Numerical study of ice accretion inside an inertial particle separator

The inertial particle separator (IPS) installed before a helicopter engine runs the risk of ice accretion. This paper describes a numerical study of ice accretion inside an IPS. The effects of the droplet diameter (MVD = 5, 10, and 20 µm), liquid water content (LWC = 0.5, 2, and 4 g/m3), and incoming velocity (U0 = 45, 60, and 90 m/s) on ice accretion are studied. The results show that ice accretes on the windward side of the hub, the bent surface of the shroud, and the leading edge of the splitter. The ice thickness on all the surfaces of the IPS generally increases with increasing U0, MVD, and LWC, with the exception that the ice layer thickness on the splitter surface decreases as the MVD increases. This exception arises because the mass of water droplets impinging on the upper surface of the splitter wall decreases with increasing MVD. The effect of ice accretion on the aerodynamic performance of the IPS is also studied. It is found that ice accretion can block the flow area of the “throat” and the inlet of the scavenge flow channel, thus modifying the aerodynamic shape of the inner surface of the IPS and the internal flow field. When MVD = 10 µm and LWC = 4 g/m3, the scavenge ratio after icing decreases with increasing ice thickness. With the exception of LWC = 0.5 g/m3, the total pressure recovery coefficient of the core flow path of the IPS obviously decreases as the ice layer thickens.