Self-Cleaning Barrier Filter for Rotorcraft Engines

A parameter-based study of a novel self-cleaning barrier filter concept for rotorcraft engines is presented. Existing engie inlet barrier filters for rotorcraft achieve a high separation efficiency (up to 99% for a dust resembling AC Coarse test dust) at the expense of a pressure drop that increases over time. Other engine protection devices with invariant pressure loss signals cannot offer the same level of efficiency. Furthermore, inlet barrier filters are absent on rotocraft with larger mas flow demands, due to larger filtration area required. This work proposes a solution that addresses each of these limitations, and establishes the parametric framework upon which such a design could be realised. The drum-shaped self-cleaning barrier filter fits to the engine inlet and spins about its longitudinal axis, such that each of its fibrous filter pleats can be cleaned once per cycle. An initial ``ramping up" of pressure loss gives way to a period of sustained invariance. The key parameters are the internal particle capacity of the chosen filter medium and the speed of rotation. Other design parameters can be optimised to yield minimum pressure drop for given set of flow conditions.