Patent ID: 6149380
Filing Date: 2000-11-21
Classification: F01D,F05D

Abstract:
A hardwall fan case for encasing the radial periphery of a forward fan in a gas turbine engine, the fan including a circumferentially spaced apart array of fan blades each having: a centre of gravity; a leading edge; a trailing edge; and a tip, the fan case comprising:a rigid annular shell spaced a selected radial distance from the tips of the fan blades defining an annular internal air path surface of the fan case, the shell comprising:a fore section;an aft section radially spaced from the fore section thus defining a recess between the aft section of the rigid shell and the air path surface, said recess housing compressible material; andrigid bumper means, between the fore and aft sections, for deflecting a broken fan blade fragment rearwardly, the bumper means comprising a bumper having a rigid rear edge disposed an offset distance forwardly of the fan blade centres of gravity, whereby the broken blade fragment projectile on impact with the rigid rear edge of the bumper rotates rearwardly about the rigid rear edge under a resulting force moment proportional to the inertial force of the fragment and proportional to said offset distance.