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Aerodynamic Forces – Subsonic Flight
Published in Rose G. Davies, Aerodynamics Principles for Air Transport Pilots, 2020
There are many other devices on a wing, whose functions include increasing lift, and delaying stall, or increasing drag when it is required in flight, for example, the leading-edge slat, and trailing edge flap of a wing. Figure 4.27 shows the drooped leading-edge slat and extended trailing edge flap on a wing. The leading-edge slat extends when the aircraft takes off. This extension will increases the wing area to provide more lift, and it also form a leading-edge slat, as shown in Figure 4.27. This slot allows a stream of airflow pass from the lower part of the leading edge through the slot to the upper surface of the wing. This air stream will increase the kinetic energy in the boundary layer over the wing, so it can delay the boundary layer separation/stall, while the aircraft is in a high AoA during taking-off phase of flight. The extended trailing edge flap will increase the effective AoA, i.e. increase the lift coefficient of the wing, as well as increase the wing area so the wing will increase lift significantly at taking-off.
External Flow
Published in Ahlam I. Shalaby, Fluid Mechanics for Civil and Environmental Engineers, 2018
The flapped airfoils (wings) that are used during takeoff and landing may be slotted (single-slotted, double-slotted, or triple-slotted) in order to prevent the separation of the boundary layer from the upper surface of the wings and the flaps and to increase the lift coefficient, CL. Figure 10.29 illustrates how a flapped airfoil with a single-slot controls the boundary layer; the slot allows air to move from the high-pressure region under the wing into the low-pressure region on top of the wing, thus allowing the lift coefficient, CL to approach its maximum value CL = CL,max as the aircraft approaches its minimum velocity, vmin (stall conditions). Figure 10.30a illustrates the effects of flaps (no flap, single-slotted flap, and double-slotted flap) on the lift coefficient, CL for a range of angles of attack, α. It is interesting to note that the maximum lift coefficient, CL,max (mostly occurring at the largest angle of attack, α in the experimented range of α) increases from 1.52 to 2.67 and then to 3.48 as the airfoil starts without flaps and progresses to the single-slotted flaps and then to the double-slotted flaps.
Fluid Mechanics
Published in Raj P. Chhabra, CRC Handbook of Thermal Engineering Second Edition, 2017
Stanley A. Berger, Stuart W. Churchill, J. Paul Tullis, Blake Paul Tullis, Frank M. White, John C. Leylegian, John C. Chen, Anoop K. Gupta, Raj P. Chhabra, Thomas F. Irvine, Massimo Capobianchi
Flaps are movable sections near the trailing edge of a wing. They extend and/or deflect to increase wing area and/or increase wing camber (curvature), to provide higher lift than the clean wing. Many aircraft also are fitted with leading edge slats which open to expose a slot from the pressure side of the wing to the upper surface. The open slat increases the effective radius of the leading edge, improving maximum lift coefficient. The slot allows energized air from the pressure surface to flow into the low-pressure region atop the wing, energizing the boundary layers and delaying separation and stall.
The influence of the blade tip shape on brownout by an approach based on computational fluid dynamics
Published in Engineering Applications of Computational Fluid Mechanics, 2021
Jianping Hu, Guohua Xu, Yongjie Shi, Shuilin Huang
In this study, two non-twisted rectangular blades are used as the rotor system for the coupling simulation. The blades are NACA2415 throughout the span, the R (rotor radius) is 8.18 m, the aspect ratio (AR) is 9.132, the root cut is 20%, the Mach number at the tip is 0.65, and the collective pitch is fixed at 12°. The shape of the slotted-tip blade is shown in Figure 6. Four internal slots with a diameter of 0.067 of the chord length (C) and spacing of 0.157 C connect the flow at the leading edge of the blade and the tip. The purpose of the slots is to move the small-scale vortices and turbulence from the leading edge to the tip vortex core to accelerate the dissipation of the tip vortex. For more details of the blade parameters, please refer to Ref. (Han & Leishman, 2004; Milluzzo, 2012).
Ontology-based uncertainty management approach in designing of robust decision workflows
Published in Journal of Engineering Design, 2019
Ru Wang, Anand Balu Nellippallil, Guoxin Wang, Yan Yan, Janet K. Allen, Farrokh Mistree
A frame-based ontology for the robust design decision process template is developed using Protégé 3.5,2 which has ability to capture and document the re-usability information in the robust design and support the integrated management of uncertainty in design. The robust design decision ontology consists of the Classes and Slots, and by mapping to the robust design template, the ‘chips’ embedded in the ‘breadboard’ identify the main Classes of the ontology. Meanwhile, some sub-classes are also identified to increase the semantic richness and integrity of the robust design template ontology. Here, we focus on the definition of the Classes: ResponseFunction, Variation, and Uncertainty, the semantic relationships captured using Slots among those Classes. There are two types of Slots – data slots and object slots. Data slots are used to link the classes to the end data, while object slots are used to link the classes to the other classes. The detailed definitions of the Classes and Slots are shown in Tables 3–5. Some Classes and Slots that reuse the previously developed ontologies (Ming et al. 2016; Wang et al. 2019; Wang et al. 2018a) are not described here, such as Process_Template, hasParameter, name, value, etc.