Unphysical Flow Behavior in a Segmented Rotor–Stator CFD Model

[khemiri]

I am facing a technical issue, as illustrated in the figure. The present simulation concerns an axial fan and consists of two main components: a rotor with ten blades, where the angular spacing between the rotor blades is 36°, and a stator with three stationary blades, whose angular spacing is 120°.

I decided to segment the entire geometry and perform the simulation using ANSYS Fluent in order to investigate the hydroacoustic effects. The rotor domain was divided into ten identical sectors, so that only a single rotor blade is simulated. This corresponds to an angular extent of 36°, i.e., one tenth of the full rotor geometry.

Similarly, only one stationary blade was modeled for the stator, corresponding to an angular extent of 120°, i.e., one third of the complete stator geometry.  

In addition, the boundary surfaces were correctly defined, in particular the inlet, outlet, walls, and the rotor domain.

The objective is to restrict the simulation to a reduced model that includes only one rotor blade and one stator blade. For this purpose, the rotor geometry was limited to a 36° sector, while the stator geometry was restricted to a 120° sector.

However, during the simulation, implausible results occur. Specifically, the fluid does not flow through the entire geometry but only through certain regions of the stator.

Therefore, the question arises as to how this issue can be resolved in order to ensure a physically correct flow throughout the entire geometry.

[Petros]

 

Hello, have you used the correct interface model between rotor and stator to account for the unequal pitch?

You could also model an equal pitch by choosing an appropriate number of rotor passages, such that they would fit exactly in one stator passage. But this is not the case here as no integer number of rotor passages corresponds to a single stator passage.