Towards understanding of wake vortex evolution during approach and landing with and w/o plate lines F. Holzäpfel 1, A. Stephan 1, T. Misaka 1,2, S. Körner 1 1 Institut für Physik der Atmosphäre, DLR, Oberpfaffenhofen, Germany 2 Tohoku University, Institute of Fluid Science, Sendai, Japan new method: LES from roll-up to final decay application: cruise, approach and landing considered effects: ground effect, end effect & plate line measurement campaign: enhanced WV decay triggered by plate line Vortragstitel 3
why approach & landing? highest risk to encounter WV in ground proximity: physics: WV cannot descend below glide path rebound lidar, LES: WV may live much longer than 2 min (5 NM) NATS incident reporting: most encounters in ground proximity CDG airport: 3% WV closer than 25 m to follower a/c at threshold (V. Treve) analysis of WSVBS: 57 70% of lowest gates impede reduced separations (AIAA Paper 2011-3037) possibilities to recover limited by low altitude potentially critical situation Why is approach and landing safe under these conditions? Can we actively promote WV decay in ground proximity? answers crucial for design of optimal WVAS
bridging near- and far-field simulations en route wake initialization approach: sweeping a high-fidelity RANS flow field through LES computational domain effects of ambient turbulence and aircraft geometry can be considered e*=0.01, N*=0.0 e*=0.01, N*=0.35 Red: ω * =250, blue: ω* = 65
wake initialization RANS flow field swept through LES domain with transition function used in LES as forcing term (Fortified Solution Algorithm, Nudging technique) y f(y,a,b) LES RANS
turbulence transfer boundary conditions white noise added in transition region of RANS and LES with white noise without white noise slice-wise shift generates periodic domain after wake initialization AIAA Paper 2013-0362
Axial Vorticity RANS from axial RANS vorticity Simulation (DLR TAU-Code) outboard flap vortices, wingtip vortices and vortices from wing-fuselage junction persist after half wingspan outboard nacelle inboard nacelle outboard flap-tip wingtip wingfuselage junction
comparison with wind tunnel data horizontal velocity profiles across flap-tip vortex center x/b=0.5 x/b=1.0 x/b=1.4 vertical velocity profiles x/b=0.5 x/b=1.0 x/b=1.4 horizontal and vertical velocities agree well with those of wind tunnel Institut experiments für Physik der Atmosphäre, especially Oberpfaffenhofen at x/b=1.4
decay mechanism in ground proximity with obstacle AIAA Paper 2012-2672 1. early detachment of strong Ω-shaped secondary vortices 2. Ω shape causes self-induced fast approach to PV 3. after SV has looped around PV it separates and travels along the primary vortex (again driven by self induction) 4. the dedicated SV connects to the regular ground effect vortex and thus obtains continued supply of energy 20 s 0.76 28 s 1.06 36 s 1.37 5. highly intense interaction of PV and SVs leads to rapid WV decay independent from natural external disturbances 44 s 1.67
key mechanisms (with and w/o obstacles) 2. Ω shape causes self-induced fast approach to primary vortex (PV) 3. after SV has looped around PV it separates and travels along the PV (again driven by self induction)
possible arrangement of plate lines at runway tail (Munich airport) http://www.youtube.com/watch?v=ppuftg_mxg8
LES landing aircraft with end effect & plate line
circulation decay with end effect w/o plate line with plate line Γ 5-15 * Γ 5-15 * Γ 5-15 * r c *
Propagation speed of the disturbance helix propagation speed scaling using ring approximation ring speed formula:
WakeMUC 779 landings height above ground vortex separation
WakeMUC 779 landings height above ground circulation vortex separation 2.8 < z 0 < 3.2
WakeMUC 779 landings height above ground circulation vortex separation 2.6 < z 0 < 2.8
WakeMUC 779 landings height above ground circulation vortex separation 2.4 < z 0 < 2.6
WakeMUC 779 landings height above ground circulation vortex separation 2.2 < z 0 < 2.4
WakeMUC 779 landings height above ground circulation vortex separation 2.0 < z 0 < 2.2
WakeMUC 779 landings height above ground circulation vortex separation 1.8 < z 0 < 2.0
WakeMUC 779 landings height above ground circulation vortex separation 1.6 < z 0 < 1.8
WakeMUC 779 landings height above ground circulation vortex separation 1.4 < z 0 < 1.6
WakeMUC 779 landings height above ground circulation vortex separation 1.2 < z 0 < 1.4
WakeMUC 779 landings height above ground circulation vortex separation 1.0 < z 0 < 1.2
WakeMUC 779 landings height above ground circulation vortex separation 0.8 < z 0 < 1.0
WakeMUC 779 landings height above ground circulation vortex separation 0.4 < z 0 < 0.8 accelerated decay at low altitudes end effects?
WakeOP-GE flight experiment with HALO at airport Oberpfaffenhofen purpose: demonstrate functionality of plate line patent DE 10 2011 010 147 74 overflights at airport Oberpfaffenhofen 4 flights each 1.5 h flight altitude b 0 22 m above ground HALO heavy and slow (landing with MLW) strong WV high-lift configuration, landing gear deployed HALO instrumentation: avionic data, nose boom, 4 cameras weather impact minimized by folding away plates alternatingly weak wind & turbulence, poor visibility Lidar measurements from Falcon hangar 2 ultrasonic anemometers with microphones smoke visualization documented by video and photo
WakeOP-GE Lidar HALO USA 10 +1 m NDB 9,6 m USA 2 m Plate Line
WakeOP-GE plate line
WakeOP-GE impression
WakeOP-GE smoky vortices lidar data processing is pending smoke visualization indicates good functionality of plate line flight experiment with combined end effect and plate line planned for 2015
Conclusions combined RANS LES method enables simulation from roll-up to decay vortex merger & roll-up, wake turbulence, velocity profiles, core radii, vortex separation, decay rate in diffusion phase, lidar & simulation data indicate that end effects trigger rapid vortex decay & core radius growth plate lines accelerate decay & interfere favorably with end effects WakeOP-GE data processing will hopefully confirm functionality of plate line found in numerical and lab data