**6. CAD model of blade**

The CAD model of the blade can be made using any 3D CAD software. ANSYS Fluent supports many types of 3D file formats and can import a solid-works project directly. ANSYS also has an inbuilt geometry design software named space-claim, and an old one named design-modeller. The actual CAD design steps are out of the scope of this chapter. Fusion360 was used to design the blade model, and the same was imported as a (.stp) STEP file into ANSYS. **Figure 6** shows the blade geometry as a sketch and a body.

It is crucial to note that we are NOT modeling the blade, but rather the fluid surrounding it. Imagine a cylinder (rather a sector of a 3D cylinder spanning 120 degrees) where the blade is left hollow. The actual geometry is the air surrounding the blade, not the blade itself. It is the subtraction of the blade from the cylinder geometry. It is understandable that as air cannot penetrate the blade, that region is left hollow. One may refer to the following figures for the blade design.

One can see the blade's outline in the 3D sector (120 degrees) of a cylinder in **Figure 7**. The subtracted geometry will be used for simulation and imported into

**Figure 6.** *CAD model of blade.*

**Figure 7.** *CAD model for simulation.*

ANSYS. The following section will discuss the simulation setup, the mathematical model used, Fluent, boundary conditions, and solution iterations.
