CMC airfoil with circumventing cooling passage

A gas turbine engine comprising:

• a compressor section;
• a combustor in fluid communication with the compressor section;
• and
• a turbine section in fluid communication with the combustor, the turbine section having airfoils each including:
• an airfoil section defining pressure and suction sides, a leading edge, and a trailing edge region including a trailing edge, the airfoil section being formed of a ceramic matrix composite that includes fiber plies disposed in a ceramic matrix, the fiber plies including:
• core fiber plies defining a radial tube that circumscribes an internal cavity, the radial tube having a radiused end in the trailing edge region, and
• skin fiber plies defining an exterior of the airfoil section and wrapping around the core fiber plies from the pressure side of the trailing edge region, through the leading edge, and to the suction side of the trailing edge region;
• a filler element in the trailing edge region aft of the internal cavity and sandwiched between the skin fiber plies on the pressure side and the skin fiber plies on the suction side;
• and
• at least one cooling passage including:
• a first, inlet orifice section opening to the internal cavity at a location forward of the radiused end and extending through the core fiber plies, wherein there is a number N of the core fiber plies each having a ply thickness t, and the location is forward of the radiused end by a distance D that is greater than the product of N, t, and a multiplier X that is from five to ten,
• a second, outlet orifice section extending through the trailing edge, and
• a third, intermediate section connecting the first and second sections, and the third section laterally bound by at least two of the skin plies.

A method of fabricating an airfoil that has an airfoil section defining pressure and suction sides, a leading edge, and a trailing edge region including a trailing edge, the method comprising:

• forming a fiber preform by:
• laying-up core fiber plies to form a radial tube that circumscribes an internal cavity, the radial tube having a radiused end in the trailing edge region;
• laying-up skin fiber plies to wrap around the core fiber plies to form an exterior of the airfoil section, the skin fiber plies wrap from the pressure side of the trailing edge region, through the leading edge, and to the suction side of the trailing edge region;
• arranging a filler element in the trailing edge region aft of the internal cavity and sandwiched between the skin fiber plies on the pressure side and the skin fiber plies on the suction side;
• at least one cooling passage being formed in the airfoil section by a first, inlet orifice section that extends through the core fiber plies and that opens to the internal cavity at a location forward of the radiused end, wherein there is a number N of the core fiber plies each having a ply thickness t, and the location is forward of the radiused end by a distance D that is greater than the product of N, t, and a multiplier X that is from five to ten, a second, outlet orifice section that extends through the trailing edge, and a third, intermediate section connecting the first and second sections, the third section laterally bound by at least one of the skin plies;
• and
• densifying the fiber preform with a ceramic matrix to form a ceramic matrix composite.