AEROSPACE
NABLAFOIL
A tool for real-time airfoil
aerodynamic performance prediction
CLIENT
University of Padua
CHALLENGE
Innovative airfoil parametrization, verifying performance in real time
SUCCESS
Automatic generation of high-performing airfoil shapes for wind energy, axial compressors, pumps and other applications
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OVERVIEW
NablaFoil is a new approach to the design of airfoils. Through an interactive, real-time mode the user adapts the shape of the airfoil by hand and can check in real-time its performance. A neural network runs in the background, extrapolating results from a huge database of airfoils. The main features:
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real-time calculation of aerodynamic performance
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the ability to choose the aerodynamic target in terms of lift and drag coefficients
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easy change of the parametrization techniques
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over 500k airfoil shapes populating the airfoil map
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PARAMETRIZATION TECHNIQUES
The parametrization techniques, using the most advanced mathematical representations, make it possible to reproduce all the most common airfoils and to generate new, innovative, shapes. The discretization methods include:
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Bézier curve
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B-Spline representation
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NURBS curve
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NEURAL NETWORK
The aerodynamic prediction technique of NablaFoil is based on a Neural Network:
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first, a huge number of parametrized airfoils — over 500k — was generated
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then each airfoil was simulated with a panel code and its performance recorded in a database
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finally, a neural network was set up and trained on that database
The result is a complex mathematical function, able to instantaneously predict the polars of an airfoil from the coordinates of its control points.
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THE INTERFACE
The NablaFoil Graphical User Interface shows an interactive draw-mode environment linked to two dependent plots of the airfoil polars. Its commands allow the user to:
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change the view and colour of the airfoil, and zoom the shape
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add or subtract a point of the parametrization, and move a point along a fixed coordinate
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identify a random airfoil shape from a target value of CL and CD
Modifying the airfoil shape by hand shows the change in its performance in real time.
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APPLICATIONS
NablaFoil cuts across a broad range of applications. It is currently used to generate high-performing airfoil shapes, and couples easily with 0D and 1D engineering codes for the estimation of performances. The main fields:
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Wind energy — generating the sequence of airfoils of a horizontal-axis wind turbine, and identifying the slightly non-symmetric airfoil best suited to a vertical-axis one
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Axial compressors — the rotor blade is easily optimized with NablaFoil's algorithms
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Pumps — coupled with a 1D code to predict the performance of axial and radial pumps
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NablaFoil can also be customized on demand: different parametrization techniques and target plots can be implemented, and airfoil performance maps of different accuracy used, for stall prediction for instance
RECOGNITION
POSTER AWARD FINALIST
Our team reached the final at the CAE Conference 2018 with NablaFoil.
“We are proud of our new, innovative approach to the design of airfoils.”
Andrea Dal Monte, Ph.D.
Try creating your own neural network. Leave your email to download a sample of the dataset used: