Joubert G.,ONERA |
Pape A.L.,German Aerospace Center |
Heine B.,University of Poitiers |
Heine B.,Institute of Aerodynamics and Flow Technology |
Huberson S.,CNRS Pprime Institute
AIAA Journal | Year: 2013
An OA209 airfoil equipped with an innovative deployable vortex generator device is investigated through static stall numerical simulations. Computations are performed by solving the Reynolds Averaged Navier-Stokes equations with the elsA code, which is developed by the Office National d'Etudes et de Recherche Aérospatiale-the French Aerospace Lab. Deployable vortex generator computations are compared to a wide set of experimental data, and the actuator effect on the airfoil boundary layer is highlighted. Detailed flow analysis provides an understanding of the vortex generation mechanisms, and the influence of initial vortex interactions and merging over the control effect is shown. The influence of the deployable vortex generator thickness on static stall control efficiency is finally investigated through simulations featuring a deployable vortex generator of reduced thickness. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
Perraud J.,ONERA |
Archambaud J.-P.,ONERA |
Schrauf G.,Airbus |
Donelli R.,Italian Aerospace Research Center |
And 9 more authors.
48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition | Year: 2010
With the goal of studying Natural Laminar Flow (NLF) wings for future 'green' transport aircraft, the aim of the European Research Project TELFONA is to develop and demonstrate the possibility of testing full aircraft models with NLF wings at large Reynolds numbers in the cryogenic Wind Tunnel ETW. Two main steps were defined, first the design and test of a 'calibration' model, to be followed by a realistic transport aircraft model. This paper is dedicated to the first one, which was especially designed in order to allow a calibration of the Wind Tunnel transition N-factors at large values of the chord Reynolds number typical of testing in ETW. The paper will describe these different phases of the activities, from design, testing and numerical validation, with a focus on the validation and calibration of transition prediction tools. Examples of numerical results obtained by the project partners will be confronted to the experiments. Copyright © 2010 by ONERA.
Yin J.,German Aerospace Center |
Yin J.,Institute of Aerodynamics and Flow Technology |
Stuermer A.,German Aerospace Center |
Stuermer A.,Institute of Aerodynamics and Flow Technology |
And 2 more authors.
Journal of Aircraft | Year: 2012
In this paper, the aeroacoustic phenomena characteristic of a pusher-propeller configuration and their aerodynamic causes are discussed and analyzed. The work was done in the framework of the European-funded projectCESAR(for 'cost effective small aircraft'). The configuration under study is based on an industrially relevant business aircraft design with a wing-mounted pusher propeller, which features a close coupling of the turboshaftengine exhaust nozzles and a five bladed propeller. An established numerical analysis approach is applied in this study, which couples a high-fidelity unsteady aerodynamic simulation using theDLRunstructured finite volume flow solver (TAU) code with theDLRFfowcs-Williams-Hawkings code APSIM for a subsequent aeroacoustic evaluation. A detailed analysis of the contributions of various components of the installation as well as flight-condition specific parameters toward the overall noise generation by the propeller is presented, which highlights the dominant role the engine-jet impingement on the propeller plays for the aeroacoustic characteristics of this type of aircraft configuration. A detailed analysis of specific aspects of the input surface used for the aeroacoustic analysis is made through a comparison between the results achieved using both impermeable and permeable Ffowcs-Williams- Hawkings formulations. The numerical error due to both jet exhaust and propeller wake impingement on the Ffowcs-Williams-Hawkings permeable surface as well as the impact of cutting a hole in this permeable surface to avoid possible issues of these effects are discussed. Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc.
Imiela M.,German Aerospace Center |
Imiela M.,Institute of Aerodynamics and Flow Technology |
Wienke F.,German Aerospace Center |
Wienke F.,Institute of Aeroelasticity |
And 8 more authors.
33rd Wind Energy Symposium | Year: 2015
Reliable predictions for wind turbines become more and more difficult with the increase in overall size and weight. On the one hand external factors such as the influence of wind shear become more important for bigger turbines, internal factors such as structural layout and challenges in the manufacturing process need to be addressed on the other hand. Accurate aerodynamic simulations are an essential requirement for further analyses of aeroelastic stability and aeroacoustic footprint. While the calculations in all of these individual disciplines are challenging the combined simulation of all these disciplines, namely the multidisciplinary simulation is a tough but gainful undertaking. This task is being addressed in the DLR project MERWind which will be presented here. The focus of the paper lays on the aerodynamic and aeroelastic simulation of the NREL 5MW wind turbine using high-fidelity methods. © 2015, American Institute of Aeronautics and Astronautics Inc. All rights reserved.
Rudnik R.,German Aerospace Center |
Rudnik R.,Institute of Aerodynamics and Flow Technology |
Huber K.,German Aerospace Center |
Huber K.,Institute of Aerodynamics and Flow Technology |
And 2 more authors.
30th AIAA Applied Aerodynamics Conference 2012 | Year: 2012
The paper describes the experimental evidence for the DLR-F11 high lift configuration to be used within the context of the 2nd phase of the AIAA High Lift Prediction Workshop. The model geometry is representative for a wide-body commercial aircraft. For the present purpose a wing/body combination is considered with a continuous slat and flap system in landing setting. Slat and flap are intersecting with the fuselage in order to suppress side edge interference effects and their aerodynamic impact on maximum lift. A CAD model in various degrees of detail has been refurbished, serving as the common geometrical basis for the scheduled CFD investigations. Experimental data of the European project EUROLIFT for low and high Reynolds number conditions have been made available, making use of the same wind tunnel model. The data for low Reynolds numbers have been gathered in the Low Speed Wind Tunnel of Airbus in Bremen, B-LSWT, Germany, while the high Reynoldsnumber data have been measured in the European Transonic Windtunnel, ETW, under cryogenic conditions. The Reynolds numbers between both datasets differ by an order of magnitude. In addition to force and moment data, which are available from both wind tunnel tests, a comprehensive validation database is available of the tests in the B-LSWT. The experimental data comprise oil flow pictures, transition information by hotfilms and infrared thermography, as well as PIV velocity data in various locations of the F11 configuration for a sample of angles of attack up to and beyond maximum lift. The main features of the experimental evidence are analyzed, comparing pressures and forces for low and high Reynolds number conditions. Examples of the oil flow pictures, transition information, and off-body velocity data are presented and briefly discussed. © 2012 by Ralf Rudnik.
Raffel M.,German Aerospace Center |
Raffel M.,Institute of Aerodynamics and Flow Technology |
AIAA Journal | Year: 2014
Recent interest has focused on applying image-based measurements to problems encountered in rotating blade aerodynamics. Because optimum image sharpness with conventional lens arrangements can only be obtained when object plane and image plane are parallel, out-of-plane imaging can occur, if oblique viewing is required. For constant rotational frequencies of the rotor under investigation, the mirror rotational frequency can be controlled sufficiently accurate with a high-precision function generator connected to the stepper motor. A digital controller based on a phase-locked loop design can alternatively be used to ensure fixed-phase relation of the mirror and the rotating blade. In addition to that, a small surface defect can be seen at approximately half-radius as a white dot. Recording was made via the mirror with the mirror surface being horizontal and the axis of the mirror being coincident with the fan axis. The line at the leading edge depicts the location at which the intensity of the image has been measured.
Da Ronch A.,University of Liverpool |
Da Ronch A.,University of Southampton |
McCracken A.J.,University of Liverpool |
Badcock K.J.,University of Liverpool |
And 3 more authors.
Journal of Aircraft | Year: 2013
Dynamic derivatives are used to represent the influence of the aircraft motion rates on the aerodynamic forces and moments needed for studies of flight dynamics. The use of computational fluid dynamics has potential to supplement costly wind-tunnel testing. The paper considers the problem of the fast computation of forced periodic motions using the Euler equations. Three methods are evaluated. The first is computation in the time domain, which provides the benchmark solution in the sense that the time-accurate solution is obtained. Two acceleration techniques in the frequency domain are compared. The first uses a harmonic solution of the linearized problem, referred to as the linear frequency-domain approach. The second uses the harmonic balance method, which approximates the nonlinear problem using a number of Fourier modes. These approaches are compared for the ability to predict dynamic derivatives and for computational cost. The NACA 0012 aerofoil and the DLR-F12 passenger jet wind-tunnel model are the test cases. Compared to time-domain simulations, an order of magnitude reduction in computational costs is achieved and satisfactory predictions are obtained for cases with a narrow frequency spectrum and moderate amplitudes using the frequency-domain methods. © 2012 by Ernesto Benini.