Gas turbine engine rotor blade transition

A rotor blade for a gas turbine engine, comprising:

• a suction side;
• a pressure side;
• an airfoil that extends radially between a tip end and an airfoil root end, the airfoil including a plurality of internal cooling air passages;
• an attachment section having a base surface;
• and
• a neck section disposed between the attachment section and the airfoil;
• wherein a forward center cooling air passage is open at the base surface and extends through the attachment section and the neck section and is in fluid communication with the plurality of internal cooling air passages;
• and
• wherein an aft center cooling air passage is open at the base surface and extends through the attachment section and the neck section and is in fluid communication with the plurality of internal cooling air passages;
• and
• wherein a wall to wall (W2W) cooling air passage is open at the base surface and extends through the attachment section and the neck section and is in fluid communication with the plurality of internal cooling air passages, and the W2W cooling air passage is disposed between the forward center cooling air passage and the aft center cooling air passage;
• and
• wherein in a transition in a direction from a cross-sectional plane disposed in the attachment section to the airfoil root end, a suction side segment progressively extends outwardly from the W2W cooling air passage and a pressure side segment progressively extends outwardly from the W2W cooling air passage;
• wherein in a first cross-sectional plane that extends through the neck section and is perpendicular to the W2W cooling air passage, the suction side segment (SSS) has a first SSS length SSL1 and a first SSS area SSA1, and in a second cross-sectional plane that extends through the neck section and is perpendicular to the W2W cooling air passage, the suction side segment has a second SSS length SSL2 and a second SSS area SSA2;
• wherein in the first cross-sectional plane, the pressure side segment (PSS) has a first PSS length PSL1 and a first PSS area PSA1, and in the second cross-sectional plane, the pressure side segment has a second PSS length PSL2 and a second PSS area PSA2;
• wherein the first cross-sectional plane is spaced apart from the airfoil root end a first distance D1, and the second cross-sectional plane is spaced apart from the airfoil root end a second distance D2, and the first distance D1 is greater than the second distance D2;
• and
• wherein the second SSS length SSL2 is greater than the first SSS length SSL1, and the second PSS length PSL2 is greater than the first PSS length PSL1.

A rotor blade for a gas turbine engine, comprising:

• a suction side;
• a pressure side;
• an airfoil that extends radially between a tip end and an airfoil root end, the airfoil including a plurality of internal cooling air passages;
• an attachment section having a base surface;
• and
• a neck section disposed between the attachment section and the airfoil;
• wherein a forward center cooling air passage is open at the base surface and extends through the attachment section and the neck section and is in fluid communication with the plurality of internal cooling air passages;
• and
• wherein an aft center cooling air passage is open at the base surface and extends through the attachment section and the neck section and is in fluid communication with the plurality of internal cooling air passages;
• wherein a wall to wall (W2W) cooling air passage is open at the base surface and extends through the attachment section and the neck section and is in fluid communication with the plurality of internal cooling air passages, and the W2W cooling air passage is disposed between the forward center cooling air passage and the aft center cooling air passage;
• wherein in a transition in a direction from a cross-sectional plane disposed in the attachment section to the airfoil root end, a suction side segment progressively extends outwardly from the W2W cooling air passage and a pressure side segment progressively extends outwardly from the W2W cooling air passage;
• and
• wherein the suction side segment includes a forward suction side segment and an aft suction side segment, and the pressure side segment includes a forward pressure side segment and an aft pressure side segment.