scholarly journals Initial development of the hybrid semielliptical-dolphin airfoil

2021 ◽  
pp. 234-234
Author(s):  
Zorana Dancuo ◽  
Ivan Kostic ◽  
Olivera Kostic ◽  
Aleksandar Bengin ◽  
Goran Vorotovic
Keyword(s):  
Lift Coefficient ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Calculation Model ◽  
General Aviation ◽  
The Other ◽  
Aviation Industry ◽  
Initial Development ◽  
Other Hand ◽  
Nose Shape

Iosif Taposu has formulated a mathematical model and generated a family of airfoils whose geometry resembles the dolphin shape. These airfoils are characterized by a sharp leading edge and experiments have proven that they can achieve better aerodynamic characteristics at very high angles of attack than certain classical airfoils, with the nose geometry inclined downwards. On the other hand, they have not been applied to any commercial general aviation aircraft. The authors of this paper have been motivated to compare the aerodynamic characteristics of widely used NACA 2415 airfoil with Taposu?s dolphin that would have the same principal geometric characteristics. A CFD calculation model has been established and applied on NACA 2415. The results were compared with NACA experiments and very good agreements have been achieved in the major domains of lift and polar curves. The same CFD model has been applied on the counterpart Dolphin 2415. Results have shown that the Dolphin has a slightly higher lift/drag ratio in the lift coefficient domain 0.1 ? 0.35 than NACA. On the other hand, at higher and lower lift coefficients, its aerodynamic characteristics were drastically below those of the NACA section, due to the unfavorable influence of the Dolphin?s sharp nose. A series of the Dolphin?s leading edge modifications has been investigated, gradually improving its aerodynamics. Finally, version M4, consisting of about 70% of Dolphin?s original rear domain and 30% of the new nose shape, managed to exceed the NACA?s characteristics, thus paving the way to investigate the Dolphin hybrids that could be suitable for the general aviation industry.

Experimental Aerodynamic Characteristics of a Compound Wing in Ground Effect

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Saeed Jamei ◽  
Adi Maimun Abdul Malek ◽  
Shuhaimi Mansor ◽  
Nor Azwadi Che Sidik ◽  
Agoes Priyanto
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Center Of Pressure ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Ground Effect ◽  
Reynolds Numbers ◽  
Aerodynamic Characteristics ◽  
Ground Clearance

Wing configuration is a parameter that affects the performance of wing-in-ground effect (WIG) craft. In this study, the aerodynamic characteristics of a new compound wing were investigated during ground effect. The compound wing was divided into three parts with a rectangular wing in the middle and two reverse taper wings with anhedral angle at the sides. The sectional profile of the wing model is NACA6409. The experiments on the compound wing and the rectangular wing were carried to examine different ground clearances, angles of attack, and Reynolds numbers. The aerodynamic coefficients of the compound wing were compared with those of the rectangular wing, which had an acceptable increase in its lift coefficient at small ground clearances, and its drag coefficient decreased compared to rectangular wing at a wide range of ground clearances, angles of attack, and Reynolds numbers. Furthermore, the lift to drag ratio of the compound wing improved considerably at small ground clearances. However, this improvement decreased at higher ground clearance. The drag polar of the compound wing showed the increment of lift coefficient versus drag coefficient was higher especially at small ground clearances. The Reynolds number had a gradual effect on lift and drag coefficients and also lift to drag of both wings. Generally, the nose down pitching moment of the compound wing was found smaller, but it was greater at high angle of attack and Reynolds number for all ground clearance. The center of pressure was closer to the leading edge of the wing in contrast to the rectangular wing. However, the center of pressure of the compound wing was later to the leading edge at high ground clearance, angle of attack, and Reynolds number.

scholarly journals Effect of Leading-Edge Bulges on Aerodynamic Characteristics of Bionic Wingsail

2021 ◽  
Author(s):  
Chen Li ◽  
Peiting Sun ◽  
Hongming Wang
Keyword(s):  
Stokes Equations ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Suction Surface ◽  
Ansys Fluent ◽  
Navier Stokes Equations ◽  
Extension Direction ◽  
Lift And Drag

The leading-edge bulges along the extension direction are designed on the marine wingsail. The height and the spanwise wavelength of the protuberances are 0.1c and 0.25c, respectively. At Reynolds number Re=5×105, the Reynolds Averaged Navier-Stokes equations are applied to the simulation of the wingsail with the bulges thanks to ANSYS Fluent finite-volume solver based on the SST K-ω models. The grid independence analysis is carried out with the lift and drag coefficients of the wingsail at AOA = 8° and AOA=20°. The results show that while the efficiency of the wingsail is reduced by devising the leading-edge bulges before stall, the bulges help to improve the lift coefficient of the wingsail when stalling. At AOA=22° under the action of the leading-edge tubercles, a convective vortex is formed on the suction surface of the modified wingsail, which reduces the flow loss. So the bulges of the wingsail can delay the stall.

scholarly journals Research on the forward flight performance of rotor based on variable-droop leading edge

2021 ◽  
Vol 39 (3) ◽  
pp. 668-674
Author(s):  
Congcong Li ◽  
Yongjie SHI ◽  
Guohua Xu ◽  
Xingliang Liu
Keyword(s):  
Flow Control ◽  
Control Method ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Integral Form ◽  
Simulation Method ◽  
Aerodynamic Characteristics ◽  
Control Effect ◽  
Forward Flight ◽  
Force Coefficient

Aiming at the dynamic stall phenomenon of the retreating side of the rotor in forward flight, the existing flow control method of dynamic leading edge droop was applied to the flow control of forward-flying rotor at three-dimensional scale. A numerical simulation method based on variable droop leading edge is established in this paper. The seesaw rotor is taken as the research object, the moving overset mesh method and RBF grid deformation technology are used, the integral form of Reynolds average N-S equation is the main control equation. The influence of the dynamic leading edge at r/R=0.75~1 on the aerodynamic characteristics of the rotor when the forward ratio is 0.3 is investigated. It is found that variable droop leading edge on the retreating side can effectively inhibit the generation and development of separation vortices near the trailing edge, and has a significant effect on lifting lift coefficient and section normal force coefficient, reducing torque coefficient, and thus improving the equivalent lift-drag ratio of the rotor. In a certain range, the control effect is better with the increase of the droop amplitude under the leading edge.

Impact of Gurney Flaplike Strips on the Aerodynamic and Vortex Flow Characteristic of a Reverse Delta Wing

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
T. Lee
Keyword(s):  
Vortex Flow ◽  
Delta Wing ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Force Balance ◽  
Vortex Control ◽  
Lift Curve ◽  
Lift And Drag ◽  
The Impact

The impact of Gurney flaplike strips, of different geometric configurations and heights, on the aerodynamic characteristics and the tip vortices generated by a reverse delta wing (RDW) was investigated via force-balance measurement and particle image velocimetry (PIV). The addition of side-edge strips (SESs) caused a leftward shift of the lift curve, resembling a conventional trailing-edge flap. The large lift increment overwhelmed the corresponding drag increase, thereby leading to an improved lift-to-drag ratio compared to the baseline wing. The lift and drag coefficients were also found to increase with the strip height. The SES-equipped wing also produced a strengthened vortex compared to its baseline wing counterpart. The leading-edge strips (LESs) were, however, found to persistently produce a greatly diffused vortex flow as well as a small-than-baseline-wing lift in the prestall α regime. The downward LES delivered a delayed stall and an increased maximum lift coefficient compared to the baseline wing. The LESs provide a potential wingtip vortex control alternative, while the SESs can enhance the aerodynamic performance of the RDW.

scholarly journals Experimental Study on Aerodynamic Characteristics of a Gurney Flap on a Wind Turbine Airfoil under High Turbulent Flow Condition

2020 ◽  
Vol 10 (20) ◽  
pp. 7258 ◽  
Author(s):  
Junwei Yang ◽  
Hua Yang ◽  
Weijun Zhu ◽  
Nailu Li ◽  
Yiping Yuan
Keyword(s):  
Wind Tunnel ◽  
Turbulent Flow ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Chord Length ◽  
Turbulence Level ◽  
Gurney Flaps ◽  
Gurney Flap ◽  
Delay Phenomenon

The objective of the current work is to experimentally investigate the effect of turbulent flow on an airfoil with a Gurney flap. The wind tunnel experiments were performed for the DTU-LN221 airfoil under different turbulence level (T.I. of 0.2%, 10.5% and 19.0%) and various flap configurations. The height of the Gurney flaps varies from 1% to 2% of the chord length; the thickness of the Gurney flaps varies from 0.25% to 0.75% of the chord length. The Gurney flap was vertical fixed on the pressure side of the airfoil at nearly 100% measured from the leading edge. By replacing the turbulence grille in the wind tunnel, measured data indicated a stall delay phenomenon while increasing the inflow turbulence level. By further changing the height and the thickness of the Gurney flap, it was found that the height of the Gurney flap is a very important parameter whereas the thickness parameter has little influence. Besides, velocity in the near wake zone was measured by hot-wire anemometry, showing the mechanisms of lift enhancement. The results demonstrate that under low turbulent inflow condition, the maximum lift coefficient of the airfoil with flaps increased by 8.47% to 13.50% (i.e., thickness of 0.75%), and the Gurney flap became less effective after stall angle. The Gurney flap with different heights increased the lift-to-drag ratio from 2.74% to 14.35% under 10.5% of turbulence intensity (i.e., thickness of 0.75%). However, under much a larger turbulence environment (19.0%), the benefit to the aerodynamic performance was negligible.

Optimal wingtip device design for transport airplane

2018 ◽  
Vol 90 (5) ◽  
pp. 743-763 ◽  
Author(s):  
Bento Silva de Mattos ◽  
Paulo Jiniche Komatsu ◽  
Jesuíno Takachi Tomita
Keyword(s):  
Optimization Design ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
The Other ◽  
Full Potential ◽  
Design Framework ◽  
Viscous Effects ◽  
Content Type ◽  
Fuel Burn ◽  
Cfd Analyses

Purpose The present work aims to analyze the feasibility of wingtip device incorporation into transport airplane configurations considering many aspects such as performance, cost and environmental impact. A design framework encompassing optimization for wing-body configurations with and without winglets is described and application examples are presented and discussed. Design/methodology/approach modeFrontier, an object-oriented optimization design framework, was used to perform optimization tasks of configurations with wingtip devices. A full potential code with viscous effects correction was used to calculate the aerodynamic characteristics of the fuselage–wing–winglet configuration. MATLAB® was also used to perform some computations and was easily integrated into the modeFrontier frameworks. CFD analyses of transport airplanes configurations were also performed with Fluent and CFD++ codes. Findings Winglet provides considerable aerodynamic benefits regarding similar wings without winglets. Drag coefficient reduction in the order of 15 drag counts was achieved in the cruise condition. Winglet also provides a small boost in the clean-wing maximum lift coefficient. In addition, less fuel burn means fewer emissions and contributes toward preserving the environment. Practical implications More efficient transport airplanes, presenting considerable lower fuel burn. Social implications Among other contributions, wingtip devices reduce fuel burn, engine emissions and contribute to a longer engine lifespan, reducing direct operating costs. This way, they are in tune with a greener world. Originality/value The paper provides valuable wind-tunnel data of several winglet configurations, an impact of the incorporation of winglets on airplane design diagram and a direct comparison of two optimizations, one performed with winglets in the configuration and the other without winglets. These simulations showed that their Pareto fronts are clearly apart from each other, with the one from the configuration with winglets placed well above the other without winglets. The present simulations indicate that there are always aerodynamic benefits present regardless the skeptical statements of some engineers. that a well-designed wing does not need any winglet.

scholarly journals URGENCY OF REGULATION: AIRCRAFT AS OBJECT OF CREDIT GUARANTEE

2020 ◽  
Vol 5 (1) ◽  
pp. 19-33
Author(s):  
Annalisa Yahanan ◽  
Murzal Murzal ◽  
Mada Apriandi ◽  
Febrian Febrian
Keyword(s):  
Legal Protection ◽  
The Other ◽  
Aviation Industry ◽  
Legal Basis ◽  
Legal Certainty ◽  
Credit Guarantee ◽  
Other Hand ◽  
Legal Uncertainty ◽  
Specific Regulation

Until now in Indonesia, there is no specific regulation regarding aircraft as collateral object. As a result, in practice, the aviation industry players experienced obstacles related to aircraft financing by guarantee agreements with aircraft objects. Such conditions create legal uncertainty both for credit providers (creditors) and the aircraft guarantees (debtors), because there are no references or signs that can provide direction in the guarantee agreement. If there is a default by the debtor, the creditor has no legal basis for how to execute it. To fill the legal vacuum, in practice, a guarantee agreement was found with the fiduciary deed of the aircraft. Whereas the Fiduciary Law expressly states that it does not apply to (mortgages) aircraft. While on the other hand, Law No. 20 of 2014 concerning Notary Position gives authority to the notary to make an aircraft mortgage deed. Thus the regulations in Indonesia give signals to use aircraft as collateral object. Such a situation demands the urgency for regulations on aircraft guarantee that can provide legal certainty and legal protection for the parties.

Aerodynamic Characteristics of the LS(1)-0417MOD Airfoil Model

2003 ◽  
Author(s):  
Jolanta M. Janiszewska ◽  
Gerald Gregorek ◽  
John Lee
Keyword(s):  
Steady State ◽  
Unsteady Flow ◽  
Lift Coefficient ◽  
Three Dimensional ◽  
Hysteresis Loops ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Vortex Generators ◽  
Three Dimensional Model ◽  
Three Dimensional Configuration

The LS(1)-0417MOD airfoil model was tested in The Ohio State University’s 3×5 wind tunnel both clean and with the application of leading edge grit roughness and with vortex generators. The tests were conducted in both two-dimensional and three-dimensional model configurations and for steady state and unsteady flow conditions. Pressure data were obtained from six spanwise stations. The results showed that the application of the grit roughness reduces the maximum lift coefficients in all configurations. Unsteady maximum lift coefficients were always higher than those for steady state and had, generally, large hysteresis loops. In the case of the unsteady flow however, the hysteresis loops were smaller for the three dimensional (wing) flows. The smallest hysteresis loops were found at the tip spanwise station. The application of the vortex generators at certain chordwise locations reduced the hysteresis loops and increased the maximum lift coefficient, especially in the three dimensional configuration.

Investigation of leading-edge slat on aerodynamic performance of wind turbine blade

2020 ◽  
pp. 095440622094188
Author(s):  
Tao Chen ◽  
Xiao Jiang ◽  
Haipeng Wang ◽  
Qian Li ◽  
Mingzhou Li ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Flow Region ◽  
Aerodynamic Characteristics ◽  
Chord Length ◽  
Wind Turbine Blade ◽  
Wind Speeds ◽  
Trailing Vortices

In this paper, the numerical simulation was used to investigate the effects of the leading-edge slat installation angles ( β for airfoils from 0° to 40° and β1 for blades from −20° to 40°) on the aerodynamic characteristics of the airfoil and the wind turbine blade. The chord length of the leading-edge slat is 0.1c (the chord length of the clean airfoil). The horizontal and vertical distances from its center to the leading edge of the clean airfoil are 0.005c and 0.009c, respectively. The results indicated that the lift coefficient could be significantly improved by the leading-edge slat (except β = 40°) when the attack angle exceeded 10.2°. For β = 0°, the lift coefficient increased the most. The trailing vortex of the leading-edge slat played an important role at the process of flow control. It could transfer kinetic energy from the bounder layer to its out-flow region. Furthermore, the vorticities of trailing vortex generated by the leading-edge slat with different installation angles were different, promoting several effects on the airfoil at the different cases. The torque of the blade with leading-edge slat (except β1 = −20°) was improved significantly as the leading-edge slat trailing-vortices became stronger with the higher wind-speeds.

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