Gebhardt, Anna

Hue, David

Minervino, Mauro

Prachar, Ales

Vrchota, Petr

Wallin, Stefan

Wild, Jochen

Institute of Transport Research:Publications

Coordinator : Martin WahlichAirbus Deutschland GmbHWP Leader: Michael Meyer (Airbus Group)DESIGN OF ACTIVE FLOW CONTROL AT THE WING/PYLON/ENGINE JUNCTIONA. PRACHAŘ, P. VRCHOTA / VZLUA. GEBHARDT, J. WILD / DLRS. WALLIN / KTHD. HUE / ONERAM. MINERVINO / CIRAOutline➢ Motivation➢ Baseline geometry and flow➢ Pulsed blowing actuation➢ Synthetic jet actuation➢ Full aircraft scale evaluation➢ Summary and conclusionsMOTIVATIONMotivationground clearancecutout➢Modern transport aircraft configuration with engines mounted under the wing➢Further increase of the aircraft efficiency with Ultra High Bypass Ratio (UHBR) engines➢Larger nacelle diameter➢Problem with ground clearance➢Heavy landing gear extension➢Closer coupling of engine and wing➢leading edge high-lift devices blocked by the engine nacelle➢Cutout of leading edge high-lift devices in the wake of the nacelleMotivation➢Separation in the wake of the nacelle triggers the total wing stall which limits the CL,max➢CL,max is a sizing parameter of the high-lift system➢Heavy high-lift system counteracts benefit by UHBR➢Local separation can be suppressed by active flow control➢CL,max increases which allows a downsizing of the high-lift system➢Increase of overall aircraft efficiency by local application of active flow controlnacelle-wake separationactuatorsCLCL,maxCL,maxangle of attackPotential of active flowcontrolBASELINE GEOMETRY AND FLOWWind Tunnel Geometry➢ Full scale 2.5D model➢ UHBR nacelle with strake➢ Wing span: 5.8m➢ Chord: 3.29m➢ DLR F15-profile➢ Sweep angle: 28°➢ Landing configuration➢ M=0.2➢ ISA condition on MSL ➢ Re=15x106Through-flow nacelle, UHBR sizeSide platesstrakeslatSlat cutoutslatSingle slotted flap (not visible)Realistic vs. Wind tunnel configuration➢ Vortex structure depends on the level of simplification➢ Separated areas similar – from pylon axis inboard➢ Mirrored!Baseline Configuration Vortices Separation areasRealistic ConfigurationResults: Baseline Flow➢Vortices at pre-stall conditions➢made visible with the λ2-criteria➢Sense of rotation made visible with ωxPULSED BLOWING➢Pulsed jet actuators➢Air injected➢Design parameter of the actuators➢Slit size➢Number of actuators➢Blow velocity➢Pulse frequency➢Blowing direction➢Position of the actuators➢Position of the strake➢Very large parameter spacePossible positions of the actuatorsPJA - design problemAnalysed Configuration➢ 7 actuators at the inboard side of the nacelle-wing-junction, total required massflow with pulsed operation: 0.6 to 0.9 kg/s➢ Yaw angle: 0°➢ Blow angle against the surface 30°: Must be high to reach the freeflow to enable the mixing of the boundary layer with the free streamflowActive Flow Control➢ Active flow control  Active flow separation control is the active manipulation of the kinetic energy of the boundary layer ➢ Steady blowing directly increases the kinetic energy of the boundary layer➢ Pulsed blowing induces vortices which transfer free stream momentum to the boundary layer➢ Unsteady blowing can achieve same effect as steady blowing with less air flowVelocity-profilewith active flowcontrolVelocity-profile ofthe baselinePulsed Blowing Results: Blowing Velocity➢ Exit velocity of 272m/s leads to a suppression of the nacelle-wake-separation➢ The introduced impulse with the actuator exit velocity of 200m/s isnot sufficient for the suppression of the flow separationUj=200m/s (dm/dt=0.62kg/s), f=60Hz Uj=272m/s (dm/dt=0.84kg/s) , f=60Hz SYNTHETIC JET ACTUATIONSynthetic jet actuation➢ Synthetic jet – zero net mass flux➢ No need for pressure source, electricity driven➢ Suction of air from BL, return with higher energy➢ CFD➢ Simulated by mass flow inlet/outlet BC➢ Switching between MF I/O is controlled by step or harmonic function➢ Peak velocity and frequency➢ Sonic velocity at the boundary is limit for the BC  peak velocitySynthetic jets, set-up➢ Circular actuator➢ Actuator’s area 5mm2➢ Pitch angle 30deg➢ Cavity physically modelled➢ Five configurations➢ Actuators in two rows➢ between the inboard slat and pylon nacelle’s axis➢ 1st row is located at 0.01%c, 85 actuators➢ 2nd row is placed 0.021%c, 84 actuators➢ placed in cascade➢ One row of actuators➢ Three modifications of two rows of actuators➢ Based on structure of vortices17Results – SJA➢ Effect of SJA on CL and flow separation➢ Two rows of actuators➢ Actuation frequency  100Hz➢ Peak velocity Vj = 150m/s➢ Stall angle delayed by about 2 deg➢ CL,max improved by about 8 lc18AoAResults – SJA frequency➢ One AoA (CL,max)➢ Cm and frequency effect➢ One row of actuators➢ Cm to one half compared to two rows➢ Actuation frequency preserved - 100Hz➢ CL decreased by about 6lc➢ Frequency increased➢ From 100Hz to 1kHz ➢ CL increased by about 3lc19Cm = 0.0252%, f=100Hz Cm = 0.0127%, f=100Hz Cm = 0.0127%, f=1kHzFULL AIRCRAFT SCALE EVALUATIONGeometry and grids➢ Realistic configuration➢ Structured Overset grid (ca 70 mil cells)AFC setups➢ Steady and pulsed jet blowing slots➢ Variation of slot width (2-6 mm)➢ Jet outlet velocity ➢ Influence Cμ➢ Pulsed jet blowing➢ f=60 Hz, Phase shift➢ Reduced Cμ compared to steady blowing23Results of Steady blowing calculations➢ Effect of Cμ and grid refinement24Selected cases for URANS calculations➢ From RANS with steady blowing to URANSResults of URANS calculations➢ Differences at the stall region – (U)RANS bls., CB / PJ) SUMMARY AND CONCLUSIONSSummary and Conclusions➢ CFD tools in theory➢ Provide insight into flow behaviour, vortex structure, separation areas➢ Parametric studies➢ Promising results in terms of separation reduction, CL,max increment➢ Practical issues➢ Lenghty unsteady calculations➢ Gap between time scales related to the aircraft and to the AFC➢ Results close to stall - needs to be verified by experimentTHANK YOU FOR YOUR ATTENTION!The presented results & the research leading to these results have received funding from the European Community's Seventh Framework ProgrammeFP7/2007-2013, under grant agreement n° 604013, AFLONEXT project

Design of Active Flow Control at the Wing/Pylon/Engine Junction

http://elib.dlr.de/118811/1/AFLoNext_CEAS2017_AFCWingPylonEngine_VZLU_DLR_KTH_ONERA_CIRA.pdf

Design of Active Flow Control at the Wing/Pylon/Engine Junction

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