Rotary Brush Air Cleaner for Gas Turbine Engines

A parameteric study was made of the variables associated with a rotary brush air cleaner for helicopter gas turbine engines. Tests were conducted at air volumes ranging 3000-8000 ft³/min and brush speeds of 1200-3000 rpm. While centrifugal effects were found to be an important cleaning mechanism, impaction effects significantly improved dust separation at brush speeds above 2400 rpm. On a constant impaction area basis, brushes with 1 mm diameter wires were more efficient than brushes with 2 mm wires. Wires added in the axial direction were more effective than wires added in a radial direction. Separation efficiency at 8000 ft³/min of dust laden air and brush speeds of 3000 rpm approached 100% for size classified test dusts in the 15-35 μm size range. The separation efficiency on a 2.7 μm mass mean diameter test dust was a respectable 66%. Only 7 hp was required to rotate the brush shaft at 3000 rpm; the pressure drop of 4 in of H₂O was independent of brush speed.