Study of the flow and impingement of water droplets inside an inertial particle separator

Abstract

An inertial particle separator (IPS) mounted before a helicopter engine faces the danger of ice accretion caused by the impingement of super-cooled water droplets. This paper shows the results of a numerical study on the flow and impingement of water droplets in the IPS using the Eulerian–Eulerian method. Cases for different medium volume diameters (MVDs = 5 μm, 10 μm, and 20 µm), liquid water contents (LWCs = 0.5 g/m3, 2 g/m3, and 4 g/m3), and incoming velocities (U0s = 40 m/s, 65 m/s, and 90 m/s) are examined to study their effects on the flow and impingement of water droplets in the IPS. The results indicate that the IPS can reduce the water that enters the core flow path by trapping the water on the inner walls and separating it into the scavenge flow path. The ratio between the flow rate of water at the outlet of the core flow path and that at the inlet (ṁc/ṁinlet) decreases with an increased MVD or incoming velocity, which, however, does not change with the LWC. The results also show that the water collection coefficient (β) on the hub and shroud walls increases with a greater MVD, while the β on the splitter wall reaches its maximum at an MVD of 10 µm in the studied cases. The LWC does not have any effect on β for any of the IPS walls, while β increases on all IPS surfaces with the incoming velocity.