Patent ID: 8197186

Claim:
A gas turbine engine turbine assembly comprising: an annular turbine casing having an annular shell circumscribed about a central axis, axially spaced apart forward and aft flanges extending radially outwardly from the annular shell, forward and aft case hooks depending radially inwardly from the annular shell of the casing, a shroud assembly depending radially inwardly from the turbine casing and being connected to the forward and aft case hooks, a circular row of axially extending cooling holes disposed through the aft flange circumscribing the central axis and radially located between an outer diameter of the aft flange and the annular shell, a radially outwardly facing annular impingement surface of the aft flange at the outer diameter of the aft flange, an annular manifold circumscribing the central axis and spaced radially outwardly of the annular shell, an annular space disposed between the manifold and the annular shell, impingement holes disposed through the manifold and located for spraying cooling air radially inwardly and directly on the annular impingement surface of the aft flange, radially outwardly facing cylindrical surfaces at outer diameters of the forward and rear flanges and the radially outwardly facing annular impingement surface of the aft flange being axially curved, and the axially curved annular impingement surface being semi-spherical, having a radius of curvature, and the radius of curvature having an origin on the central axis.