Wing modelling example

In this example, we demonstrate, how to build up a wing surface by starting with a list of curves. These curves are then interpolated using a B-spline suface interpolation

Importing modules

Again, all low lovel geomtry functions can be found in the tigl3.geometry module. For a more convenient use, the module tigl3.surface_factories offers functions to create surfaces. Lets use this!



In [1]:

    
import tigl3.curve_factories
import tigl3.surface_factories
from OCC.gp import gp_Pnt
from OCC.Display.SimpleGui import init_display
import numpy as np

Create profile points

Now, we want to create 3 profiles that are the input for the profile curves. The wing should have one curve at its root, one at its outer end and one at the tip of a winglet.



In [2]:

    
# list of points on NACA2412 profile
px = [1.000084, 0.975825, 0.905287, 0.795069, 0.655665, 0.500588, 0.34468, 0.203313, 0.091996, 0.022051, 0.0, 0.026892, 0.098987, 0.208902, 0.346303, 0.499412, 0.653352, 0.792716, 0.90373, 0.975232, 0.999916]
py = [0.001257, 0.006231, 0.019752, 0.03826, 0.057302, 0.072381, 0.079198, 0.072947, 0.054325, 0.028152, 0.0, -0.023408, -0.037507, -0.042346, -0.039941, -0.033493, -0.0245, -0.015499, -0.008033, -0.003035, -0.001257]

points_c1 = np.array([pnt for pnt in zip(px, [0.]*len(px), py)]) * 2.
points_c2 = np.array([pnt for pnt in zip(px, [0]*len(px), py)])
points_c3 = np.array([pnt for pnt in zip(px, py, [0.]*len(px))]) * 0.2

# shift sections to their correct position
# second curve at y = 7
points_c2 += np.array([1.0, 7, 0])

# third curve at y = 7.5
points_c3[:, 1] *= -1
points_c3 += np.array([1.7, 7.8, 1.0])

Build profiles curves

Now, lets built the profiles curves using tigl3.curve_factories.interpolate_points as done in the Airfoil example.



In [3]:

    
curve1 = tigl3.curve_factories.interpolate_points(points_c1)
curve2 = tigl3.curve_factories.interpolate_points(points_c2)
curve3 = tigl3.curve_factories.interpolate_points(points_c3)

Create the surface

The final surface is created with the B-spline interpolation from the tigl3.surface_factories package.

If you want, comment out the second line and play around with the curve parameters, especially the second value. What influence do they have on the final shape?



In [4]:

    
surface = tigl3.surface_factories.interpolate_curves([curve1, curve2, curve3])
# surface = tigl3.surface_factories.interpolate_curves([curve1, curve2, curve3], [0., 0.7, 1.])
# surface = tigl3.surface_factories.interpolate_curves([curve1, curve2, curve3], degree=1)

The function tigl3.surface_factories.interpolate_curves has many more parameters that influence the resulting shape. Lets have a look:



In [5]:

    
tigl3.surface_factories.interpolate_curves?

Visualize the result

Now, lets draw our wing. How does it look like? What can be improved?

Note: a separate window with the 3D Viewer is opening!



In [6]:

    
# start up the gui
display, start_display, add_menu, add_function_to_menu = init_display()

# make tesselation more accurate
display.Context.SetDeviationCoefficient(0.0001)

# draw the curve 
display.DisplayShape(curve1)
display.DisplayShape(curve2)
display.DisplayShape(curve3)
display.DisplayShape(surface)

# match content to screen and start the event loop
display.FitAll()
start_display()









    



INFO:OCC.Display.backend:backend loaded: qt-pyqt5
INFO:OCC.Display.SimpleGui:GUI backend set to: qt-pyqt5

Result: