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Lift-induced drag

About: Lift-induced drag is a research topic. Over the lifetime, 2861 publications have been published within this topic receiving 41094 citations.


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TL;DR: The effect of the aerodynamic drag force on an object in flight is well known and has been described in this and other journals many times as discussed by the authors, and experiments are often conducted with very light objects such as a balloon 1,2 or coffee filter 3 or muffin cup, 4 or are conducted in a liquid rather than in air.
Abstract: The effect of the aerodynamic drag force on an object in flight is well known and has been described in this and other journals many times. At speeds less than about 1 m/s, the drag force on a sphere is proportional to the speed and is given by Stokes' law. At higher speeds, the drag force is proportional to the velocity squared and is usually small compared with the gravitational force if the object mass is large and its speed is low. In order to observe a significant effect, or to measure the terminal velocity, experiments are often conducted with very light objects such as a balloon 1,2 or coffee filter 3 or muffin cup, 4 or are conducted in a liquid rather than in air. The effect of the drag force can also be increased by increasing the surface area of the object.

17 citations

Journal ArticleDOI
TL;DR: In this paper, an experimental and computational investigation of the aerodynamic characteristics of planar and nonplanar outboard wing forms is presented. But the results are limited to two different spans, and the authors conclude that the effective span, as determined by the location of the tip vortex, might not be a sufficient yardstick of the induced performance of a non-planar wing.
Abstract: It is possible for a constant span to obtain better aerodynamic performance from a wing with a nonplanar outboard wing form than from a wing with a planar outboard form, despite the added drag from the increased wetted area. Furthermore, the semispan rolling-moment characteristics indicate the lower wing-root bending moment for some nonplanar configurations. These conclusions are based on an experimental and computational investigation of the aerodynamic characteristics of planar and nonplanar outboard wing forms. Seven different configurations - planar rectangular, nonplanar rising arc, nonplanar drooping arc, planar sheared, sheared with dihedral, sheared with anhedral, and planar elliptical - were investigated for two different spans. Flow-visualization photographs indicate that there are three vortex systems associated with the sheared forms. The lower induced drag coefficients of nonplanar wings are believed to accrue from the movement of vorticity away from the center-of-span line, resulting, in some instances, in induced efficiencies higher than that of a planar elliptical wing. Flow surveys indicate that the effective span, as determined by the location of the tip vortex, might not be a sufficient yardstick of the induced performance of a nonplanar wing.

17 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed two ways to reduce the drag coefficient: pushing the vortices away from the wall and changing their amplitude or their dynamics, and coupling the two procedures.
Abstract: A vortex generated behind a simplified vehicle induces a pressure force at the back wall that contributes to a significant part of the drag coefficient. This pressure force depends on two parameters: the distance of the vortex to the wall and its amplitude or its circulation. Therefore there are two ways to reduce the drag coefficient: pushing the vortices away from the wall and changing their amplitude or their dynamics. Both analytical studies and numerical simulations show that these two actions decrease the pressure force and consequently reduce the drag coefficient. The first action is achieved by an active control procedure using pulsed jets and the second action is achieved by a passive control procedure using porous layers that change the vortex shedding. The best drag coefficient reduction is obtained by coupling the two procedures.

17 citations

Journal Article
TL;DR: In this article, a detailed component drag buildup that interpolates airfoil drag and moment data across operational lift-coefficient, Reynolds-number, and flap-deflection ranges is presented.
Abstract: Although theoretical tools for the design of winglets for low-speed aircraft were initially of limited value, simple methods were used to design winglets that gradually became accepted as benefiting overall aircraft performance. As understanding was gained, improved methods were developed, which ultimately resulted a number of successful applications of winglets. The current approach incorporates a detailed component drag buildup that interpolates airfoil drag and moment data across operational lift-coefficient, Reynolds-number, and flap-deflection ranges. Induced drag is initially predicted using a relatively fast multiple lifting-line method. In the final stages of the design process, a full panel method, including relaxed-wake modeling, is employed. The drag predictions are used to compute speed polars for both level and turning flight, yielding predicted performance that is in good agreement with flight-test results. These methods have been successfully applied to the design of winglets to improve the cross-country soaring performance of both span-limited and span-unlimited, high-performance sailplanes, as well as to improve various mission capabilities for several different categories of powered aircraft.

17 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202344
2022105
202138
202046
201944
201849