Gas turbine combustor heat shield of casted super alloy

An annular-shaped segmented heat shield for a gas turbine engine combustor having a concentrically-disposed annular array of air/fuel mixers, the segmented annular heat shield having a radially-outward perimeter defined by a first annular-shaped segmented centerbody and a radially-inward perimeter defined by a second annular-shaped segmented centerbody, the annular-shaped segmented heat shield comprising a plurality of heat shield members, each of the heat shield members comprising:

• a base portion in a radial plane of the heat shield member, the base portion having a radially-outward first end, a radially-inward second end, and an opening disposed between the first and second ends, the opening defining an axial axis of the heat shield member that is substantially normal to the radial plane, the base portion having a radial axis in the radial plane and intersecting the axial axis;
• a first arcuate wall portion extending axially from the first end of the base portion and forming a segment of the first annular-shaped segmented centerbody of the annular-shaped segmented heat shield, a first fillet being disposed between the first wall portion and the base portion, a cooling passage being disposed within the first arcuate wall portion and forming an outlet at a distal end of the first arcuate wall portion;
• and
• a second arcuate wall portion extending axially from the second end of the base portion and forming a segment of the second annular-shaped segmented centerbody of the annular-shaped segmented heat shield, a second fillet being disposed between the second wall portion and the base portion, a cooling passage being disposed within the second arcuate wall portion and forming an outlet at a distal end of the second arcuate wall portion;
• wherein each of the heat shield members is a single crystal superalloy casting having a primary crystal orientation and a secondary crystal orientation, the primary crystal orientation being substantially parallel to the axial axis of the heat shield member, the secondary crystal orientation being in the radial plane of the heat shield member.

A method for reducing stresses in a heat shield member of a segmented heat shield for a gas turbine engine combustor having a concentrically-disposed annular array of air/fuel mixers and operating with a lean fuel mixture, the method comprising the steps of:

• casting the heat shield member from a superalloy such that the heat shield member includes:
• a base portion disposed in a radial plane of the heat shield member, the base portion having a radially-outward first end, a radially-inward second end, and an opening disposed between the first and second ends, the opening defining an axial axis of the heat shield member that is substantially normal to the radial plane, the base portion having a radial axis in the radial plane and intersecting the axial axis;
• a first wall portion extending axially from the first end of the base portion;
• and
• controlling the casting step such that the heat shield member is a single crystal casting having a primary crystal orientation and a secondary crystal orientation, the primary crystal orientation being substantially parallel to the axial axis of the heat shield member, the secondary crystal orientation being in the radial plane of the heat shield member.