Abstract: A vortex tube including an annular downstream scavenge duct is provided with a number of occluding members spaced circumferentially around the upstream entrance to the scavenge duct so as to restrict the entrance area of the duct. The occluding members are each generally triangular in section, are each attached to the wall of the vortex tube, and taper upstream from the entrance to the scavenge duct.

Abstract: An inlet particle separator for a gas tubine engine, comprises, (a) an annular air inlet duct, (b) downstream of the inlet duct an annular obturating member having a continuous surface, the menber arranged to bifurcate the inlet duct into annular compressor and scavenge ducts, the compressor duct leading downstream to an engine compressor stage, the scavenge duct being located radially inwardly of the compresor duct and directed upstream thereof, and arranged to scavenge solid matter from the air flow through the inlet duct. The inlet duct is provided with an annular constriction at its downstream end extending radially inwards from a radially outer wall of the inlet duct.