Streamlining Aircraft Icing Simulations. D. Snyder, M. Elmore

Transcription

1 Streamlining Aircraft Icing Simulations D. Snyder, M. Elmore

2 Industry Analysis Needs / Trends Fidelity Aircraft Ice Protection Systems-Level Modeling Optimization

3 Background Ice accretion can critically alter performance Aerodynamic performance of wings Engine performance due to inlet icing Improper readings from instrumentation Aircraft must be certified to fly in certain icing conditions Simulation is important Designing and estimating performance of ice protection systems Estimating how ice accretion affects aircraft performance

4 Icing Topics Thermal Ice Protection Systems Internal/External Flow Conjugate Heat Transfer Collection Efficiency Ice Accretion Fluid Films Ice Shapes (2D / Pseudo-2D / 3D) Aerodynamic Performance Degradation Common industry practice is to use a separate code for each of the above steps Slow, cumbersome, expensive, prone to errors (mapping, translation, etc.)

5 STAR-CCM+: Streamlining The Process Thermal Ice Protection Systems 3D Internal/External Flow Droplet Impingement & Distribution Formation of Fluid Film Conjugate Heat Transfer Runback/Evaporate Fluid Film Ice Accretion & Aerodynamic Performance Flowfield (3D Navier-Stokes) Dispersed Phase Fluid Film Freeze/Melt One Tool One Model One Process Update Ice Shape Mesh Morph / Remesh

6 Unified Process: Thermal Ice Protection Systems 3D Internal/External Flow Droplet Impingement & Distribution Formation of Fluid Film Conjugate Heat Transfer Runback/Evaporate Fluid Film 6

7 Example: Piccolo Tube Internal/external flows with complex geometry Simultaneous, coupled solution of internal and external flowfields Piccolo tubes, jet orifices, leading-edge cavity, etc. Conjugate heat transfer Simultaneous, coupled solution for fluid and solid thermal Holes Wing Skin Piccolo Tube

8 3D Droplet Modeling Lagrangian Multiphase (LMP) Individually track particles Can be run fully coupled with flowfield or with frozen flowfield Injection locations are arbitrary and customizable Dispersed Multiphase (DMP) Lightweight one-way-coupled Eulerian approach Better model of the cloud than LMP Concentration is solved everywhere in the flowfield Shadow zones identified Can be run fully coupled with flowfield or with frozen flowfield No injection locations: particles exist throughout the freestream flow μm μm

9 Dispersed Multiphase Model (1/2) Continuous treatment of the subcooled droplets Conservation equations solved in a segregated manner Continuity Momentum Energy Multiple phases can exist simultaneously to represent distributions of droplet properties E.g. Langmuir-D Distribution

10 Dispersed Multiphase Model (2/2) One-way coupled Background flowfield influences droplets but not vice versa Drag (Schiller-Naumann) Pressure Gradient Force Heat Transfer (Ranz-Marshall) Update of dispersed phase on instantaneous frozen background Collection efficiencies as a post-processing step Multi-shot icing simulations Compatible with many models and numerical schemes Impingement onto fluid films Segregated or Coupled solver for background flow Lagrangian (stripping or simultaneous modelling of SLD's)

11 DMP Collection Efficiency GLC-305 Airfoil α =

12 DMP Collection Efficiency 737 Inlet: Mesh & Setup Solver Setup 3D Segregated Solver Steady K-ω SST turbulence Dispersed Multiphase Physics Conditions 0 AoA V 75 m/s Static temperature 7.0 C Static pressure kpa Particle diameter μm Compressor face MFR 7.8 kg/s

13 DMP Collection Efficiency 737 Inlet: Contours

14 DMP Collection Efficiency 737 Inlet: Validation

15 DMP Collection Efficiency 737 Inlet: Validation

16 DMP Collection Efficiency 737 Inlet: Validation

17 DMP Collection Efficiency 737 Inlet: Productivity Surface Preparation Import 737 inlet STL Create domain, name faces Man-Time: 5 minutes Machine Time: N/A 5 Minutes Meshing Solving Postprocessing Trim volume mesh with prism layers Mesh size: 2.1M cells Man Time: 2 minutes Machine Time: 1.5 minutes on 1 CPU Define physics conditions Define BCs Man Time: 10 Minutes Machine Time: 20 minutes on 16 CPUs Define Collection Efficiency FFs Export data for use with Excel Man Time: 5 minutes Machine Time: N/A 3.5 Minutes 30 Minutes 5 Minutes

18 Unified Process: Ice Accretion Flowfield (3D Navier-Stokes) Dispersed Phase Fluid Film Freeze/Melt Single Shot Multi-Shot Fully Transient Update Ice Shape Mesh Morph / Remesh

19 Fluid Film Example: Runback Capabilities Droplet deposition from DMP / LMP Run-back Heat transfer Freeze / Thaw / Evaporation / Sublimation Edge- and wave-based stripping to LMP

20 Melting-Solidification Model (1/2) Based on an Enthalpy balance formulation for the film

21 Melting-Solidification Model (2/2) Within a timestep, iteratively finds the mass that freezes by repeatedly: Computing a relative solid volume fraction (based on water temperature) 0 above K 1 below K Updating the thickness of film to be removed in timestep At convergence, either All liquid film is removed (rime conditions) or There is a liquid remainder at K (glaze conditions) Morph the solid boundary according to newly formed ice Optional smoothing

22 Approaches to Ice Accretion Analysis Single-Shot Frozen flowfield during ice buildup Multi-Shot Frozen flowfield, updated periodically during ice buildup Fully Transient Flowfield updated at each time step throughout ice buildup Approximately 2x the computational cost of single-shot

23 Validation: 2D CT Airfoil Geometry

24 Validation: 2D CT Airfoil Icing Tunnel

25 Validation: 2D CT Airfoil Run 142: 2 Minutes Commercial Transport Airfoil Mach 0.45 Airspeed 285 kts AoA 0.0 T static C g/m 3 LWC 2 minutes

26 Validation: 2D CT Airfoil Run 112: 6 Minutes Commercial Transport Airfoil Mach 0.45 Airspeed 282 kts AoA 0.0 T static C g/m 3 LWC 6 minutes

27 Validation: 2D CT Airfoil Run 106: 6 Minutes Commercial Transport Airfoil Mach 0.45 Airspeed 279 kts AoA 0.0 T static C g/m 3 LWC 6 minutes

28 Validation: 2D CT Airfoil Run 107: 22.5 Minutes Commercial Transport Airfoil Mach 0.45 Airspeed 279 kts T static C AoA g/m 3 LWC 22.5 minutes

29 STAR-CCM+ Icing Simulation Summary STAR-CCM+ V9.02 provides a streamlined process for performing various aircraft icing related simulations Benefits Fully 3-Dimensional, Navier Stokes Internal and external situations Dispersed Multiphase (DMP) is a better model of the cloud than LMP and is computationally fast Mesh morphing and/or remeshing for large ice shapes Increased productivity and less prone to errors Single tool, model, and process for internal/external flows, CHT, collection efficiency and ice accretion One Tool. One Model. One Process.

30 Questions?