Patent Description:
Components of gas turbine engines, for example, turbine vanes or the like, are subjected to high temperatures during operation of the gas turbine engine, which limits the service life of the components. Through combinations of material selection and internal cooling of the components via a cooling airflow, the service life may be extended. In order to meet cooling air requirements for components in the turbine, a solution of interest in the industry is switching from single crystal Ni-based superalloys to high temperature materials capable of exposure to absolute temperatures hundreds of degrees in excess of current capabilities. Often these higher temperature materials, however, have significantly reduced allowable stresses during operation. For components such as turbine vanes, the thermo-mechanical stresses experienced are often heavily weighted towards thermally induced stresses arising from thermal gradients within the part, for example, between an outer component surface exposed to the hot gas path or the gas turbine engine and an inner component surface exposed to the cooling airflow inside of the component.

<CIT> discloses a turbine nozzle segment including a single hollow airfoil.

<CIT> discloses a turbine blade comprising a profiled vane with a first and second channel system.

<CIT> discloses a turbine nozzle baffle within a nozzle vane, wherein the baffle includes a plurality of apertures inclined through a shell.

<CIT> discloses a gas turbine engine component comprising a shell and a multi-part insert.

<CIT> discloses a turbine airfoil comprising a flow displacement element positioned in an interior portion of the airfoil body.

In one embodiment, a turbine vane assembly is provided as described in claim <NUM>.

The insert pocket may include one or more tabs to retain the flow discourager at the insert pocket.

The vane insert may urge the flow discourager into contact with one or more of the pressure side or the suction side.

The flow discourager may be one of a rope seal or a fabric seal.

The flow discourager may be formed from a metallic material or a ceramic material.

A cover plate may be positioned or disposed at the turbine vane to redirect the cooling airflow through the turbine vane.

In yet another embodiment, a gas turbine engine is provided as described in claim <NUM>.

The flow discourager is retained in an insert pocket of the insert and the insert pocket may include one or more tabs to retain the flow discourager at the insert pocket.

The following descriptions are given by way of example only and should not be considered limiting in any way.

In a further example, the engine <NUM> bypass ratio is greater than about six (<NUM>), with an example embodiment being greater than about ten (<NUM>), the geared architecture <NUM> is an epicyclic gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about <NUM> and the low pressure turbine <NUM> has a pressure ratio that is greater than about five (<NUM>). In one disclosed embodiment, the engine <NUM> bypass ratio is greater than about ten (<NUM>:<NUM>), the fan diameter is significantly larger than that of the low pressure compressor <NUM>, and the low pressure turbine <NUM> has a pressure ratio that is greater than about five (<NUM>:<NUM>). The geared architecture <NUM> may be an epicyclic gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about <NUM>:<NUM>. It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present disclosure is applicable to other gas turbine engines including direct drive turbofans.

The fan section <NUM> of the engine <NUM> is designed for a particular flight condition--typically cruise at about <NUM> Mach and about <NUM>,<NUM> feet (<NUM>,<NUM> meters).

Referring now to <FIG>, the low pressure turbine <NUM> includes one or more turbine rotors <NUM> positioned in a turbine case <NUM> and rotatable about the engine central longitudinal axis A. While the following description is in the context of a low pressure turbine <NUM>, one skilled in the art will readily appreciate that the present disclosure may be readily applied to the high pressure turbine <NUM>. Each of the turbine rotors <NUM> includes a rotor disc <NUM> with a plurality of rotor blades <NUM> extending radially outwardly from the rotor disc <NUM> toward the turbine case <NUM>. One or more rows of stator vanes <NUM> are located, for example, between adjacent turbine rotors <NUM>, and/or upstream or downstream of the turbine rotors <NUM>. The stator vanes <NUM> may be retained at the turbine case <NUM>. The stator vanes <NUM> include a vane outer cavity <NUM> located at a vane outer diameter <NUM> between the stator vane <NUM> and the turbine case <NUM>. Further, a vane inner cavity <NUM> is located at a vane inner diameter <NUM> between the stator vane <NUM> and an inner air seal <NUM>. The vane outer cavity <NUM> is connected to a cooling airflow inlet <NUM> to direct a cooling airflow <NUM> into the stator vane <NUM> from, for example, a turbine cooling air (TCA) pipe <NUM>. The cooling airflow <NUM> flows through one or more cooling passages in the stator vane <NUM> and into the vane inner cavity <NUM>, then exits the vane inner cavity <NUM> at an outlet orifice <NUM> in, for example, the inner air seal <NUM>.

Referring now to the cross-sectional view of stator vane <NUM> in <FIG>, the stator vane <NUM> includes a vane leading edge <NUM> and a vane trailing edge <NUM>, relative to the direction of core airflow along the core flowpath C. The vane includes a vane pressure side <NUM> and a vane suction side <NUM> each extending from the vane leading edge <NUM> to the vane trailing edge <NUM>. One or more internal vane ribs <NUM> extend between the vane suction side <NUM> and the vane pressure side <NUM> defining one or more vane cavities <NUM> directing the cooling airflow <NUM> through the stator vane <NUM> and for structural support of the stator vane <NUM>.

Typically, due to their direct exposure to the core airflow, the vane suction side <NUM> and the vane pressure side <NUM> are exposed to much higher temperatures than the internal vane ribs <NUM>, which typically are exposed directly to the cooling airflow <NUM>. Thus, in a typical vane configuration, there is a high thermal gradient between the internal vane ribs <NUM> and the vane pressure side <NUM> and vane suction side <NUM>, which reduces the service life of the stator vane <NUM>.

To combat the thermal gradient, the stator vane <NUM> includes a vane insert <NUM> located in one or more of the vane cavities <NUM> and a flow discourager <NUM> disposed between the vane insert <NUM> and the internal vane rib <NUM>. The vane insert <NUM> urges the flow discourager <NUM> into contact with the internal vane rib <NUM> and/or the vane pressure side <NUM> or the vane suction side <NUM> to prevent the cooling airflow <NUM> from flowing past the internal vane rib <NUM>. The lack of cooling airflow <NUM> past the internal vane rib <NUM> increases a temperature of the internal vane rib <NUM> and reduces the thermal gradient across the internal vane rib <NUM>. In the embodiment of <FIG>, the vane insert <NUM> is positioned between two internal vane ribs <NUM> and four flow discouragers <NUM> are installed to the vane insert <NUM>, with two flow discouragers <NUM> positioned at each internal vane rib <NUM> to prevent cooling airflow <NUM> from flowing across the internal vane rib <NUM>. It is to be appreciated that other quantities and locations of vane inserts <NUM> and flow discouragers <NUM> may be utilized.

The vane insert <NUM> is formed by, for example, casting, additive manufacturing, or stamping, while the flow discourager <NUM> is, in some embodiments, a seal such as a rope seal or fabric seal, and may be formed from, for example, a metallic or ceramic material. Referring now to <FIG>, the vane insert <NUM> includes an insert pocket <NUM> into which the flow discourager <NUM> is installed. The vane insert <NUM> may also include one or more tabs <NUM> at the insert pocket <NUM> to locate and retain the flow discourager <NUM> at the insert pocket <NUM>. Referring to <FIG>, a cap <NUM> may be installed at the cooling airflow inlet <NUM> over the vane insert <NUM> to prevent cooling airflow <NUM> from flowing between the vane insert <NUM> and the internal vane rib <NUM> from a radially outwardly direction.

Referring to <FIG>, in some embodiments the vane insert <NUM> is hollow and includes an insert cavity <NUM>. Cooling airflow <NUM> may be directed through the insert cavity. In the embodiment illustrated in <FIG>, the stator vane <NUM> is configured as a multipass stator vane <NUM> in which the cooling airflow <NUM> enters the stator vane <NUM> at the vane outer diameter <NUM> and also exits the stator vane <NUM> at the vane outer diameter <NUM>. In such embodiments, the stator vane <NUM> includes a cover plate <NUM> at the vane inner diameter <NUM> to turn the cooling airflow <NUM> and redirect the cooling airflow <NUM> toward the vane outer diameter <NUM>.

The vane insert <NUM> and flow discourager <NUM> arrangements described herein reduces thermal gradients in the stator vane <NUM>, which allows for the use of high temperature materials such as ceramic matrix composite (CMC) materials in forming of the stator vane <NUM>.

Claim 1:
A turbine vane assembly, comprising:
a stator vane (<NUM>), including:
a pressure side (<NUM>) extending from a leading edge (<NUM>) to a trailing edge (<NUM>); and
a suction side (<NUM>) extending from the leading edge to the trailing edge, the pressure side and the suction side together defining an internal vane cavity (<NUM>) therebetween, the internal vane cavity configured for a cooling airflow (<NUM>) to flow therethrough;
an internal vane rib (<NUM>) extending into the internal vane cavity from one or more of the pressure side or the suction side;
a vane insert (<NUM>) positioned in the internal vane cavity; and
a flow discourager (<NUM>) configured to prevent the cooling airflow from flowing past the internal vane rib;
characterized in that:
the flow discourager (<NUM>) is positioned at the vane insert and retained in an insert pocket (<NUM>) of the vane insert (<NUM>).