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Article
Publication date: 1 June 2001

Jung‐Chul Shin

The potential flow field for the transitional region in a constant radius, two‐dimensional duct was studied. The potential velocity and pressure profiles in various duct…

Abstract

The potential flow field for the transitional region in a constant radius, two‐dimensional duct was studied. The potential velocity and pressure profiles in various duct geometries with different turning angles and duct heights were investigated. A generalized solution of potential flow in a transitional bend was obtained.

Details

Aircraft Engineering and Aerospace Technology, vol. 73 no. 3
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 1 November 2002

M.A. Antar and M.A.I. El‐Shaarawi

Boundary‐layer flow around a spinning liquid sphere moving steadily in a gas stream is investigated numerically. The shear stress exerted on the sphere's surface results in…

Abstract

Boundary‐layer flow around a spinning liquid sphere moving steadily in a gas stream is investigated numerically. The shear stress exerted on the sphere's surface results in surface rotation in the meridional direction in addition to the azimuthal velocity resulting from the spinning of the liquid sphere. The parameters controlling the flow around the sphere are the external flow Reynolds number (Re), the liquid‐to‐gas viscosity ratio (μ*) and the spinning parameter (Rer/Re)2. The effect of these parameters on the velocity components (namely the meridional, radial and azimuthal velocity components) and on the shear stress is shown. Moreover, their effect on the location of external flow point of separation is also demonstrated.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 12 no. 7
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 1 December 1957

R. Hirsch and Ingr. Dr

The circulation which is established around an aerofoil section which has i trailing edge jet, and thus also the lift, is directly dependent on a trailing edge condition similar…

Abstract

The circulation which is established around an aerofoil section which has i trailing edge jet, and thus also the lift, is directly dependent on a trailing edge condition similar to the Joukowski condition in conventional steady and unsteady flow. There is a downwash made up of elementary vortices but in this case the vortex density is not zero when the sheet extends to infinity. The problem is govcrnec by an equation similar to the Wagner equation, into which is introduced the curvature of the downwash at the trailing edge. Certain precautions have to be taker when calculating this. The law governing the movement of the elementary vortices in the downwash plays a very important part. It is directly dependent on the viscous damping of the vorticity. This effect has also had to be taken into consideration, and the drag law of the jet behind the nozzle established. Other results follow concerning the solution of the transient case, and the determination of the circulation up to the moment of reaching its steady limit value, which is achieved in finite time. The velocity distribution on the aerofoil can be found at any instant, and thus also all the properties concerning the aerodynamic forces. The method has been applied to two cases, and a comparison is made with experimental results. An extension to the case of a conventional aerofoil (without jet) is possible; in this case the circulation must have a slightly lower value than in the Joukowski case, the difference depending on the Reynolds number. There is a potential drag resulting from the existence of the downwash and its loss of momentum. In Part II the finite span case is considered. The basic equations are established, and an approximate solution of the steady How case found, where the distribution of circulation is elliptical. A wing interrupted by a fuselage is also considered, and comparison with experimental results given.

Details

Aircraft Engineering and Aerospace Technology, vol. 29 no. 12
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 20 December 2018

Soheil Bazazzadeh, Arman Shojaei, Mirco Zaccariotto and Ugo Galvanetto

The purpose of this paper is to apply the Peridynamic differential operator (PDDO) to incompressible inviscid fluid flow with moving boundaries. Based on the potential flow

Abstract

Purpose

The purpose of this paper is to apply the Peridynamic differential operator (PDDO) to incompressible inviscid fluid flow with moving boundaries. Based on the potential flow theory, a Lagrangian formulation is used to cope with non-linear free-surface waves of sloshing water in 2D and 3D rectangular and square tanks.

Design/methodology/approach

In fact, PDDO recasts the local differentiation operator through a nonlocal integration scheme. This makes the method capable of determining the derivatives of a field variable, more precisely than direct differentiation, when jump discontinuities or gradient singularities come into the picture. The issue of gradient singularity can be found in tanks containing vertical/horizontal baffles.

Findings

The application of PDDO helps to obtain the velocity field with a high accuracy at each time step that leads to a suitable geometry updating for the procedure. Domain/boundary nodes are updated by using a second-order finite difference time algorithm. The method is applied to the solution of different examples including tanks with baffles. The accuracy of the method is scrutinized by comparing the numerical results with analytical, numerical and experimental results available in the literature.

Originality/value

Based on the investigations, PDDO can be considered a reliable and suitable approach to cope with sloshing problems in tanks. The paper paves the way to apply the method for a wider range of problems such as compressible fluid flow.

Details

Engineering Computations, vol. 36 no. 1
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 24 June 2022

Yu Bai, Qiaoli Tang and Yan Zhang

The purpose of this study is to investigate the two-dimensional unsteady inclined stagnation point flow and thermal transmission of Maxwell fluid on oscillating…

Abstract

Purpose

The purpose of this study is to investigate the two-dimensional unsteady inclined stagnation point flow and thermal transmission of Maxwell fluid on oscillating stretched/contracted plates. First, based on the momentum equation at infinity, pressure field is modified by solving first-order differential equation. Meanwhile, thermal relaxation characteristic of fluid is described by Cattaneo–Christov thermal diffusion model.

Design/methodology/approach

Highly coupled model equations are transformed into simpler partial differential equations (PDE) via appropriate dimensionless variables. The approximate analytical solutions of unsteady inclined stagnation point flow on oscillating stretched and contracted plates are acquired by homotopy analysis method for the first time, to the best of the authors’ knowledge.

Findings

Results indicate that because of tensile state of plate, streamline near stagnation point disperses to both sides with stagnation point as center, while in the case of shrinking plate, streamline near stagnation point is concentrated near stagnation point. The enhancement of velocity ratio parameter leads to increasing of pressure variation rate, which promotes flow of fluid. In tensile state, surface friction coefficient on both sides of stagnation point has opposite symbols; when the plate is in shrinkage state, there is reflux near the right side of the stagnation point. In addition, although the addition of unsteady parameters and thermal relaxation parameters reduce heat transfer efficiency of fluid, heat transfer of fluid near the plate can also be enhanced by considering thermal relaxation effect when plate shrinks.

Originality/value

First, approximate analytical solutions of unsteady inclined stagnation point flow on oscillating stretched and contracted plates are researched, respectively. Second, pressure field is further modified. Finally, based on this, thermal relaxation characteristic of fluid is described by Cattaneo–Christov thermal diffusion model.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 32 no. 12
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 21 March 2016

Martin Leary, Richard Piola, Jeff Shimeta, Steven Toppi, Scott Mayson, Matthew McMillan and Milan Brandt

Biofouling of marine vessels results in significant operational costs, as well as the bio-security risk associated with the transport of marine pests. Biofouling is particularly…

Abstract

Purpose

Biofouling of marine vessels results in significant operational costs, as well as the bio-security risk associated with the transport of marine pests. Biofouling is particularly rapid in sea-chest water intakes due to elevated temperatures and circulating flow. Inspection challenges are exacerbated, as sea chests are difficult to inspect and clean. This paper aims to present a method that utilises the flexibility and low-batch capabilities of additive manufacture to manufacture custom sea-chest inserts that eliminate circulating flow and increase the uniformity of shear stress distributions to enable more constant ablation of anti-biofouling coatings.

Design/methodology/approach

An automated design procedure has been developed to optimise sea-chest insert geometry to achieve desirable flow characteristics, while eliminating the necessity for support material in FDM manufacture – thereby significantly reducing build cost and time.

Findings

Numerical flow simulation confirms that the fluid-flow approximation is robust for optimising sea-chest insert geometry. Insert geometry can be manipulated to enable support-free additive manufacture; however, as the threshold angle for support-free manufacture increases, the set of feasible sea-chest aspect ratios decreases.

Research limitations/implications

The surface of revolution that defines the optimal insert geometry may result in features that are not compatible with additive manufacture constraints. An alternate geometry is proposed that may be more useful in practice without compromising anti-biofouling properties.

Practical implications

Marine sea-chest biofouling results in significant negative environmental and economic consequence. The method developed in this paper can reduce the negative impact of sea-chest biofouling.

Social implications

Marine sea-chest biofouling results in significant resource consumption and emissions. The method developed in this paper can reduce the negative impact of sea-chest biofouling.

Originality/value

The method presented in this paper provides an entirely original opportunity to utilise additive manufacture to mitigate the effects of marine biofouling.

Article
Publication date: 1 August 1956

Svetopolk Pivko

Using the results of earlier investigations, a method for determination of the velocity or pressure distribution and the aerodynamic properties of a low‐aspect‐ratio swept wing…

Abstract

Using the results of earlier investigations, a method for determination of the velocity or pressure distribution and the aerodynamic properties of a low‐aspect‐ratio swept wing with slender body of elliptical cross‐section and vertical tail surface, having arbtrary form, is briefly presented. The method can be used for the prediction of the load distribution, aerodynamic forces and moments on inclined slender wing, body and vertical tail combinations travelling at subsonic or supersonic speeds.

Details

Aircraft Engineering and Aerospace Technology, vol. 28 no. 8
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 1 September 2021

Said Chaabani and Naoufel Azouz

This paper presents preliminary results of the modeling of a large autonomous quad-rotor airship, with flying wing shape. This airship is supposed to be a flexible body. This…

Abstract

Purpose

This paper presents preliminary results of the modeling of a large autonomous quad-rotor airship, with flying wing shape. This airship is supposed to be a flexible body. This study promotes an entirely analytical methodology with some assumptions. In this study and as first assumption, the shape of the careen is supposed to be an elliptic cone. To retrieve the velocity potential shapes, this paper solved the Laplace’s equation by using the sphero-conal coordinates. This leads to the Lamé’s equations. The whole system equations governing the interaction of air–structure, including the boundary conditions, is solved in an analytical setting.

Design/methodology/approach

This paper opted for a modeling and determination of the added masses of a flexible airship by an analytical method illustrated by a comparison with a geometric method. This analytical method includes the study of complex functions which are the Lamé functions.

Findings

This paper provides an analytical way to estimate an aerodynamic phenomenon which acts on the airship and in particular on its envelope and known as the phenomenon of added masses or virtual masses, as well as the means of defining it and the calculation analytically for the case of the flexible airship.

Research limitations/implications

Considering that the calculation of the added masses is very difficult and the numerical methods increase the number of degrees of freedom, the analytical method established in this paper has become a solution of calculations of these virtual masses.

Practical implications

This paper includes an application for determining the added masses of a new generation MC500 airship.

Originality/value

This paper allows defining an analytical method which determines the added masses of an airship, which helps the automation engineer to develop a control strategy to stabilize this airship.

Details

Aircraft Engineering and Aerospace Technology, vol. 94 no. 4
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 1 May 1948

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the United States National…

Abstract

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the United States National Advisory Committee for Aeronautics and publications of other similar Research Bodies as issued

Details

Aircraft Engineering and Aerospace Technology, vol. 20 no. 5
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 5 September 2016

J. Rajakumar, P. Saikrishnan and A. Chamkha

The purpose of this paper is to consider axisymmetric mixed convection flow of water over a sphere with variable viscosity and Prandtl number and an applied magnetic field.

Abstract

Purpose

The purpose of this paper is to consider axisymmetric mixed convection flow of water over a sphere with variable viscosity and Prandtl number and an applied magnetic field.

Design/methodology/approach

The non-similar solutions have been obtained from the origin of the streamwise co-ordinate to the point of zero skin friction using quasilinearization technique with an implicit finite-difference scheme.

Findings

The effect of M is not notable on the temperature and heat transfer coefficient when λ is large. The skin friction coefficient and velocity profile are enhance with the increase of MHD parameter M when λ is small. Viscous dissipation has no significant on the skin friction coefficient under MHD effect. For M=1, the movement of the slot or slot suction or slot injection do not cause any effect on flow separation. The slot suction and the movement of the slot in downstream direction delay the point of zero skin friction for M=0.

Originality/value

The present results are original and new for water boundary-layer flow over sphere in mixed convection flow with MHD effect and non-uniform mass transfer. So this study would be useful in analysing the skin friction and heat transfer coefficient on sphere of mixed convection flow of water boundary layer with MHD effect.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 26 no. 7
Type: Research Article
ISSN: 0961-5539

Keywords

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