2.3 Boundary conditions
As boundary conditions a total pressure and temperature imposed at the
inlet, while a static pressure at the outlet which was varied to sweep
the totality of flow range for each rotational speed. On the rough walls
a no-slip boundary condition was applied. Upstream IGV free stream
turbulence intensity \(\text{Tu}=\frac{{(2k/3)}^{0.5}}{V}\) is set
where the representative velocity is that at inlet. The inlet turbulence
intensity was set at 5 % and the length scale equal to 0.1 times the
guide vane span, whereas the turbulent viscosity was evaluated using
Wilcox’s model [28].
STEADY FLOW RESULTS
First, the steady flow simulations used the stage interface for the
aerodynamic performance computation. On the other hand, the frozen
interface produced the steady solution to multiple frames with some
account of interaction between them, which served in the flow structures
characterization.