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Article
Publication date: 1 November 1945

A.R. Weyl

Assisted high‐lift devices which are based on the removal or the addition of air jets from the flow over the wings may be classified as follows, in accordance with their…

Abstract

Assisted high‐lift devices which are based on the removal or the addition of air jets from the flow over the wings may be classified as follows, in accordance with their method of operation:

Details

Aircraft Engineering and Aerospace Technology, vol. 17 no. 11
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 October 1945

A.R. Weyl

THE present conception of the air flow over aeroplane wings assumes that, in general, the flow pattern conforms closely to that of potential flow (i.e. the inviscid…

Abstract

THE present conception of the air flow over aeroplane wings assumes that, in general, the flow pattern conforms closely to that of potential flow (i.e. the inviscid, incompressible flow of hydrodynamic theory) with the exception of a very thin layer of air which is in contact with the wing surface. This layer of fluid, the boundary layer, is characterized by the fact that all phenomena of viscosity (shear forces within the fluid) are restricted to it. Further, it is established that the lift is generated by a circulation about the aerofoil, and that stalling is a result of separation of the boundary layer from the wing surface at or near to the leading edge, with resulting vorticity over the dorsal wing surface, instead of an ordered flow with circulation. Thus at the stall, the circulation suffers a more or less complete breakdown.

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Aircraft Engineering and Aerospace Technology, vol. 17 no. 10
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 11 October 2018

Wienczyslaw Stalewski and Andrzej Krzysiak

The purpose of this study is to develop the concept of self-adapting system which would be able to control a flow on the wing-high-lift system and protect the flow against…

Abstract

Purpose

The purpose of this study is to develop the concept of self-adapting system which would be able to control a flow on the wing-high-lift system and protect the flow against strong separation.

Design/methodology/approach

The self-adapting system has been developed based on computational approach. The computational studies have been conducted using the URANS solver. The experimental investigations have been conducted to verify the computational results.

Findings

The developed solution is controlled by closed-loop-control (CLC) system. As flow actuators, the main-wing trailing-edge nozzles are proposed. Based on signals received from the pressure sensors located at the flap trailing edge, the CLC algorithm changes the amount of air blown from the nozzles. The results of computational simulations confirmed good effectiveness and reliability of the developed system. These results have been partially confirmed by experimental investigations.

Research limitations/implications

The presented research on an improvement of the effectiveness of high-lift systems of modern aircraft was conducted on the relatively lower level of the technology readiness. However, despite this limitation, the results of presented studies can provide a basis for developing innovative self-adaptive aerodynamic systems that potentially may be implemented in future aircrafts.

Practical implications

The studies on autonomous flow-separation control systems, operating in a closed feedback loop, are a great hope for significant advances in modern aeronautical engineering, also in the UAV area. The results of the presented studies can provide a basis for developing innovative self-adaptive aerodynamic systems at a higher level of technological readiness.

Originality/value

The presented approach is especially original and valuable in relation to the innovative concept of high-lift system supported by air-jets blown form the main-wing-trailing-edge nozzles; the effective and reliable flow sensors are the pressure sensors located at the flap trailing edge, and the effective and robust algorithm controlling the self-adapting aerodynamic system – original especially in respect to a strategy of deactivation of flow actuators.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 3
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 20 December 2019

Nikhil Kalkote, Ashutosh Kumar, Ashwani Assam and Vinayak Eswaran

The purpose of this paper is to study the predictability of the recently proposed length scale-based two-equation k-kL model for external aerodynamic flows such as those…

Abstract

Purpose

The purpose of this paper is to study the predictability of the recently proposed length scale-based two-equation k-kL model for external aerodynamic flows such as those also encountered in the high-lift devices.

Design/methodology/approach

The two-equation k-kL model solves the transport equations of turbulent kinetic energy (TKE) and the product of TKE and the integral length scale to obtain the effect of turbulence on the mean flow field. In theory, the use of governing equation for length scale (kL) along with the TKE promises applicability in a wide range of applications in both free-shear and wall-bounded flows with eddy-resolving capability.

Findings

The model is implemented in the in-house unstructured grid computational fluid dynamics solver to investigate its performance for airfoils in difficult-to-predict situations, including stalling and separation. The numerical findings show the good capability of the model in handling the complex flow physics in the external aerodynamic computations.

Originality/value

The model performance is studied for stationary turbulent external aerodynamic flows, using five different airfoils, including two multi-element airfoils in high-lift configurations which, in the knowledge of the authors, have not been simulated with k-kL model until now.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 22 no. 8
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 25 January 2021

Mohamed Arif Raj Mohamed, Rajesh Yadav and Ugur Guven

This paper aims to achieve an optimum flow separation control over the airfoil using a passive flow control method by introducing a bio-inspired nose near the leading edge…

Abstract

Purpose

This paper aims to achieve an optimum flow separation control over the airfoil using a passive flow control method by introducing a bio-inspired nose near the leading edge of the National Advisory Committee for Aeronautics (NACA) 4 and 6 series airfoil. In addition, to find the optimised leading edge nose design for NACA 4 and 6 series airfoils for flow separation control.

Design/methodology/approach

Different bio-inspired noses that are inspired by the cetacean species have been analysed for different NACA 4 and 6 series airfoils. Bio-inspired nose with different nose length, nose depth and nose circle diameter have been analysed on airfoils with different thicknesses, camber and camber locations to understand the aerodynamic flow properties such as vortex formation, flow separation, aerodynamic efficiency and moment.

Findings

The porpoise nose design that has a leading edge with depth = 2.25% of chord, length = 0.75% of chord and nose diameter = 2% of chord, delays the flow separation and improves the aerodynamic efficiency. Average increments of 5.5% to 6° in the lift values and decrements in parasitic drag (without affecting the pitching moment) for all the NACA 4 and 6 series airfoils were observed irrespective of airfoil geometry such as different thicknesses, camber and camber location.

Research limitations/implications

The two-dimensional computational analysis is done for different NACA 4 and 6 series airfoils at low subsonic speed.

Practical implications

This design improves aerodynamic performance and increases the structural strength of the aircraft wing compared to other conventional high lift devices and flow control devices. This universal leading edge flow control device can be adapted to aircraft wings incorporated with any NACA 4 and 6 series airfoil.

Social implications

The results would be of significant interest in the fields of aircraft design and wind turbine design, lowering the cost of energy and air travel for social benefits.

Originality/value

Different bio-inspired nose designs that are inspired by the cetacean species have been analysed for NACA 4 and 6 series airfoils and universal optimum nose design (porpoise airfoil) is found for NACA 4 and 6 series airfoils.

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Article
Publication date: 1 August 1945

A.R. Weyl

IN the tailless aeroplane, side‐slip motions during take‐off and landing manoeuvres are specially undesirable, since it tends to be deficient in lateral stability, as we…

Abstract

IN the tailless aeroplane, side‐slip motions during take‐off and landing manoeuvres are specially undesirable, since it tends to be deficient in lateral stability, as we have seen. Hence, arrangements which provide for early compensation of unintentional side‐slipping may have some justification.

Details

Aircraft Engineering and Aerospace Technology, vol. 17 no. 8
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 October 1964

Alberto Alvarez Calderon

A SPANWISE rotating cylinder placed at a suitable location in an aerofoil with the cylinder's upper surface moving rearwards in the direction of the local air flow can…

Abstract

A SPANWISE rotating cylinder placed at a suitable location in an aerofoil with the cylinder's upper surface moving rearwards in the direction of the local air flow can serve to re‐energize the boundary layer on the aerofoil. For example, when placed between a flap and a wing with the cylinder protruding substantially into the air flow as shown schematically in no. 1, the moving surface of the cylinder destroys, by viscous shear action, the low‐energy boundary layer impinging on the cylinder from the wing and results in a new boundary layer on the flap's upper surface which has a higher energy level adequate to negotiate the adverse pressure gradients and flow conditions existing at the rear of a flap deflected through a large angle. The boundary layer re‐energizing function of the cylinder depends on its upward protrusion, on its peripheral speed, and on the local flap geometry. The beneficial effects of the rotating cylinder on the flow fields have been visualized in two dimensional smoke studies conducted by Alvarez Caldcrón and Arnold of Stanford University on a flap designed for deflected slipstream V/S.T.O.L. aircraft. Fig. 2 shows flow around the flap with the cylinder stationary. It exhibits complete flow separation at the flap which is also typical of a slotted flap deflected through a large angle. The large white disk is a cylinder end plate; the actual cylinder appears in the darker circular shade of small diameter. The photograph of FIG. 3 was taken with the cylinder rotating: it shows a radical flow change not only in the total elimination of flow separation on the flap but in the induction of strong upwash fields and low pressure regions toward the leading edge of wing itself which obviously greatly increases lift and decreases wing pitching moments.

Details

Aircraft Engineering and Aerospace Technology, vol. 36 no. 10
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 September 1955

T.R. Nonweiler

WRITING an introduction to an article by Mr S. B. Gates on Trailing‐Edge Flaps, which appeared in these columns in 1937, the Editor felt constrained to admit his…

Abstract

WRITING an introduction to an article by Mr S. B. Gates on Trailing‐Edge Flaps, which appeared in these columns in 1937, the Editor felt constrained to admit his bewilderment over the number and variety of types of high‐lift aid which then existed. Without intending any disrespect, I imagine that the progress of years must have added to his embarrassment. It has certainly added to the number of devices in use and under test.

Details

Aircraft Engineering and Aerospace Technology, vol. 27 no. 9
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 22 November 2011

Markus Kintscher, Martin Wiedemann, Hans Peter Monner, Olaf Heintze and Timo Kühn

The purpose of this paper is to describe the pre‐design and sizing of a smart leading edge section which is developed in the project SADE (Smart High Lift Devices for Next…

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Abstract

Purpose

The purpose of this paper is to describe the pre‐design and sizing of a smart leading edge section which is developed in the project SADE (Smart High Lift Devices for Next Generation Wings), which is part of the seventh framework program of the EU.

Design/methodology/approach

The development of morphing technologies in SADE concentrates on the leading and trailing edge high‐lift devices. At the leading edge a smart gap and step‐less droop nose device is developed. For the landing flap a smart trailing edge of the flap is in the focus of the research activities. The main path in SADE follows the development of the leading edge section and the subsequent wind tunnel testing of a five meter span full‐scale section with a chord length of three meters in the wind tunnel T‐101 at the Russian central aero‐hydrodynamic institute (TsAGI) in Moscow.

Findings

The presented paper gives an overview over the desired performance and requirements of a smart leading edge device, its aerodynamic design for the wind tunnel tests and the structural pre‐design and sizing of the full‐scale leading edge section which will be tested in the wind tunnel.

Originality/value

SADE aims at a major step forward in the development and evaluation of the potential of morphing airframe technologies.

Details

International Journal of Structural Integrity, vol. 2 no. 4
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 1 May 1972

THE PRIMARY FUNCTIONAL SYSTEMS — hydraulic, electrical electronic, environmental control, and auxiliary power systems — are separated into localised centres to allow…

Abstract

THE PRIMARY FUNCTIONAL SYSTEMS — hydraulic, electrical electronic, environmental control, and auxiliary power systems — are separated into localised centres to allow simultaneous inspection and maintenance with minimum congestion between ground personnel and equipment. Other factors considered in the design layout of the service centres were the distribution of components in each system, aircraft weight and balance, component size, area environment and accessibility. Isolation from the hazards of possible engine turbine‐blade and wheel tyre failures was another important consideration. Standardisation and interchangeability of equipment within the L1011 aircraft, and among other transports operating in the same time period also influenced the functional system design.

Details

Aircraft Engineering and Aerospace Technology, vol. 44 no. 5
Type: Research Article
ISSN: 0002-2667

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