generator (PVG). It can delay the stall point in a low-wing aircraft. This delay leads to a significant increase in the CLmax of an aircraft. The results of this research show that the use of PVG, due to its longitudinal position, does not affect the aerodynamic center of the aircraft as well as its static stability. This is an advantage for this method compared to the method based on LEX, in which the aerodynamic center moves forward and the static stability of the aircraft reduces. As a case study, this research focused on a low-wing advanced training jet. Additionally, the aerodynamic characteristics of the aircraft were investigated in three points, including takeoff /landing condition, one maneuvering point, and one MMO condition. To evaluate the concept of PVG in more realistic situations, the wing airfoil was optimized at the same three points using the adjoint method. Then, the effect of PVG on various configurations of the aircraft, including the clean configuration and the different types of flap, was investigated. Since all the analyses were performed using computational fluid dynamics, at first, the validation of numerical methods was conducted on two test cases in low-speed and high-speed flows. The results of the case study show that the PVG greatly delays the separation and increases the value of CLmax. For example, in the case of a hinged leading-edge flap and single slotted trailing-edge flap, more than 12 degrees of delay in the stall was achieved, and the value of CLmax increased from 1.4 to 2.05 (46% increase).

Experimental Investigation of Flow Control on a High-Lift Wing Using Modulated Pulse Jet Vortex Generator

In this paper, the potential of a novel active flow control strategy by means of a modulated pulse jet vortex generator to enhance high-lift performance is demonstrated on a two-dimensional supercritical National Aeronautics and Space Administration (NASA) SC(2)-0714 airfoil with a single slotted trailing-edge flap at a high deflection angle. Fast-switching solenoid valves and compressed air were used as actuators to excite the flow. The vortex generator slot pairs were incorporated into the shoulder of the trailing-edge flap, where the flow separation occurs due to the high flow deflection and severe adverse pressure gradient. In these experiments, in addition to the simple square-wave excitation signal, a burst-modulated excitation signal as a novel pulse jet sequence was implemented to produce the unsteady blowing. The burst-modulation signal was used for the first time for a fast-switching solenoid valve actuator. The experiments were performed at a freestream velocity of 25 m/s with a corresponding Reynolds number of about 1×106 for a range of angles of attack from 0° to 20° at flap deflection angles from 0° to 35°. The results indicated that the ejection from vortex generator slot pairs was able to prevent flow separation completely in most conditions. These measurements revealed that the burst-modulated excitation was accompanied by more aerodynamic improvements and less air consumption relative to the simple pulsed jet excitation. In the best flow control mode, the results showed about a 12.6% increase in the lift coefficient and a 19.8% decrease in the drag coefficient.

AERODYNAMIC STUDY OF SLOTTED FLAP FOR NACA 24012 AIRFOIL BY DYNAMIC MESH TECHNIQUES AND VISUALIZATION FLOW

Slotted flap is one of high lift devices. It considered as a moving part of the airfoil which is used as a control instrument in a form of elevator, rudders and ailerons. The main focus of work is to investigate the effect of flap chord, gap and overlap on aerodynamic characteristic of NACA 24012 airfoil. The model was tested with 20% C, 30% C and 40% C single slotted flaps at zero angle of attack. The dynamic mesh and user defined function is applied to control the flap distance with respect to wing at any position. The simulation was done by solving the governing equations (Continuity, Reynolds Averaging Naveir- Stokes and Energy Equation) in 2-D using Fluent analysis at Reynolds number of 3.1x〖10〗^6. Based on the results presented, larger increment of lift coefficient is obtained with the larger flap chord, but this increase is accompanied by a drag penalty. Furthermore, the loss of lift coefficient associated with larger extending flap at 3% C had a very detrimental effect on the attainable lift coefficient. The simulation result also shows that an optimum gap is 1% C in order to derive the maximum lift capability from the flap model. The code is validated against field measurements to show how close the CFD model simulates the reality.

Increase in high-lift devices efficiency of swept wing

The use of Fowler flaps and slotted slats in sweptwing aircraft is the standard solution to increase wing lift at take off and landing. In the literature this solution is known as a classical option of high-lift system of commercial subsonic aircraft. The results of numerical and experimental studies of some solutions intended to increase the efficiency of classical high-lift devices are presented. The concept of the trailing-edge devices called "the adaptive flap" is considered as a way to improve flap efficiency. The adaptive concept is characterized by the integration of spoiler downward deflection to the Fowler flap function. Integration of the spoiler with a movable flap provided an increase of lift in the linear region due to flaps deflected to a higher angle. The steeper upwash angle at a leading-edge device may be the reason of an early stall of the main wing. To protect the leading edge a slotted Kruger flap with streamline form has been used. Preliminary design of classical and improved high-lift systems included the determination of aerodynamic shapes and the optimized position for the high-lift devices. Aerodynamic analysis and design were carried out using 2D RANS Navier-Stokes method. A comparison of computed results has shown visible aerodynamic advantages of an improved high-lift system for maximum lift coefficient and refining the behavior of stall characteristics at high angles of attack. The results of wind tunnel tests of aircraft model with adaptive flap showed its effectiveness.

Aerodynamic efficacy of adding yaw-wise rotational degree of freedom to an airplane flap

This study scrutinized the aerodynamic change of adding a yaw-wise rotational degree of freedom to a single slotted flap of airplane via computational fluid dynamic analyses. Existing slotted flaps have spanwise constant gaps and are disharmonious with the 3D nature of the flow field. A flap geometry and its angle condition are sensitive to aerodynamic performance; small variations in them must be useful in aerodynamic improvement. To add the yaw-wise rotation to a flap is a lower hurdle than to attain other high-lift systems. Therefore, after defining a simple configuration consisting of a fuselage, a wing, and a single slotted flap, we investigated the mesh dependency to consider the diversity in flow phenomena precisely; we examined the effect of the yaw-wise rotation for the flap on improving the whole lift. To place the flap at suitable yaw-wise rotation angles consequently effected raising the lift. We revealed the physical mechanism that accelerating the fluid in the gap between the wing and the flap changes the separation structure on the flap upper surface and grows the lift.

Experimental and CFD study of slotted Krueger flaps aerodynamics in critical locations

PurposeSome recent effort showed that usage of Krueger flaps helps to maintain laminar flow in cruise flight. Such flaps are positioned higher relative to the chord to shield the leading edge from the insect contamination during take-off. The flap passes several through critical intermediate position during the deployment to its design position. The purpose of this paper is to analyse the aerodynamics.Design/methodology/approachTo better understand such flow phenomena, the combined approach of computational fluid dynamics and experimental methods were used. Flow simulation was performed with in-house finite volume Navier–Stokes solver in fully turbulent unsteady RANS regime. The experimental data were obtained by means of force and pressure measurements and some areas of the flow field were examined with 2 C particle image velocimetry.FindingsThe airfoil with flap in critical position has a very limited maximum lift coefficient. The maximum achievable lift coefficient during the deployment is significantly affected by the vertical position of the trailing edge of the flap. The most unfavourable position during the deployment is not the flap perpendicular to the chord, but the flap inclined closer to it is the retracted position.Research limitations/implicationsThe flap movement was not simulated either in the simulation or in the experiment. Only intermediate static positions were examined.Practical implicationsA better understanding of aerodynamic phenomena connected with the deployment of a Krueger flap can contribute to the simpler and lighter of kinematics and also to decrease time-to-market.Originality/valueLimited experimental and computational results of Krueger flap in critical positions during the deployment are published in the literature.

Electro-Actuation System Strategy for a Morphing Flap

Within the framework of the Clean Sky-JTI (Joint Technology Initiative) project, the design and technological demonstration of a novel wing flap architecture were addressed. Research activities were carried out to substantiate the feasibility of morphing concepts enabling flap camber variation in compliance with the demanding safety requirements applicable to the next generation green regional aircraft. The driving motivation for the investigation on such a technology was found in the opportunity to replace a conventional double slotted flap with a single slotted camber-morphing flap assuring similar high lift performances—in terms of maximum attainable lift coefficient and stall angle—while lowering emitted noise and system complexity. The actuation and control logics aimed at preserving prescribed geometries of the device under variable load conditions are numerically and experimentally investigated with reference to an ‘iron-bird’ demonstrator. The actuation concept is based on load-bearing actuators acting on morphing ribs, directly and individually. The adopted un-shafted distributed electromechanical system arrangement uses brushless actuators, each rated for the torque of a single adaptive rib of the morphing structure. An encoder-based distributed sensor system generates the information for appropriate control-loop and, at the same time, monitors possible failures in the actuation mechanism. Further activities were then discussed in order to increase the TRL (Technology Readiness Level) of the validated architecture.

Mechanism/structure/aerodynamic multidisciplinary optimization of flexible high-lift devices for transport aircraft

Mission adaptive variable camber wing in both chord-wise and span-wise directions that can improve the aerodynamic performance during takeoff, landing and cruising flight, will be the state-of-the-art high-lift system for next generation airliners. Based on NASA TrapWing model released on the 1st AIAA CFD High-lift Prediction Workshop, a smart high-lift system with “Flexible Droop Nose & Single Slotted Hinge Flap combined with spoiler deflection & Flexible Trailing Edge Flap” is proposed in this paper. The Flexible Droop Nose is actuated by kinematic chains mechanism, the Single Slotted Hinge Flap is actuated by simple hinge mechanism and the Flexible Trailing Edge Flap is actuated by link/track mechanism.A mechanism/structure/aerodynamic multidisciplinary optimization platform based on iSIGHT software is constructed for this smart high-lift system. This platform consists of stress analysis, high-lift configuration generation, high-lift configuration structure grid generation, computational fluid dynamics and optimization algorithm modules. The optimal takeoff and landing configurations with comprehensive performance of mechanism, aerodynamic and structure is then obtained after multidisciplinary optimization. Finally, the CFD results show that the aerodynamics performance of this smart high-lift system is more effective than the original NASA TrapWing model.

Load Mitigation Using Slotted Flaps in Offshore Wind Turbines

This paper focuses on load mitigation by implementing controllable trailing-edge slotted flaps on the blades of an offshore wind turbine (OWT). The benchmark NREL 5 MW horizontal axis OWT is subjected to coupled stochastic aerodynamic-hydrodynamic analysis for obtaining the responses. The OWT is supported on three different fixed-bottom structures situated in various water depths. Blade element momentum (BEM) theory and Morison's equation are used to compute the aerodynamic and hydrodynamic loads, respectively. Presently, the load reduction obtained by means of the slotted flaps is regulated using an external dynamic link library considering the proportional-integral-derivative (PID) controller. BEM theory is presently modified to account for unsteady effects of flaps along the blade span. The present analysis results show reduction up to 20% in blade and tower loads for the turbine with different support structures on implementing controllable trailing edge flaps (TEFs). This study can form the basis for evaluating the performance of large-scale fixed OWT rotors.

Experimentaland Numerical Analysis over the Truncated Airfoil with Slotted Flap Configuration

Objectives: The objective of this work is to investigate the flow over the truncated NACA2414 airfoil with slotted flap configuration. Investigation is carried using wind tunnel and commercial CFD tools with the consequences of the variation of speed, angle of attack of control surface and effective angle of attack. Methods/Statistical Analysis: Wind tunnel tests are performed on a reduced scale model (3:10) in wind tunnel at Manipal University. Experimentally determined static pressure distribution data at equal interval stations, placed over the wing are used to generate pressure data. The results obtained are used in turn as a benchmark to validate the CFD simulations. Findings: Findings clearly states that the blunt trailing edge has high drag coefficient. Although off set cavity and cavity has proven to be the ideal modification for trailing edge shape in a plane wing from the study. It can be concluded that the same is not true when such modifications are applied to slotted flap configuration. Application/Improvements: Further studies can be carried out with the alternative designs and a rigorous research can contribute in efficient designs in high lift devices. Keywords: High-lift Devices, Numerical Analysis, Slotted Flaps, Truncated Airfoil, Wind Tunnel

Experimentaland Numerical Analysis over the Truncated Airfoil with Slotted Flap Configuration

Experimentaland Numerical Analysis over the Truncated Airfoil with Slotted Flap Configuration

A single slotted morphing flap based on SMA technology

A single slotted morphing flap based on SMA technology