Radial turbine assembly with ceramic matrix composite airfoils having dovetail retention

A radial turbine rotor incorporating ceramic matrix composite turbine blades is disclosed. The radial turbine rotor can include a dovetail shape retention features for coupling the ceramic matrix composite turbine blades to a central hub.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to radial turbines, and more specifically to radial turbine rotors.

BACKGROUND

Radial turbine rotors are characterized by rotating in response to a flow of working fluid radially inwardly toward the axis of rotation. In many applications, radial turbine rotors can be more efficient than axial turbine rotors that rotate in response to a flow of working fluid primarily parallel to the axis of rotation.

To increase efficiency of radial turbine rotors, it can be beneficial to increase the temperature of the working fluid that interacts with the rotors. However, manufacturing radial turbine rotors from high temperature materials and/or incorporating an active supply of cooling air into radial turbines presents challenges.

SUMMARY

The present disclosure may comprise one or more of the following features and combinations thereof in an effort to address challenges in radial turbine rotor design and manufacture.

A radial turbine rotor is disclosed in this paper. The rotor illustratively includes a metallic hub and a number of ceramic matrix composite turbine blades. The hub extends around a central axis and is shaped to define dovetail shape channels that extend primarily along the axis. The turbine blades are each shaped to include a dovetail root arranged in a corresponding one or more of the dovetail shape channels of the hub and an airfoil that extends radially-outward from the dovetail root.

In illustrative embodiments, dovetail shape channels are open along only one of a forward or an aft end of the hub. This opening allows for insertion of the turbine blades. In the exemplary embodiment, the dovetail shape channels are open along only an aft end of the hub.

In illustrative embodiments, the rotor also includes a retainer. The retainer is mounted along an aft face of the hub and the turbine blades to block undesired withdrawal of the turbine blades from the dovetail shape channels.

In illustrative embodiments, the retainer includes a retention ring and a shaft. The retention ring blocks undesired withdrawal of the turbine blades from the dovetail shape channels. The shaft is engaged with radially-inward facing surfaces of both the hub and the retention ring to couple the turbine rotor components together for rotation about the axis.

In illustrative embodiments, each of the plurality of turbine blades is further formed to include a platform. The platform extends circumferentially between airfoils of adjacent turbine blades to shield at least a portion of the hub radially inward of the platform.

DETAILED DESCRIPTION OF THE DRAWINGS

A radial turbine rotor10of the present disclosure is configured to extract energy from a working fluid, such as hot, high pressure combustion products, flowing through a gas path18. The radial turbine rotor10rotates about a central axis11to extract mechanical work from the flow of working fluid to drive other components of the gas turbine engine. The flow of working fluid in the radial turbine rotor10may be, at least in majority part, radial to the central axis11.

The radial turbine rotor10of the present disclosure is adapted for use in a gas turbine engine. The rotor10includes a hub12made of metallic materials, turbine blades14made of ceramic matrix composite materials (CMCs), and a retainer16. The retainer16facilitates coupling of the CMC turbine blades14to metallic the hub12as shown inFIGS.1-4.

The hub12is shaped to have a generally diminishing diameter from a forward end12F to an aft end12A as shown inFIGS.2and3. The hub12defines dovetail shape channels13that extend primarily along the central axis11. The turbine blades14are inserted into the channels13to couple the blades14to the hub12without fasteners.

In the illustrative embodiment, the dovetail channels13of the hub12are open at the aft end12A of the hub12as shown inFIG.3. This allows for insertion of the turbine blades14during assembly. Further, in the exemplary embodiment, the dovetail channels13are not open at the forward end12F of the hub12such that the hub12blocks movement forward along the axis11. In other embodiments contemplated, the channels13may be open at the forward end and/or both ends of the hub12.

In some embodiments, the hub12comprises nickel superalloy, such as, but not limited to, Udimet 720. In some embodiments, the hub12comprises nickel powder alloy, such as, but not limited to, RR1000. In some embodiments, the hub12comprises polycrystalline nickel-based superalloy, such as, but not limited to, Mar-M-247. In the illustrative embodiment, the hub12is integrally formed (cast/forged/machined) as a single component.

The turbine blades14are able to withstand relatively high temperatures on account of the CMC material used to create the blades14. In the illustrative embodiment, the blades14comprise silicon-carbide fibers in a silicon-carbide matrix (SiC-SiC). The turbine blades14are coupled to the hub12via a dovetail coupling.

Each of the plurality of turbine blades14is shaped to include a dovetail root26and an airfoil28as shown inFIGS.2-4. The root26is arranged in a dovetail shape channel13of the hub12. The airfoil28extends radially-outwardly for interaction with hot gasses that flow over the radial turbine rotor10during use.

Each of the plurality of turbine blades14can be formed to include a platform30as shown inFIG.1. Each of the optional platforms30extend circumferentially between airfoils28of adjacent turbine blades14to shield the hub12radially inward of the platform30.

The retainer16is illustratively mounted along the aft end12A of the hub12to block undesired withdrawal of the turbine blades14from the dovetail shape channels13as shown inFIG.4. The retainer16includes a retention ring40and a shaft42. The retention ring40engages the aft end12A of the hub12. The shaft42of the retainer16is engaged via interference fit with radially-inward facing surfaces of both the hub12and the retention ring40to couple the turbine rotor10components together for rotation about the axis11.

The retention ring40is configured to couple the plurality of turbine blades14to the hub12as shown inFIG.2. The retention ring40abuts the aft end12A of the hub12and an aft face of the dovetail root26of each of the plurality of turbine blades14to block axial movement of the plurality of turbine blades14relative to the hub12as shown inFIG.2. The shaft42includes a protrusion and a body extending axially away from the protrusion along the axis11as shown inFIGS.2and3. A radial outer surface of the body engages radially-inwardly facing surfaces of each of the hub12and the retention ring40to couple the hub12and the retention ring40together for rotation about the axis11as shown inFIG.2. The protrusion locates the retention ring40in place relative to the body of the shaft42and the hub12as shown inFIG.2. In the illustrative embodiment, an axial face of the protrusion that faces toward the aft end12A of the hub12engages an aft face of the retention ring40that faces away from the aft end12A of the hub12as shown inFIG.2. As shown inFIGS.2and3, the protrusion of the shaft42has a greater diameter than the body of the shaft42. In some embodiments, the protrusion of the shaft42forms a terminal end of the shaft42as shown inFIGS.2and3. The body of the shaft42extends axially away from the protrusion of the shaft42at a center point of the protrusion as shown inFIG.3.