Patent ID: 8562289
Filing Date: 2013-10-22
Classification: F01D,F04D,F05D,Y10T

Abstract:
1. A fan assembly comprising a fan casing including a longitudinal centerline axis extending from an upstream inlet opening to a downstream outlet opening, said assembly comprising: a rotor comprising a hub and a plurality of rotor blades extending radially outward from said hub, said plurality of rotor blades each comprising a leading edge and a trailing edge in a direction of fluid flow through said fan casing, and a blade tip at a radially distal end of said blade, said tips of said plurality of rotor blades defining a rotor diameter, said rotor configured to rotate about said centerline axis; a first substantially cylindrical casing segment extending circumferentially about and substantially axially aligned with said blade tips, said first casing segment comprising a first inner diameter that is greater than said rotor diameter; a second substantially cylindrical casing segment configured to extend axially in a direction opposite a flow of fluid through said fan casing, said second casing segment comprising a second inner diameter, said second inner diameter less than said first inner diameter and said rotor diameter; and a third casing segment extending between said first and second casing segments, said third casing segment comprising the first inner diameter along a first circumferential edge, the second inner diameter along a second circumferential edge, and a surface extending therebetween, said surface is spaced apart from the leading edge of the plurality of blades to form a leakage gap that is less than a difference between said first inner diameter and said rotor diameter.