FLOW CONTROL APPLIED TO OUTER WING SLAT-EDGE PROBLEM: CFD & EXPERIMENT IAP 30 March 2017 Tel-Aviv University (TAU) IAI: I. Detinis, M. Steinbuch, S. Segal TAU: M. Lagutin & A. Seifert This study is part of the AFLONEXT FP7-EU project Monitored by M. Whalich/Airbus ISCFDC LTD & TAU AerolabTeam Classification-Unclassified
Problem: Slat Ends at Wingtip Slat has to be straight Can not extend to the wingtip. Outer part exposed to flow separation. The remedy to the problem is to use Active Flow Control (AFC) on wingtip to eliminate flow separation. Can lead to 2% Fuel savings NO Flow Separation Protected by slats Flow Separation No protection by slats IAP 30 March 2017 Classification-Unclassified 2
Current High-lift Systems High Lift Leading Edge & Trailing Edge devices Flaps Increases lift at high Angles of Attack Slats Delays stall at high Angles of Attack IAP 30 March 2017 Classification-Unclassified 3
General-Geometry Definition To study the effect of AFC, a generic wing similar to large plane outer wing at high-lift conditions was defined 25º Swept back wing based on airfoil designed by IAI (supercritical) Deflected slat section 20º Deflected flap unprotected wingtip IAP 30 March 2017 Classification-Unclassified 4 4
Vortices and Tip Stall AoA=17 AoA=18 AoA=19 The wingtip stalls because vortices shed from slat edge and wingtip merge IAP 30 March 2017 Classification-Unclassified 5 5
Compare Suction to Blowing AoA=19 ;wo W/T walls No AFC AoA=19 ;w/o W/T walls (Suction) 3 Slots@Vj=-40[m/sec] P=50KPa No AFC: The wingtip is separated. 3 slots (suction):there is no wingtip separation. 25 slots(blowing):the wingtip is separated. Single slot(blowing):there is no wingtip separation. 3 slots; suction Vj=-40[m/sec] AoA=19 1 slot; Vj=200[m/sec] AoA=19 ;w/o W/T walls (Blowing) 25 Slots@Vj=200[m/sec] P=100KPa AoA=19 ;w/o W/T walls (Blowing) 1 Slot@Vj=200[m/sec] P=100KPa No AFC 25slots; Vj=200[m/sec] Suction has same effect as blowing at 1/5th magnitude IAP 30 March 2017 Classification-Unclassified 6
Indeed Cost of Suction Lower for Same benefit Single slot blowing better than 25 slots blowing 3 Slots suction: Same benefit for less energy (also drag reduction) CFD is a good toll BUT it has to be VALIDATED experimentally 7 IAP 30 March 2017 Classification-Unclassified 7
Same Effects on Drag (CFD) Note: The correction due AFC actuation is not included. 25 slots blowing: Low drag reduction at high C. Single slot blowing: Significant drag rise at moderate C. 3 Slots suction: Significant drag reduction at low C @ (AoA=17,18 ) and Significant drag rise at low C @ AoA=19,20. IAP 30 March 2017 Classification-Unclassified 8
Experimental Setup TRNLF-082-9.4 2D airfoil Industrial Geometry Installed VERTICALLY at WT TAU Knapp-Meadow Wind Tunnel The model was Designed, Constructed and Mounted Main TR8 airfoil Profile & TE Flap Leading edge Slat Constant Deflection Wing Tip Semi Circular LE Incidence angles Adjustable: 0-19 Sweep angle settings 0-25 Flap deflections 0-20 Reynolds numbers 0.4-1.0 x 10 6 Overall Near 200 Pressure Taps IAP 30 March 2017 Classification-Unclassified 9
Experiment: Lift Increases Wing Tip Integrated Pressure Measuring System. Lift Comparison AoA= AoA= Efficient at AoA 8-13 Best improvement at AoA=11 10 12 Open Slots at 11-3% Improvement Suction of V/U=0.77 at 11-6.5% Improvement AoA= 14 0.65 Cl(AoA), Re=700k,WingTipCl,FL20, Slots 1-4 Cl 0.6 0.55 0.5 0.45 0.4 BUGS-TAPED 0.35 BUGS-OPEN-SLOT-1-4 BUGS-V/U=0.77 0.3 5 7 9 11 13 15 17 19 AoA[deg] IAP 30 March 2017 Classification-Unclassified 10
Experiment: Vortices Kept Apart! 3D Wake Measurements 7-Holes Probe U[m/s] Vorticity A12, Re700k AFC OFF AFC ON Vorticity, U and Pstat Maps AFC Delays Vortex Merging Cd and Integration Efficient at AoA 8-16 Drastic improvement at AoA=12 Both Reynolds Numbers Vortex separation Drag Reduce Cd/Cd Baseline AFC OFF AFC ON 1.05 0.95 0.9 0.85 0.8 IAP 30 March 2017 Classification-Unclassified 11 AoA[ deg] 1 AFC OFF Re 700 k, AFC ON Re 400 k, AFC ON 8 9 10 11 12 13 14 15 16
Flow Visualizations Performed at Re 700k,AoA 12 Oil Test Open Slots U/Uinf=0.77 Infra Red Thermography AFC OFF ON AFC ON OFF Old Separation line Tuft Test AFC OFF AFC ON New Separation line Compatible Results for all the Methods AFC delays separation New Separation line Old Separation line IAP 30 March 2017 Classification-Unclassified 12
CFD and Experiment Compared, =12 OFF OFF ON CFD CFD: AoA=12 (No suction) Exp.: AoA=12 (No suction) Exp.: AoA=12 (With Suction) IAP 30 March 2017 Classification-Unclassified 13
Conclusions & Recommendations Delaying stall, improving lift and reducing drag at incipient separation stage using slots suction Two orders of magnitude lower power compared to blowing Delays stall and lift drop caused by separation, on the wing tip To be replaced by the TAU developed SaOB Actuator (Patented) Used also for Wind turbines and Trucks A good example for Industry Academia Collaboration 3 Suction Holes Oscillatory Blowing Slots IAP 30 March 2017 Classification-Unclassified 14