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Article
Publication date: 26 June 2019

Mehdi Dadkhah, Mehran Masdari, Mohammad Ali Vaziri and Mojtaba Tahani

In this paper, experimental and numerical results of a lambda wing have been compared. The purpose of this paper is to study the behaviour of lambda wings using a CFD tool…

Abstract

Purpose

In this paper, experimental and numerical results of a lambda wing have been compared. The purpose of this paper is to study the behaviour of lambda wings using a CFD tool and to consider different numerical models to obtain the most accurate results. As far as the consideration of numerical methods is concerned, the main focus is on the evaluation of computational methods for an accurate prediction of contingent leading edge vortices’ path and the flow separation occurring because of the burst of these vortices on the wing.

Design/methodology/approach

Experimental tests are performed in a closed-circuit wind tunnel at the Reynolds number of 6 × 105 and angles of attack (AOA) ranging from 0 to 10 degrees. Investigated turbulence models in this study are Reynolds Averaged Navior–Stokes (RANS) models in a steady state. To compare the accuracy of the turbulence models with respect to experimental results, sensitivity study of these models has been plotted in bar charts.

Findings

The results illustrate that the leading edge vortex on this lambda wing is unstable and disappears soon. The effect of this disappearance is obvious by an increase in local drag coefficient in the junction of inner and outer wings. Streamlines on the upper surface of the wing show that at AOA higher than 8 degrees, the absence of an intense leading edge vortex leads to a local flow separation on the outer wing and a reverse in the flow.

Research limitations/implications

Results obtained from the behaviour study of transition (TSS) turbulence model are more compatible with experimental findings. This model predicts the drag coefficient of the wing with the highest accuracy. Of all considered turbulence models, the Spalart model was not able to accurately predict the non-linearity of drag and pitching moment coefficients. Except for the TSS turbulence model, all other models are unable to predict the aerodynamic coefficients corresponding to AOA higher than 10 degrees.

Practical implications

The presented results in this paper include lift, drag and pitching moment coefficients in various AOA and also the distribution of aerodynamic coefficients along the span.

Originality/value

The presented results include lift, drag and pitching moment coefficients in various AOA and also aerodynamic coefficients distribution along the span.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 8
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 2 August 2011

Ehud Kroll and Dror Artzi

The purpose of this paper is to present the benefits offered by rapid prototyping (RP) models for wind‐tunnel testing as part of fourth‐year aerospace engineering student…

3009

Abstract

Purpose

The purpose of this paper is to present the benefits offered by rapid prototyping (RP) models for wind‐tunnel testing as part of fourth‐year aerospace engineering student projects. Ways of overcoming some of the difficulties associated with the 3D printing technology are also discussed.

Design/methodology/approach

Polymer‐based RP was used to fabricate two‐aircraft models, which included stiffening metallic inserts. Testing in a subsonic‐wind tunnel was carried out and the results compared to analytic performance predictions.

Findings

Low‐cost rapid prototypes of wind‐tunnel models yielded satisfactory aerodynamic performance. The savings in acquisition cost and time allowed incorporating actual testing in the aircraft design process within the framework of a tight academic budget and schedule.

Practical implications

Conducting real‐wind‐tunnel testing contributes significantly to the educational experience of students; however, it had rarely been carried out when metal model fabrication was the only option. In contrast, RP facilitates an enhanced and more realistic learning experience by offering a quick and affordable means of model manufacturing.

Originality/value

Simple methods of reinforcing polymer‐based models were incorporated, thus presenting an inexpensive way to test and evaluate preliminary aircraft designs, in both academia and industry.

Details

Rapid Prototyping Journal, vol. 17 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 30 August 2018

Z.W. Teo, T.H. New, Shiya Li, T. Pfeiffer, B. Nagel and V. Gollnick

This paper aims to report on the physical distortions associated with the use of additive manufactured components for wind tunnel testing and procedures adopted to correct…

Abstract

Purpose

This paper aims to report on the physical distortions associated with the use of additive manufactured components for wind tunnel testing and procedures adopted to correct for them.

Design/methodology/approach

Wings of a joined-wing test aircraft configuration were fabricated with additive manufacturing and tested in a subsonic closed-loop wind tunnel. Wing deflections were observed during testing and quantified using image-processing procedures. These quantified deflections were then incorporated into numerical simulations and results had agreed with wind tunnel measurement results.

Findings

Additive manufacturing provides cost-effective wing components for wind tunnel test components with fast turn-around time. They can be used with confidence if the wing deflections could be accounted for systematically and accurately, especially at the region of aerodynamic stall.

Research limitations/implications

Significant wing flutter and unsteady deflections were encountered at higher test velocities and pitch angles. This reduced the accuracy in which the wing deflections could be corrected. Additionally, wing twists could not be quantified as effectively because of camera perspectives.

Originality/value

This paper shows that additive manufacturing can be used to fabricate aircraft test components with satisfactory strength and quantifiable deflections for wind tunnel testing, especially when the designs are significantly complex and thin.

Details

Rapid Prototyping Journal, vol. 24 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 19 January 2015

Chao Wang, Guofu Yin, Zhengyu Zhang, Shuiliang Wang, Tao Zhao, Yan Sun and Dangguo Yang

– The purpose of this paper is to introduce a novel method for developing static aeroelastic models based on rapid prototyping for wind tunnel testing.

Abstract

Purpose

The purpose of this paper is to introduce a novel method for developing static aeroelastic models based on rapid prototyping for wind tunnel testing.

Design/methodology/approach

A metal frame and resin covers are applied to a static aeroelastic wind tunnel model, which uses the difference of metal and resin to achieve desired stiffness distribution by the stiffness similarity principle. The metal frame is made by traditional machining, and resin covers are formed by stereolithgraphy. As demonstrated by wind tunnel testing and stiffness measurement, the novel method of design and fabrication of the static aeroelastic model based on stereolithgraphy is practical and feasible, and, compared with that of the traditional static elastic model, is prospective due to its lower costs and shorter period for its design and production, as well as avoiding additional stiffness caused by outer filler.

Findings

This method for developing static aeroelastic wind tunnel model with a metal frame and resin covers is feasible, especially for aeroelastic wind tunnel models with complex external aerodynamic shape, which could be accurately constructed based on rapid prototypes in a shorter time with a much lower cost. The developed static aeroelastic aircraft model with a high aspect ratio shows its stiffness distribution in agreement with the design goals, and it is kept in a good condition through the wind tunnel testing at a Mach number ranging from 0.4 to 0.65.

Research limitations/implications

The contact stiffness between the metal frame and resin covers is difficult to calculate accurately even by using finite element analysis; in addition, the manufacturing errors have some effects on the stiffness distribution of aeroelastic models, especially for small-size models.

Originality/value

The design, fabrication and ground testing of aircraft static aeroelastic models presented here provide accurate stiffness and shape stimulation in a cheaper and sooner way compared with that of traditional aeroelastic models. The ground stiffness measurement uses the photogrammetry, which can provide quick, and precise, evaluation of the actual stiffness distribution of a static aeroelastic model. This study, therefore, expands the applications of rapid prototyping on wind tunnel model fabrication, especially for the practical static aeroelastic wind tunnel tests.

Details

Rapid Prototyping Journal, vol. 21 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 14 June 2011

Weijun Zhu, Dichen Li, Zhengyu Zhang, Ke Ren, Xinglei Zhao, Dangguo Yang, Wei Zhang, Yan Sun and Yiping Tang

The purpose of this paper is to present a novel method to design and fabricate aeroelastic wing models for wind tunnel tests based on stereolithography (SL). This method…

Abstract

Purpose

The purpose of this paper is to present a novel method to design and fabricate aeroelastic wing models for wind tunnel tests based on stereolithography (SL). This method can ensure the structural similarity of both external and internal structures between models and prototypes.

Design/methodology/approach

An aluminum wing‐box was selected as the prototype, and its natural modes were studied by FEA and scaled down to obtain the desired dynamic behavior data. According to similarity laws, the structurally similar model was designed through a sequential design procedure of dimensional scaling, stiffness optimization and mass optimization. An SL model was then fabricated, and its actual natural modes was tested and compared with the desired data of the prototype.

Findings

The first two natural frequencies of the model presented strong correlation with the desired data of the prototype. Both the external and internal structures of the model matched the prototype closely. The SL‐based method can significantly reduce the total mass and simplify the locating operations of balance‐weights. The cost and time for the fabrication were reduced significantly.

Research limitations/implications

Further investigation into the material properties of SL resins including stiffness and damping behaviors due to layered process is recommended toward higher prediction accuracy. Wind tunnel tests are needed to study the in situ performance and durability of SL models.

Originality/value

Although the paper takes a wing‐box as the study object, structurally similar SL models of entire wings can be obtained conveniently, benefiting from the low‐stiffness material properties of SL resins and the fabrication capacity to build complex structures of SL process. This paper enhances the versatility of using SL and other rapid prototyping processes to fabricate models to predict aeroelastic characteristics of aircraft.

Details

Rapid Prototyping Journal, vol. 17 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 18 January 2011

Yang Dang‐guo, Zhang Zheng‐yu, Sun Yan and Zhu Wei‐jun

In view of the strength and stiffness deficiencies of current photopolymer resin models under high aerodynamic loads, the purpose of this paper is to introduce a…

Abstract

Purpose

In view of the strength and stiffness deficiencies of current photopolymer resin models under high aerodynamic loads, the purpose of this paper is to introduce a preliminary design and manufacturing technique for hybrid lightweight high‐speed wind‐tunnel models with internal metal frame and surface photopolymer resin based on rapid prototyping (RP).

Design/methodology/approach

Internal metal frame structure was designed to be of regular configurations that can be conveniently fabricated by conventionally mechanical manufacturing methods. Outer resin components were designed to meet configuration fidelity and surface quality, which were fabricated by RP apparatus. Combination of aerodynamics and structure was utilized to accomplish structural design, strength and stiffness calibration and vibration analysis. Structural design optimization and manufacturing method of the validated hybrid AGARD‐B models were studied by analysis of manufacturing precision, surface quality processing and mechanical capability.

Findings

The method with internal metal frame and outer resin has dramatically improved the overall strength and stiffness of RP parts of the hybrid AGARD‐B model, and it is suitable to construct the high‐speed wind‐tunnel models with complex internal structure. The method could decrease the model's weight and prevent resonance occurrence among the models, wind‐tunnel and support system, and shorten processing period, and also it leads to decrease in manufacturing period and cost.

Research limitations/implications

Stiffness of thin components for outer resin configuration is somewhat poor under high aerodynamic loads in a high‐speed wind‐tunnel test, and the effect of deformation of the components on the experimental results should be taken into account.

Originality/value

This method can enhance the versatility of using RP technique in the fabrication of high‐speed wind‐tunnel models, especially for experimental models with complex structure. Aerodynamic and structural combination design and structural optimization for hybrid models make RP techniques more practical for manufacturing high‐speed wind‐tunnel models.

Details

Rapid Prototyping Journal, vol. 17 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 11 January 2013

Yang Dang‐guo, Sun Yan, Zhang Zheng‐yu, Wang Chao and Zhu Wei‐jun

The purpose of this paper is to present a novel method to design and manufacture rapid prototyping (RP) lightweight photopolymer‐resin models for wind‐tunnel tests. This…

Abstract

Purpose

The purpose of this paper is to present a novel method to design and manufacture rapid prototyping (RP) lightweight photopolymer‐resin models for wind‐tunnel tests. This method can ensure the structural configuration similarity considering model deformation under aerodynamic loads.

Design/methodology/approach

Photopolymer‐resin based on RP technique was used to fabricate DLR‐F4 models. Testing in a subsonic and transonic wind tunnel was carried out and the test results were compared to analyze performance predictions.

Findings

RP photopolymer‐resin wind‐tunnel models fabricated by the design methods yielded satisfactory aerodynamic performance. The methods can decrease the model's weight and prevent resonance occurrence among the models, wind‐tunnel, and support system, shorten the processing period, and lead to decrease in manufacturing period and cost.

Research limitations/implications

Stiffness shortage of the thin components, such as wing tip, often leads to deformation occurrence under aerodynamic loads in transonic wind‐tunnel tests, which has significant influence on aerodynamic characteristics of the test models. Therefore, model deformation should be taken into account in the design process.

Originality/value

This design and manufacture method, aerodynamic and structural combination design and structural optimization, can obtain RP lightweight photopolymer‐resin wind‐tunnel models for satisfactory aerodynamic performance, which makes RP techniques more practical for manufacturing transonic wind‐tunnel test models, considering deformation induced by aerodynamic forces such as lift force. The methods also present an inexpensive way to test and evaluate preliminary aircraft designs, in both academia and industry.

Article
Publication date: 22 October 2020

Rawad Himo, Charbel Bou-Mosleh and Charbel Habchi

Flow separation on wings, blades and vehicles can be delayed or even suppressed by the use of vortex generators (VG). Numerous studies, documented in the literature…

Abstract

Purpose

Flow separation on wings, blades and vehicles can be delayed or even suppressed by the use of vortex generators (VG). Numerous studies, documented in the literature, extensively describe the performance of triangular and rectangular VG winglets. This paper aims to focus on the use of non-conventional VG shapes, more specifically an array of trapezoildal-perforated VG tabs.

Design/methodology/approach

In this study, computational fluid dynamic simulations are performed on an inline array of trapezoidal VG with various dimensions and inclination angles, in addition to considering perforations in the VG centers. The methodology of the present numerical study is validated with experimental data from the literature.

Findings

The performance and the associated flow structures of these tested non-conventional VG are compared to classical triangular winglets. For the proposed non-conventional trapezoidal VG, at the onset of stall, a 21% increase of lift over drag on the airfoil is observed. The trapezoidal VG enhancement is also witnessed during stall where the lift over drag ratio is increased by 120% for the airfoil and by 10% with respect to the triangular winglets documented in the literature.

Originality/value

The originality of this paper is the use of non-conventional vortex generator shape to enhance lift over drag coefficient using three-dimensional numerical simulations.

Details

Aircraft Engineering and Aerospace Technology, vol. 93 no. 1
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 9 May 2022

E. Livya and S. Nadaraja Pillai

This paper aims to study the extended trailing edge airfoil for a range of angle of attack at different intensities of turbulence.

Abstract

Purpose

This paper aims to study the extended trailing edge airfoil for a range of angle of attack at different intensities of turbulence.

Design/methodology/approach

In this paper, an experimental study on NACA 0020 airfoil with thin extended trailing edge modification of amplitude of h = 0.1c, 0.2c and 0.3c at the Reynolds number of 2.14 × 105 are tested. The research was carried out for an angle of attack ranging from 0° = α = 35° for the turbulence intensity of 0.3%, 3%, 5%, 7% and 12%. From the experimental readings, the surface pressures are scanned using a Scanivalve (MPS2464) pressure scanner for a sampling frequency of 700 Hz. The scanned pressures are converted to aerodynamic force coefficient and the results are combined and discussed.

Findings

The airfoil with the extended trailing edge will convert the adverse pressure gradient to a plateau pressure zone, indicating the delayed flow separation. The CL value at higher turbulence intensity (TI = 12%) for the extended trailing edge over perform the base airfoil at the post-stall region. The maintenance of flow stability is observed from the spectral graph.

Practical implications

A thin elongated trailing edge attached to the conventional airfoil serves as a flow control device by delaying the stall and improving the lift characteristics. Additionally, extending the airfoil's trailing edge helps to manage the performance of the airfoil even at a high level of turbulence.

Originality/value

Distinct from existing studies, the presented results reveals how the extended trailing edge attached to the airfoil performs in the turbulence zone ranging from 0.3% to 12% of TI. The displayed pressure distribution explains the need for increasing trailing edge amplitude (h) and its impact on flow behaviour. The observation is that extended trailing edge airfoil bears to maintain the performance even at higher turbulence region.

Details

Aircraft Engineering and Aerospace Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 18 January 2008

Zhihua Zhou, Dichen Li, Zhengyu Zhang and Junhua Zeng

The purpose of this paper is to develop and present a hybrid design and fabrication method based on rapid prototyping (RP) and electrochemical deposition (ED) techniques…

1186

Abstract

Purpose

The purpose of this paper is to develop and present a hybrid design and fabrication method based on rapid prototyping (RP) and electrochemical deposition (ED) techniques to fabricate a pressure wind‐tunnel model with complex internal structure and sufficient mechanical strength.

Design/methodology/approach

After offsetting inward by applied coating thickness, the airfoil model was modified with three pairs of deflecting control surfaces and 24 surface pressure taps and internal passages. The stereolithography (SL) prototype components were fabricated on SL apparatus and roughened by chemical treatments. And then metal‐coated SL components of the airfoil model were created by ED technique. After assembling, a hybrid pressure airfoil model was obtained.

Findings

Electrodeposited nickel coating has dramatically improved the overall strength and stiffness of SL parts and the hybrid fabrication method is suitable to construct the wind‐tunnel model with complex internal structure and sufficient mechanical strength, stiffness.

Research limitations/implications

Interface adhesion of SL‐coating is poor even if chemical roughening is applied and the further research is needed.

Originality/value

This method enhances the versatility of using RP in the fabrication of functional models, especially when complex structure with sufficient mechanical properties is considered. Although this paper took an airfoil wind‐tunnel model as an example, it is capable of fabricating other functional components with other rapid prototyping techniques such as FDM, SLS and LOM.

Details

Rapid Prototyping Journal, vol. 14 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

1 – 10 of 52