Helicopter Engine Inlet Barrier Filter Design

This contribution concerns the design of Intake Barrier Filters (IBF) for Helicopters. These protective devices are fitted to the engine intakes of helicopters to prevent sand and dust reaching the engine during operations in dusty environments. Their design is dependent on and unique to the rotorcraft to which they are fitted, and can be optimised for minimum pressure drop and maximum service life accordingly by tuning the filter geometry. Three main constraints govern the design of IBF. They are: 1) Intake architecture; 2) Engine mass flow; 3) Particle size distribution of local dust. The filter is a pleated multi-ply fabric. By changing the fold depth and pitch, the filter can be optimised to perform at minimum pressure drop and maximum particle capture capacity for a given constraint set. It is found that the latter of these favours fifty percent more filter folds for optimum performance.