Aeroelastische Windkanalversuche mit flexiblen Tragflügeln bei realen Reynoldszahlen (HIRENASD - ASDMAD)

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1 Aeroelastische Windkanalversuche mit flexiblen Tragflügeln bei realen Reynoldszahlen (HIRENASD - ASDMAD) J. Ballmann Lehr- und Forschungsgebiet für Mechanik (LFM) Beteiligte Institute: Institut für Leichtbau (ilb), federführend im Transferprojekt ASDMAD, Lehrstuhl für Computergestützte Analyse Technischer Systeme (CATS), Stoßwellenlabor (SWL), Institut für Geometrie und Praktische Mathematik (IGPM) Airbus Deutschland - Partner im DFG-Transferprojekt ASDMAD RWTH Aachen J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

2 Motivation Die Entwicklungszeiten für neue Flugzeuge sollen immer kürzer werden. Damit Qualität und Sicherheit dabei weiter verbesserr werden, ist zunehmend Multidisziplinarität in frühen Entwurfsphasen erforderlich. Verfahren zur numerischen Direktsimulation aerostrukturdynamischer Probleme sind für die Entwicklungsarbeit einsetzbar zu machen. Methoden sind durch Windkanalexperimente bei realitätsnahen Reynolds- und Machzahlen abzusichern. Versuche in kryogenen Windkanälen leisten das. Die betreffende Windkanaltechnik erfordert komplexe Modelle aus speziellen Werkstoffen und den Einsatz von Messtechniken, die unter den teuren kryogenen Bedingungen schnell und zuverlässig arbeiten. Durch Förderung des wechselseitigen Austauschs zwischen Hochschulen, Forschungseinrichtungen und Industrie wird das Gelingen der Lösung multidisziplinärer Fragestellungen gefördert. Daraus entstand ein wesentlicher Antrieb für das zentrale DFG-geförderte Projekt HIRENASD des SFB 401 und das daraus entwickelte Transferprojekt ASDMAD. J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

3 Objectives Main objectives of the High Reynolds Number Aero-Structural Dynamics (HIRENASD) project 1. To improve aero-structural dynamics knowledge and to get experimental data in a wide range of wing loads (expressed in terms of q/e) and Reynolds numbers up to the range of large aircraft in cruise, with emphasis on aeroelastic equilibrium configurations aero-structural dynamic processes aerodynamic damping mechanisms unsteady shock/boundary-layer interaction unsteady flow separation 2. To provide experimental data in a data base that is freely accessible to universities for transonic aeroelastic research, modelling enhancement, and validation of aeroelastic and aerodynamic numerical methods as well. J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

4 Outline The European Transonic Windtunnel (ETW) Wind Tunnel Model Assembly Measuring Equipment Test Program and Conduction of Tests Selected Results from Experiments in ETW ---- Static Test Results ---- Dynamic Test Results Conclusions and Outlook J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

5 The European Transonic Windtunnel (ETW) - Fluid temperature: 110K 313K - Pressure: 1.25bar 4.5bar - Fluid: Nitrogen gas - Test section dimensions: Height: 2.0m Width: 2.4m Length: 9.0m J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

6 The European Transonic Windtunnel (ETW) Cruise envelope of present and planned transport A/C Envelope of HIRENASD tests Take-off and landing Independent setting of Ma, Re and model load q/e enables separation of aerodynamic and aeroelastic effects J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

7 The European Transonic Windtunnel (ETW) Wind Tunnel Model Assembly Measuring Equipment Test Program and its conduction Selected Results from the Experiments in ETW ---- Static Test Results ---- Dynamic Test Results Conclusions J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

8 Numerical ASD for Model Design and Predictions After the lessons learnt in the EU-project HiReTT, for model design and test preparation extensive sets of Navier-Stokes based ASD simulations using the package SOFIA developed in SFB 401 have been performed to compute the aerodynamic loads for model design, predict expected wing deformations, analyse the dynamic aeroelastic behavior, e.g. exclude instabilities, optimise the test program, check efficiency of excitation mechanism under wind-on conditions, and perform blind test computations to compare later with experimental data to prove the reliability for ASD prediction using the simulation tool SOFIA J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

9 Views on HIRENASD Wind Tunnel Model J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

10 Wing Model Composed of Two Parts Pressure side part Suction side part Maraging steel: VASCOMAX C-200 E=181,3 GPa, R e =1430 MPa, A=13% (20 C) E=190,3 GPa, R e =1930 MPa, A=11% (-196 C) J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

11 HIRENASD Wind Tunnel Model Assembly J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

12 ASDMAD Modifications of HIRENASD Model Large winglet w/o ACS (ASDMAD1) Winglet with ACS (ASDMAD2) J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

13 The European Transonic Windtunnel (ETW) Wind tunnel Model and Assembly Measuring Equipment Test Program and Conduction of Tests Selected Results from the Experiments in ETW ---- Static Tests ---- Dynamic Tests Conclusions Wind tunnel balance Stereo Pattern Tracking (SPT) Pressure sensors Strain gauges Accelerometers J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

14 Wind Tunnel Balance and Vibration Excitation Mech. No access to wind tunnel test section during tests Due to thermal insulation, space for excitation mechanism is very limited Excitation mechanism integrated in clamping unit J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

15 Stereo Pattern Tracking (SPT) and Accelerometers 48 markers on the lower part (pressure side) of wing model for SPT, spacial accuracy 0.1 mm Positions of accelerometers In the upper (suction side) part of wing model J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

16 Measuring Equipment for Pressure Pressure Sensors: 259 Kulite in-situ pressure sensors are implemented in the wing model, distributed in 7 spanwise sections detailed high frequency measurement of transient pressure field feasible J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

17 HIRENASD Measuring Equipment In-situ pressure sensors and accelerometers Strain gauges J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

18 The European Transonic Windtunnel (ETW) Wind tunnel Model and Assembly Measuring Equipment Test Program and its Conduction Selected Results from the Experiments in ETW ---- Static Test Results ---- Dynamic Test Results Summary HIRENASD test program Ma-Range: Re-Range: q/e-range: Number of steady polars: 51 Number of dynamic tests: 135 Conclusions J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

19 Exemplarische ASDMAD Test-Enveloppe Test-Enveloppe für Ma = 0.8 ASDMAD-Konditionen Nummer der Testreihe q/e- Variation (Flügellast) Re-Variation J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

20 HIRENASD Test Program and Conduction of Tests Envelope of test conditions: Separate variation of Ma, Re, and q/e Re-effects q/e-effect Ma-effect J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

21 The European Transonic Windtunnel (ETW) Wind tunnel Model and Assembly Measuring Equipment Test Program and Conduction of Tests Selected Results from the Experiments in ETW ---- Static Test Results (low pass filtered) ----Dynamic Test Results Conclusions J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

22 Exemplary Result of SPT Measurement and Prediction q/e-variation (small Re variation, fixed transition): Influence on wing deformation (twist at wing tip) Mounted model assembly with markers for high speed Stereo Pattern Tracking (SPT) J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

23 Cp Distributions from Static Test Results, Ma varied Ma-Variation: Influence on pressure distribution 1 Re=23.5 mio. q/e=0.34e-6 alpha=2 7 η=0.14 η=0.95 J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

24 Static Test Results, Reynolds Number Varied Re-Variation: Influence on pressure distribution 1 Ma=0.80 q/e=0.48e-6 alpha=2 7 η=0.14 η=0.95 J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

25 Static Test Results, Reynolds Number Varied Re-Variation: Influence on lift and drag Ma=0.80, q/e=0.48e-6 Increasing Re Δc L ~0.02 J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

26 The European Transonic Windtunnel (ETW) Wind tunnel Model and Assembly Measuring Equipment Test Program and Conduction of Tests Here, the focus is on the following dynamic experiments No. Excitation frequency [Hz] Intended excitation of particular mode Selected Results from the Experiments in ETW ---- Static Test Results ---- Dynamic Test Results Conclusions st bending dominated (1st mode) 2nd bending dominated (2nd mode) st torsion dominated (5th mode) J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

27 Excitation Frequencies from Raw Data of Static Tests Determination of resonance frequency: Maximum effectiveness of excitation mechanism at resonance frequency Resonance frequency depending on flow conditions Determination of frequencies during steady wind tunnel tests from power spectra Accurate determination neccessary due to low aerodynamic damping of higher modes 1 st bending Acc13(1) 2 nd bending 1 st torsion J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

28 Band Filtering Process by Fourier Analysis of Dynamic Measurement Data, e. g. for Exp. 346 Ma=0.85, Re= , q/e= Control voltage of excitation piezo stacks Force meas. elements Excitation piezo stacks Unfiltered Band filtered band width 11 Hz f A = 83.3Hz 2. Bending dominated mode shape Balance force component normal to wing plane J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

29 Band Filtering Process by Fourier Analysis of Dynamic Measurement Data e. g. for Exp. 346 J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

30 Dynamic Test Results from Experiment 270 Results for 1 st bending excitation (Exp. #270): section 7 (η=0.95) Ma= 0.80 Re= 23.5 mio. q/e= 0.48e-6 alpha= f E = 29.1 Hz J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

31 Dynamic Test Results from Experiments 272 and 407 Re-Variation: Influence on unsteady pressure (1 st torsion mode excited, Exp. #272and 407) Note: Distances to resonance frequency may differ and thus cause part of amplitude & phase differences Ma=0.80 q/e=0.48e-6 alpha=-1.34 Re=23.5 mio. section 7 (η=0.95) Re=50.0 mio. J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

32 Conclusions and Outlook Elastic wing model assembly with internal forced vibration technique developed for transonic high Reynolds ASD Design, test program and predictions based on CASD analysis using SOFIA New piezo-electric balance for ASD measurements in ETW Aeroelastic experiments with and without dynamic excitation performed using high frequency measuring techniques with synchronised data acquisition: Root forces, pressure, acceleration, strain recorded with frequencies from 4kHz to 36kHz Static and dynamic transonic measurements in a wide range of parameters Dynamic perturbances in static tests evaluated for subsequent forced vibration near resonance Outlook: DFG-Transfer Project with AIRBUS: Evaluation of ASDMAD 1 experiments and performing experiments with the wing model modified by winglet with ACS (ASDMAD 2) J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

33 HIRENASD Wing Model Modifications Modification No. 2, CASD result for winglet with ACS Re= , q/e= , α=3. Experiments planned for Dec 2010 Modification No.1 in wind tunnel, Experiments performed in Feb o additional sweep J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

34 DFG-Transferprojekt RWTH-Airbus (Winglet 1) Test 2010 abgeschlossen ASDMAD 1 Modell im ETW Schwingendes Modell im Test J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

35 Project Partners Project Partners at Aachen University: Department of Mechanics Institute for Lightweight Structures Institute for Geometry and Applied Mathematics Shock Wave Laboratory Thanks to... German Research Foundation (DFG) for funding HIRENASD Airbus Industry for supporting the balance for dynamic force measurement DLR for advice concerning data acquisition and providing AMIS II ETW for providing windtunnel adaptations, for e.g. dynamic force measurement, and continuous advice during preparation of model and measuring equipment J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,

36 Thank you for your attention! J.Ballmann Wissenschaftstag DLR Institut FA, Braunschweig,