Patent Description:
Gas turbine engines typically include at least a compressor section, a combustor section, and a turbine section. In general, during operation, air is pressurized in the compressor section and is mixed with fuel and burned in the combustor section to generate hot combustion gases. The hot combustion gases flow through the turbine section, which extracts energy from the hot combustion gases to power the compressor section and other gas turbine engine loads.

The compressor and turbine sections of a gas turbine engine typically include multiple stages of alternating rows of rotating blades and flow directing vanes. The rotating blades of the turbine section extract energy from the airflow that is communicated through the gas turbine engine, while the vanes direct the airflow to a downstream row of blades.

The vanes can be manufactured to a fixed flow area that is optimized for a single flight point. Alternatively, it is possible to alter the flow area between two adjacent vanes by providing one or more variable vanes that rotate about a given axis to vary the flow area. Altering the flow area in this manner changes the pressure distributions of the variable vane as well as nearby hardware. The pressure distribution changes can alter the amount of cooling fluid necessary to condition the vanes and surrounding hardware.

<CIT> discloses a prior art variable area turbine arrangement according to the preamble of claim <NUM> and a prior art method according to the preamble of claim <NUM>.

According to a first aspect of the present invention, there is provided a variable area turbine arrangement as set forth in claim <NUM>.

According to a further aspect of the present invention, there is provided a gas turbine engine as set forth in claim <NUM>. According to a further aspect of the present invention, there is provided a method as set forth in claim <NUM>. Further embodiments are provided, as set forth in the dependent claims.

This disclosure is directed to a variable area turbine arrangement for a gas turbine engine. Among other features, the variable area turbine arrangement includes a variable vane assembly and a secondary flow system associated with the variable vane assembly. The variable vane assembly includes a variable airfoil and an actuation system. Either the vane airfoil itself or the actuation system may be used to modulate a flow of a cooling fluid through the secondary flow system to condition the variable vane assembly and/or nearby hardware of the variable area turbine arrangement. Coupling actuation of the variable vane assembly and the secondary flow system reduces hardware requirements, thereby reducing weight, cost, and complexity of the variable area turbine arrangement. These and other features are described in detail within this disclosure.

The exemplary gas turbine engine <NUM> is a two-spool turbofan engine that generally incorporates a fan section <NUM>, a compressor section <NUM>, a combustor section <NUM> and a turbine section <NUM>. Alternative engines might include an augmenter section (not shown) or a second bypass stream (not shown) among other systems or features. The fan section <NUM> drives air along a bypass flow path B, while the compressor section <NUM> drives air along a core flow path C for compression and communication into the combustor section <NUM>. The hot combustion gases generated in the combustor section <NUM> are expanded through the turbine section <NUM>. Although depicted as a turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to turbofan engines and these teachings could extend to other types of engines, including but not limited to, three-spool engine architectures.

The gas turbine engine <NUM> generally includes a low speed spool <NUM> and a high speed spool <NUM> mounted for rotation about an engine centerline longitudinal axis A. The low speed spool <NUM> and the high speed spool <NUM> may be mounted relative to an engine static structure <NUM> via several bearing systems <NUM>. It should be understood that other bearing systems <NUM> may alternatively or additionally be provided.

The low speed spool <NUM> generally includes an inner shaft <NUM> that interconnects a fan <NUM>, and in some configurations a low pressure compressor <NUM> and a low pressure turbine <NUM>. The inner shaft <NUM> can be connected to the fan <NUM> through a geared architecture <NUM> to drive the fan <NUM> at a lower speed than the low speed spool <NUM>. The high speed spool <NUM> includes an outer shaft <NUM> that interconnects a high pressure compressor <NUM> and a high pressure turbine <NUM>. In this embodiment, the inner shaft <NUM> and the outer shaft <NUM> are supported at various axial locations by bearing systems <NUM> positioned within the engine static structure <NUM>.

A combustor <NUM> is arranged between the high pressure compressor <NUM> and the high pressure turbine <NUM>. A mid-turbine frame <NUM> may be arranged generally between the high pressure turbine <NUM> and the low pressure turbine <NUM>. The mid-turbine frame <NUM> can support one or more bearing systems <NUM> of the turbine section <NUM>. The mid-turbine frame <NUM> may include one or more airfoils <NUM> that extend within the core flow path C. Alternatively, a transition duct may or may not be arranged generally between the high pressure turbine <NUM> and the low pressure turbine <NUM>.

The inner shaft <NUM> and the outer shaft <NUM> are concentric and rotate via the bearing systems <NUM> about the engine centerline longitudinal axis A, which is colinear with their longitudinal axes. The core airflow is compressed by the fan <NUM> and/or the low pressure compressor <NUM> and the high pressure compressor <NUM>, is mixed with fuel and burned in the combustor <NUM>, and is then expanded through the high pressure turbine <NUM> and the low pressure turbine <NUM>. The high pressure turbine <NUM> and the low pressure turbine <NUM> rotationally drive the respective high speed spool <NUM> and the low speed spool <NUM> in response to the expansion.

The pressure ratio of the low pressure turbine <NUM> can be calculated by measuring the pressure prior to the inlet of the low pressure turbine <NUM> and relating it to the pressure measured at the outlet of the low pressure turbine <NUM> and prior to an exhaust nozzle of the gas turbine engine <NUM>. In one non-limiting embodiment, the bypass ratio of the gas turbine engine <NUM> 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>). 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 compressor section <NUM> and the turbine section <NUM> may include alternating rows of rotor assemblies and vane assemblies (shown schematically) that carry airfoils. For example, rotor assemblies carry a plurality of rotating blades <NUM>, while vane assemblies carry flow directing vanes <NUM> that extend into the core flow path C to influence the hot combustion gases. The blades <NUM> extract energy (in the form of pressure) from the core airflow that is communicated through the gas turbine engine <NUM> along the core flow path C. The vanes <NUM> direct the core airflow to the blades <NUM> to extract energy.

<FIG> illustrates a variable area turbine arrangement <NUM> that may be incorporated into a gas turbine engine, such as the gas turbine engine <NUM> of <FIG>, a conventional, non-geared gas turbine engine, or any other type of gas turbine engine. In one embodiment, the variable area turbine arrangement <NUM> represents a portion of a turbine section of a gas turbine engine. In another embodiment, the variable area turbine arrangement <NUM> may make up the entire turbine section.

In one embodiment, the variable area turbine arrangement <NUM> includes a first turbine section <NUM> (i.e., a high pressure turbine) and a second turbine section <NUM> (i.e., a low pressure turbine) positioned downstream from the first turbine section <NUM>. However, the variable area turbine arrangement <NUM> could include additional sections beyond what is illustrated by <FIG>. For example, in another non-limiting embodiment, the variable area turbine arrangement <NUM> could include an intermediate pressure turbine disposed between the first turbine section <NUM> and the second turbine section <NUM> as part of a three-spool engine architecture.

Each of the first turbine section <NUM> and the second turbine section <NUM> includes one or more stages of alternating rows of vanes and blades. In the illustrated embodiment, the first and second turbine sections <NUM> and <NUM> both include two stages; however, the first turbine section <NUM> and the second turbine section <NUM> could include any number of stages within the scope of this disclosure.

A turbine case structure <NUM> circumscribes the first turbine section <NUM> and the second turbine section <NUM>. The turbine case structure <NUM> represents an outer casing that houses the first turbine section <NUM> and the second turbine section <NUM> of the variable area turbine arrangement <NUM>.

In one embodiment, the first turbine section <NUM> includes a variable vane assembly 65A having at least one variable airfoil 66A. The second turbine section <NUM> may also include a variable vane assembly 65B having at least one variable airfoil 66B. The variable vane assemblies 65A, 65B may include an array of variable airfoils circumferentially disposed about the engine centerline longitudinal axis A. Alternatively, the variable vane assemblies 65A, 65B could include a combination of both fixed and variable vanes.

In one non-limiting embodiment, the variable vane assembly 65A is positioned at an inlet <NUM> of the first turbine section <NUM> and the variable vane assembly 65B is disposed at an inlet <NUM> of the second turbine section <NUM>. However, the variable vane assemblies 65A, 65B could be disposed elsewhere or in more than one location within the variable area turbine arrangement <NUM>.

The variable vane assemblies 65A, 65B may include any number of variable airfoils 66A, 66B that are selectively configurable to change a flow parameter associated with the variable area turbine arrangement <NUM>. In other words, the variable airfoils 66A, 66B are adjustable to change a flow area of the first and second turbine sections <NUM>, <NUM> by controlling the amount of core airflow F that is communicated through the first and second turbine sections <NUM>, <NUM>. As is known, the variable airfoils 66A, 66B are pivotable (via an actuation system (not shown)) about a spindle axis SA in order to change the rotational positioning of the variable airfoils 66A, 66B (i.e., change the angle of attack of the variable airfoils relative to core airflow F entering the first and second turbine sections <NUM>, <NUM>). This change in rotational positioning influences the flow area of the variable area turbine arrangement <NUM>.

The variable airfoils 66A, 66B may rotate relative to inner platforms 68A, 68B and outer platforms 70A, 70B of the variable vane assemblies 65A, 65B. The inner platforms 68A, 68B and the outer platforms 70A, 70B may be mounted to the turbine case structure <NUM> in any known manner.

Each of the first turbine section <NUM> and the second turbine section <NUM> may additionally include a second vane assembly 75A, 75B, respectively. In one embodiment, the second vane assembly 75A, 75B is a stationary or fixed vane assembly that includes stationary airfoils that provide a fixed flow area.

A rotor assembly <NUM> is positioned downstream from each vane assembly of the first turbine section <NUM> and the second turbine section <NUM>. Each rotor assembly <NUM> includes at least one rotor disk <NUM> that carries one or more rotor blades <NUM>. The rotor blades <NUM> extract energy from the core airflow F, thereby moving the disk <NUM> and powering various gas turbine engine loads.

The blades <NUM> rotate relative to blade outer air seals (BOAS) <NUM> that establish an outer radial flow path boundary for channeling the core airflow F through the variable area turbine arrangement <NUM>. The BOAS <NUM> may extend from the turbine case structure <NUM> relative to a tip of each rotating blade <NUM> in order to seal between the blade <NUM> and the turbine case structure <NUM>.

Altering the flow area associated with the variable area turbine arrangement <NUM> by moving the variable airfoils 66A, 66B changes the pressure distributions of the variable vane assemblies 65A, 65B as well as nearby hardware (i.e., the rotor assemblies <NUM>, vane assemblies 75A, 75B, BOAS <NUM>, etc.). These pressure distribution changes can alter the amount of cooling fluid necessary to condition the vanes and other nearby hardware. Arrangements for simultaneously actuating the variable vane assemblies 65A, 65B and addressing these cooling needs are detailed below with respect to <FIG>.

<FIG> illustrates a variable vane assembly <NUM> and associated secondary flow system <NUM> that may be incorporated into a variable area turbine arrangement <NUM>. In one embodiment, the functionality of the variable vane assembly <NUM> and the secondary flow system <NUM> are synchronized to address the cooling needs of the hardware of the variable area turbine arrangement <NUM>. These cooling needs may vary due to the pressure distribution changes that are caused by altering a flow area of the variable area turbine arrangement <NUM> (i.e., by altering a rotational positioning of a variable airfoil <NUM>).

In one embodiment, the variable airfoil <NUM> of the variable vane assembly <NUM> extends between an outer spindle <NUM> and an inner spindle <NUM>. The outer spindle <NUM> extends through an outer platform <NUM> and the inner spindle <NUM> extends through an inner platform <NUM>. An actuation system <NUM> (shown schematically) is configured to rotate the variable airfoil <NUM> about a spindle axis SA that extends through the outer spindle <NUM> and the inner spindle <NUM>. The actuation system <NUM> could include a synchronizing ring system, a ring gear system, or any other system suitable to move the variable airfoil <NUM> to change a flow area of the variable area turbine arrangement <NUM>. At least one of the spindles <NUM>, <NUM> (here, the outer spindle <NUM>) may include a window <NUM> for receiving a cooling fluid F2 from the secondary flow system <NUM>, additional details of which are discussed below.

The secondary flow system <NUM> communicates the cooling fluid F2 relative to the variable vane assembly <NUM>. In one embodiment, the cooling fluid F2, which may be bleed airflow from a compressor section of the gas turbine engine, is communicated in a cavity <NUM> that extends between the turbine case structure <NUM> and the outer platform <NUM> of the variable vane assembly <NUM>. The cooling fluid F2 is directed toward the window <NUM> of the outer spindle <NUM>, in one embodiment.

A tube <NUM> may be positioned inside of the outer spindle <NUM>. The tube <NUM> includes a flange <NUM> that abuts the turbine case structure <NUM> and a tube body <NUM> that extends into the outer spindle <NUM>. The tube body <NUM> may include at least one port <NUM>. In one embodiment, the at least one port <NUM> is at least partially radially aligned with the window <NUM> of the outer spindle <NUM>, such that when aligned, the cooling fluid F2 may enter inside of the variable airfoil <NUM> through the aligned window <NUM> and port <NUM>.

In one embodiment, the actuation system <NUM> moves the outer spindle <NUM>, such as by rotation, relative to the tube <NUM> in order to cover or uncover the port <NUM> and control an amount of the cooling fluid F2 permitted to enter the variable airfoil <NUM> through the port <NUM>. For example, the outer spindle <NUM> may move between a first position in which the port <NUM> is completely covered by the outer spindle <NUM> and a second position in which the port <NUM> at least partially aligns with the window <NUM> to permit a portion of the cooling fluid F2 to enter through the port <NUM>, or any intermittent position between fully covered and fully uncovered. The cooling fluid F2 may then be communicated to condition the variable airfoil <NUM> and other nearby hardware. The amount of cooling fluid F2 permitted to enter the port <NUM> can be modulated by changing a rotational positioning of the variable airfoil <NUM> and the outer spindle <NUM>. In this way, modulation of the flow of the cooling fluid F2 is linked to the function of the variable vane assembly <NUM>.

<FIG> illustrate additional embodiments of a variable vane assembly <NUM> and associated secondary flow system <NUM> that are linked to simultaneously vary a flow area and address variable cooling needs of the hardware of a variable area turbine arrangement <NUM>. In this disclosure, like reference numerals designate like elements where appropriate and reference numerals with the addition of <NUM> or multiples thereof designate modified elements that are understood to incorporate the same features and benefits of the corresponding original elements.

In the embodiment of <FIG>, a variable vane assembly <NUM>-<NUM> includes a variable airfoil <NUM>-<NUM>, an outer spindle <NUM>-<NUM>, an inner spindle <NUM>-<NUM> and an actuation system <NUM>-<NUM>. The actuation system <NUM> can rotate the variable airfoil <NUM>-<NUM> about a spindle axis SA that extends through the outer spindle <NUM>-<NUM> and the inner spindle <NUM>-<NUM>. At least one of the spindles <NUM>-<NUM>, <NUM>-<NUM> (here, the inner spindle <NUM>-<NUM>) may include a window <NUM>-<NUM> for communicating a cooling fluid F2 to a portion of the secondary flow system <NUM>.

For example, the secondary flow system <NUM>-<NUM> may include a tangential on-board injector (TOBI) assembly <NUM>-<NUM> positioned radially inboard of the variable vane assembly <NUM>-<NUM>. The TOBI assembly <NUM>-<NUM> may be a cast ring style or tube style. The function of the TOBI assembly <NUM>-<NUM> is to orient the secondary cooling flow delivered through the airfoils of the variable vane assembly <NUM> such that pressure losses are minimized as the cooling flow is introduced to the downstream rotor assembly. The TOBI assembly <NUM>-<NUM> includes a passage <NUM>-<NUM> that may selectively align with the window <NUM>-<NUM> to direct cooling fluid F2 to downstream hardware. In one embodiment, the TOBI assembly <NUM>-<NUM> may direct cooling fluid F2 to blades and disks of downstream rotor assemblies.

In one non-limiting embodiment, the secondary flow system <NUM>-<NUM> communicates the cooling fluid F2 into the variable vane assembly <NUM>-<NUM> via the outer spindle <NUM>-<NUM>. The cooling fluid F2 may travel through the interior of the variable airfoil <NUM>-<NUM> until it reaches the inner spindle <NUM>-<NUM>. Once inside the inner spindle <NUM>-<NUM>, the cooling fluid F2 is directed toward the window <NUM>-<NUM>.

In one embodiment, the actuation system <NUM>-<NUM> rotates the variable airfoil <NUM>-<NUM> (via the outer spindle <NUM>-<NUM>) to move the inner spindle <NUM>-<NUM> relative to the TOBI assembly <NUM>-<NUM>, thereby covering or uncovering the window <NUM>-<NUM> to control an amount of cooling fluid F2 permitted to exit the window <NUM>-<NUM> and enter the passage <NUM>-<NUM>. For example, the inner spindle <NUM>-<NUM> may move between a first position in which the window <NUM>-<NUM> is completely blocked by a surface of the TOBI assembly <NUM>-<NUM> and a second position in which the window <NUM>-<NUM> at least partially aligns with the passage <NUM>-<NUM> to permit a portion of the cooling fluid F2 to enter the passage <NUM>-<NUM>. The cooling fluid F2 may then be communicated to condition nearby hardware. The amount of cooling fluid F2 permitted to enter the passage <NUM>-<NUM> can be modulated by changing the rotational positioning of the variable airfoil <NUM> and inner spindle <NUM>-<NUM>. In this way, modulation of the flow of the cooling fluid F2 through the secondary flow system <NUM>-<NUM> is linked to actuation of the variable vane assembly <NUM>-<NUM>.

Referring to <FIG>, another embodiment of a variable vane assembly <NUM>-<NUM> could include multiple windows <NUM>-2A, <NUM>-2B for modulating cooling fluid F2 through multiple passages <NUM>-2A, <NUM>-2B of a TOBI assembly <NUM>-<NUM> of a secondary flow system <NUM>-<NUM>. Similar to the <FIG> embodiment, the variable vane assembly <NUM>-<NUM> can be moved (by rotating a variable airfoil <NUM>-<NUM> via an actuation system <NUM>-<NUM>) to simultaneously modulate the flow of cooling fluid F2 through the TOBI assembly <NUM>-<NUM> to address the cooling needs of nearby hardware. For example, the cooling fluid F2 can be used to cool both radially outboard hardware (vane and blade platforms, etc.) through the passage <NUM>-2B and radially inboard hardware (disks, etc.) through the passage <NUM>-2A. A positioning of the windows <NUM>-2A, <NUM>-2B relative to the passages <NUM>-2A, <NUM>-2B can be controlled to modulate the amount of cooling fluid F2 permitted to enter each of the passages <NUM>-2A, <NUM>-2B.

<FIG> illustrate two non-limiting embodiments of possible window/passage configurations. It should be appreciated that various other window/passage configurations can additionally or alternatively be provided.

Another variable vane assembly <NUM>-<NUM> and associated secondary flow system <NUM>-<NUM> are illustrated in <FIG>. In this embodiment, a spindle <NUM>-<NUM> (here, an inner spindle) of the variable vane assembly <NUM>-<NUM> is mechanically linked to an exit nozzle vane <NUM>-<NUM> of a TOBI assembly <NUM>-<NUM> of the secondary flow system <NUM>-<NUM> by a linkage assembly <NUM>-<NUM>. In one embodiment, the linkage assembly <NUM>-<NUM> includes a spur gear <NUM>-<NUM> connected to the spindle <NUM>-<NUM> and a lever arm <NUM>-<NUM> connected to the exit nozzle vane <NUM>-<NUM> (or a rotating blocker <NUM>-<NUM> such as shown in <FIG>, which is section A-A of <FIG>). Actuation of the variable vane assembly <NUM>-<NUM> by an actuation system <NUM>-<NUM> can simultaneously modulate a flow of a cooling fluid F2 through the TOBI assembly <NUM>-<NUM> by changing a rotational positioning of the exit nozzle vane <NUM>-<NUM>.

Alternatively, the linkage assembly <NUM>-<NUM> may be connected to a rotating blocker <NUM>-<NUM> positioned between adjacent exit nozzle vanes <NUM>-<NUM> (See <FIG>). The rotating blocker <NUM>-<NUM> may be moved simultaneously with movement of the variable vane assembly <NUM>-<NUM> to modulate a flow of a cooling fluid F2 through the TOBI assembly <NUM>-<NUM>. In one embodiment, the rotating blocker <NUM>-<NUM> is moved by changing a rotational positioning of the variable vane airfoils <NUM>-<NUM>.

<FIG> illustrates another exemplary variable vane assembly <NUM> and associated secondary flow system <NUM>. In this embodiment, the variable vane assembly <NUM> includes a variable airfoil <NUM> that extends between an outer spindle <NUM> and an inner spindle <NUM> that span a spindle axis SA. An actuation system <NUM> is configured to rotate the variable airfoil <NUM> about the spindle axis SA to change a direction of core airflow F communicated across the variable airfoil <NUM> and vary the flow area of a variable area turbine arrangement <NUM>.

In one embodiment, the actuation system <NUM> includes a gear system <NUM> suitable to move the variable airfoil <NUM> to change a flow area associated with the variable area turbine arrangement <NUM>. The gear system <NUM> includes a first gear <NUM>, a second gear <NUM>, a third gear <NUM> and a fourth gear <NUM>. In one embodiment, the first gear <NUM> is a worm gear, the second and fourth gears <NUM>, <NUM> are ring gears and the third gear <NUM> is a bevel spur gear. Of course, other gear combinations may be suitable for use in the gear system <NUM>.

In one embodiment, the actuation system <NUM> provides motive force to the worm gear <NUM>. The worm gear <NUM> drives the outer surface of the ring gear <NUM>. The aft face of the ring gear <NUM> has a bevel gear tooth arrangement that drives the bevel spur gear <NUM>. The bevel spur gear <NUM> then drives a bevel gear tooth arrangement on the ring gear <NUM>, which may feature cooling air ports <NUM>. In one embodiment, the bevel spur gear <NUM> is directly attached to the variable vane outer spindle <NUM>. Thus, when the bevel spur gear <NUM> rotates so does the variable vane airfoil <NUM>.

At least one of the spindles <NUM>, <NUM> (here, the outer spindle <NUM>) may include a window <NUM> for communicating a cooling fluid F2 into a port 298A of the secondary flow system <NUM>. In one embodiment, the port 298A extends through an outer platform <NUM>. The window <NUM> is selectively exposed to the port 298A during movement of the variable airfoil <NUM> (via the actuation system <NUM> and the rotation of the bevel spur gear <NUM>) to modulate a flow of the cooling fluid F2 through the port 298A. The cooling fluid F2 that is channeled through the port 298A may be communicated to condition downstream hardware, including but not limited to a BOAS <NUM>.

Alternatively or additionally, the secondary flow system <NUM> may include a second port 298B disposed through a rail <NUM> of the outer platform <NUM>. In one embodiment, a portion of the gear system <NUM> (here, the fourth gear <NUM>) acts as a port blocker to selectively block the flow of cooling fluid F2 into the second port 298B. In one embodiment, the fourth gear <NUM> includes the port <NUM> that may align with the second port 298B during rotation of the fourth gear <NUM> to modulate the amount of cooling fluid F2 permitted to enter the second port 298B. In this way, modulation of the flow of the cooling fluid F2 is directly linked to the actuation system <NUM>. The cooling fluid F2 that is channeled through the second port 298B may condition downstream hardware, including but not limited to the BOAS <NUM>.

<FIG> illustrates yet another variable vane assembly <NUM> and associated secondary flow system <NUM> that may be incorporated into a variable area turbine arrangement <NUM>. In this embodiment, the variable vane assembly <NUM> and the secondary flow system <NUM> may be simultaneously actuated to vary a flow area and address variable cooling needs of the hardware of the variable area turbine arrangement <NUM>.

The variable vane assembly <NUM> may include a variable airfoil <NUM> that extends between an outer spindle <NUM> and an inner spindle <NUM> that extend along a spindle axis SA. An actuation system <NUM> is configured to rotate the variable airfoil <NUM> about the spindle axis SA.

In one embodiment, the actuation system <NUM> is configured to move the variable airfoil <NUM> to change a flow area associated with the variable area turbine arrangement <NUM>. The actuation system <NUM> may include a first bevel gear <NUM>, a second bevel gear <NUM>, a spur gear <NUM>, a sync ring <NUM>, and a vane arm <NUM>. In one embodiment, motive force delivered through a shaft <NUM> rotates the first bevel gear <NUM>. The first bevel gear <NUM> meshes with the second bevel gear <NUM>, thereby rotating it. Mounted on the same shaft as second bevel gear <NUM> is the spur gear <NUM>. Rotation of the second bevel gear <NUM> thus rotates the spur gear <NUM>. Spur gear <NUM> meshes with gear tooth features on the outer circumference of the sync ring <NUM>. Rotational drive of the sync ring <NUM> by the spur gear <NUM> results in articulation of the individual vane arms <NUM> connected to variable vane airfoils <NUM>, thereby rotating the variable vane airfoils <NUM>.

In one embodiment, the secondary flow system <NUM> may include one or more cooling pipes <NUM> for directing a cooling fluid F2 to the variable area turbine arrangement <NUM>. The cooling pipe <NUM> may house a modulation valve <NUM> that is mechanically linked to the actuation system <NUM> via the shaft <NUM>. In one embodiment, the modulation valve <NUM> is a butterfly valve. In operation, actuation of the variable airfoil <NUM> by the actuation system <NUM> simultaneously adjusts a positioning of the modulation valve <NUM> to modulate a flow of the cooling fluid F2 that is permitted to enter the variable airfoil <NUM>.

Although the different non-limiting embodiments are illustrated as having specific components, the embodiments of this disclosure are not limited to those particular combinations.

Claim 1:
A variable area turbine arrangement (<NUM>), comprising:
a variable vane assembly (<NUM>-<NUM>; <NUM>-<NUM>; <NUM>-<NUM>); and
a secondary flow system (<NUM>-<NUM>; <NUM>-<NUM>; <NUM>-<NUM>) associated with said variable vane assembly (<NUM>-<NUM>; <NUM>-<NUM>; <NUM>-<NUM>),
wherein flow modulation of a cooling fluid through said secondary flow system (<NUM>-<NUM>; <NUM>-<NUM>; <NUM>-<NUM>) is changed simultaneously with actuation of said variable vane assembly (<NUM>-<NUM>; <NUM>-<NUM>; <NUM>-<NUM>),
characterized in that:
the secondary flow system (<NUM>-<NUM>; <NUM>-<NUM>; <NUM>-<NUM>) includes a TOBI assembly (<NUM>-<NUM>; <NUM>-<NUM>; <NUM>-<NUM>).