Operational Performance Parameters of Engine Inlet Barrier Filtration Systems for Rotorcraft

This contribution addresses the subject of engine intake filtration systems for rotorcraft. The reader is introduced to their purpose, which is to eliminate the risk of particle ingestion by the engine, a situation which can cause irrevocable damage to key components. The risk is significantly elevated during a condition known as brownout, in which the rotor wake of a helicopter in ground effect interacts with loose sediment, causing the generation of a dust cloud. In such a condition, IBF successfully removes particles from the engine-bound air at the expense of a pressure drop which grows temporally. This decreases the overall intake efficiency, but at varying degrees dependent on certain factors. An increase in deterioration rate is caused by but not limited to: an increase in incident velocity; and a decrease of mean particle size. However the rate may be slowed by operating the filter at a tangential angle to the flow. The present work uses CFD to carry out a parametric study into the factors affecting particle deposition and uses the results to form a semi-analytical model of pressure drop and ultimately predict the transient intake efficiency for IBF-fitted rotorcraft.