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Noise emissions from commercial aircraft
Published in Emily S. Nelson, Dhanireddy R. Reddy, Green Aviation: Reduction of Environmental Impact Through Aircraft Technology and Alternative Fuels, 2018
Slats are high-lift devices installed on the wing leading edge to enhance the wing's lift by allowing it to operate at higher angles of attack at low flight speeds. Slats are deployed during landing to allow the aircraft to operate close to its stall speed. As shown in Figure 1.14, when slats are deployed a gap is generated between the slats and the main wing, which allows a highly unsteady flow to be established inside the slat cavity called the slat cove. A main feature of that flow is the cove vortex whose impingement on the leeward face of the cove is thought to be a major source of slat noise. Added to this source is the vortex shedding that occurs at the slat trailing edge and, potentially, the unsteady flow interactions with the main wing's leading edge. Slat noise is broadband but more directional than the landing gear noise with its dominant radiation in a quadrant directly below and just to the aft of the aircraft.
Aircraft
Published in Milica Kalić, Slavica Dožić, Danica Babić, Introduction to the Air Transport System, 2022
Milica Kalić, Slavica Dožić, Danica Babić
Slats. Slats are parts on the leading edge of the wing. They move forward to increase the camber of the wing. Their purpose is to increase lift during low-speed operations such as take-off, initial climb, approach, and landing. Slats commonly have several possible positions, depending on needed configuration, and extend progressively simultaneously with flap extension, Figure 2.5 and Figure 2.6.
Flight Control and Autonomous Operations
Published in Ranjan Vepa, Electric Aircraft Dynamics, 2020
The basic principles governing the design and operation of aircraft flight control systems are well known. Generally the term “flight control systems” for manned or autonomous flight includes not only the primary flying control systems, including digital fly-by-wire control systems, but also a host of secondary/slat and flap (high-lift) flight control systems, rudder and yaw controllers, stabilizer control systems, spoiler control electronics and the associated monitoring systems, autopilots and flight control units, actuator control electronics and any associated remote electronics units, collision avoidance systems, vehicle management systems/computers and systems for prognostic assessment and health management. From a hardware standpoint, it also includes the multiple redundant flight control and flight management computers, as well as pilot controls such as control sticks and sidesticks with their associated trim and feel control systems. The flight control computers compute and transmit all primary surface (rudder, elevators, ailerons, flaperons and stabilizers) actuator commands, pre-flight and other signals to control and maintain normal flight. Also referred to as high-lift or secondary flight controls, slat and flap controllers enable optimum take-off and landing speeds by increasing wing lift. The primary purpose of the slats and flaps is to increase the area of the wing, thus enabling the aircraft to reduce speed while generating the same lift. Thus, controlling the slats and flaps can be used to increase or decrease the area generating lift, which enables the pilot to control the speed. Slats and flaps are extended and retracted, and the spoilers are raised and lowered using suitable actuators. The actuator controller hardware transmits commands directly, or through remote electronic units, to surface actuators and provides surface commands in specialized flight and system modes. Finally, a flight control system also includes data interface capabilities and data buses defined in accordance with one of several standards such as ARINC, as well as data concentration and distribution facilities and flight data acquisition systems. In this chapter only the basic concepts and principles of flight control systems and optimal flight path synthesis relevant to electric aircraft will be examined. For a general overview of flight control systems, the reader is referred to Vepa [1].
Integrated Modeling of Fatigue Impacts on C-17 Approach and Landing Performance
Published in The International Journal of Aerospace Psychology, 2023
Bella Z. Veksler, Megan B. Morris, Michael A. Krusmark, Glenn Gunzelmann
Real, operational C-17 approach and landing data was obtained from Air Mobility Command’s Military Flight Operations Quality Assurance (MFOQA) Program. Various flight parameters such as landing gear position, flap positions, aircraft magnetic heading, autopilot engagement, and others, were collected from an aircraft flight recorder and then processed for further parameter calculation and analysis through the MFOQA program. Our research group received a portion of these parameters associated with the approach and landing segments of respective missions from the study (the last 375 seconds of flight). Specifically, for this effort we focused on performance parameters associated with unstable approach events defined by MFOQA, including late gear and late flaps. We also examined additional parameters that might be affected by fatigue such as speed brake engagement (when flaps/slats are in the 0/Retracted, 0/Extended, or ½ flap position, the speed brake is used as a drag device). In total, we had 33 landings that had corresponding actigraph watch data, collected over the course of 6 months. One landing was excluded from the analysis because it had missing data and considerably different initial conditions (higher initial height above aerodrome) than all other landings.
Analytical and numerical study of wave interaction with a vertical slotted barrier
Published in Ships and Offshore Structures, 2021
Sunny Kumar Poguluri, I. H. Cho
In the present study, the wave interaction with a partially submerged slotted barrier with/without a vertical backing wall was analysed under the assumption of linear potential theory. A matched eigenfunction expansion method (MEEM) was applied to solve the wave scattering problem with an energy dissipation model at the slotted barrier. A CFD-based 2D channel flow with symmetric slats was solved to obtain a drag coefficient representing energy dissipation. A 3D implicit unsteady turbulent simulation based on incompressible RANS equations were conducted on Star-CCM+ to assess the developed analytical model. The analytical and numerical solutions were compared with the experimental results obtained by Zhu and Chwang (2001). The energy dissipation effect of the porous slotted barrier was explored by investigating the wave reflection and transmission, wave trapping between the barrier and rigid wall, and wave force on a slotted barrier.
Numerical investigation of aerodynamic characteristics of naca 23112 using passive flow control technique – gurney flaps
Published in Cogent Engineering, 2023
Lift enhancement devices are used in most aircraft to enhance their aerodynamic efficiency, especially during the takeoff and landing phases. Over the years, designers and engineers have come up with various ingenious ideas to improve the performance of aircraft wings and turbine blades, notably flaps, slats, leading-edge root extensions, co-flow jets, etc. High-lift systems of today can be intricate and are often operated using hydraulics or servos. The most common high-lift equipment in commercial aircraft is flaps and slats, detachable wing components that may be extended to produce extra lift. When deployed, the wing section is altered to improve the camber and surface area. The layout and features of these control interfaces strike a compromise between opposing requirements.