Patent Description:
Air modulating systems can be used in various locations in a gas turbine engine to control air flow. For example, air modulation systems can be used to control air flow to heat exchangers based on sensed temperatures of the fluids. Some applications of air modulation require that fluid passageways be closed to stop air flow and that passageway inlets be fully sealed to eliminate leakage. In addition, some applications require that a plurality of fluid passageways be closed and sealed synchronously. Current air modulation systems may have nontrivial leakage when closed. Additionally, actuation methods and systems used to guide doors or closure structures over air passage inlets may experience system binding due tight tolerances and deformation of components through vibrational or frictional forces.

<CIT> discloses a prior art air modulating system. Other examples are disclosed in <CIT>, <CIT>, <CIT> and <CIT>.

In one aspect of the present invention, an air modulating system for a gas turbine engine is provided according to claim <NUM>.

In another aspect of the present invention, a method of modulating air flow is provided according to claim <NUM>. Other embodiments of the present invention are defined by the dependent claims <NUM> to <NUM> and <NUM>.

The present summary is provided only by way of example, and not limitation. Other aspects of the present disclosure will be appreciated in view of the entirety of the present disclosure, including the entire text, claims and accompanying figures.

<FIG> is a quarter sectional view that schematically illustrates an example gas turbine engine <NUM> that includes a fan section <NUM>, a compressor section <NUM>, a combustor section <NUM> and a turbine section <NUM>. Alternative engines might include an afterburner (not shown) among other systems or features. The fan section <NUM> drives air along a bypass flow path B through a bypass duct <NUM> while the compressor section <NUM> draws air in along a core flow path C where air is compressed and communicated to a combustor section <NUM>. In the combustor section <NUM>, air is mixed with fuel and ignited to generate a high pressure exhaust gas stream that expands through the turbine section <NUM> where energy is extracted and utilized to drive the fan section <NUM> and the compressor section <NUM>.

Although the disclosed non-limiting embodiment depicts a turbofan gas turbine engine, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines; for example, an industrial gas turbine; a reverse-flow gas turbine engine; and a turbine engine including a three-spool architecture in which three spools concentrically rotate about a common axis and where a low spool enables a low pressure turbine to drive a fan via a gearbox, an intermediate spool that enables an intermediate pressure turbine to drive a first compressor of the compressor section, and a high spool that enables a high pressure turbine to drive a high pressure compressor of the compressor section.

The example engine <NUM> generally includes a low speed spool <NUM> and a high speed spool <NUM> mounted for rotation about an engine central longitudinal axis relative to an engine static structure <NUM> via several bearing systems <NUM>. It should be understood that various bearing systems <NUM> at various locations may alternatively or additionally be provided.

The low speed spool <NUM> generally includes an inner shaft <NUM> that connects a fan <NUM> and a low pressure (or first) compressor section <NUM> to a low pressure (or first) turbine section <NUM>. The inner shaft <NUM> drives the fan <NUM> through a speed change device, such as 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 (or second) compressor section <NUM> and a high pressure (or second) turbine section <NUM>. The inner shaft <NUM> and the outer shaft <NUM> are concentric and rotate via the bearing systems <NUM> about the engine central longitudinal axis.

A combustor <NUM> is arranged between the high pressure compressor <NUM> and the high pressure turbine <NUM>. In one example, the high pressure turbine <NUM> includes at least two stages to provide a double stage high pressure turbine <NUM>. In another example, the high pressure turbine <NUM> includes only a single stage. As used herein, a "high pressure" compressor or turbine experiences a higher pressure than a corresponding "low pressure" compressor or turbine.

The example low pressure turbine <NUM> has a pressure ratio that is greater than about <NUM>. The pressure ratio of the example low pressure turbine <NUM> is measured prior to an inlet of the low pressure turbine <NUM> as related to the pressure measured at the outlet of the low pressure turbine <NUM> prior to an exhaust nozzle.

A mid-turbine frame <NUM> of the engine static structure <NUM> can be arranged generally between the high pressure turbine <NUM> and the low pressure turbine <NUM>. The mid-turbine frame <NUM> further supports bearing systems <NUM> in the turbine section <NUM> as well as setting airflow entering the low pressure turbine <NUM>.

The core airflow C is compressed by the low pressure compressor <NUM> then by the high pressure compressor <NUM> mixed with fuel and ignited in the combustor <NUM> to produce high speed exhaust gases that are then expanded through the high pressure turbine <NUM> and low pressure turbine <NUM>. The mid-turbine frame <NUM> includes vanes <NUM>, which are in the core airflow path and function as an inlet guide vane for the low pressure turbine <NUM>. Utilizing the vane <NUM> of the mid-turbine frame <NUM> as the inlet guide vane for low pressure turbine <NUM> decreases the length of the low pressure turbine <NUM> without increasing the axial length of the mid-turbine frame <NUM>. Reducing or eliminating the number of vanes in the low pressure turbine <NUM> shortens the axial length of the turbine section <NUM>. Thus, the compactness of the gas turbine engine <NUM> is increased and a higher power density may be achieved.

<FIG> is a front elevation view of one embodiment of an air modulating system <NUM> that includes a fixed plate <NUM> with a fluid passage inlet <NUM>, a floating plate <NUM>, an actuated mount <NUM>, and a linkage element <NUM>. The fixed plate <NUM> can be fixedly supported within engine <NUM> by a structure not shown. The floating plate <NUM> sits adjacent the fixed plate <NUM> and is removably connected to the actuated mount <NUM> through the linkage element <NUM>. The actuated mount <NUM> is capable of being rotated during use such that the floating plate <NUM> moves along a direction <NUM> to cover the fluid passage inlet <NUM> and in an opposite direction to uncover the fluid passage inlet <NUM>.

In one embodiment, the fixed plate <NUM> with a fluid passage inlet <NUM> comprises a heat exchanger, wherein the fluid passage inlet <NUM> is configured to receive a stream of fluid (e.g., air). In another embodiment, the fixed plate <NUM> with fluid passage inlet <NUM> comprises a fluid duct absent a heat exchanger. The air modulating system <NUM> can be located in the bypass duct <NUM> of the gas turbine engine <NUM>, however, it will be understood by one skilled in the art that the air modulating system <NUM> is not limited to a bypass duct location. The air modulating system <NUM> can be used to modulate air flow in other flow paths of the gas turbine engine <NUM>.

The actuated mount <NUM> can be a sync ring, which is connected to one or more actuators (not shown). The one or more actuators selectively rotate the mount <NUM> circumferentially about an axis A in direction <NUM> to close the fluid passage inlet <NUM> and in the opposite direction to open the fluid passage inlet <NUM>. When the actuated mount <NUM> is rotated in direction <NUM>, the floating plate <NUM> is moved about an inner circumference of the actuated mount <NUM> to cover the fluid passage inlet <NUM> and block fluid flow into the fluid passage inlet <NUM>. When the actuated mount <NUM> is rotated in the opposite direction, the floating plate <NUM> is moved to uncover the fluid passage inlet <NUM> to allow fluid flow into the fluid passage inlet <NUM>. The circumferential movement of the floating plate <NUM> is generally confined by a limited range of rotation of the actuated mount <NUM>. However, the circumferential movement of the floating plate <NUM> can be further constrained by one or a plurality of stops <NUM>, protruding from a surface of the fixed plate <NUM> and located at a circumferential end of movement, which catch the floating plate <NUM> and prevent continued movement past the stop <NUM>.

Although the present invention is generally described in terms of open and closed positions, the floating plate <NUM> can also be positioned to partially open the fluid passage, covering any portion of the fluid passage inlet <NUM> that is less than the whole.

The linkage element <NUM> removably connects the actuated mount <NUM> to the floating plate <NUM>. In one embodiment, the linkage element <NUM> includes an arm <NUM> extending from an inner radius of the actuated mount <NUM> to a flange structure <NUM> at an inner radial end of the arm <NUM>. The linkage element <NUM> is removably fixed to the actuated mount <NUM> with a fastener (not shown), such that the linkage element <NUM> can be replaced as needed to account for deterioration through vibrational and frictional forces.

The removable linkage element <NUM> can be made of a material with hardness value less than that of a material or materials of the actuated mount <NUM> and the floating plate <NUM>, such that deformation of the actuated mount <NUM> and floating plate <NUM> through contact with the linkage element <NUM> is reduced. In other words, the easily replaceable linkage element <NUM> can absorb wear and damage that might otherwise accrue to the larger and more difficult to replace floating plate <NUM> and actuated mount <NUM>. A location of the floating plate <NUM> at which the floating plate <NUM> and linkage element <NUM> interact can be additionally coated with a hard coating, such as chrome carbide, to further protect the floating plate <NUM> from damage. The linkage element <NUM> can similarly be coated with a hard coating to extend the lifetime of the linkage element <NUM>. The actuated mount <NUM> and the floating plate <NUM> in some embodiments are each made of a nickel-based superalloy (e.g., material available under the trademark INCONEL) or titanium alloy to withstand high temperatures, however, other materials may be better suited for different environments and can be used. The linkage element <NUM> can also be made of a nickel-based superalloy or titanium, or a material of lesser hardess to reduce damage to the floating plate. Alternatively, the linkage element <NUM> can be made of another material suited to the particular environment in which the air modulating system <NUM> is operating.

The floating plate <NUM> comprises a receptacle <NUM> for slidably receiving the linkage element <NUM>. The receptacle <NUM> is substantially the same cross-sectional shape as the linkage element <NUM>, such that the floating plate <NUM> is radially retained by the flange portion <NUM> of the linkage element <NUM>.

<FIG> shows another embodiment of the air modulating system <NUM> floating plate assembly of <FIG>. The floating plate <NUM> in <FIG> further comprises an opening <NUM> substantially matching the cross-sectional shape of the fluid passage inlet <NUM>. When the actuated mount <NUM> is rotated in the direction <NUM>, a body portion <NUM> of the floating plate <NUM> is moved to cover the fluid passage inlet <NUM> to block the flow of fluid into the fluid passage inlet <NUM>. When the actuated mount <NUM> is rotated in the opposite direction, the opening <NUM> of the floating plate <NUM> aligns with the fluid passage inlet <NUM> thereby allowing fluid to enter the fluid passage inlet <NUM>.

Due to manufacturing tolerances and wear and damage on the surfaces of the fixed plate <NUM> and floating plate <NUM> through vibrational and frictional forces, in any embodiment (e.g., as shown in <FIG> or <FIG>), a gap may exist or develop between the floating plate <NUM> and the fluid passage inlet <NUM> when the floating plate <NUM> is in a closed position. When a gap is present, a portion of fluid may reach the fluid passage inlet. To improve sealing at the fluid passage inlet, the floating plate <NUM> is configured to slide axially along the linkage element <NUM>, such that the floating plate <NUM> makes contact with the fixed plate <NUM>.

<FIG> shows a perspective view of the receptacle <NUM> of the floating plate <NUM> configured to slidably receive the linkage element <NUM>. According to the invention, the receptacle <NUM> is substantially the same cross-sectional shape as the linkage element <NUM>, such that the flange portion <NUM> is radially retained by the receptacle <NUM>, but larger than the cross-sectional shape of the linkage element <NUM> to permit the floating plate <NUM> to translate axially relative to the actuated mount <NUM> and pivot about the linkage element <NUM> in clockwise and counterclockwise directions. In one embodiment, the surfaces of the receptacle <NUM> adjacent the arm <NUM> of the linkage element <NUM> are rounded to provide the floating plate <NUM> additional freedom of movement about the linkage element <NUM>. The receptacle <NUM> extends through a thickness <NUM> of the floating plate <NUM> such that the receptacle <NUM> is open at both a first side <NUM> and second side <NUM> opposite the first side <NUM>. In one embodiment, the thickness <NUM> of the floating plate <NUM> at the receptacle <NUM> is greater than a thickness of the linkage element <NUM>. In other embodiments, the thickness <NUM> of the floating plate <NUM> at the receptacle <NUM> is substantially the same as or less than the thickness of the linkage element <NUM>.

<FIG> shows a perspective view of one embodiment of a linkage element <NUM>. The linkage element <NUM> includes a cylindrical arm <NUM> and larger cylindrical or puck-shaped flange <NUM> at a lower end of the arm <NUM>. The arm <NUM> extends from an inner radius of the actuated mount <NUM>. The linkage element <NUM> is removably fixed to the actuated mount <NUM> with a fastener <NUM>. A bolt, nut, screw, rivet or other suitable fastener can be used to fasten the linkage element <NUM> to the actuated mount <NUM>. The fastener <NUM> can extend through a bottom surface of the flange portion <NUM> radially outward and into the actuated mount <NUM>. In one example, the fastener <NUM> is a bolt secured with a nut at the actuated mount <NUM>. The head of the fastener <NUM> is streamlined (e.g., countersunk) such that it does not extend outward from the bottom surface of the linkage element <NUM> and interfere with the movement of the floating plate <NUM>. It will be understood by one skilled in the art that the positioning of the fastener can be changed without altering the function of the fastener. For example, the fastener can extend radially inward from the actuated mount <NUM> into the linkage element <NUM>. Additionally, the linkage element <NUM> can comprise a nut for securing the fastener. Although the linkage element is generally described as being fastened to the actuated mount with an element that extends through both the actuated mount <NUM> and the linkage element <NUM>, the fastener is not limited to these structures and can alternatively be a weld or suitable adhesive. Alternatively, the linkage element <NUM> can be integrally and monolithically formed with the actuated mount <NUM>.

<FIG> shows a perspective view of another embodiment of a linkage element <NUM>. The linkage element <NUM> includes an arm <NUM> and flange <NUM> at a lower end of the arm <NUM>, which have rectangular cross-sections and which together have a T-shape. The arm <NUM> extends from an inner radius of the actuated mount <NUM>. The linkage element <NUM> is removably fixed to the actuated mount <NUM> with a fastener <NUM> similar to that described in <FIG>. It will be understood to one skilled in the art that the shape of the mounting flange is not limited to the embodiments shown, but can comprise any shape that permits slidable engagement with the floating plate <NUM>. In general, the shape of the linkage element <NUM> can be determined by the system requirements, such as loading and material composition. The T-shaped and puck-shaped examples represent only one possible system application.

<FIG> shows a schematic cross-sectional view of the air modulating system <NUM> of <FIG> taken along the line <NUM>-<NUM> of <FIG> with the floating plate <NUM> in a fully closed position covering the fluid passage inlet <NUM> (shown in phantom in <FIG>). A fluid stream <NUM> acts on the second side <NUM> of the floating plate <NUM>. As the fluid stream <NUM> is unable to enter the fluid passage inlet <NUM>, fluid pressure (P2) increases on the second side <NUM>, such that it exceeds fluid pressure (P1) on the first side <NUM> of the floating plate <NUM> axially adjacent the fluid passage inlet <NUM>. The increased pressure load on the second side <NUM> forces the floating plate <NUM> to translate axially and form a seal against the fluid passage inlet <NUM>. In some embodiments, material has been removed from the second side <NUM> of the floating plate <NUM> to reduce weight, leaving a ledge <NUM> on the second side <NUM> extending from an outer perimeter of the second side <NUM> of the floating plate <NUM> and circumscribing the second side <NUM> of the floating plate <NUM>.

When the actuated mount <NUM> is rotated to open the fluid passage inlet <NUM>, the pressure load on the second side <NUM> of the floating plate <NUM> is reduced as fluid begins to flow into the fluid passage inlet <NUM>. With the reduced pressure load on the second side <NUM>, the floating plate <NUM> can translate axially away from the fixed plate <NUM> and fluid passage inlet <NUM>. As the floating plate <NUM> is moved across the fixed plate <NUM> with the rotation of the actuated mount <NUM>, the axial position of the floating plate <NUM> relative to the fixed plate <NUM> is self-corrected to reduce or prevent system binding. The ability of the floating plate <NUM> to self-correct positioning relative the fixed plate additionally accommodates manufacturing tolerances, pressure deflections of the hardware, and thermal distortion of the hardware.

A fixed member <NUM>, which can be fixedly supported relative to the engine <NUM>, prevents the floating plate <NUM> from axially disengaging from the linkage element <NUM>. The floating plate <NUM> is retained in a space between the fixed plate <NUM> and the fixed member <NUM> at both open and closed positions and as the floating plate <NUM> is moved circumferentially between open and closed positions. The fixed member <NUM> can be an air flow duct or similar structure configured to direct fluid flow. In one example, the fixed member <NUM> comprises an air flow duct with a cross-sectional opening substantially the same shape as the fluid passage inlet <NUM>. The circumference of the duct body serves as the retaining member and the duct comprises an additional retaining body (not shown) to limit axial movement of the floating plate <NUM>, such as when the floating plate <NUM> is transitioning to and is in a closed position.

Claim 1:
An air modulating system (<NUM>) for a gas turbine engine (<NUM>), the air modulating system (<NUM>) comprising:
a fixed plate (<NUM>) comprising a fluid passage inlet (<NUM>);
a floating plate (<NUM>) with a first side (<NUM>), wherein the first side (<NUM>) is adjacent to the fluid passage inlet (<NUM>);
an actuated mount (<NUM>) selectively rotatable circumferentially about an axis (A) and configured to move the floating plate (<NUM>) relative to the fixed plate (<NUM>); and
a linkage element (<NUM>) for connecting the floating plate (<NUM>) to the actuated mount (<NUM>), wherein:
the linkage element (<NUM>) comprises a mounting flange (<NUM>) configured to slidably engage the floating plate (<NUM>), characterised in that
the floating plate (<NUM>) further comprises a receptacle (<NUM>) configured to slidably receive the linkage element (<NUM>), wherein the receptacle (<NUM>) is substantially the same cross-sectional shape as the linkage element (<NUM>), such that the mounting flange (<NUM>) is radially retained by the receptacle (<NUM>), but larger than the cross-sectional shape of the linkage element (<NUM>) to permit the floating plate (<NUM>) to translate axially relative to the actuated mount (<NUM>), and
when the actuated mount (<NUM>) is rotated in a first direction (<NUM>), the floating plate (<NUM>) is moved about an inner circumference of the actuated mount (<NUM>) to cover the fluid passage inlet (<NUM>), and when the actuated mount (<NUM>) is rotated in a second opposite direction, the floating plate (<NUM>) is moved to uncover the fluid passage inlet (<NUM>).