High-Lift Aerodynamics: STAR-CCM+ Applied to AIAA HiLiftWS1 D. Snyder

Aerospace Application Areas Aerodynamics Subsonic through Hypersonic Aeroacoustics Store release & weapons bay analysis High lift devices Stage separation Plume analysis Ablation Engine integration

Aerospace Application Areas Aerodynamics Subsonic through Hypersonic Aeroacoustics Store release & weapons bay analysis High lift devices Stage separation Plume analysis Ablation Engine integration Propulsion Systems Pumps Rocket Motor, Ramjet & Scramjet Fans and Turbines Combustion, sprays, chemistry Inlets & ducting Nozzles Fuel systems, sloshing Filters Heat Transfer and Thermal Management Mechanical Systems (APU s, undercowling, etc.) Ice Protection Avionics / Electronics Systems Battery Heat Management Heat Exchangers Blade cooling Other Conjugate Heat Transfer

High-Lift Aerodynamics Aerodynamics of 3D swept wings in high-lift configurations is very complex Separation Unsteadiness Confluent boundary layers Transition Vortical flow AIAA HiLiftWS1 (2010) Assess capabilities of current-generation codes Meshing Numerics Turbulence Modeling High-performance computing

NASA Trap Wing Model Tested in 1998-1999, 2002-2003 at NASA Langley and NASA Ames wind tunnels Re ~ 4.6M No turbulent trips transition is a factor Data collected Aerodynamic forces/moments * Pressure distributions * Transition location Acoustics * Evaluated in HiLiftWS1 Trap Wing in NASA LaRC 14x22 WT

Computational Domain Geometry provided in IGES format Minor surface cleanup Configuration 1 Slats at 30 deg, Flaps at 25 deg Fully-deployed configuration Farfield boundaries created in STAR-CCM+ Extend 100MAC in all directions

Boundary Conditions No-slip wall conditions No transition location specified Symmetry plane Freestream Mach 0.2 T = 520R P = 1 ATM (Re = 4.3M based on MAC) a = 6, 13, 21, 28, 32, 34, 35, 36, 37 deg

Mesh Overview Polyhedral mesh Wide range of angles of attack on a single mesh Strong streamline curvature Massive recirculation regions Prism layers 30 layers Grid refinement study Results from Medium grid are presented Grid Size Very Coarse Coarse Medium Fine Number of cells 10M 21M 34M 43M * Very Coarse mesh shown (10M cells)

Additional Mesh Features Text * Very Coarse mesh shown (10M cells)

Solver Settings Density-Based Coupled Solver Low Mach number preconditioning 2nd-order spatial discretization Steady-state RANS equations SST (Menter) k-w Turbulence Model Integrated to the wall 1st prism layer y+ < 1.0 g-re θ Transition Model

Transition Model AoA=13 Transition g-re θ Transition Model Predicts laminar-turbulent transition in the boundary layer Correlation-based model formulated for unstructured CFD codes Models transport of Momentum Thickness Re and Intermittency Without transition modeling Lift coefficient generally underpredicted Stall predicted too late

Convergence Behavior 3.5 Turn on transition model 3 2.5 CL 2 1.5 1 0.5 0 6 degrees 13 degrees 21 degrees 28 degrees 32 degrees 34 degrees 0 2000 4000 6000 8000 10000 12000 14000 Iterations (n) * At higher angles of attack, stability required running without transition model for a time.

Complex Flowfield AOA=6 AOA=13 AOA=28 AOA=37

Lift Prediction 3.5 3 Experiment STAR-CCM+: Medium Configuration 1 2.5 CL 2 1.5 1 0.5 0-5 0 5 10 15 20 25 30 35 40 Angle of Attack (Degrees)

Drag Prediction 1 0.9 0.8 Experiment STAR-CCM+: Medium CD 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0-5 0 5 10 15 20 25 30 35 40 Angle of Attack (Degrees)

Pitching Moment Prediction 0-0.1 Experiment STAR-CCM+: Medium -0.2 CM -0.3-0.4-0.5-0.6-5 0 5 10 15 20 25 30 35 40 Angle of Attack (Degrees)

Pressure Data Pressure measurements were made at ~800 locations on the wing surface Similarly, CFD data was extracted at 9 corresponding spanwise locations 0.17 0.28 0.41 0.50 0.65 0.70 0.85 Experimental pressure tap locations CFD data extraction locations 0.95 0.98

Cp Comparison: η=0.50 (mid-span) AoA=6 AoA=21 AoA=34 AoA=37

Cp Comparison: η=0.95 (tip) AoA=6 AoA=21 AoA=34 AoA=37

Conclusions STAR-CCM+ accurately predicted the aerodynamic behavior of the NASA Trap Wing high-lift case Lift, drag, and pitching moment Pressure distribution Proper meshing techniques were important Boundary layer Element wake interactions Massive separation region Tip vortex Transition modeling was necessary Fully-turbulent under-predicted lift at high AoA (pre-stall) Fully-turbulent over-predicted stall AoA AoA=6 AoA=21

Upcoming HiLiftWS1 Special Session (June 2012) Addition of support brackets Hysteresis effects Aeroelastic Prediction Workshop (April 2012) Propulsion Aerodynamics Workshop (July 2012) Eglin Store Separation Validation

Questions?