Gas turbine airfoil including integrated leading edge and tip cooling fluid passage and core structure used for forming such an airfoil
A core structure ( 10 ) includes a first core element ( 16 ) including a leading edge section ( 30 ), a tip section ( 32 ), and a turn section ( 34 ) joining the leading edge and tip sections ( 30, 32 ). The first core element ( 16 ) is adapted to be used to form a leading edge cooling circuit ( 102 ) in a gas turbine engine airfoil ( 100 ). The leading edge cooling circuit ( 102 ) includes a cooling fluid passage ( 104 ) having a leading edge portion ( 106 ) formed by the first core element leading edge section ( 30 ), a tip portion ( 108 ) formed by the first core element tip section ( 32 ), and a turn portion ( 110 ) formed by the first core element turn section ( 34 ). Each of the leading edge portion ( 106 ), the tip portion ( 108 ), and the turn portion ( 110 ) of the cooling fluid passage ( 104 ) are formed concurrently in the airfoil ( 100 ) by the first core element ( 16 ).
1. An airfoil in a gas turbine engine comprising:
an outer wall including a leading edge, a trailing edge, a pressure side, a suction side, a radially inner end, and a radially outer end, wherein a chordal direction is defined between the leading and trailing edges;
a leading edge cooling circuit defined in the outer wall, the leading edge cooling circuit receiving cooling fluid for cooling the outer wall and comprising:
a cooling fluid passage including:
a leading edge portion extending radially through the airfoil adjacent to the leading edge;
a tip portion extending chordally from adjacent to the leading edge to adjacent to the trailing edge; and
a turn portion that facilitates fluid communication between the leading edge portion and the tip portion;
wherein the leading edge portion of the cooling fluid passage includes a plurality of flow directing features that effect a helical flow pattern for cooling fluid flowing radially outwardly through the leading edge portion;
wherein the leading edge portion of the cooling fluid passage includes first and second leading edge passages extending generally radially through the airfoil,
a plurality of transition passages providing fluid communication from the first leading edge passage to the second leading edge passage, wherein cooling fluid entering the second leading edge passage from the first leading edge passage through the transition passages impinges on a surface of the airfoil defining an outer boundary of the second leading edge passage to provide impingement cooling of the surface, and
wherein:
the flow directing features comprise grooves extending into a surface of the airfoil defining an outer boundary of the leading edge portion, the grooves extending circumferentially and radially with respect to a radial axis of the leading edge portion; and
the grooves extend around the surface of the airfoil defining the outer boundary of the leading edge portion from an inner end of the leading edge portion to an outer end of the leading edge portion.
2. The airfoil according to claim 1 , wherein each portion of the cooling passage is formed concurrently with the other portions using a first core element of a core structure.
3. The airfoil according to claim 2 , further comprising:
a mid-chord cooling circuit that is formed by a mid-chord section of the core structure integral with the first core element, the mid-chord cooling circuit being formed concurrently with the first core element forming the leading edge cooling circuit; and
a trailing edge cooling circuit that is formed by a trailing edge section of the core structure integral with the mid-chord section, the trailing edge cooling circuit being formed concurrently with the core structure forming the leading edge cooling circuit.
4. The airfoil according to claim 1 , wherein the transition passages are located closer to one of the pressure and suction sides of the airfoil than the other.
5. The airfoil according to claim 1 , further comprising an inlet passage that introduces cooling fluid into an inner end of the leading edge portion of the cooling passage at an angle of between 25 degrees to 65 degrees relative to a radial axis of the leading edge portion.