- Aerodynamics influence aircraft fuel consumption and noise levels
- Engineers use simulation to design and test aircraft structures
- New algorithms used on Piz Daint supercomputer lead to improved models
Aerodynamic behaviour is crucial to an aircraft’s fuel consumption and noise levels. The characteristics of airflow along the fuselage and through turbines determine whether the craft can take off and fly.
To save time and development and production costs, engineers often use simulation techniques in the initial design and testing of streamlined structures.
However, in 2014, NASA in its Vision 2030 report identified room for improvement in such simulations. Conventional algorithms are no longer efficient at using the theoretical quantity of Floating Point Operations per Second (FLOPS) available from modern computer architectures.
A research group led by Peter Vincent, Reader in Aeronautics at Imperial College in London, has been helping to drive further improvements in this area with a new code and simulations on supercomputer Piz Daint, the hybrid system of the Swiss National Supercomputing Center (CSCS).
New open source software for graphics processors
It's an engineering design headache to optimize the usually unsteady and turbulent airflows along an aeroplane’s fuselage, landing flaps, and turbines. The simulation method used is called Computational Fluid Dynamics (CFD).
Vincent and his team seek to enhance simulation realism by developing a new generation of CFD technologies based on high-order flux reconstruction methods and running on computer hardware with graphics processors, like Piz Daint.
“This computer architecture is particularly suited to solving problems of such complexity,” says Vincent. He and his team developed the open source code PyFR for performing high-order flux reconstruction simulations.
With their new method, the scientists have now managed to run high-precision simulations of a special flow problem: The airflow over a NACA0021 aerofoil with incident air impinging at a critical angle of 60 degrees.
This kind of situation causes the previously laminar airflow to develop turbulence, usually leading to deep stall. The worst-case outcome is a crash.
Simulation of turbulence without using approximation methods
The researchers employed the new method to simulate turbulence at many different scales around the wing and right down to its surface, which they were able to accomplish with great precision and without using approximation methods.
Their objective was to model turbulence with the finest detail and realism possible. The resulting simulations correlate very well with wind tunnel test results — far closer than previous simulations.
In 2016, aircraft worldwide carried 3.8 billion passengers while emitting around 700 million tons of carbon dioxide (CO2).
Not only can simulations like these help to improve engineering designs in general, Vincent is convinced that when focused specifically on turbines and airframes, they can also reduce aircraft CO2 emissions and noise.