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Principles and Applications of Plasma Actuators
Published in Ranjan Vepa, Electric Aircraft Dynamics, 2020
The basic idea of wing tip modification was inspired by the nature of bird wings. Winglets are a bioinspired concept, where the spanwise wing tip of a wing is modified primarily to reduce induced drag. Winglet types include a raked tip, a continuously varying dihedral winglet where the wingtip is finally pointing up, a canted winglet, MD 11, 12 style up-down winglets, a spiroid, a tip fence, a scimitar winglet, a “sharklet” Airbus A350 type winglet, blended winglets and feathers to emulate the birds. It was found several decades ago that a non-planar lifting system was required in order to reduce induced drag. It was also found that it is possible to increase the efficiency of wings and reduce induced drag by imitating bird feathers in splitting the wing-tip. The optimal performance could be achieved by imitating birds and spreading the wing tip as is done by birds when they spread their feathers over the wing tip. Thus, the development of winglets has evolved and most current aircraft employ a winglet to reduce induced drag. A negative aspect of winglets, in particular for cruise flight conditions, is that they introduce additional friction drag through the added wetted area. But the benefits seem to far outweigh the losses.
Greenhouse Gas Emissions, Persistent Contrails, and Commercial Aviation
Published in Elizabeth A. Hoppe, Ethical Issues in Aviation, 2018
Technological advances have reduced the fuel consumption rates of commercial aircraft by well over one half since the 1960s, and further fuel efficiency should be possible by increasing core thermal efficiency, increasing aerodynamic efficiency of the airframes and engine nacelle inlet section, and by reducing aircraft and engine weight by increasingly using new materials (Lee 2003). Use of extended fly-by-wire and eventual fly-by-light (fiber optic) technology could improve aircraft fuel efficiency by 1–3 percent, and active center of gravity control could provide another 1–2 percent in savings (Lee 2003). Winglets, wing extensions that reduce drag, are beginning to have widespread use and can often be retrofitted. More radical possibilities such as blended wing-body aircraft in which the wings and body are both part of the same airframe might produce very significant fuel savings (General Accounting Office 2009). There is a powerful environmental impetus to aircraft manufacturers investing in research to make these improvements, and this impetus is consistent with the economic advantages of reduced fuel use in a world with decreasing fossil fuel supplies. More speculative environmental benefits from technological advances might be made by producing sulfur-free kerosene for fuel from biomass using the Fischer–Tropsch (FT) synthesis process, or by developing hydrogen-powered aircraft, although the latter could also exacerbate the environmental impacts of contrails discussed later (Lee 2003).
Cost and Production Analysis: The General Concepts
Published in Bijan Vasigh, Ken Fleming, Thomas Tacker, Introduction to Air Transport Economics, 2018
Bijan Vasigh, Ken Fleming, Thomas Tacker
Other fuel efficiency methods center on technological advances—for example, the installation of blended winglets. Aviation Partners Boeing, the joint-venture company that manufacturers blended winglets, estimates that the winglets reduce fuel burn by 3.5–4.0 per cent on flights greater than 1,000 nautical miles for Boeing 737ngs (aPB, 2006). The winglet technology does not provide substantial savings on short flights as the fuel-burn advantage is offset by the increased weight. Winglets were originally offered on just 737NG aircraft, but their success has led to their installation on a number of different aircraft types.7
Experimental study of a winglet added small wind turbine with a flanged diffuser for domestic applications
Published in International Journal of Ambient Energy, 2022
M. Udhayakumar, P. Saravanan, K.M. Parammasivam
It's a small attachment that has the same cross section of the blade at the tip of the blade. The objective of mounting the winglet to the blades of wind turbine is to reduce the total blade drag and increase the turbine's aerodynamic efficiency. If the additional drag of the winglet is less than the reduction of the induced drag on the remaining blade length, the total drag is obtained. The design of winglet optimises drag reduction, maximises power generation and minimises thrust increase (Johansen and Sorensen 2006). The pressure difference in the operating wind turbine blade is the inward span wise flow on the suction side and the outward span wise flow on the pressure side near the tip. There is a vorticity at the trailing edge, which is the origin of the induced drag. A winglet is a device that reduces the span wise flow, diffuses and moves the tip vortex away from the rotor plane reducing the induced drag on the blade (Dreese 2000). A range of parameters are involved in the winglet design, such as winglet height, angle of sweep, angle of tip, radius of curvature, angle of toe and twist angle as shown in Figure 1. In the aerodynamics perspective, it is proposed to study the effect of winglet on this small wind turbine rotor efficiency. Teak wood blade model was fabricated with a scale of 1:120 and used as a standard for GFRP (Glass Fiber Reinforced Polymer) blades (Figures 2 and 3) (Martin and Hansen 2008).
Preliminary investigation on the effects of folding wingtips on the aerodynamics characteristics of flexible aircraft
Published in International Journal of Ambient Energy, 2022
V. Madhan Raj, Dilip A. Shah, P. Boomadevi
Wing is an essential part of aeroplane design. It enables to produce lift for an aeroplane. On commercial aircraft, the main objective is to reduce the drag which is created by the wingtip vortex and increasing the lift. This can be done by using winglets on the tip of the wings. The winglet is a part of a wing which is mainly used to reduce wingtip vortex, induced drag and fuel consumption. The prime objective of this project is by changing the angle of attack the efficiency of the winglet is improved. Reduced the wingtip vortices and induced drag maintains fuel saving up to 6% better lift performance (Whitcomb 1976). To study and analyse the effects of foldable wingtips at a various angle of attack the optimised method from literature is used. Winglet optimisation has great attention, because of its potential to reduce the induced drag. It is a vertical projection on the tip of the wing which reduces wingtip vortices and Induced Drag. Wingtip vortices are formed by the difference in pressure of above and below the wing. It also helps to improve aircraft characteristics and increases the aspect ratio. Accounting 40% of drag during the cruise and 80% of drag during in climb condition is occurring (Guerrero, Maestro, and Bottaro 2012). By reducing drag and fuel consumption thereby increasing lift performance made us to take up this idea. The aim of this project is to carry out the experimental analysis of foldable wingtips. When the aircraft moves in air, wingtip vortices are produced due to its lift generation. To reduce the vortex and by reducing the drag induced on the wing, the lift performance can be enhanced. The fabricated model will be tested in the wind tunnel for lift and drag characteristics (L/D ratio) and force measurement using load cell (Sohaib 2011). The experimental model is made in such a way that the winglet can be foldable up to a certain cant angle. By changing the Cant angle and Angle of attack of the wing and winglet during testing, the experimental data’s can be calculated for lift and drag coefficient using force measurement load cell (Manigandan, Kumar, et al. 2017). Figure 1 represents the winglet with different cant angles. The cant angles are as follows: 90, 180, 150, and 270 degrees.