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.

Drag reducing deflector

Abstract: A drag reducing deflector system is disclosed. The drag reducing deflector system provides aerodynamic drag reduction during crosswind flow (CF) conditions including zero crosswind flow conditions in which the crosswind flow angle, α, is 0.0. The crosswind flow angle α is measured from the vehicle longitudinal axis A that also defines the vehicle direction of motion. Embodiments of the drag reducing deflector system 100 may also be utilized to assist braking of a vehicle.

Development of a real-time transport performance optimization methodology

Abstract: The practical application of real-time performance optimization is addressed (using a wide-body transport simulation) based on real-time measurements and calculation of incremental drag from forced response maneuvers. Various controller combinations can be envisioned although this study used symmetric outboard aileron and stabilizer. The approach is based on navigation instrumentation and other measurements found on state-of-the-art transports. This information is used to calculate winds and angle of attack. Thrust is estimated from a representative engine model as a function of measured variables. The lift and drag equations are then used to calculate lift and drag coefficients. An expression for drag coefficient, which is a function of parasite drag, induced drag, and aileron drag, is solved from forced excitation response data. Estimates of the parasite drag, curvature of the aileron drag variation, and minimum drag aileron position are produced. Minimum drag is then obtained by repositioning the symmetric aileron. Simulation results are also presented which evaluate the affects of measurement bias and resolution.

Investigation of Delta Wing Leading-Edge Devices

Abstract: Leading-edge flow manipulators for alleviating the subsonic lift-dependent drag of highly-swept wings were investigated experimentally. The potential of several devices—fences, chordwise slots, pylon vortex generators, and a vortex plate concept—was evaluated in wind tunnel tests on a 60 deg cropped delta wing research model. Simultaneous balance and pressure measurements at increasing angles of attack provided an insight into the spanwise leading-edge flow development and its modification by the devices. The results demonstrated significant drag reductions through partial recovery of leading-edge suction at elevated angles of attack. In most cases, improvement in longitudinal stability also was obtained.

A wind-tunnel investigation of the effects of flap span and deflection angle, wing planform and a body on the high-lift performance of a 28 degrees swept wing

Abstract: : Lift, drag and pitching moment have been measured over an extensive range of configurations of the high-lift system on a wing of basic aspect ratio 835 and with a trailing-edge planform extension and a body added The results were analysed and compared with two linear-theory prediction methods The measured increments in lift generated by the various elements of the high-lift system were lower than the predicted levels An exploratory analysis of the drag results showed that the lift-dependent drag factor was considerably underestimated by linear theory, particularly when the slat was deployed The limitations of the planar vortex sheet used in the theory and the neglect of viscous effects are suggested as the principal reasons for the differences between experiment and theory Deflection of the flap produced a load, which acted at a distance forward of the mean quarter chord of the flap, that was practically independent of incidence and flap span The wing/body interference effect was insensitive to flap span and there was some evidence of a download being generated on the rear body when the high-lift system was deployed The performance of the high-lift system was downgraded when the wing planform was extended in the root region and this was attributed to the greater non-uniformity of the spanwise loading (Author)

Investigation of Tip Vortex on Aerodynamic Performance of a Micro Air Vehicle

Abstract: Tip vortex induces downwash movement that reduces the effective angle of attack. When a wing has a relatively low aspect ratio, such as that employed by the micro air vehicle (MAV), the induced drag by the tip vortex is relatively large and therefore the aerodynamic performances of the vehicle are deteriorated. In this paper we study the MAV wing aerodynamics using the endplate to help probe the tip vortex effects. The investigation is facilitated by solving the Navier-Stokes equations around a rigid wing with a root chord Reynolds number of 9x10. It is confirmed that with modest angle of attack, the endplate can reduce the downwash, and therefore increase the effective angle of attack and the lift. However, as the angle of attack becomes higher than 15, the wing tip vortex is stronger and the endplate can no longer affect the vortex structure to improve lift. Furthermore, drag also increases along with the endplate.