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Article
Publication date: 18 December 2017

Oliver Krammer, László Jakab, Balazs Illes, David Bušek and Ivana Beshajová Pelikánová

The attack angle of stencil printing squeegees with different geometries was analysed using finite element modelling.

Abstract

Purpose

The attack angle of stencil printing squeegees with different geometries was analysed using finite element modelling.

Design/methodology/approach

A finite element model (FEM) was developed to determine the attack angle during the stencil printing. The material properties of the squeegee were included in the model according to the parameters of steel AISI 4340, and the model was validated by experimental measurements. Two geometric parameters were investigated; two different unloaded angles (45° and 60°) and four overhang sizes of the squeegee (6, 15, 20 and 25 mm).

Findings

It was found that the deflection of the blade is nearly homogenous along the length of the squeegee. This implies that the attack angle does not change significantly along the squeegee length. The results showed significant differences between the initial and the attack angle. For example, the angle of the squeegee with 15 mm overhang size and with 60° initial angle decreased by more than 5° for a specific squeegee force of 0.3 N/mm; resulting in an attack angle of 53.4°.

Originality/value

The attack angle during the printing is considerably lower than the initial angle as a result of the printing force. The papers, which were dealing with the numerical modelling of the stencil printing presumed that the squeegees were having their initial angle. This could have led to invalid numerical results. Therefore, we decided to investigate the attack angle during stencil printing for squeegees with different initial geometries to enhance the numerical modelling of stencil printing.

Details

Soldering & Surface Mount Technology, vol. 30 no. 2
Type: Research Article
ISSN: 0954-0911

Keywords

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Article
Publication date: 10 April 2019

Navid Ahmadi Cheloii, Omid Ali Akbari and Davood Toghraie

This study aims to numerically investigate the heat transfer and laminar forced and two-phase flow of Water/Cu nanofluid in a rectangular microchannel with oblique ribs…

Abstract

Purpose

This study aims to numerically investigate the heat transfer and laminar forced and two-phase flow of Water/Cu nanofluid in a rectangular microchannel with oblique ribs with angle of attacks equal to 0-45°. This simulation was conducted in the range of Reynolds numbers of 5-120 in volume fractions of 0, 2 and 4 per cent of solid nanoparticles in three-dimensional space.

Design/methodology/approach

This study investigates the effect of the changes of angle of attack of rectangular rib on heat transfer and hydrodynamics of two-phase flow. This study was done in three-dimensional space and simulation was done with finite volume method. SIMPLEC algorithm and second-order discretization of equations were used to increase the accuracy of results. The usage of nanofluid, application of rips with different angles of attacks and using the two-phase mixture method is the distinction of this paper compared with other studies.

Findings

The results of this research revealed that the changing angle of attack of ribs is an effective factor in heat transfer enhancement. On the other hand, the existence of rib on the internal surfaces of a microchannel increases friction coefficient. By increasing the volume fraction of nanoparticles, due to the augmentation of fluid density and viscosity, the pressure drop increases significantly. For all of the angle of attacks studied in this paper, the maximum rate of performance evaluation criterion has been obtained in Reynolds number of 30 and the minimum amount of performance evaluation criterion was been obtained in Reynolds numbers of 5 and 120.

Originality/value

Many studies have been done in the field of heat transfer in ribbed microchannel. In this paper, the laminar flow in the ribbed microchannel Water/Cu nanofluid in a rectangular microchannel by using two-phase mixture method is numerically investigated with different volume fractions (0-4 per cent), Reynolds numbers (5-120) and angle of attacks of rectangular rib in the indented microchannel (0-45°).

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 2 October 2017

M. Tahani, M. Masdari and M. Kazemi

This paper aims to analyze the influence of the changings in geometrical parameters on the aerodynamic performance of the control canard projectiles.

Abstract

Purpose

This paper aims to analyze the influence of the changings in geometrical parameters on the aerodynamic performance of the control canard projectiles.

Design/methodology/approach

Because of the mentioned point, the range of projectiles increment has a considerable importance, and the design algorithm of a control canard projectile was first written. Then, were studied the effects of canard geometric parameters such as aspect ratio, taper ratio and deflectable nose on lift to drag coefficient ratio, static margin based on the slender body theory and cross section flow.

Findings

The code results show that aspect ratio increment, results in an increase in lift-to-drag ratio of the missile, but increase in canard taper ratio results in increasing of lift-to-drag ratio at 1° angle of attack, while during increasing the canard taper ratio up to 0.67 at 4° angle of attack, lift to drag first reaches to maximum and then decreases. Also, static margin decreases with canard taper ratio and aspect ratio increment. The developed results for this type of missile were compared with same experimental and computational fluid dynamic (CFD) results and appreciated agreement with other results at angles of attack between 0° and 6°.

Practical implications

To design a control canard missile, the effect of each geometric parameter of canard needs to be estimated. For this purpose, the suitable algorithm is used. In this paper, the effects of canard geometric parameters, such as aspect ratio, taper ratio and deflectable nose on lift-to-drag coefficient ratio and static margin, were studied with help of the slender body theory and cross-section flow.

Originality/value

The contribution of this paper is to predict the aerodynamic characteristics for the control canard missile. In this study, the effect of the design parameter on aerodynamic characteristics can be estimated, and the effect of geometrical characteristics has been analyzed with a suitable algorithm. Also, the best lift-to-drag coefficient for the NASA Tandem Control Missile at Mach 1.75 was selected at various angles of attack. The developed results for this type of missile were compared with same experimental and CFD results.

Details

Aircraft Engineering and Aerospace Technology, vol. 89 no. 6
Type: Research Article
ISSN: 1748-8842

Keywords

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Article
Publication date: 1 June 2002

Zdobysław Goraj, Alfred Baron and Jan Kacprzyk

This paper focuses mainly on the experimental and in‐flight spin investigations for an executive light airplane, named I‐23 and built in the Institute of Aviation (Warsaw…

Abstract

This paper focuses mainly on the experimental and in‐flight spin investigations for an executive light airplane, named I‐23 and built in the Institute of Aviation (Warsaw, Poland). It is a single‐engine, all composite, straight wing, retractable undercarriage, conventional configuration and flight control system airplane. In‐flight spin tests confirmed good rudder and elevator effectiveness for spin recovery in a wide range of positions of the center of gravity. A typical time history of a spin entry and the developed spin and recovery is shown as well.

Details

Aircraft Engineering and Aerospace Technology, vol. 74 no. 3
Type: Research Article
ISSN: 0002-2667

Keywords

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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: 18 October 2018

Yang Tingting, Li Aijun, Muhammad Taimoor and Rooh ul Amin

The purpose of this paper is to propose a high angle of attack short landing model for switched polytopic systems as well as to derive an equation for fluidic thrust…

Abstract

Purpose

The purpose of this paper is to propose a high angle of attack short landing model for switched polytopic systems as well as to derive an equation for fluidic thrust vector deflection angle based on pressure to reduce the velocity during the landing phase of flight.

Design/methodology/approach

In this paper, robust control algorithm is proposed for a non-linear high angle of attack aircraft under the effects of non-linearities, tottering hysteresis, irregular and wing rock atmosphere. High angle of attack short landing flight under asynchronous switching is attained by using the robust controller method. Lyapunov function and the average dwell time scheme is used for obtaining the switched polytopic scheme. The asynchronous switching and loss of data are controlled asymptotically. The velocity of aircraft has been lucratively reduced during the landing phase of flight by using the robust controller technique.

Findings

The proposed algorithm based on robust controller including the effects of non-linearities guarantee the successful reduction of velocity for high angle of attack switched polytopic systems.

Practical implications

As the landing phase of an aircraft is one of the complicated stage, this algorithm plays a vital role in stable and short landing under the condition of high angle of attack (AOA).

Originality/value

In this paper, not only the velocity of flight has been reduced, but also the high angle of attack has been attained during the landing phase, because of which the duration of landing has been reduced as well, while in most of the previous research, it is based on low angle of attack and long landing duration.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 1
Type: Research Article
ISSN: 1748-8842

Keywords

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Article
Publication date: 3 January 2017

Mojtaba Tahani, Mehran Masdari and Ali Bargestan

This paper aims to investigate the aerodynamic characteristics as well as static stability of wing-in-ground effect aircraft. The effect of geometrical characteristics…

Abstract

Purpose

This paper aims to investigate the aerodynamic characteristics as well as static stability of wing-in-ground effect aircraft. The effect of geometrical characteristics, namely, twist angle, dihedral angle, sweep angle and taper ratio are examined.

Design/methodology/approach

A three-dimensional computational fluid dynamic code is developed to investigate the aerodynamic characteristics of the effect. The turbulent model is utilized for characterization of flow over wing surface.

Findings

The numerical results show that the maximum change of the drag coefficient depends on the angle of attack, twist angle and ground clearance, in a decreasing order. Also, it is found that the lift coefficient increases as the ground clearance, twist angle and dihedral angle decrease. On the other hand, the sweep angle does not have a significant effect on the lift coefficient for the considered wing section and Reynolds number. Also, as the aerodynamic characteristics increase, the taper ratio befits in trailing state.

Practical implications

To design an aircraft, the effect of each design parameter needs to be estimated. For this purpose, the sensitivity analysis is used. In this paper, the influence of all parameter against each other including ground clearance, angle of attack, twist angle, dihedral angle and sweep angle for the NACA 6409 are investigated.

Originality/value

As a summary, the contribution of this paper is to predict the aerodynamic performance for the cruise condition. In this study, the sensitivity of the design parameter on aerodynamic performance can be estimated and the effect of geometrical characteristics has been investigated in detail. Also, the best lift to drag coefficient for the NACA 6409 wing section specifies and two types of taper ratios in ground effect are compared.

Details

Aircraft Engineering and Aerospace Technology, vol. 89 no. 1
Type: Research Article
ISSN: 1748-8842

Keywords

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Article
Publication date: 6 July 2010

Hamed Sadeghi, Mahmoud Mani and S.M. Hossein Karimian

The primary purpose of this paper is to investigate the characteristics of the unsteady flow field in the wake of Eppler‐361 airfoil undergoing harmonic pitch oscillation…

Abstract

Purpose

The primary purpose of this paper is to investigate the characteristics of the unsteady flow field in the wake of Eppler‐361 airfoil undergoing harmonic pitch oscillation in both pre‐stall and post‐stall regimes.

Design/methodology/approach

Experimental measurements were carried out to study the characteristics of the unsteady flow field within the wake of an airfoil. All of the experiments were conducted in a low‐speed wind tunnel, and the velocity field was measured by a hot‐wire anemometry. The airfoil was given a harmonic pitching motion about its half chord axis at two reduced frequencies of 0.091 and 0.273. All experimental data were taken at the oscillation amplitude of 8°. During the experiments, the mean angle of attack was altered from 2.5 to 10° that this made it possible to study the wake in both pre‐stall and post‐stall regimes.

Findings

From the results, it can be concluded that different velocity profiles are formed in the wake at different phase angles. In addition, the hysteresis of the velocity field in the wake is captured between increasing and decreasing incidences. It is also found that the velocity field in the wake is strongly affected by the operating conditions of the airfoil, e.g. mean angle of attack, reduced frequency and instantaneous angle of attack. Huge variations in the profiles of the wake are observed at high instantaneous angles of attack when the mean angle of attack is 10°, i.e. when the airfoil experiences significant oscillations beyond the static stall. It is concluded that this is due to dynamic stall phenomenon.

Practical implications

Findings of the present study give valuable information, which can be used to characterize wakes of micro air vehicles, helicopter's rotor blades, and wind turbine blades. In addition to this, present findings can be used to predict dynamic stall of the above applications.

Originality/value

The paper is the first to investigate the unsteady wake of Eppler‐361 airfoil and to predict the dynamic stall phenomenon of this airfoil.

Details

Aircraft Engineering and Aerospace Technology, vol. 82 no. 4
Type: Research Article
ISSN: 0002-2667

Keywords

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Article
Publication date: 1 April 2000

Leonidas D. Evangelou, Andrew Self and John Allen

The increasing demand on high performance fighter aircraft has introduced areas of concern associated with the handling qualities, control and safety at high angles of

Abstract

The increasing demand on high performance fighter aircraft has introduced areas of concern associated with the handling qualities, control and safety at high angles of incidence. Pilots are limiting combat effectiveness by cautiously avoiding hazardous regions of the flight envelope. This paper presents the results of the work undertaken in analysing the F‐16 aircraft’s handling characteristics during the departure condition. In‐flight experience shows that there are two types of F‐16 control problems when flying at high angles of attack: the “pitch departures” and the resulting “deep stall trim”. Avoidance of the departure requires the aeroplane to have sufficient nose‐down pitch and roll control moment. This paper investigates departure condition during high angles of attack and suggests a method of recovery.

Details

Aircraft Engineering and Aerospace Technology, vol. 72 no. 2
Type: Research Article
ISSN: 0002-2667

Keywords

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Article
Publication date: 14 May 2020

Daniel Klatt, Alina Mielke and Christian Mundt

Spinning slender bodies are affected by lateral Magnus forces and moments when exposed to cross-flow. The effects occurring for spinning bodies of revolution in…

Abstract

Purpose

Spinning slender bodies are affected by lateral Magnus forces and moments when exposed to cross-flow. The effects occurring for spinning bodies of revolution in combination with stabilising or control surfaces such as canards are not yet fully explained. Therefore the present work aims to investigate the phenomena arising from the interactions of a roll-decoupled guidance unit with a spinning rear body are investigated.

Design/methodology/approach

A generic tangential-ogive-cylinder projectile equipped with deflectable canards on a roll-decoupled nose is investigated by means of 3D Reynolds-averaged Navier–Stokes simulations at Mach number 2 for angles of attack up to 22 degrees. Different canard deflection angles up to 9 degrees are considered. Global aerodynamic coefficients as well as local flow fields are analysed to explain the interactions occurring between the roll-decoupled guidance unit and the spinning rear body.

Findings

The deflected canards lead to flow interactions resulting in lateral forces and moments even without a spinning motion of the rear part. Depending on the canard deflection angles, these forces act in or against the direction of the classical Magnus effect. For angles of attack smaller than 10 degrees it is possible for the current body geometry to directly superpose the lateral effects resulting from the fins for the non-spinning model with those occurring for the non-finned but spinning model to obtain the total forces and moments acting on a spinning model with canted canards. However, the lateral effects generated on the guidance unit itself are insignificant compared to the canard-induced effects on the rear body.

Originality/value

A detailed analysis of the interaction effects arising from a decoupled guidance unit containing canards with a non-spinning/spinning rear body is performed and the underlying phenomena are revealed.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 2
Type: Research Article
ISSN: 0961-5539

Keywords

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