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.