Achieving Accurate High-Lift Aerodynamic Predictions for Conventional Aircraft

Designing efficient high-lift systems for aircraft is a complex engineering challenge. The interplay of turbulent airflows, vortices, and wake-boundary layer interactions creates a dynamic environment that’s difficult to predict. However, recent advances in computational fluid dynamics (CFD) are revolutionizing our ability to model these phenomena, leading to more optimized aircraft designs.

The Challenges of High-Lift Aerodynamics

• Turbulent Boundary Layer Flow Separation: As airflow interacts with high-lift devices like flaps and slats, the boundary layer (the thin layer of air closest to the surface) becomes turbulent and prone to separation. This separation significantly alters lift and drag characteristics.
• Off-Body Vortex Tubes: High-lift configurations generate complex vortex structures that extend outwards from the aircraft’s surface. These vortices can strongly influence overall aerodynamic performance.
• Wake-Boundary Layer Mergers: The wake generated by aircraft wings and high-lift devices interacts with the boundary layers on downstream surfaces. This complex interaction affects the pressure distribution and potential for flow separation.

A Cutting-Edge CFD Solution: Volcano ScaLES

To tackle these challenges, researchers are turning to advanced CFD solvers like Volcano ScaLES. Key features include:

• Compressible Navier-Stokes Solver: Accurately models high-speed airflows relevant to aircraft aerodynamics.
• Octree Cartesian Grids: A flexible meshing approach that handles complex geometries with high efficiency.
• Wall-Modelled Large Eddy Simulations (WMLES): A sophisticated turbulence modeling technique for capturing intricate flow details.

Real-World Simulation: HLPW5 Test Cases

Dr. Neil Ashton of AWS demonstrated the power of Volcano ScaLES by simulating HLPW5 Test Cases 2.2, 2.3, and 2.4. These standardized benchmarks offer a rigorous test for CFD models.

• Simulation Setup:
  • Mesh: One billion cells
  • Time: 7 seconds of simulated flow time
  • Hardware: One Amazon EC2 g5.48xlarge (8x Nvidia A10g) node

The Value of Advanced Simulations

By accurately predicting high-lift aerodynamics, simulations like these offer numerous benefits to aircraft designers:

• Optimized Designs: Identify the most efficient flap and slat configurations.
• Reduced Flight Testing: Minimize the need for expensive wind tunnel and flight tests.
• Faster Development: Accelerate the aircraft design process.
• Enhanced Safety: Understand the behavior of aircraft in critical takeoff and landing scenarios.