Numerical Study of an Inlet Particle Separator

Helicopters operating in a desert region are often subjected to the environmental effects of sand ingestion that can erode gas turbine engines and block the cooling passages. Traditional method of removing sand particles include barrier filters that employed vortex tube and impact filter designs, and inertial particle separator (IPS). Barrier filters are normally quite heavy and require constant servicing or replacement. IPS relies on contoured surfaces to direct particulates to a scavenge area through the actions of the viscous forces and bounce characteristics of the sand particles. The geometrical design of an IPS plays an important role in determining the sand separation efficiency. This paper presents a numerical study of the RTM322 IPS, which includes the effects of changing the hub, splitter and scavenge duct geometries on the sand separation efficiency. The flow field calculation in the IPS was performed with the commercial CFD software package called TASCflow. The particle trajectories were computed using an in-house developed trajectory code, which was based on the lagrangian method. The effects of flow turbulence on the trajectory were simulated using the eddy lifetime concept. Several design geometrical modifications were investigated such as the shape of the hub and splitter and their relative locations. Particle trajectories and separation efficiency were performed for a range of sand particle sizes, inlet mass flow rates and scavenge ratios.