Effect of 90 Degree Flap on the Aerodynamics of a Two-Element Airfoil

1989 ◽  
Vol 111 (1) ◽  
pp. 93-94 ◽  
Author(s):  
J. Katz ◽  
R. Largman
Keyword(s):  
Lift Coefficient ◽  
Aerodynamic Performance ◽  
Trailing Edge ◽  
Wide Range ◽  
Trailing Edge Flap ◽  
Drag Ratio

The aerodynamic performance of a two-element airfoil with a 90 deg. trailing edge flap was experimentally investigated. The 5 percent-chord long flap, significantly increased the lift of the baseline airfoil, throughout a wide range of angles of attack. The maximum lift coefficient of the flapped wing increased too, whereas the lift/drag ratio decreased.

Influence of Flap Deflection Angle on Wind Turbine Airfoil with Trailing Edge Flaps

2014 ◽  
Vol 977 ◽  
pp. 222-227
Author(s):  
Ya Lei Jia ◽  
Zhong He Han ◽  
Fu You Li ◽  
Ya Kai Bai ◽  
Ji Xuan Wang
Keyword(s):  
Wind Turbine ◽  
Deflection Angle ◽  
Aerodynamic Performance ◽  
Main Body ◽  
Trailing Edge ◽  
Trailing Edge Flaps ◽  
Wind Turbine Airfoil ◽  
Trailing Edge Flap ◽  
Flap Deflection ◽  
Drag Ratio

To improve the ability of capturing the wind energy of wind turbine and shorten the design period is of great importance to designing wind turbine blade. The article established S809 airfoil model with trailing edge flaps, The gap of the frontal subject and trailing edge flap adopt uniform gap structure, this structure will reduce the influence of the gap on aerodynamic characteristics.Using the k-ω Two equation turbulence model , the article calculated aerodynamic performance of S809 with 10% chord length trailing edge flaps under different deflecting angles. Results show that gap between the main body and trailing edge flap has little effect on airfoil aerodynamic performance, however, the deflection Angle of Trailing edge flap have great affect on airfoil aerodynamic performance, when deflection Angle of trailing edge flap is 14 ° degrees ,the lift-to-drag ratio is the largest.

scholarly journals Aerodynamic Performance Analysis of a Modified Joukowsky Airfoil: Parametric Control of Trailing Edge Thickness

2021 ◽  
Vol 11 (18) ◽  
pp. 8395 ◽  
Author(s):  
Pan Xiong ◽  
Lin Wu ◽  
Xinyuan Chen ◽  
Yingguang Wu ◽  
Wenjun Yang
Keyword(s):  
Vortex Structure ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Performance ◽  
Vortex Generation ◽  
Trailing Edge ◽  
K Value ◽  
Blunt Trailing Edge ◽  
The Impact ◽  
Drag Ratio

In order to ensure the blade strength of large-scale wind turbine, the blunt trailing edge airfoil structure is proposed, aiming at assessing the impact of the trailing edge shape on the flow characteristics and airfoil performance. In this paper, a Joukowsky airfoil is modified by adding the tail thickness parameter K to achieve the purpose of accurately modifying the thickness of the blunt tail edge of the airfoil. Using Ansys Fluent as a tool, a large eddy simulation (LES) model was used to analyze the vortex structure of the airfoil trailing edge. The attack angles were used as variables to analyze the aerodynamic performance of airfoils with different K-values. It was found that when α = 0°, α = 4°, and α = 8°, the lift coefficient and lift–drag ratio increased with increasing K-value. With the increase in the angle of attack from 8° to 12°, the lift–drag ratio of the airfoil with the blunt tail increased from +70% to −7.3% compared with the original airfoil, which shows that the airfoil with the blunt trailing edge has a better aerodynamic performance at a small angle of attack. The aerodynamic characteristics of the airfoil are affected by the periodic shedding of the wake vortex and also have periodic characteristics. By analyzing the vortex structure at the trailing edge, it was found that the value of K can affect the size of the vortex and the position of vortex generation/shedding. When α = 0°, α = 4°, and α = 8°, the blunt trailing edge could improve the aerodynamic performance of the airfoil; when α = 12°, the position of vortex generation changed, which reduced the aerodynamic performance of the airfoil. Therefore, when designing the trailing edge of an airfoil, the thickness of the trailing edge can be designed according to the specific working conditions. It can provide valuable information for the design and optimization of blunt trailing edge airfoil.

scholarly journals Aerodynamic Performance of Biomimicry Snake-Shaped Airfoil

2019 ◽  
Vol 9 (2) ◽  
pp. 3319-3323
Keyword(s):  
Cross Section ◽  
Lift Coefficient ◽  
Design Parameters ◽  
Drag Forces ◽  
Cross Section Shape ◽  
Section Shape ◽  
Wide Range ◽  
Lift And Drag ◽  
Drag Ratio ◽  
Lift To Drag Ratio

The cross-section shape and proportionality between geometrical dimensions are the most important design parameters of any lifting surfaces. These parameters affect the amount of the aerodynamic forces that will be generated. In this study, the focus is placed on the snake-cross-section airfoil known as the S-airfoil. It is found that there is a lack of available researches on S-airfoil despite its important characteristics. A parametric study on empty model of the S-airfoil with a cross-section shape that is inspired by the Chrysopelea paradise snake is conducted through numerical simulation. Simulation using 2D-ANSYS FLUENT17 software is used to generate the lift and drag forces to determine the performance of airfoil aerodynamic. Based on the results, the S-airfoil can be improved in performance of aerodynamic by reducing the thickness at certain range, whereby changing the thickness-to-chord ratio from 0.037 to 0.011 results in the increment of lift-to-drag ratio from 2.629 to 3.257. On other hand, increasing the height-to-chord ratio of the S-airfoil will increase maximum lift coefficient but drawback is a wide range of angles of attack regarding maximum lift-to-drag ratio. Encouraging results obtained in this study draws attention to the importance of expanding the research on S-airfoil and its usage, especially in wind energy.

The Effects of Recessed Lower Surface Shape on the Lift and Drag of Conical Wings at High Incidence and High Mach Number

1975 ◽  
Vol 26 (1) ◽  
pp. 1-10 ◽  
Author(s):  
L C Squire
Keyword(s):  
Theoretical Study ◽  
Lift Coefficient ◽  
Lower Surface ◽  
Surface Shape ◽  
Wide Range ◽  
High Incidence ◽  
Design Value ◽  
High Mach ◽  
Lift And Drag ◽  
Drag Ratio

SummaryFor lifting re-entry there may be advantages in using wings which give as high a lift coefficient as possible at the design value of the lift/drag ratio. This paper presents the results of an experimental and theoretical study of wings with recessed lower surfaces designed to give high values of CL. The calculations show that a wide range of wing shapes can be found that give values of CL which are much larger than those on a flat wing with the same lift/drag ratio.

Computational evaluation of geometric effects on aerodynamic performance of circulation control airfoils

2021 ◽  
pp. 095441002098372
Author(s):  
Yu-Wei Chu ◽  
He-Yong Xu ◽  
Chen-Liang Qiao ◽  
Yu-Hang Wang ◽  
Yue Xu
Keyword(s):  
Lift Coefficient ◽  
Axial Ratio ◽  
Aerodynamic Performance ◽  
Careful Consideration ◽  
Circulation Control ◽  
Trailing Edge ◽  
Instability Phenomenon ◽  
Computational Evaluation ◽  
Coanda Jet ◽  
Geometric Effects

The geometric effects of Coanda trailing edges on the aerodynamic performance of an airfoil are numerically evaluated for a range of different freestream Mach numbers and momentum coefficients. A Circulation control (CC) airfoil with a circular trailing edge (ACTE) proves to have better control effectiveness at low subsonic freestream speeds (Mach = 0.1). A CC airfoil having an elliptic trailing edge (AETE) outperforms the ACTE at high subsonic flow conditions. The occurrence of C μ-stall for the AETE is greatly postponed, and meanwhile the maximum net lift coefficient increment achieved for the AETE (Δ C L = 0.51) is slightly higher than that of the ACTE (Δ C L = 0.50) at Mach 0.6. Compared to the ACTE, the AETE is found to have better control consistency at different operating velocities and better control stability when the Coanda jet is supersonic. Through careful consideration of the aerodynamic performance and the control effects, the most appropriate axial ratio for an AETE ellipse is within the interval from 1.5 to 2. Finally, the flow field instability phenomenon and the jet detachment induced by the supersonic Coanda jet are investigated. A self-sustained shock-wave instability phenomenon without jet detachment is first observed in this paper.

scholarly journals Low-speed airfoil optimization using constrained differential evolution

2020 ◽  
Vol 12 (4) ◽  
pp. 83-94
Author(s):  
Mihai-Vladut HOTHAZIE ◽  
Matei MIRICA
Keyword(s):  
Evolutionary Algorithm ◽  
Lift Coefficient ◽  
Optimization Procedure ◽  
Aerodynamic Performance ◽  
Optimum Shape ◽  
Design Problems ◽  
Airfoil Optimization ◽  
Engineering Design Problems ◽  
Wide Range ◽  
Differential Evolutionary Algorithm

Nowadays, algorithms designed to optimize the shape of an airfoil are being developed by many researchers. In this paper, to achieve an optimum shape configuration, a methodology based on an evolutionary algorithm is proposed. The main objective is to find the optimum shape of a known airfoil that gives the best aerodynamic performance for a fixed lift coefficient. For the airfoil parametrization, the class-shape method is used to develop a well-behaved geometry. The paper underlines the implementation of a constrained differential evolutionary algorithm using the free penalty scheme by varying the coefficients of the shape parametrization function. The aim is to obtain a better aerodynamic performance for a predetermined lift coefficient by imposing a fixed maximum airfoil thickness interval. The method is a general optimization procedure and can be implemented in a wide range of engineering design problems.

scholarly journals Design And Aerodynamic Analysis Of Compliant Mechanism Based Morphing Wings

2021 ◽  
Author(s):  
Stephen D. Sharp
Keyword(s):  
Flow Separation ◽  
Compliant Mechanism ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Discrete Control ◽  
Morphing Wing ◽  
Trailing Edge ◽  
Morphing Wings ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Aircraft today use discrete control surface, typically mounted using pin and sliding joints. These designs can lead to high part-count assemblies and backlash within the assemblies that require lubrication and frequent maintenance. These wing designs also feature fixed dimensions and do not allow for geometry changes mid-flight. These limitations lead to a compromised design that must work relatively well in all situations. This causes inefficiencies in all stages of flight. The Wright brothers, who achieved the first successful powered flight did not use these techniques. Instead they used a system on cables to apply tension and bend the wings to changes their angle of attack. They called this technique wing warping. As aviation advanced it quickly moved from the wing-warping technique towards the discrete element control surfaces. However, there is renewed interest in techniques such as wing warping as the idea of morphing wings becomes more prevalent in aerospace research. Morphing wings would allow for changing major characteristics, such as camber, span, sweep, etc. of the wing mid-flight and allow for continuous optimization through all stages of its mission. The design covered in this thesis was centered around camber morphing of the wing in flight. Biomimicry played a large role in the design, with research into the skeletal systems of birds and fish used to dictate the rib structures. This bio-inspired path led to the use of compliant mechanisms for the ribs. This choice allowed for a low part-count and zero-backlash design that would require no maintenance and have a very long service life due to an extremely low amount of fatigue. Several design iterations were tested with different common desktop 3-D printing materials. The final rib design was made of PETG and whose compliant shape was directly inspired by the skeletal structure of the spine of a fish. The design proved to be extremely reliable and robust. Skin design has long been one of the biggest hurdles of morphing wing design. Most research reviewed in this paper used an elastomer style skin that was pre-stretched to reduce buckling under compression. Through testing it was found that this method is difficult and unreliable to maintain a smooth and continuous surface. Even when pre-stretching, the elastomer would fatigue and buckle under compression. The final design was a PETG panel with a web and flange that would interact with the rib structure and was able to translate chordwise along the rib as the wing altered its camber. The skin had built-in flexures to reduce bending actuation forces. The wing also featured a rigid leading-edge skin panel with which the other skin panels would be able to slide under to maintain skin coverage under both extension and compression of the wing surfaces. This however led to aerodynamic problems that were discovered in the CFD analysis. The wing was prepared for CFD using finite element analysis to produced morphed wing bodies for a 0, 10, 20, and 30-degree trailing edge deflection angles. A model was also produced of the same base airfoil (NACA 0018) with a hinged flap of 30% chord length deflected by the same amount to serve as a performance benchmark for the morphing wing. The main criteria used to evaluate the performance were the lift, drag, and lift-to-drag ratios. For the 0⁰ tests, the morphing wing had up to almost 29% higher drag at high speeds. The results showed that the 10⁰ deflection tests found up to a 115% increase in lift over the hinged flap design and a lift-to-drag ratio of up to 161% higher for the morphing wing. The 20⁰ and 30⁰ tests saw the lift advantage of the morphing wing decrease but on average across all tests, the morphing wing had a lift coefficient higher than the hinged flap by 43%. Additionally, for the large deflection tests the hinged flap had up to a 60.5% advantage in lift-to-drag ratio. The computational fluid dynamic analysis showed that due to the larger effective angle of attack and the step-down in the skin of the morphing wing, at larger deflection angles the flow would separate much earlier along the chord. Therefore, based on the analysis, the morphing wing would create a substantial performance and efficiency gains when wing trailing edge deflection was kept below 20⁰. This meant it would be suitable for stages of flight such as takeoff and climb. Planned future work aims to reduce the 0⁰ drag of the morphing wing as well as the early flow separation at high angles of deflection. It is assumed, that by scaling up the wing, the proportion of the step size will decrease dramatically and as a result would improve the flow characteristics. Additionally, the placement and rotational limits of the flexures can be tested further to optimize the morphed shape to reduce the severity of the adverse pressure gradient along the upper surface when in high deflection states. With continued work on improving the flow separation, this design proves promising for even high-deflection cases. Overall the V4 rib design and the accompanying compliant skin panel design were very successful for their initial tests.

scholarly journals Design And Aerodynamic Analysis Of Compliant Mechanism Based Morphing Wings

2021 ◽  
Author(s):  
Stephen D. Sharp
Keyword(s):  
Flow Separation ◽  
Compliant Mechanism ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Discrete Control ◽  
Morphing Wing ◽  
Trailing Edge ◽  
Morphing Wings ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Aircraft today use discrete control surface, typically mounted using pin and sliding joints. These designs can lead to high part-count assemblies and backlash within the assemblies that require lubrication and frequent maintenance. These wing designs also feature fixed dimensions and do not allow for geometry changes mid-flight. These limitations lead to a compromised design that must work relatively well in all situations. This causes inefficiencies in all stages of flight. The Wright brothers, who achieved the first successful powered flight did not use these techniques. Instead they used a system on cables to apply tension and bend the wings to changes their angle of attack. They called this technique wing warping. As aviation advanced it quickly moved from the wing-warping technique towards the discrete element control surfaces. However, there is renewed interest in techniques such as wing warping as the idea of morphing wings becomes more prevalent in aerospace research. Morphing wings would allow for changing major characteristics, such as camber, span, sweep, etc. of the wing mid-flight and allow for continuous optimization through all stages of its mission. The design covered in this thesis was centered around camber morphing of the wing in flight. Biomimicry played a large role in the design, with research into the skeletal systems of birds and fish used to dictate the rib structures. This bio-inspired path led to the use of compliant mechanisms for the ribs. This choice allowed for a low part-count and zero-backlash design that would require no maintenance and have a very long service life due to an extremely low amount of fatigue. Several design iterations were tested with different common desktop 3-D printing materials. The final rib design was made of PETG and whose compliant shape was directly inspired by the skeletal structure of the spine of a fish. The design proved to be extremely reliable and robust. Skin design has long been one of the biggest hurdles of morphing wing design. Most research reviewed in this paper used an elastomer style skin that was pre-stretched to reduce buckling under compression. Through testing it was found that this method is difficult and unreliable to maintain a smooth and continuous surface. Even when pre-stretching, the elastomer would fatigue and buckle under compression. The final design was a PETG panel with a web and flange that would interact with the rib structure and was able to translate chordwise along the rib as the wing altered its camber. The skin had built-in flexures to reduce bending actuation forces. The wing also featured a rigid leading-edge skin panel with which the other skin panels would be able to slide under to maintain skin coverage under both extension and compression of the wing surfaces. This however led to aerodynamic problems that were discovered in the CFD analysis. The wing was prepared for CFD using finite element analysis to produced morphed wing bodies for a 0, 10, 20, and 30-degree trailing edge deflection angles. A model was also produced of the same base airfoil (NACA 0018) with a hinged flap of 30% chord length deflected by the same amount to serve as a performance benchmark for the morphing wing. The main criteria used to evaluate the performance were the lift, drag, and lift-to-drag ratios. For the 0⁰ tests, the morphing wing had up to almost 29% higher drag at high speeds. The results showed that the 10⁰ deflection tests found up to a 115% increase in lift over the hinged flap design and a lift-to-drag ratio of up to 161% higher for the morphing wing. The 20⁰ and 30⁰ tests saw the lift advantage of the morphing wing decrease but on average across all tests, the morphing wing had a lift coefficient higher than the hinged flap by 43%. Additionally, for the large deflection tests the hinged flap had up to a 60.5% advantage in lift-to-drag ratio. The computational fluid dynamic analysis showed that due to the larger effective angle of attack and the step-down in the skin of the morphing wing, at larger deflection angles the flow would separate much earlier along the chord. Therefore, based on the analysis, the morphing wing would create a substantial performance and efficiency gains when wing trailing edge deflection was kept below 20⁰. This meant it would be suitable for stages of flight such as takeoff and climb. Planned future work aims to reduce the 0⁰ drag of the morphing wing as well as the early flow separation at high angles of deflection. It is assumed, that by scaling up the wing, the proportion of the step size will decrease dramatically and as a result would improve the flow characteristics. Additionally, the placement and rotational limits of the flexures can be tested further to optimize the morphed shape to reduce the severity of the adverse pressure gradient along the upper surface when in high deflection states. With continued work on improving the flow separation, this design proves promising for even high-deflection cases. Overall the V4 rib design and the accompanying compliant skin panel design were very successful for their initial tests.

scholarly journals Study on Multi-Objective Optimization Design and Passive Control of Wind Turbine Airfoil

2019 ◽  
Author(s):  
Yong Peng ◽  
Jun Wang ◽  
Wei Wang ◽  
Guoqing Yin
Keyword(s):  
Optimization Design ◽  
Passive Control ◽  
Lift Coefficient ◽  
Multi Objective Optimization ◽  
Trailing Edge ◽  
Multi Objective ◽  
Blunt Trailing Edge ◽  
Trade Offs ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Abstract. In this paper, the class-shape function transform (CST) parametric method is used to parameterize the airfoil configuration, and a new airfoil is randomly generated within a limited range. The 2D Reynolds-Averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) solver is used to compute the quantities such as lift-to-drag ratio. The multi-objective genetic algorithm performs multi-objective optimization design on the airfoil plane shape to achieve high lift-to-drag ratio with low drag in operating ranges of angle of attack, and finally obtains the Pareto optimal solution set. The mixed function of index method is used to increase the thickness of the trailing edge of the airfoil. From the multi-objective solutions and blunt trailing edge solutions which represent the best trade-offs between the design objectives, one can select a set of airfoil shapes with a low relative drag force and with improved aerodynamic performance. Taking a typical airfoil NACA4418 as an example. The results show that the optimized airfoil has a better pressure distribution than the original airfoil, effectively increasing the lift coefficient and reducing the drag coefficient. After thickening the trailing edge of the optimized airfoil, the results show that the lift coefficient is improved at all angles of attack and the stall is delayed. And the blunt trailing edge airfoil has better lift-to-drag characteristics than the original airfoil and the optimized airfoil.

Sign in / Sign up

Export Citation Format

Share Document