Bleed valve outlet flow deflector

A bleed valve assembly for discharging bleed air into a gas turbine engine bypass plenum includes a bleed flow duct, a bleed valve, and a flow deflector. The bleed flow duct is contoured such that it delivers uniformly flowing bleed air to the flow deflector when the bleed valve is in the open position. The flow deflector has a plurality of openings formed therein. Each opening fluidly communicates the bleed air flow passage with the bypass plenum. A portion of the openings are oriented at a discharge angle such that bleed air is discharged from each opening in a direction that does not have a vector component in the direction in which air is flowing in the bypass plenum, and another portion of the openings are oriented to provide stress relief to the deflector.

TECHNICAL FIELD

The present invention relates to bleed valves and, more particularly, to a structurally enhanced bleed valve flow deflector/noise attenuator that improves the mixing of relatively high temperature bleed air with lower temperature engine bypass air.

BACKGROUND OF THE INVENTION

A particular type of gas turbine engine that may be used to power aircraft is a turbofan gas turbine engine. A turbofan gas turbine engine may include, for example, five major sections, a fan section, a compressor section, a combustor section, a turbine section, and an exhaust section. The fan section is positioned at the front, or “inlet” section of the engine, and includes a fan that induces air from the surrounding environment into the engine, and accelerates a fraction of this air toward the compressor section. The remaining fraction of air induced into the fan section is accelerated into and through a bypass plenum, and out the exhaust section.

The compressor section raises the pressure of the air it receives from the fan section to a relatively high level. In a multi-spool engine, the compressor section may include two or more compressors. For example, in a triple spool engine, the compressor section may include a high pressure compressor, and an intermediate compressor. The compressed air from the compressor section then enters the combustor section, where a ring of fuel nozzles injects a steady stream of fuel. The injected fuel is ignited by a burner, which significantly increases the energy of the compressed air.

The high-energy compressed air from the combustor section then flows into and through the turbine section, causing rotationally mounted turbine blades to rotate and generate energy. Specifically, high-energy compressed air impinges on turbine vanes and turbine blades, causing the turbine to rotate. The air exiting the turbine section is exhausted from the engine via the exhaust section, and the energy remaining in this exhaust air aids the thrust generated by the air flowing through the bypass plenum.

Many gas turbine engines, such as the above-described turbofan gas turbine engine, include one or more bleed valve assemblies. The bleed valve assemblies are used to selectively bleed some of the compressed air from the compressor section, and most notably the high pressure compressor, before it passes through the remaining sections of the engine. As is generally known, selectively bleeding air from a compressor, via the bleed valve assemblies, is conducted to preclude the compressor from exceeding its surge limits. For turbofan gas turbine engines, such as the one described above, the bleed air may be discharged into the bypass plenum.

Typically, a bleed valve assembly includes a bleed valve and a bleed air duct. When the bleed valve is open, the bleed valve duct directs bleed air flow into the bypass plenum. In most instances, the outlet ports of these discharge ducts may include a flow diffuser and/or noise attenuator through which the bleed air is discharged. Although present bleed valve assemblies and flow diffuser/noise attenuator designs are generally safe, robust, and reliable, these devices do suffer certain drawbacks. For example, the bypass air in the bypass plenum is typically at a relatively low temperature. As such, components within the plenum, including the plenum itself, may not be designed to withstand relatively high temperature air. However, the bleed air from the compressor section is typically at a relatively high temperature. Thus, when the bleed air is discharged into the bypass plenum, if it is not sufficiently mixed with the relatively low temperature bypass air, the temperature of various components within the bypass plenum, and/or the plenum itself, can reach undesirably high temperatures. In addition, the configuration of some previously designed deflectors can result in relatively high stresses in various regions thereof.

Hence, there is a need for a bleed valve assembly and flow deflector that improves the mixing of relatively high temperature bleed air with relatively low temperature bypass air, to thereby minimize the increase in temperature of various components within the bypass plenum, and that is structurally enhanced to reduce stresses in the deflector. The present invention addresses one or more of these needs.

SUMMARY OF THE INVENTION

In one embodiment, and by way of example only, a bleed valve assembly for discharging bleed air into a gas turbine engine bypass plenum having bypass air flowing therein in a first flow direction includes a bleed flow duct, a bleed valve, and a flow deflector. The bleed flow duct has a bleed air inlet and a bleed air outlet. The bleed air inlet is adapted to receive bleed air from a turbine engine compressor, and the bleed air outlet is configured to discharge the bleed air into the bypass plenum. The bleed valve is disposed at least partially within the bleed flow duct and is movable between at least a closed position, in which the bleed air does not flow through the bleed flow duct, and an open position, in which the bleed air flows through the bleed flow duct. The flow deflector is disposed adjacent the bleed air outlet, and has a plurality of openings formed therein. Each opening is symmetrically disposed about a central axis, includes an inlet port in fluid communication with the bleed air flow passage, an outlet port in fluid communication with the bypass plenum, and is oriented at a discharge angle. The plurality of openings includes a first set of openings and a second set of openings. The first set of openings at least partially surrounds the second set of openings. The discharge angle of each opening is an angle relative to a first plane that is tangent to the outlet port of the opening and intersects the central axis of the opening. The discharge angle of each of the first set of openings is substantially perpendicular to the first plane, and the discharge angle of each of the second set of openings is such that bleed air is discharged therefrom in a direction that does not have a vector component in the first flow direction.

In a further exemplary embodiment, a flow deflector for use in discharging a first gas into a passage through which a second gas flows in a flow direction, includes a dome section and a plurality of openings. The dome section has a first side and a second side that is configured to be disposed within the passage. The plurality of openings extend between the first and second sides, and each opening includes an inlet port and an outlet port, and is symmetrically disposed about a central axis. Each opening is further disposed at a discharge angle relative to a plane that is tangent to the outlet port of the opening and intersects the central axis of the opening. The plurality of openings includes a first set of openings and a second set of openings. The first set of openings at least partially surrounds the second set of openings, the discharge angle of each of the first set of openings is substantially perpendicular to the plane, and the discharge angle of each of the second set of openings is an acute angle.

In still another exemplary embodiment, a method of making a bleed valve flow deflector includes forming a substantially concave dome section in at least a portion of a plate that has a first major surface and a second major surface. A first set of openings is formed through an outer peripheral region of the substantially concave dome section, and a second set of openings is formed through a central region of the substantially flat plate. The second set of openings is disposed radially inwardly of, and is spaced apart from, the first set of openings. Each opening of the first set of openings is symmetrically disposed about a line that is normal to the first and second major surfaces, and each opening of the second set of openings is symmetrically disposed about a central axis that is disposed at an acute angle relative to a line that is normal to the first and second major surfaces.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

An exemplary embodiment of a multi-spool turbofan gas turbine jet engine100is depicted inFIG. 1, and includes an intake section102, a compressor section104, a combustion section106, a turbine section108, and an exhaust section110. The intake section102includes a fan112, which is mounted in a fan case114. The fan112draws air into the intake section102and accelerates it. A fraction of the accelerated air exhausted from the fan112flows, in a flow direction, referred to herein as a bypass air flow direction115, through a bypass plenum116disposed between the fan case114and an engine cowl118, and provides a forward thrust. The remaining fraction of air exhausted from the fan112is directed into the compressor section104.

The compressor section104includes two compressors, a low pressure compressor120, and a high pressure compressor122. The low pressure compressor120raises the pressure of the air directed into it from the fan112, and directs the compressed air into the high pressure compressor122. The high pressure compressor122compresses the air still further, and directs the high pressure air into the combustion section106. In the combustion section106, which includes a combustor124, the high pressure air is mixed with fuel and combusted. The combusted air is then directed into the turbine section108.

The turbine section108includes three turbines disposed in axial flow series, a high pressure turbine126, an intermediate pressure turbine128, and a low pressure turbine130. The combusted air from the combustion section106expands through each turbine, causing it to rotate. The air is then exhausted through a propulsion nozzle132disposed in the exhaust section110, providing addition forward thrust. As the turbines rotate, each drives equipment in the engine100via concentrically disposed shafts or spools. Specifically, the high pressure turbine126drives the high pressure compressor122via a high pressure spool134, the intermediate pressure turbine128drives the low pressure compressor120via an intermediate pressure spool136, and the low pressure turbine130drives the fan112via a low pressure spool138.

As is shown schematically inFIG. 1, a portion of the compressed air from the high pressure compressor may be selectively directed into the bypass plenum116. To do so, one or more bleed valve assemblies200are disposed between the high pressure compressor122and the bypass plenum116. A cross section view of an exemplary bleed valve assembly200that includes a preferred flow deflector is illustrated inFIG. 2, and with reference thereto will now be described in more detail.

The bleed valve assembly200includes a bleed flow duct202, a bleed valve204, and a flow deflector206. The bleed flow duct202includes a bleed air inlet208, a bleed air outlet212, and an inner surface214that defines a bleed air flow passage216between the bleed air inlet208and bleed air outlet212. The bleed air inlet208is coupled to a bleed air flow passage (not illustrated) that receives relatively hot bleed air from the high pressure compressor122, and the bleed air outlet212is coupled to the engine cowl118. In the depicted embodiment, the bleed flow duct202is contoured such that bleed air is introduced into the flow deflector in a substantially uniform manner.

The bleed valve204, at least in the depicted embodiment, is mounted within the bleed flow duct202and is movable between a closed position and an open position. In the closed position, bleed air at the bleed air inlet208does not flow through the bleed air flow passage216to the bleed air outlet212. Conversely, and asFIG. 2depicts, when the bleed valve204is in the open position, bleed air at the bleed air inlet208flows into and through the bleed air flow passage216, through the bleed air outlet212, and into the bypass plenum116via the flow deflector206. It will be appreciated that the location of the bleed valve204depicted inFIG. 2is merely exemplary, and that the bleed valve may be mounted in any one of numerous locations within, or outside of, the bleed flow duct202. Moreover, the bleed valve204may be implemented as any one of numerous types of valves and not just the particular physical implementation that is depicted inFIG. 2.

The flow deflector206is disposed adjacent the bleed air outlet212, such that bleed air that is discharged from the bleed flow duct202flows through the flow deflector206. Although the specific physical location may vary, in a preferred embodiment the flow deflector206is mounted on the bleed air outlet212and, when mounted within the gas turbine engine, protrudes into the bypass plenum116. To facilitate flow through the flow deflector206, a plurality of openings218are formed in, and extend through the flow deflector206. Moreover, as shown in simplified form inFIG. 2, each opening218is oriented at a discharge angle such that, when the bleed valve204is in the open position, the bleed air, rather than being discharged unidirectional or omnidirectional, is discharged from a majority of the openings218in a direction that opposes the bypass air flow direction115.

Turning now toFIGS. 3 and 4, perspective views of a particular embodiment of the flow deflector206are shown and will be described in more detail. As shown inFIGS. 3 and 4, the flow deflector206preferably includes a rim section402and a dome section404. The rim section402extends from the dome section404and is used to couple the flow deflector206to the bleed flow duct202. Thus, the rim section402is preferably shaped substantially similar to that of the bleed flow duct202, especially near the bleed air outlet212. For example, in the depicted embodiment, in which the bleed flow duct202is substantially circular in cross section near the bleed air outlet212, the rim section402is substantially circular in shape. It will be appreciated that the rim section402may be coupled to the bleed flow duct202using any one of numerous techniques such as, for example, fasteners, brazing, or welding. In the preferred embodiment, the rim section402is coupled using a welding process.

The dome section404has the plurality of openings218formed therein and, asFIGS. 3 and 4depict, the openings218include two sets of openings, a first set of openings218-1, and a second set of openings218-2. The first set of openings218-1are formed in an outer peripheral region406of the dome section404, and the second set of openings218-2are formed in a central region408of the dome section404. Thus, the first set of openings218-1surrounds, or at least partially surrounds, the second set of openings218-2. AsFIGS. 3 and 4further depict, the first and second sets of openings218-1,218-2are spaced apart from each other, thereby defining a boundary region412between the outer peripheral region406and the central region408, in which no openings218are formed. It is noted that, solely for clarity, the central region408is shown bounded by a dotted line.

As shown more clearly inFIGS. 5 and 6, each of the openings218that comprise the first and second sets of openings218-1,218-2extend between an inner side414and an outer side416of the dome section404. Each opening218further includes an inlet port418that is coextensive with the dome inner side414, and an outlet port422that is coextensive with the dome outer side416, to thereby provide fluid communication between the dome inner and outer sides414,416. Thus, as described above, when the flow deflector206is coupled to the bleed flow duct202, the openings218facilitate bleed air flow through the flow deflector206.

It will be appreciated that the shape, configuration, number, and size of the openings218may vary. In a preferred embodiment, however, each opening218is substantially cylindrical in shape and, as shown most clearly inFIG. 6, are thus each symmetrically disposed about a central axis702. In addition to variations in shape, configuration, number, and size, the discharge angle and orientation of each opening218may also vary to provide a desired relative discharge direction. For example, each opening218may be formed at the same or different discharge angles, the openings218located along different planes may be formed at different discharge angles, or openings located at different radii from the center of the dome section404may be formed at different discharge angles. Preferably, however, each opening that comprises the first set of openings218-1is formed at a discharge angle (α1) that is perpendicular, or at least substantially perpendicular, to a plane704that is tangent to its outlet port422and intersects its central axis702, and each opening that comprises the second set of openings218-2is formed at a non-perpendicular discharge angle (α2) relative to a plane706that is tangent to its outlet port422and intersects its central axis702. It will be appreciated that the non-perpendicular discharge angle (α2) may vary depending, for example, on the radius of curvature of the dome section404. However, the non-perpendicular discharge angle (α2) is selected to ensure that each of the second set of openings218-2, whether located at a relatively upstream or downstream position, discharges bleed air in a direction that does not have a vector component in the bypass air flow direction115. In a particular preferred embodiment, in which the dome section404is formed with a radius of curvature of about 5.8 inches, a non-perpendicular discharge angle (α2) of about 60° provides this preferred configuration.

By forming each of the first set of openings218-1at a perpendicular, or at least substantially perpendicular, discharge angle (α1), stress in the dome outer peripheral region406is reduced relative to a dome section404having no openings or openings oriented similar to those of the second set of openings218-2. Moreover, due to the curvature of the dome section404, each of the second set of openings218-2at different positions on the dome section404relative to the bypass air flow direction115, are oriented differently. As a result, the direction in which bleed air is discharged from the second set of openings218-2into the bypass plenum116also varies. More specifically, and as shown most clearly inFIG. 5, for bleed air discharged from the second set of openings218-2, bleed air discharged from openings218located at relatively upstream positions is discharged in a direction that opposes bypass air flow more so than bleed air that is discharged from openings218that are located at relatively downstream positions.

Each opening218that comprises the first and second sets of openings218-1,218-2are preferably equally spaced from each other. The number and size of the openings that comprise each set of openings218-1,218-2are selected to provide a sufficient amount of flow area through the dome section404so as to not adversely restrict bleed air flow through the flow deflector206. Although the percent flow area through the dome section404may vary between, for example, approximately 20% and approximately 45%, in a particular preferred embodiment the percent flow area is approximately 32%. Additionally, the openings that comprise the first set of openings218-1are selected to provide sufficient stress relief in the dome peripheral section406.

It will be appreciated that the flow deflector206may be formed using any one of numerous techniques and any one of numerous processes. With reference now toFIGS. 7 and 8a particular preferred process for forming the flow deflector206will be described. Referring first toFIG. 7, the flow deflector206is preferably formed from a substantially flat, circular plate constructed of a suitable material, and having a suitable diameter and suitable thickness. In a particular preferred embodiment, the plate802is constructed of a metal such as, for example, nickel alloy, and has a diameter of about 8 inches, and a thickness of about 0.125 inches. No matter the specific material and dimensions, the plate802is formed into a three dimensional contour that includes the rim section402and the dome section404. It will be appreciated that the dome section404may be spherical, a rotation of an ellipse, or any one of numerous other curved shapes. Preferably, the dome section404is substantially spherical and is formed by pressing the flat plate802over a form having the desired curvature.

After the plate802has been formed into the three dimensional contour, the first and second sets of openings218-1,218-2are then formed through the plate802via a suitable process such as, for example, a drilling process. As noted above, the number and size of each opening218that comprises the first and second sets of openings218-1,218-2may vary to provide a suitable amount of flow area and stress relief. In the embodiment depicted inFIG. 7and described herein, about 450 evenly spaced openings218, configured in three concentric rows, comprise the first set of openings218-1, and about 1700 evenly spaced openings218comprise the second set of openings218-2. Moreover, each opening218preferably has a diameter of about 0.085±0.003 inches, to provide the desired amount of flow area and stress relief.

Each opening218that comprises the first set of openings218-1is formed through the plate802at the perpendicular, or at least substantially perpendicular, angle (α1), and each opening218that comprises the second set of openings218-2is formed through the plate802at the same non-perpendicular angle (α2). In particular, and with reference now toFIG. 8, it is seen that each opening218that comprises the second set of openings218-2is preferably formed at a predetermined angle (β) relative to a line902that is normal to each major surface904,906of the plate802. This angle may vary, but in the depicted embodiment the predetermined angle (β) is about 30° relative to the normal line902. AsFIG. 8additionally depicts, a predetermined angle (β) of 30° relative to the normal line902, corresponds to the above-described non-perpendicular discharge angle (α2) of 60° relative to the plane706.

After the flow deflector206is formed, it is coupled to the bleed flow duct202and the bleed valve assembly200may then be installed in the engine100. In doing so, the bleed valve assembly200is preferably installed in the configuration depicted inFIG. 2a, so that when bleed air is discharged from the valve assembly200, it is discharged in a direction that either opposes, or is substantially perpendicular to, the bypass air flow direction115. In other words, none of the bleed air is discharged from the bleed valve assembly200in a direction having a vector component that is in the same direction as the bypass air flow direction115.

Because the bleed air is discharged from a vast majority of the openings218in a direction that opposes the bypass air flow direction115, mixing of the relatively hot bleed air with the relatively cool bypass air is enhanced. This enhanced mixing ensures that the bypass plenum116and various components disposed within the bypass plenum116are exposed to relatively cooler air. For example, and with reference now toFIG. 9, in some aircraft engines, when the aircraft thrust reversers are deployed, a plurality of blocker doors1002(only one shown) are rotated into the bypass plenum116. In this position, the blocker doors1002redirect the bypass air flow in a forward direction through, for example, a plurality of cascade vanes1004, creating a reverse thrust. In such engines, the enhanced mixing of the relatively hot bleed air with the relatively cool bypass air reduces the temperatures to which the blocker doors1002and cascade vanes1004are exposed when the aircraft thrust reversers are deployed.