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Article
Publication date: 3 May 2013

Rachid Saim, Hamidou Benzenine, Hakan F. Öztop and Khaled Al‐Salem

The purpose of this paper is to examine the turbulent fluid flow and heat transfer characteristics for rectangular channel provided with solid plate baffles which are…

Abstract

Purpose

The purpose of this paper is to examine the turbulent fluid flow and heat transfer characteristics for rectangular channel provided with solid plate baffles which are arranged on the bottom and top channel walls in a periodically staggered way.

Design/methodology/approach

The turbulent governing equations are solved by a finite volume method with the second‐order up winding scheme and the k‐ω turbulence model to describe the turbulent structure. The velocity and pressure terms of momentum equations are solved by SIMPLE (semi‐implicit method for pressure‐linked equation) algorithm. The parameters studied include the entrance Reynolds number Re (5.103‐2.104), the baffles height are fixed at (h=0.08 m); whereas three different baffle spacing were considered S1 = D, S2 = D/2 and S3=3D/2 and the working medium is air.

Findings

In this work, it is found that vortex shedding generated by the baffle on the upper wall can additionally enhance heat transfer along the baffle surfaces. The wavy flow significantly changes the recirculating zone behind the last baffle. Finally, changing the baffles spacing seemed to reduce to changing the heat transfer surface between the solid and the fluid in the sense that higher heat transfer is obtained for lower spacing between baffles.

Originality/value

The results of the numerical calculations of the flow field indicate that the flow patterns around the solid baffles depending on the spacing of the baffles and it significantly influences the local heat transfer coefficient distributions. The problem is inversely proportional for the friction factor.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 23 no. 4
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 1 February 1997

Cheryl L. Sellers and Suresh Chandra

For high speed shear layers, variable density extensions of standard incompressible turbulence models have not proved to be adequate in explaining the experimentally…

Abstract

For high speed shear layers, variable density extensions of standard incompressible turbulence models have not proved to be adequate in explaining the experimentally observed reduction in growth rate with increase in the convective Mach number. Recently, Sarkar et al. suggested that, in addition to modelling the pressure dilatation, another dilatational correlation ‐ the compressible dissipation ‐ should be considered because of the enhanced dissipation known to be present in compressible turbulence. They have used the compressibility‐corrected model ‐ limited to the second power of the turbulent Mach number ‐ with the SPARK code for the computation of high speed shear layers and have obtained satisfactory agreement with some of the available experimental data. This simple algebraic compressibility model has been modified to include a fourth order turbulent Mach number term. Comparison of the predictions with results of several analytical models and experimental work shows good agreement.

Details

Engineering Computations, vol. 14 no. 1
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 7 August 2019

Jian-Ming Fu, Hai-Min Tang and Hong-Quan Chen

The purpose of this paper is to develop a new approach for rapid computation of subsonic and low-transonic rotary derivatives with the available steady solutions obtained…

Abstract

Purpose

The purpose of this paper is to develop a new approach for rapid computation of subsonic and low-transonic rotary derivatives with the available steady solutions obtained by Euler computational fluid dynamics (CFD) codes.

Design/methodology/approach

The approach is achieved by the perturbation on the steady-state pressure of Euler CFD codes. The resulting perturbation relation is established at a reference Mach number between rotary derivatives and normal velocity on surface due to angular velocity. The solution of the reference Mach number is generated technically by Prandtl–Glauert compressibility correction based on any Mach number of interest under the assumption of simple strip theory. Rotary derivatives of any Mach number of interest are then inversely predicted by the Prandtl–Glauert rule based on the reference Mach number aforementioned.

Findings

The resulting method has been verified for three typical different cases of the Basic Finner Reference Projectile, the Standard Dynamics Model Aircraft and the Orion Crew Module. In comparison with the original perturbation method, the performance at subsonic and low-transonic Mach numbers has significantly improved with satisfactory accuracy for most design efforts.

Originality/value

The approach presented is verified to be an efficient way for computation of subsonic and low-transonic rotary derivatives, which are performed almost at the same time as an accounting solution of steady Euler equations.

Details

Engineering Computations, vol. 36 no. 9
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 29 November 2018

Moshe Szweizer

The purpose of this paper is to extend the studies of commercial property yields by providing a cross-field approach through the implementation of methods used in physics.

Abstract

Purpose

The purpose of this paper is to extend the studies of commercial property yields by providing a cross-field approach through the implementation of methods used in physics.

Design/methodology/approach

Based on the equations used to describe real gases in physics, the commercial property yields are expressed through a model, as a product of two terms. The first term estimates the influence of the income change and investment on yields. The second estimates the yield variation as a function of property size. Additionally, the model combines the macroeconomic and microeconomic components influencing yield adjustment. Calculation of each component involves procedures developed in physics, with the investment volume being linked to the amount of gas and the microeconomic yield being linked to the gas compressibility.

Findings

The model was applied to the Auckland office and industrial markets, both to the historic and current cycle. At the macro-level, it was found that the use of accumulation of investment over a relevant cycle, results in a high data to model correlation. When modelling the yields at the micro-level, a relationship between the outlying properties and the yield softening was observed.

Practical implications

The paper provides an enhanced modelling power through association of the cyclic and investment activity with the yield change. Moreover, the model may be used to decouple the local and the international investment components and the extent of their influence on the local property market. Furthermore, it may be used to estimate the influence of the property size on the yield.

Originality/value

This research provides a new cross-field application of modelling techniques and enhances the understanding of factors influencing yield adjustments.

Details

Journal of Property Investment & Finance, vol. 37 no. 1
Type: Research Article
ISSN: 1463-578X

Keywords

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Article
Publication date: 1 July 1949

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

Abstract

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, 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. 21 no. 7
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 December 1959

Svetopolk Pivko

The operating conditions of a conventional aerofoil type propeller or helicopter rotor in both subsonic and supersonic regions are separately considered, in the absence of…

Abstract

The operating conditions of a conventional aerofoil type propeller or helicopter rotor in both subsonic and supersonic regions are separately considered, in the absence of direct shock and blade interference effects and other disturbances. The performance of a propeller or rotor is approximately predicted by applying the conventional strip‐type analysis and the results of the two‐dimensional aerofoil theory.

Details

Aircraft Engineering and Aerospace Technology, vol. 31 no. 12
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 July 1950

E.N. Brailsford

The uses to which a lift‐coefficient indicator could be put are presented, and it is suggested that a good case could be made for displacing the airspeed‐indicator on the…

Abstract

The uses to which a lift‐coefficient indicator could be put are presented, and it is suggested that a good case could be made for displacing the airspeed‐indicator on the pilot's panel at least. The chief advantages accompanying the use of the lift‐coefficient indicator lie in its contributions to safety and in rationalizing flight conditions at the various flying weights of each aircraft. A type of indicator is considered in detail which utilizes the relationship between aerofoil surface‐pressures and various parameters notably angle of attack and Mach No. It is shown that although complex relationships may exist, it is possible to evolve a simple solution. Reliability in all atmosphere conditions is attained by design‐detail, and accuracy is expected to approach 1 per cent.

Details

Aircraft Engineering and Aerospace Technology, vol. 22 no. 7
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 May 1942

Alexander Klemin

IN our report of the tenth annual meeting of the Institute of the Aeronautical Sciences we shall not follow precisely the order in which the sessions occurred nor at all…

Abstract

IN our report of the tenth annual meeting of the Institute of the Aeronautical Sciences we shall not follow precisely the order in which the sessions occurred nor at all times classify the papers in exactly the manner of the meeting. Unfortunately, certain of the papers presented will not be found in our review owing to lack of preprints, but this in no way reflects on the value or timeliness of the papers omitted in the review.

Details

Aircraft Engineering and Aerospace Technology, vol. 14 no. 5
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 November 1952

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Reports and Technical Memoranda of the United…

Abstract

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Reports and Technical Memoranda 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. 24 no. 11
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 7 March 2016

Nikita Ageev and Alexander Pavlenko

This study aims to decrease the aerodynamic drag of the body of revolution at supersonic speeds. Supersonic area rule is widely used in modern supersonic aircraft design…

Abstract

Purpose

This study aims to decrease the aerodynamic drag of the body of revolution at supersonic speeds. Supersonic area rule is widely used in modern supersonic aircraft design. Further reduction of the aerodynamic drag is possible in the framework of Euler and Reynolds averaged Navier–Stokes (RANS) equations. Sears–Haack body of revolution shape variation, which decreased its aerodynamic drag in compressible inviscid and viscous gas flow at Mach number of 1.8 under constraint of the volume with lower bound equal to volume of initial body, was numerically investigated.

Design/methodology/approach

Calculations were carried out in two-dimensional axisymmetric mode in the framework of Euler and RANS with SST model with compressibility correction equations at structured multiblock meshes. Variation of the radius as function of the longitudinal coordinate was given as a polynomial third-order spline through five uniformly distributed points. Varied parameters were increments of the radius of the body at points that defined spline. Drag coefficient was selected as an objective function. Parameter combinations corresponding to the objective function minimum under volume constraint were obtained by mixed-integer sequential quadratic programming at second-order polynomial response surface and IOSO algorithm.

Findings

Improving variations make front part of the body become slightly blunted, transfer part of volume from front part of the body to back part and generate significant back face. In the framework of RANS, the best variation decreases aerodynamic drag by approximately 20 per cent in comparison with Sears–Haack body.

Practical implications

The results can be applied for the aerodynamic design of the bullets and projectiles. The second important application is knowledge of the significance of the difference between linearized slender body theory optimization results and optimization results obtained by modern computational fluid dynamics (CFD) optimization techniques.

Social implications

Knowledge about the magnitude of the difference between linearized slender body theory optimization results and optimization results obtained by modern CFD optimization techniques can stimulate further research in related areas.

Originality/value

The optimization procedure and optimal shapes obtained in the present work are directly applicable to the design of small aerodynamic drag bodies.

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 88 no. 2
Type: Research Article
ISSN: 1748-8842

Keywords

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