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Article
Publication date: 23 March 2010

D.W. Marshall, S.J. Newman and C.B. Williams

The purpose of this paper is to investigate the effect a variety of different boundary layers have on a wing in ground‐effect.

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Abstract

Purpose

The purpose of this paper is to investigate the effect a variety of different boundary layers have on a wing in ground‐effect.

Design/methodology/approach

Experiments were carried out in the University of Southampton's 3′×2′ wind tunnel. A variable length splitter plate was designed and manufactured in order to generate four boundarylayer thicknesses at a selected measurement position. A single element inverted GA(W)‐1 aerofoil was then introduced to the flow at varying heights above the plate. Laser Doppler anemometry (LDA) and surface static pressure measurements (both on the aerofoil surface and on the splitter plate) were recorded.

Findings

The flow beneath the wing is found to be affected considerably by the presence of the boundary layer. As the boundarylayer thickness is increased, the under‐wing pressure is observed to increase, hence resulting in decreased suction. Further, the LDA results indicate a modification to the wake profile. In particular, at low wing heights, the wake is observed to become entrained in the boundary layer, to differing degrees dependant on the boundary layer present and the wing height.

Research limitations/implications

The acquisition of force values from the tests will have allowed further understanding of the “real world” implications of the presence of the boundarylayer thicknesses on a wing in ground‐effect but this is not possible in the test facility used.

Practical implications

The aerodynamics of a wing in ground‐effect are of great interest for both lifting surfaces for aircraft and downforce generation in motorsport applications. The implications of this paper enhance the importance of understanding the boundary conditions present when wind tunnel testing for these applications.

Originality/value

Although the influence of the boundary layer on low ground clearance objects has been well documented, the methods used here, in particular the use of the pressure tapped splitter plate and LDA, allow a further insight into the explanations behind this influence.

Details

Aircraft Engineering and Aerospace Technology, vol. 82 no. 2
Type: Research Article
ISSN: 0002-2667

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Book part
Publication date: 12 May 2017

Mitsuru Kodama

This chapter goes into deeper discussion and consideration of holistic leadership through the concept of holistic leadership presented in Part 1 and analysis of a number…

Abstract

This chapter goes into deeper discussion and consideration of holistic leadership through the concept of holistic leadership presented in Part 1 and analysis of a number of case studies presented in Part 2. The chapter first analyzes and considers the concept of dialectical leadership, which is an element for achieving a balance between centralized leadership and distributed leadership at the psychological boundary layer located at the boundary layer between the formal organizational layer and the informal organizational layer from the perspective of four dimensions: the time axis, spatial axis, strategic axis, and management axis. This is because there is new knowledge gained from multiple case analyses and because dialectical leadership has an impact on management elements in these four dimensions when companies execute strategic knowledge creation processes to achieve business innovation. Second, the chapter discusses the concept of leadership interaction which occurs among leaders at the individual boundaries of the three-layered structure (practice layers) of the informal organization layer located in the business community, the psychological boundary layer located in the boundary layer of the business community, and the formal organization layer located in the formal organization, and the three management layers. Third, as demonstrated in the cases of Apple, Cisco Systems, Dyson, SoftBank, and Sony, strategic collaboration with other companies including customers is extremely important for those practitioners who are promoting business ecosystem strategies across different companies. To achieve this, synchronization of leadership at the three practice layers and three management layers in holistic leadership through boundary negotiations among individual leaderships across different companies is important. These concepts are discussed in this chapter. Fourth, this chapter indicates that excellent holistic leadership is necessary for practitioners to achieve strategic knowledge creation high in quality, but this requires leadership for value creation for the formation of new business communities that originate in the formation of “Ba.” The chapter also indicates that “practical wisdom” is an important element for practitioners in such value creation, and the presence of this element is a necessary condition for generating excellent holistic leadership.

Details

Developing Holistic Leadership
Type: Book
ISBN: 978-1-78714-421-7

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Book part
Publication date: 12 May 2017

Mitsuru Kodama

As a company that has continuously achieved business innovation, Apple in the United States has successfully applied strategic knowledge creation to produce a series of…

Abstract

As a company that has continuously achieved business innovation, Apple in the United States has successfully applied strategic knowledge creation to produce a series of products that integrate various digital devices as well as diverse contents and applications, such as the iPod, iPhone, and iPad, based on a corporate vision of a digital hub concept. At the same time, the redefining of corporate boundaries that expanded Apple’s business in a horizontal direction from the Macintosh PC business to the delivery of music, smartphones, and tablets is also an indication of the evolution of a corporate vision involving Apple’s strategic transformation. This chapter presents the strategic and creative processes that enabled practitioners, including the late Steve Jobs, to demonstrate “strategic innovation capability” by “holistic leadership” at every level of management at Apple and successfully achieve a business ecosystem strategy through “creative collaboration” across diverse boundaries within and outside the company.

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Article
Publication date: 1 May 1993

MICHAEL J. NUSCA

An aerothermodynamic design code for axisymmetric projectiles has been developed using a viscous‐inviscid interaction scheme. Separate solution procedures for the inviscid…

Abstract

An aerothermodynamic design code for axisymmetric projectiles has been developed using a viscous‐inviscid interaction scheme. Separate solution procedures for the inviscid and the viscous (boundary layer) fluid dynamic equations are coupled by an iterative solution procedure. Non‐equilibrium, equilibrium and perfect gas boundary layer equations are included. The non‐equilibrium gas boundary layer equations assume a binary mixture (two species; atoms and molecules) of chemically reacting perfect gases. Conservation equations for each species include finite reaction rates applicable to high temperature air. The equilibrium gas boundary layer equations assume infinite rate reactions, while the perfect gas equations assume no chemical reactions. Projectile near‐wall and surface flow profiles (velocity, pressure, density, temperature and heat transfer) representing converged solutions to both the inviscid and viscous equations can be obtained in less than two minutes on minicomputers. A technique for computing local reverse flow regions is included. Computations for yawed projectiles are accomplished using a coordinate system transformation technique that is valid for small angle‐of‐attack. Computed surface pressure, heat transfer rates and aerodynamic forces and moments for 1.25 &le Mach No. &le 10.5 are compared to wind tunnel and free flight measurements on flat plate, blunt‐cone, and projectile geometries such as a cone‐cylinder‐flare.

Details

Engineering Computations, vol. 10 no. 5
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 28 October 2013

Lelanie Smith, Oliver Oxtoby, A. Malan and Josua Meyer

– The purpose of this paper is to introduce a unique technique to couple the two-integral boundary layer solutions to a generic inviscid solver in an iterative fashion.

Abstract

Purpose

The purpose of this paper is to introduce a unique technique to couple the two-integral boundary layer solutions to a generic inviscid solver in an iterative fashion.

Design/methodology/approach

The boundary layer solution is obtained using the two-integral method to solve displacement thickness point by point with a local Newton method, at a fraction of the cost of a conventional mesh-based, full viscous solution. The boundary layer solution is coupled with an existing inviscid solver. Coupling occurs by moving the wall to a streamline at the computed boundary layer thickness and treating it as a slip boundary, then solving the flow again and iterating. The Goldstein singularity present when solving boundary layer equations is overcome by solving an auxiliary velocity equation along with the displacement thickness.

Findings

The proposed method obtained favourable results when compared with the analytical solutions for flat and inclined plates. Further, it was applied to modelling the flow around a NACA0012 airfoil and yielded results similar to those of the widely used XFOIL code.

Originality/value

A unique method is proposed for coupling of the boundary layer solution to the inviscid flow. Rather than the traditional transpiration boundary condition, mesh movement is employed to simulate the boundary layer thickness in a more physically meaningful way. Further, a new auxiliary velocity equation is presented to circumvent the Goldstein singularity.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 23 no. 8
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 March 1962

G.V. Lachmann

Since the end of the Second World War, many spectacular advances have been made in aeronautics, thanks chiefly to the development of more powerful and economical jet…

Abstract

Since the end of the Second World War, many spectacular advances have been made in aeronautics, thanks chiefly to the development of more powerful and economical jet engines. As to the parasitic drag of manned aircraft, progress has been confined to reducing unfavourable compressibility effects (area rule, Whitcombe bodies); methods to suppress separation have been developed but no new methods to reduce the drag resulting from turbulent boundary layers developing over the exposed surfaces have as yet found practical application.

Details

Aircraft Engineering and Aerospace Technology, vol. 34 no. 3
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 February 1993

M. HASNAOUI, P. VASSEUR and E. BILGEN

Thermally driven flow in a tall inclined cavity bounded by porous layers is studied analytically and numerically. A constant heat flux is applied for heating and cooling…

Abstract

Thermally driven flow in a tall inclined cavity bounded by porous layers is studied analytically and numerically. A constant heat flux is applied for heating and cooling of two opposing walls of the cavity, while the other two are insulated. The Beavers—Joseph slip condition on velocity is applied at the interface between the fluid and porous layers. An analytical solution is obtained by assuming parallel flow in the core region of the cavity and a numerical solution by solving the complete governing equations. The flow and heat transfer variables are obtained in terms of the Rayleigh number, Ra, slip condition parameter N and angle of inclination of the cavity Φ. The critical Rayleigh numbers for the onset of convection in a layer heated from below are predicted for various hydrodynamic boundary conditions. The results for a fluid layer bounded by solid walls (N → ∞) and by free surfaces (N → 0) emerge from the present analysis as limiting cases.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 3 no. 2
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 15 May 2009

Juntao Chang and Yi Fan

The purpose of this paper is to study the effects of boundarylayers bleeding on performance parameters of hypersonic inlets.

Abstract

Purpose

The purpose of this paper is to study the effects of boundarylayers bleeding on performance parameters of hypersonic inlets.

Design/methodology/approach

The inner flowfield of a hypersonic inlet at different bleeding rates is simulated with a Reynolds‐averaged Navier‐Stokes solver using a renormalization group kε turbulence model.

Findings

In contrast with no bleeding, the performance parameter of hypersonic inlets without backpressure is reduced slightly, but the flow uniformity is improved. The interaction between boundary layers and shocks is weakened at the action of the bleeding, which leads to that the boundarylayers separations at the entrance of the isolator caused by the high‐backpressure occur later, and it can improve the maximum backpressure ratio of hypersonic inlets. With the bleeding rate increasing, the maximum backpressure ratio of hypersonic inlets is added, while the total‐pressure recovery coefficient and mass‐captured coefficient are reduced.

Originality/value

This paper is a useful reference to the design and performance improvement of hypersonic inlets and propulsion systems.

Details

Aircraft Engineering and Aerospace Technology, vol. 81 no. 3
Type: Research Article
ISSN: 0002-2667

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Book part
Publication date: 12 May 2017

Mitsuru Kodama

Bearing in mind reviews of the existing corporate management leadership theory, this chapter presents a theoretical framework of holistic leadership for top and middle…

Abstract

Bearing in mind reviews of the existing corporate management leadership theory, this chapter presents a theoretical framework of holistic leadership for top and middle management as well as the staff for strategically promoting knowledge creation activities in companies in industries with rapidly changing competitive environments. “Holistic leadership” here refers to leadership with characteristics that allow for the coexistence of centralized leadership, distributed leadership, and dialectical leadership and their dynamic application according to circumstances by practitioners at each management level (top management, middle management, and staff) of the three practice layers, that is, the formal organizational layer, the psychological boundary layer, and the informal organizational layer. This new theoretical concept of leadership has been derived a posteriori from existing theory and cumulative fieldwork by the author to date.

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Article
Publication date: 1 December 2001

Konstantinos A. Tarabanis

Presents algorithms for determining the paths employed by the Proteus rapid prototyping system when building three‐dimensional parts. Proteus is a fused deposition…

Abstract

Presents algorithms for determining the paths employed by the Proteus rapid prototyping system when building three‐dimensional parts. Proteus is a fused deposition modeling system that extrudes a thermoplastic in beads through a nozzle. Determines within each layer of the layered manufacturing process, the material deposition paths as well as the regions where local structures are required to support these paths. Computes the paths with the goal of reducing the amount of supports needed to build the physical prototype of the part by taking advantage of the two novel manufacturing techniques of shelving and bridging that had been developed previously. The path planning algorithms presented are designed to utilize the above techniques and address the variety of conditions that appear in practice allowing the Proteus system to “build in air”.

Details

Rapid Prototyping Journal, vol. 7 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

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