Streamlining Aircraft Icing Simulations D. Snyder, M. Elmore - - PowerPoint PPT Presentation

Streamlining Aircraft Icing Simulations

• D. Snyder, M. Elmore

Fidelity Systems-Level Modeling Optimization

Industry Analysis Needs / Trends

Aircraft Ice Protection

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

• f ice protection systems

– Estimating how ice accretion affects aircraft performance

Background

Common industry practice is to use a separate code for each of the above steps

– Slow, cumbersome, expensive, prone to errors (mapping, translation, etc.)

Icing Topics

• Internal/External Flow
• Conjugate Heat Transfer
• Collection Efficiency

Thermal Ice Protection Systems

• Fluid Films
• Ice Shapes (2D / Pseudo-2D / 3D)
• Aerodynamic Performance Degradation

Ice Accretion

One Tool One Model One Process

STAR-CCM+: Streamlining The Process

3D Internal/External Flow Droplet Impingement & Distribution Formation of Fluid Film Conjugate Heat Transfer Runback/Evaporate Fluid Film

Flowfield (3D Navier-Stokes) Dispersed Phase Fluid Film Freeze/Melt Update Ice Shape Mesh Morph / Remesh

Thermal Ice Protection Systems Ice Accretion & Aerodynamic Performance

Unified Process: Thermal Ice Protection Systems

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3D Internal/External Flow Droplet Impingement & Distribution Formation of Fluid Film Conjugate Heat Transfer Runback/Evaporate Fluid Film

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

Example: Piccolo Tube

Piccolo Tube Holes Wing Skin

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

• r with frozen flowfield

– No injection locations: particles exist throughout the freestream flow

3D Droplet Modeling

16.45 μm 20.36 μm

Continuous treatment of the subcooled droplets Conservation equations solved in a segregated manner Multiple phases can exist simultaneously to represent distributions of droplet properties

– E.g. Langmuir-D Distribution

Dispersed Multiphase Model (1/2)

Continuity Momentum Energy

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)

Dispersed Multiphase Model (2/2)

DMP Collection Efficiency GLC-305 Airfoil

α = 1.5 α = 6.0

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 95.840 kPa – Particle diameter 20.36 μm – Compressor face MFR 7.8 kg/s

DMP Collection Efficiency 737 Inlet: Mesh & Setup

DMP Collection Efficiency 737 Inlet: Contours

DMP Collection Efficiency 737 Inlet: Validation

DMP Collection Efficiency 737 Inlet: Validation

DMP Collection Efficiency 737 Inlet: Validation

DMP Collection Efficiency 737 Inlet: Productivity

Surface Preparation

• Import 737 inlet STL
• Create domain, name faces
• Man-Time: 5 minutes
• Machine Time: N/A

Meshing

• Trim volume mesh with prism layers
• Mesh size: 2.1M cells
• Man Time: 2 minutes
• Machine Time: 1.5 minutes on 1 CPU

Solving

• Define physics conditions
• Define BCs
• Man Time: 10 Minutes
• Machine Time: 20 minutes on 16 CPUs

Post- processing

• Define Collection Efficiency FFs
• Export data for use with Excel
• Man Time: 5 minutes
• Machine Time: N/A

5 Minutes 3.5 Minutes 30 Minutes 5 Minutes

Unified Process: Ice Accretion

Flowfield (3D Navier-Stokes) Dispersed Phase Fluid Film Freeze/Melt Update Ice Shape Mesh Morph / Remesh

Single Shot Multi-Shot Fully Transient

Capabilities

– Droplet deposition from DMP / LMP – Run-back – Heat transfer – Freeze / Thaw / Evaporation / Sublimation – Edge- and wave-based stripping to LMP

Fluid Film Example: Runback

Based on an Enthalpy balance formulation for the film

Melting-Solidification Model (1/2)

Within a timestep, iteratively finds the mass that freezes by repeatedly:

– Computing a relative solid volume fraction (based on water temperature)

• 0 above 273.15K
• 1 below 273.15K

– 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 273.15K (glaze conditions)

– Morph the solid boundary according to newly formed ice

• Optional smoothing

Melting-Solidification Model (2/2)

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

Approaches to Ice Accretion Analysis

Validation: 2D CT Airfoil – Geometry

Validation: 2D CT Airfoil – Icing Tunnel

Commercial Transport Airfoil

– Mach 0.45 – Airspeed 285 kts – AoA 0.0 – T

static -18.1 C

– 0.100 g/m3 LWC – 2 minutes

Validation: 2D CT Airfoil – Run 142: 2 Minutes

Commercial Transport Airfoil

– Mach 0.45 – Airspeed 282 kts – AoA 0.0 – T

static -15.4 C

– 0.285 g/m3 LWC – 6 minutes

Validation: 2D CT Airfoil – Run 112: 6 Minutes

Commercial Transport Airfoil

– Mach 0.45 – Airspeed 279 kts – AoA 0.0 – T

static -20.2 C

– 0.295 g/m3 LWC – 6 minutes

Validation: 2D CT Airfoil – Run 106: 6 Minutes

Commercial Transport Airfoil

– Mach 0.45 – Airspeed 279 kts – T

static -20.2 C

– AoA 0.0 – 0.295 g/m3 LWC – 22.5 minutes

Validation: 2D CT Airfoil – Run 107: 22.5 Minutes

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

STAR-CCM+ Icing Simulation Summary

One Tool. One Model. One Process.

Questions?