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Article
Publication date: 8 May 2018

Antonio Memmolo, Matteo Bernardini and Sergio Pirozzoli

This paper aims to show results of numerical simulations of transonic flow around a supercritical airfoil at chord Reynolds number Rec = 3 × 106, with the aim of…

Abstract

Purpose

This paper aims to show results of numerical simulations of transonic flow around a supercritical airfoil at chord Reynolds number Rec = 3 × 106, with the aim of elucidating the mechanisms responsible for large-scale shock oscillations, namely, transonic buffet.

Design/methodology/approach

Unsteady Reynolds-averaged Navier–Stokes simulations and detached-eddy simulations provide a preliminary buffet map, while a high fidelity implicit large-eddy simulation with an upstream laminar boundary layer is used to ascertain the physical feasibility of the various buffet mechanisms. Numerical experiments with unsteady RANS highlight the role of waves travelling on pressure side in the buffet mechanism. Estimates of the propagation velocities of coherent disturbances and of acoustic waves are obtained, to check the validity of popular mechanisms based on acoustic feedback from the trailing edge.

Findings

Unsteady RANS numerical experiments demonstrate that the pressure side of the airfoil plays a marginal role in the buffet mechanism. Implicit LES data show that the only plausible self-sustaining mechanism involves waves scattered from the trailing edge and penetrating the sonic region from above the suction side shock. An interesting side result of this study is that buffet appears to be more intense in the case that the boundary layer state upstream of the shock is turbulent, rather than laminar.

Originality/value

The results of the study will be of interest to any researcher involved with transonic buffet.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 28 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 3 June 2020

Mehran Masdari, Maryam Ghorbani and Arshia Tabrizian

The purpose of this paper is to analyze experimentally subsonic wake of a supercritical airfoil undergoing a pitch–hold–return motion. The focus of the investigation has…

Abstract

Purpose

The purpose of this paper is to analyze experimentally subsonic wake of a supercritical airfoil undergoing a pitch–hold–return motion. The focus of the investigation has been narrowed to concentrate on the steadiness of the flow field in the wake of the airfoil and the role of reduced frequency, amplitude and the hold phase duration.

Design/methodology/approach

All experiments were conducted in a low sub-sonic closed-circuit wind tunnel, at a Reynolds number of approximately 600,000. The model was a supercritical airfoil having 10% thickness and wall-to-wall in ground test facilities. To calculate the velocity distribution in the wake of the airfoil, total and static pressures were recorded at a distance of one chord far from the trailing edge, using pressure devices. The reduced frequency was set at 0.012, 0.03 and the motion pivot was selected at c/4.

Findings

Analysis of the steadiness of the wake flow field ascertains that an increase in reduced frequency leads to further flow time lag in the hold phase whereas decreases the time that the wake remains steady after the start of the return portion. Also, the roles of amplitude and stall condition are examined.

Practical implications

Examination of a pitch–hold–return motion is substantial in assessment of aerodynamics of maneuvers with a rapid increase in angle of attack. Moreover, study of aerodynamic behavior of downstream flow field and its steadiness in the wake of the airfoil is vital in drag reduction and control of flapping wings, dynamic stability and control of aircrafts.

Originality/value

In the present study, to discuss the steadiness of the flow field behind the airfoil some statistical methods and concept of histogram using an automatic algorithm were used and a specific criterion to characterize the steadiness of flow field was achieved.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 7
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 6 November 2017

Mojtaba Tahani, Mehran Masdari, Hamidreza Eivazi and Massoud Tatar

This paper aims to investigate numerical solution of transonic flow around NACA0012 airfoil under sinusoidal pitch oscillation. Accordingly, effects of the amplitude and…

Abstract

Purpose

This paper aims to investigate numerical solution of transonic flow around NACA0012 airfoil under sinusoidal pitch oscillation. Accordingly, effects of the amplitude and frequency of oscillations on aerodynamic coefficients are evaluated and the efficiency of the turbulent models, K-ω shear-stress transport (SST), scale adaptive simulation (SAS) and delayed detached eddy simulation (DDES), in simulation of the nonlinear phenomena – i.e. the interaction between shock and boundary layer and the shock oscillations – is studied.

Design/methodology/approach

K-ω SST, SAS and DDES models are used as turbulence approaches. The numerical results are compared with available experimental and numerical information.

Findings

According to the results inside the buffet boundaries, the DDES turbulent model expresses results that are more appropriate; however, SAS and SST models are not efficient enough in evaluating the characteristics of nonlinear flow.

Originality/value

In this research study, hybrid RANS-LES turbulence model is engaged to simulate transonic flow around pitching NACA0012 airfoil, and results are compared to the SAS and Reynolds Average Navier–Stocks simulations as well as available numerical and experimental data. In addition, effects of the amplitude and frequency of oscillations on aerodynamic coefficients are evaluated in buffet regions.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 27 no. 11
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 28 May 2021

M.R. Saber and M.H. Djavareshkian

In the present research, the effect of the flexible shells method in unsteady viscous flow around airfoil has been studied. In the presented algorithm, due to the…

Abstract

Purpose

In the present research, the effect of the flexible shells method in unsteady viscous flow around airfoil has been studied. In the presented algorithm, due to the interaction of the aerodynamic forces and the structural stiffness (fluid-structural interaction), a geometrical deformation as the bump is created in the area where the shock occurs. This bump causes instead of compressive waves, a series of expansion waves that produce less drag and also improve the aerodynamic performance to be formed. The purpose of this paper is to reduce wave drag throughout the flight range. By using this method, we can be more effective than recent methods throughout the flight because if there is a shock, a bump will form in that area, and if the shock does not occur, the shape of the airfoil will not change.

Design/methodology/approach

In this simulation pressure-based procedure to solve the Navier-Stokes equation with collocated finite volume formulation has been developed. For this purpose, a high-resolution scheme for fluid and structure simulation in transonic flows with an arbitrary Lagrangian-Eulerian method is considered. To simulate Navier-Stokes equations large eddy simulation model for compressible flow is used.

Findings

A new concept has been defined to reduce the transonic flow drag. To reduce drag force and increase the performance of airfoil in transonic flow, the shell can be considered flexible in the area of shock on the airfoil surface. This method refers to the use of smart materials in the aircraft wing shell.

Originality/value

The value of the paper is to develop a new approach to improve the aerodynamic performance and reduce drag force and the efficiency of the method throughout the flight. It is noticeable that the new algorithm can detect the shock region automatically; this point was disregarded in the previous studies. It is hoped that this research will open a door to significantly enhance transonic airfoil performance.

Details

Aircraft Engineering and Aerospace Technology, vol. 93 no. 4
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 8 May 2018

Chawki Abdessemed, Yufeng Yao, Abdessalem Bouferrouk and Pritesh Narayan

The purpose of this paper is to use dynamic meshing to perform CFD analyses of a NACA 0012 airfoil fitted with a morphing trailing edge (TE) flap when it undergoes static…

Abstract

Purpose

The purpose of this paper is to use dynamic meshing to perform CFD analyses of a NACA 0012 airfoil fitted with a morphing trailing edge (TE) flap when it undergoes static and time-dependent morphing. The steady CFD predictions of the original and morphing airfoils are validated against published data. The study also investigates an airfoil with a hinged TE flap for aerodynamic performance comparison. The study further extends to an unsteady CFD analysis of a dynamically morphing TE flap for proof-of-concept and also to realise its potential for future applications.

Design/methodology/approach

An existing parametrization method was modified and implemented in a user-defined function (UDF) to perform dynamic meshing which is essential for morphing airfoil unsteady simulations. The results from the deformed mesh were verified to ensure the validity of the adopted mesh deformation method. ANSYS Fluent software was used to perform steady and unsteady analysis and the results were compared with computational predictions.

Findings

Steady computational results are in good agreement with those from OpenFOAM for a non-morphing airfoil and for a morphed airfoil with a maximum TE deflection equal to 5 per cent of the chord. The results obtained by ANSYS Fluent show that an average of 6.5 per cent increase in lift-to-drag ratio is achieved, compared with a hinged flap airfoil with the same TE deflection. By using dynamic meshing, unsteady transient simulations reveal that the local flow field is influenced by the morphing motion.

Originality/value

An airfoil parametrisation method was modified to introduce time-dependent morphing and used to drive dynamic meshing through an in-house-developed UDF. The morphed airfoil’s superior aerodynamic performance was demonstrated in comparison with traditional hinged TE flap. A methodology was developed to perform unsteady transient analysis of a morphing airfoil at high angles of attack beyond stall and to compare with published data. Unsteady predictions have shown signs of rich flow features, paving the way for further research into the effects of a dynamic flap on the flow physics.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 28 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 30 October 2007

Nikolaos Kehayas

A review is attempted with the objective to indicate the most promising aeronautical technology for application to future subsonic civil transport aircraft.

Abstract

Purpose

A review is attempted with the objective to indicate the most promising aeronautical technology for application to future subsonic civil transport aircraft.

Design/methodology/approach

A methodology is put forward, according to which direct operating costs (DOC) are examined in order to identify those that can be reduced, and, then, specific technology is assessed in relation to its efficiency in reducing these DOC, operational feasibility and cost‐effectiveness.

Findings

This assessment suggests the selection of propfan and powered lift as the leading future aeronautical technology. These findings are supported by a comparison of a number of advanced technology designs.

Originality/value

Provides a starting point for further investigation of advanced aeronautical technology and unconventional configurations for large subsonic civil transport aircraft.

Details

Aircraft Engineering and Aerospace Technology, vol. 79 no. 6
Type: Research Article
ISSN: 0002-2667

Keywords

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Article
Publication date: 21 March 2019

Huan Zhao and Zhenghong Gao

The high probability of the occurrence of separation bubbles or shocks and early transition to turbulence on surfaces of airfoil makes it very difficult to design…

Abstract

Purpose

The high probability of the occurrence of separation bubbles or shocks and early transition to turbulence on surfaces of airfoil makes it very difficult to design high-lift and high-speed Natural-Laminar-Flow (NLF) airfoil for high-altitude long-endurance unmanned air vehicles. To resolve this issue, a framework of uncertainty-based design optimization (UBDO) is developed based on an adjusted polynomial chaos expansion (PCE) method.

Design/methodology/approach

The γ ̄Re-θt transition model combined with the shear stress transport k-ω turbulence model is used to predict the laminar-turbulent transition. The particle swarm optimization algorithm and PCE are integrated to search for the optimal NLF airfoil. Using proposed UBDO framework, the aforementioned problem has been regularized to achieve the optimal airfoil with a tradeoff of aerodynamic performances under fully turbulent and free transition conditions. The tradeoff is to make sure its good performance when early transition to turbulence on surfaces of NLF airfoil happens.

Findings

The results indicate that UBDO of NLF airfoil considering Mach number and lift coefficient uncertainty under free transition condition shows a significant deterioration when complicated flight conditions lead to early transition to turbulence. Meanwhile, UBDO of NLF airfoil with a tradeoff of performances under both fully turbulent and free transition conditions holds robust and reliable aerodynamic performance under complicated flight conditions.

Originality/value

In this work, the authors build an effective uncertainty-based design framework based on an adjusted PCE method and apply the framework to design two high-performance NLF airfoils. One of the two NLF airfoils considers Mach number and lift coefficient uncertainty under free transition condition, and the other considers uncertainties both under fully turbulent and free transition conditions. The results show that robust design of NLF airfoil should simultaneously consider Mach number, lift coefficient (angle of attack) and transition location uncertainty.

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Article
Publication date: 26 February 2019

Corrado Groth, Emiliano Costa and Marco Evangelos Biancolini

Numerical simulation of icing has become a standard. Once the iced shape is known, however, the analyst needs to update the computational fluid dynamics (CFD) grid. This…

Abstract

Purpose

Numerical simulation of icing has become a standard. Once the iced shape is known, however, the analyst needs to update the computational fluid dynamics (CFD) grid. This paper aims to propose a method to update the numerical mesh with ice profiles.

Design/methodology/approach

The present paper concerns a novel and fast radial basis functions (RBF) mesh morphing technique to efficiently and accurately perform ice accretion simulations on industrial models in the aviation sector. This method can be linked to CFD analyses to dynamically reproduce the ice growth.

Findings

To verify the consistency of the proposed approach, one of the most challenging ice profile selected in the LEWICE manual was replicated and simulated through CFD. To showcase the effectiveness of this technique, predefined ice profiles were automatically applied on two-dimensional (2D) and three-dimensional (3D) cases using both commercial and open-source CFD solvers.

Practical implications

If ice accreted shapes are available, the meshless characteristic of the proposed approach enables its coupling with the CFD solvers currently supported by the RBF4AERO platform including OpenFOAM, SU2 and ANSYS Fluent. The advantages provided by the use of RBF are the high performance and reliability, due to the fast application of mesh smoothing and the accuracy in controlling surface mesh nodes.

Originality/value

As far as authors’ knowledge is concerned, this is the first time in scientific literature that RBF are proposed to handle icing simulations. Due to the meshless characteristic of the RBF mesh morphing, the proposed approach is cross solver and can be used for both 2D and 3D geometries.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 4
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 2 January 2020

Abderahmane Marouf, Yannick Bmegaptche Tekap, Nikolaos Simiriotis, Jean-Baptiste Tô, Jean-François Rouchon, Yannick Hoarau and Marianna Braza

The purpose of this study illustrates the morphing effects around a large-scale high-lift configuration of the Airbus A320 with two elements airfoil-flap in the take-off…

Abstract

Purpose

The purpose of this study illustrates the morphing effects around a large-scale high-lift configuration of the Airbus A320 with two elements airfoil-flap in the take-off position. The flow around the airfoil-flap and the near wake are analysed in the static case and under time-dependent vibration of the flap trailing-edge known as the dynamic morphing.

Design/methodology/approach

Experimental results obtained in the subsonic wind tunnel S1 of Institut de Mécanique des Fluides de Toulouse of a single wing are discussed with high-fidelity numerical results obtained by using the Navier–Stokes multi-block (NSMB) code with advanced turbulent modelling able to capture the predominant instabilities and coherent structure dynamics. An explanation of the dynamic time-dependent grid deformation is provided, which is used in the NSMB code to simulate the flap’s trailing-edge deformation in the morphing configuration. Finally, power spectral density is performed to reveal the coherent wake structures and their modification because of the morphing.

Findings

Frequency of vibration and amplitude of deformation effects are investigated for different morphing cases. Optimal morphing regions at a specific frequency and a slight deformation were able to attenuate the predominant natural shear-layer frequency and to considerably decrease the width of the von Kármán vortices with a simultaneous increase of aerodynamic performances.

Originality/value

The new concept of future morphed wings is proposed for a large scale A320 prototype at the take-off position. The dynamic morphing of the flap’s trailing-edge is simulated for the first time for high-lift two-element configuration. In addition, the wake analysis performed helped to show the turbulent structures according to the organised eddy simulation model.

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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Article
Publication date: 1 July 1980

IAN S. MACDONALD

This article seeks to discuss some of the many technical and operational changes that will soon be taking place in the advancing world of commercial aviation.

Abstract

This article seeks to discuss some of the many technical and operational changes that will soon be taking place in the advancing world of commercial aviation.

Details

Aircraft Engineering and Aerospace Technology, vol. 52 no. 7
Type: Research Article
ISSN: 0002-2667

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