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.
Highlights
Helicopters are required to operate in different types of environments
This paper shows the results of a numerical study on the flow and impingement of water droplets in the inertial particle separator (IPS) using the Eulerian–Eulerian method
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
Summary
Helicopters are required to operate in different types of environments. In dusty environments, the ingestion of solid particles can cause severe engine damage. A helicopter may need to operate under icing conditions In this case, super-cooled water droplets can impact the surfaces of the helicopter and its engine and cause ice accretion, which is dangerous to flight. The FAA (Federal Aviation Administration) requires the helicopter manufacturers to strictly obey the requirements presented in Federal Airworthiness Regulations (FAR) Part 29 Appendix C.8 To meet these requirements, certificate tests have to be done in icing environments on different parts of the helicopters, such as the whole helicopter, the rotors, engine air intake, and the IPS.. Designing an anti-icing system requires a good understanding of the flow and impingement of super-cooled water droplets in the IPS, which still needs additional research. This paper uses numerical methods to study the flow and impingement of typical droplets in the IPS and uses the Eulerian–Eulerian scheme for simulations. The typical flow and impingement features for water droplets in the IPS are analyzed, and the effects of the MVD, LWC, and incoming velocity on the flow and impingement in the IPS are studied
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