Patent ID: 9624789
Date: 2017-04-18
CPC Classifications: F01D,F04D,F05D

Claim:
1. A turbomachine casing assembly comprising a casing adapted to encase an aerofoil structure, the aerofoil structure having a tip, a leading edge and a trailing edge, wherein the casing has a set-back portion radially outward of either the leading edge or the trailing edge so as to increase the tip clearance in the region of the leading edge or trailing edge, and wherein the casing has no set-back portion radially outward of the other of the leading edge and trailing edge, wherein the turbomachine casing assembly further comprises a porous liner provided in the set-back portion of the casing, the porous liner being capable of permitting the flow over the tip of the aerofoil structure to pass through the porous liner, and wherein a porosity of the porous liner is selected so that the flow through the porous liner in an area adjacent to a surface of the porous liner is resisted less than the flow through the porous liner in an area further away from the surface.