How can i draw turbine blade like the drawing below?

Hi everyone, im studying manufacturing engineering and trying to improve myself on professional 3d design. I have a 2d drawing of a design i attached below that i couldnt 3d design. Its a top view of a turbine blade, i tried to draw it with splines but couldnt dimension the angles stated, how can i do it? the other photo is the one i tried

1 Answer

Using an interpolation spline is the correct way to do it. But there need to be many control points. The coordinates for these control points need to be carefully calculated and not just laid in by hand. I've tried doing it by hand and it really just doesn't work.

As an example I've included the following screen shots of a method I used for NACA 4-digit airfoil. There are a lot of complex calculations. Fortunately it only required a lot of cutting and pasting to get it all in. This attempt was for a rough turbine blade layout. I say rough because in the end it would look about right but would probably not perform all that well. I doubt a NACA 4-digit airfoil would be the correct airfoil anyway. There is a lot of science behind a turbine airfoil that I can't even begin to understand.

My example would be a NACA (13)315
The camber is 13% (outside the normal 4-digit range)
The camber position is 30%
The maximum thickness is 15%
The camber is normally only a single digit but I was stretching it to make the exaggerated camber of a turbine blade.
I have the whole airfoil (X-axis) rotated 40° for a high angle of attack.

If I had to guess, the camber on your example is around 40% and the angle of attack is more like 20°. Again the NACA 4-digit airfoil is likely not the one to use. Maybe someone else can steer you towards a better airfoil.

I show you my work only to indicate the magnitude of the calculations involved just to layout the blade airfoil.

Airfoil1 shows the calculations for each X and Y coordinate and the thickness at each point.
Airfoil2 shows the constants and variables.
Airfoil3 shows the sketch with the single spline connecting them all.
Airfoil4 is a screen shot from the website where I obtained the base equations:
http://airfoiltools.com/airfoil/naca4digit