BACKGROUND

A gas turbine engine typically includes a fan section, a compressor section, a combustor section and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-speed exhaust gas flow. The high-speed exhaust gas flow expands through the turbine section to drive the compressor and the fan section. The compressor section may include low and high pressure compressors, and the turbine section may also include low and high pressure turbines.

Airfoils in the turbine section are typically formed of a superalloy and may include thermal barrier coatings to extend temperature capability and lifetime. Ceramic matrix composite (“CMC”) materials are also being considered for airfoils. Among other attractive properties, CMCs have high temperature resistance. Despite this attribute, however, there are unique challenges to implementing CMCs in airfoils.

SUMMARY

An airfoil according to an example of the present disclosure includes an airfoil body that has a trailing edge region. the trailing edge region includes first and second monolithic ceramic exterior walls, a flow discharge passage between the first and second monolithic ceramic exterior walls, a ceramic matrix composite (CMC) liner at least a portion of which is disposed in the flow discharge passage between the first and second monolithic ceramic exterior walls, and an array of pedestals disposed in the flow discharge passage. Each pedestal bridges the CMC liner and at least one of the first and second monolithic ceramic exterior walls.

In a further example of any of the foregoing embodiments, the CMC liner divides the flow discharge passage into first and second sub-passages between, respectively, the CMC liner and the first monolithic ceramic wall and the CMC liner and the second monolithic ceramic wall.

In a further example of any of the foregoing embodiments, the pedestals are monolithic ceramic.

In a further example of any of the foregoing embodiments, one of the first or second monolithic ceramic exterior walls includes a cutback.

In a further example of any of the foregoing embodiments, the CMC liner extends beyond the cutback.

In a further example of any of the foregoing embodiments, one of the first or second monolithic ceramic walls is scalloped.

In a further example of any of the foregoing embodiments, the CMC liner includes a liner pressure side wall and a liner suction side wall, and the flow discharge passage is between the liner pressure side wall and the liner suction side wall.

In a further example of any of the foregoing embodiments, the liner pressure side wall and the liner suction side wall meet at a position beyond a terminal edge of at least one of the first or second monolithic ceramic exterior walls.

In a further example of any of the foregoing embodiments, the CMC liner includes orifices connecting the flow discharge passage to an exterior of the airfoil.

An airfoil according to an example of the present disclosure includes a monolithic ceramic shell that defines a leading end, a shell pressure side wall, and a shell suction side wall. the monolithic ceramic shell circumscribes a core passage. A ceramic matrix composite (CMC) liner defines a liner pressure side wall that lines the shell pressure side wall and a liner suction side wall that lines the shell suction side wall. The liner pressure side wall and the liner suction side wall converge to form a liner tail. The pressure side wall and the suction side wall converge around the liner tail in a trailing end region. There is a flow discharge passage in the trailing edge region between the shell pressure side wall and the shell suction side wall. The flow discharge passage is connected with the core passage, and there are pedestals disposed in the flow discharge passage.

In a further example of any of the foregoing embodiments, the pedestals are bonded to at least one of the shell pressure side wall or the shell suction side wall.

In a further example of any of the foregoing embodiments, the pedestals are monolithic ceramic.

In a further example of any of the foregoing embodiments, the pedestals are bonded to the CMC liner.

In a further example of any of the foregoing embodiments, the liner pressure side wall and the liner suction side wall meet to form the liner tail.

In a further example of any of the foregoing embodiments, the liner pressure side wall and the liner suction side wall include metering orifices therein or between the pedestals connecting the core passage and the flow discharge passage.

In a further example of any of the foregoing embodiments, the liner tail divides the flow discharge passage into sub-passages.

In a further example of any of the foregoing embodiments, the shell pressure side wall includes a cutback.

An airfoil according to an example of the present disclosure includes a monolithic ceramic shell that defines a leading end, a shell pressure side wall, and a shell suction side wall. The shell pressure side and the shell suction side converge in a trailing end region. A ceramic matrix composite (CMC) liner lines the monolithic ceramic shell. There is a flow discharge passage in the trailing edge region between the shell pressure side wall and the shell suction side wall. There are pedestals disposed in the flow discharge passage, and each pedestal is bonded to the shell pressure side wall and to the shell suction side wall.

In a further example of any of the foregoing embodiments, the pedestals are bonded to the CMC liner.

In a further example of any of the foregoing embodiments, the CMC liner includes a liner pressure side wall lining the shell pressure side wall and a liner suction side wall lining the shell suction side wall, the liner pressure side wall and the liner suction side wall meeting to form a liner tail that extends in the flow discharge passage.

