Nablafoil

A tool for the real-time airfoil aerodynamic performance prediction.

CLIENT

University of Padua

challenge

Innovative airfoils parametrization by verifying their performance in real time

success

Automatic generation of high-performing airfoil shapes for Wind Energy, Axial Compressors, Pumps and other applications

Overview:

NablaFoil represents a new, innovative approach for the design of the airfoils. Elaborations from different discipline compose the tool. Some algorithms allow to parametrize the airfoil shapes using the most advanced mathematic representations. Through an interactive, real-time mode the user can adapt, by hand, the shape of the airfoil and check in real-time the performances. A neural network run in background in order to extrapolate the results from a huge database of airfoils. The database has been created using one of the most accurate panel code.

The main features are:

• Real-time calculation of aerodynamic performances

• Possibility to chose the aerodynamic target in terms of Lift and Drag Coefficients

• Easy change of the parametrization techniques

Over 500k airfoil shapes used to populate the airfoil map.

Parametrization Techniques:

The parametrization techniques, allowable in NablaFoil make possible to reproduce all the most used airfoils and to generate new, innovative, shapes. The discretization methods include:

• Bezier curve

• B-Spline representation

• Nurbs curve

Neural Network:

The aerodynamic prediction technique of NablaFoil is based on a Neural Network.

• First, a huge number of parametrized airfoils (over 500k) has been generated

• Therefore, each airfoil has been simulated using a panel code and its performance recorded in a database

• Finally, a neural network has been set and trained on the database

The result of the procedure is a complex mathematical function, capable of instantaneously predict the polars of an airfoil from the coordinates of its control points.

NablaFoil GUI:

The NablaFoil Graphical User Interface shows an interactive draw-mode environment (on the right) linked to two dependent plots of the airfoil polars (on the left). Furthermore, some commands allows to:

• Change the view and color of the airfoil, zoom the shape

• Add/Subtract a point of the parametrization, move a point along a fixed coordinate

• Identify a random airfoil shape from a target value of CL and CD.

Real-time Shape Modification:

The hand-mode modification of the airfoil shape shows, in real-time, the change in the performance of the airfoil.

APPLICATIONS:

NablaFoil cuts across a broad range applications. Currently, it is used to generate high-performing airfoil shapes and it is easily coupled with 0D and 1D engineering codes for the estimation of performances. The main application fields are:

Wind Energy: generation of the sequence of airfoils of an Horizontal Axis Wind Turbine, identification of the slightly non-symmetric airfoil most suitable for a Vertical Axis Wind Turbine

Axial Compressors: the rotor blade can be easily optimized with NablaFoil algoritms

Pumps: coupled with a 1D code to predict the perfromances of axial and radial pumps

• ……..: NablaFoil can be customized on-demand. Different parametrization techniques, target plots can be implemented. Airfoil performance maps of different accuracy (e.g. for stall predictions) can be used.


Poster Award Finalist

Our team got to the final at the CAE Conference 2018

We are proud of our new, innovative approach to the design of the airfoils.

Andrea Dal Monte, Ph.D.

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