Patent ID: 12258870

DETAILED DESCRIPTION OF THE DRAWINGS

For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to a number of illustrative embodiments illustrated in the drawings and specific language will be used to describe the same.

A fan case assembly10is adapted for use in a gas turbine engine110as shown inFIG.1. The gas turbine engine110includes a fan112, a compressor114, a combustor116, and a turbine118as shown inFIG.1. The fan112is driven by the turbine118and provides thrust for propelling an aircraft. The compressor114compresses and delivers air to the combustor116. The combustor116mixes fuel with the compressed air received from the compressor114and ignites the fuel. The hot, high pressure products of the combustion reaction in the combustor116are directed into the turbine118to cause the turbine118to rotate about a central axis11of the gas turbine engine110and drive the compressor114and the fan112.

The fan112includes a fan rotor12and a fan case assembly10as shown inFIG.1. The fan rotor12has a number of fan blades14. The fan case assembly10extends circumferentially around the fan blades14of the fan rotor12such that the fan case assembly10is aligned axially with the fan blades14.

The fan case assembly10includes, among other components, a case20and an inlet distortion mitigation system22as shown inFIGS.2-4. The case20extends circumferentially at least partway about the central axis11to define an outer boundary of a gas path25of the gas turbine engine110. The case20is formed to define a plenum24that extends circumferentially at least partway about the central axis11and is open to the gas path25of the gas turbine engine110. The inlet distortion mitigation system22is configured to control fluid communication between the plenum24and the gas path25of the gas turbine engine110.

The inlet distortion mitigation system22includes a plurality of rotatable drums26and a control unit30as shown inFIGS.2-4. The plurality of drums26are rotatably coupled to the case20in the plenum24to rotate about a drum axis A. Each drum26of the plurality of drums26includes a slot28that extends completely through the corresponding drum26to allow airflow through the corresponding drum26. The slots28extend axially partway along the drums26relative to the drum axis A.

The drums26may be substantially cylindrical in shape, with a generally cylindrical outer surface46. Additionally or alternatively, the drums26may be any shape capable of rotating between the various positions described herein and controlling a flow of air between the flow path25and the plenum24. The plurality of drums26are each configured to rotate between a closed position as shown inFIGS.6and7, a plurality of partially open positions as shown inFIGS.9and10, and a fully open position as shown inFIGS.5and8. The control unit30is configured to rotate each of the plurality of drums26about the corresponding drum axis A between the different positions in response to preselected operating conditions to control fluid communication between the plenum24and the gas path25so as to minimize the negative effects of pressure and swirl distortions in the gas turbine engine110to improve stall margin for the gas turbine engine110.

Embedded engines on an aircraft may experience high distortion in the form of pressure gradients and swirl. The pressure and swirl distortions may cause engine stall or other undesirable aeromechanical behavior. Additionally, there may be points during a mission or moments with maneuvers where it may be desirable to incorporate a different available stall margin or to be able to more evenly distribute flows. Attempting to solve the worst stall condition while maintaining performance over all of the cycles or flight conditions may be difficult and result in compromised efficiency or a limited flight envelope.

Therefore, the fan case assembly10includes the inlet distortion mitigation system22which includes the plurality of drums26that rotate relative to the case20to control fluid communication between the plenum24and the gas path25. In this way, the negative effects of pressure and swirl distortions are minimized to improve stall margin. The negative effects may include loss of efficiency or overall performance of the engine110and/or other negative operating conditions known to one of ordinary skill in the art.

In the closed position, the slot28of each corresponding closed drum26extends circumferentially relative to the central axis11to close off the slot28from the gas path25to block fluid communication between the gas path25and the plenum24through the slot28as shown inFIG.7. In other words, in the closed position, the slot28extends relatively parallel to the inner surface21of the case20. A portion of the outer surface46of each of the closed drums26cooperates with an inner surface21of the case20to define the outer boundary of the gas path25. The outer surface46of each drum26forms a part of the outer boundary of the gas path25thereby covering any opening of the plenum24to block fluid communication between the gas path25and the plenum24when each of the drums26are in the closed position.

In the fully open position, the slot28of each corresponding fully open drum26extends radially relative to the central axis11to open the slot28to the gas path25to allow fluid communication between the gas path25and the plenum24through the slot28as shown inFIG.8. In other words, in the fully open position, the slot28extends perpendicular to or at a 90° angle to the inner surface21of the case20. Allowing fluid communication between the gas path25and the plenum24permits air pressure and flows to better equalize circumferentially about the fan112to improve stall margin.

The plurality of partially open positions are between the closed position and the fully open position. In any one of the partially open positions, the slot28of each drum26extends at an intermediate angle26B,26C relative to the gas path25as shown inFIGS.9and10. In other words, in one of the partially open positions, the slot28of each drum26is angled such that the slot28extends radially and circumferentially relative to the central axis11. The intermediate angle26B,26C is between the angle of the slot28when it is in the closed position and extending circumferentially relative to the central axis11and the angle of the slot28when it is in the fully opened position and extending radially relative the central axis11, perpendicular to the inner surface21of the case20.

In the plurality of partially open positions, the slot28may be partially blocked by a portion of the case22so as to vary the fluid communication between the gas path25and the plenum24. Each of the drums26may be rotated between any one of the plurality of partially open positions, so as to modulate the size of the opening of the slot28open to the gas path25thereby varying the fluid communication between the gas path25of the gas turbine engine110and the plenum24.

In the plurality of partially open positions, the slot28may be angled to direct flow from the gas path25into the plenum24in either a first circumferential direction as shown inFIG.9or a second circumferential direction opposite to the first circumferential direction as shown inFIG.10. The plurality of partially open positions includes a first partially open position as shown inFIG.9and a second partially open position as shown inFIG.10. In the first partially open position, the slot28of the corresponding drum26is angled in a first circumferential direction about the central axis11. In the second partially opened position, the slot28of the corresponding drum26is angled in a second circumferential direction about the central axis11. In some embodiments, one of the circumferential directions, for example, the first circumferential direction, is aligned with an advancing motion of the blades12they rotate around the fan rotor12and angled so air is directed by the advancing blades12from the flow path25directly into the plenum24. In some embodiments, the other circumferential direction, for example, the second circumferential direction, is aligned with a retreating motion of the blades12and angled to direct air flowing out of plenum24back into the gas path25.

The control unit30is configured to rotate the drums26between the different positions in response to preselected operating conditions. The preselected operating conditions include a plurality of preprogrammed aircraft maneuvers stored on a memory64included in the control unit30. The plurality of preprogrammed aircraft maneuvers include banks, turns, rolls, etc.

The control unit30is configured to detect a preprogrammed aircraft maneuver included in the plurality of preprogrammed aircraft maneuvers on the memory64. Once the preprogrammed aircraft maneuver is detected, the control unit30directs each of the drums26to rotate to a corresponding position in response to detecting the preprogrammed aircraft maneuver.

For example, the plurality of drums26may normally be in the closed position during a cruise condition so that no additional stall margin is created, but performance is not compromised. The cruise condition included in the preselected operating conditions corresponds to when the aircraft is in the cruise portion of the flight cycle.

Then, when the control unit30detects a preprogrammed aircraft maneuver, i.e. banks, turns, rolls, the control unit30directs the drums26to rotate to one of the partially open positions or to the fully open position so that flow is permitted through the slots28and into the plenum24. This permits air pressure and flows to better equalize circumferentially around the fan112thereby minimizing the negative effects of pressure and swirl distortions to improve stall margin.

The control unit30is configured to direct some or all of the drums26to rotate from the closed position to one of the partially open positions or to the fully open position based on the detected preprogrammed aircraft maneuver. Depending on the preprogrammed aircraft maneuver, the control unit30may direct only certain drums26to move to one of the partially open positions or the fully open position, while keeping others in the closed position.

Additionally, the control unit30may direct some of the drums26to remain in the closed position, while directing some of the drums26to rotate to the fully opened position and others to one of the partially open positions. The control unit30is configured to direct some of the drums26to rotate to one of the partially open position while others are rotated to another one of the partially open position. In other words, the control unit30is configured to individual vary the angle of the slot28or position of each of the drums26.

The preselected operating conditions may further include a sensor input from at least one sensor66included in the control unit30. The sensor66is configured to measure one of pressure, air speed, altitude, blade tip timing, blade rotational speed, attitude or aircraft orientation, and acceleration. In some embodiments, the control unit30includes a plurality of sensors66each configured to measure one of pressure, air speed, and acceleration.

The control unit30is configured to receive a measurement from the at least one sensor66or sensors66and direct the drums26to rotate to a corresponding position in response to the measurement of the at least one sensor66. The control unit30may be configured to rotate the drums26to be in the closed position when the measurements from the sensor66are within a predetermined threshold.

Then, when the measurement from the sensor66is outside of the predetermined threshold, the control unit30directs the drums26to rotate to one of the partially open positions or the fully open position. Based on the difference of the measurement from the sensor66compared to the predetermined threshold, the control unit30may vary the position of the drums26to control the amount of fluid communication between the gas path25and the plenum24through the openings of the slots28of the drums26.

The control unit30is configured to direct some or all of the drums26to rotate from the closed position to one of the partially open positions or the fully open position based on the measurement from the sensor66. The control unit30may direct some of the drums26to remain in the closed position, while directing some of the drums26to rotate to the fully opened position and others to a partially open position based on the measurement from the sensor66.

In some embodiments, the control unit30may be configured to use a combination of the sensor measurements and the detected preprogrammed aircraft maneuver to control the position of the plurality of drums26. For example, when the control unit30detects a preprogrammed aircraft maneuver and the measurement is outside of the predetermined threshold, the control unit30directs some or all of the drums26to rotate to one of the partially open positions or the fully open position. The control unit30is configured to direct some of the drums26to rotate to one partially open position while others are rotated to another partially open position. The control unit30is configured to individual vary the angle of the slot28of each of the drums26.

In some embodiments, the control unit30is configured to use the measurements from the sensor66to anticipate the aircraft maneuver. The control unit30is configured to direct some or all of the plurality of drums26to move to one of the partially open positions or the fully open position in response to the measurement from the sensor66even though no preprogrammed aircraft maneuver is detected.

Alternatively, there may be a delay in the measurements from the sensor66. Therefore, the control unit30is also configured to direct some or all of the drums26to move to one of the partially open positions or the fully open position when the one of the preprogrammed aircraft maneuvers is detected, even though the measurements from the sensor66are within the predetermined thresholds.

In some embodiments, the control unit30may detect one of the preprogrammed aircraft maneuvers, but the measurements from the sensors66are within the predetermined threshold. If so, the control unit30may direct some or all of the drums26to remain in the current position.

Turning again to the fan case assembly10, the fan case assembly10extends circumferentially at least partway about the central axis11in the illustrative embodiment. In some embodiments, the fan112may include multiple fan case assemblies10arranged circumferentially about the axis11to form a full hoop. In other embodiments, the fan case assembly10may be annular and extends circumferentially about the axis11. In some embodiments, the case20may extend around the axis11, while the plenum24only extends partway about the axis11.

In some embodiments, the fan112may include multiple fan case assemblies10spaced apart circumferentially about the axis11to define segments between each fan case assembly10. The segments between the fan case assemblies10may not have a plenum24so that the plenums24of each of the fan case assemblies10are independent from each other.

The case20includes a forward section32and an aft section34as shown inFIG.4. The aft section34is configured to be coupled to the forward section32to trap the plurality of drums26axially therebetween in the plenum24.

In the illustrative embodiment, the plenum24is formed in the case22so that the plenum24extends axially across the tips of the fan blades14between a leading edge16and a trailing edge18of the fan blades14as shown inFIGS.2,5, and6. Each drum26extends axially across the tips of the fan blades14. The slot28of each drum28extends between the leading edge16and the trailing edge18in the illustrative embodiment. In some embodiments, the slot28may extend forward/aft of the leading and trailing edges16,18.

In some embodiments, like as shown inFIGS.14and15, the plenum is disposed at or near the leading edge16of the fan blades14and the slot formed in each drum is disposed at or near the leading edge16. In some embodiments, like as shown inFIGS.16and17, the plenum is disposed at or near the trailing edge18of the fan blades14and the slot formed in each drum is disposed at or near the trailing edge18.

In the illustrative embodiment, the plenum24has a rectangular cross-sectional shape. In some embodiments, the plenum24may have a forward-leaning cross-sectional shape. In other embodiments, the plenum24may have another cross-sectional shape.

In the illustrative embodiment, the case20is formed to include a plurality of openings36that open to the gas path25and the plenum24as shown inFIGS.3,4, and7-13. The openings36are spaced apart circumferentially about the central axis11to define partitions38in the case22. Each drum26is arranged in the plenum24so that the drum26is aligned with one of the openings36and each partition38is arranged between adjacent drums26as shown inFIGS.7-13. In the illustrative embodiment, each of the drums26extends partway into the corresponding opening36. In this way, the outer surface46of each drum26cooperates with the inner surface21of the case22to define the outer boundary of the gas path25.

It will be understood that the spacing of the drums26inFIGS.1-13are not to scale. For example, the drums26may be circumferentially spaced closer together or may be circumferentially spaced further apart in some embodiments.

In some embodiments, the plenum24formed in the case22may completely open to the gas path25such that there are no partitions38. The drums26may be arranged closer together to minimize gaps there between and prevent fluid communication between the gas path25and the plenum24. In some embodiments, the assembly may include seals between adjacent drums26to limit leakage therebetween. In some embodiments, the partitions38may be formed between some, but not every drum26.

If the case22is a split case, like as shown inFIG.4, the partitions38may be included in the forward case32. In some embodiments, the partitions38may be part of the aft case34. In some embodiments, the partitions38may be included in both the forward and aft cases32,34. The partitions38may partially block the slot28of the drums, for example, when the drums are in one of the partially opened positions as shown inFIGS.9and10. The partitions38may be at least partially contoured to the shape of the drums26to seal or block a flow of fluid between the gas path25and the plenum24when the drums26are in the closed position, while still allowing all or partial flow between the gas path25and the plenum24when the drums26are in the fully open or partially open position.

The inlet distortion mitigation system22includes the plurality of drums26and the control unit30as shown inFIGS.2-4. Each of the drums26includes a drum body40and a pair of pegs42,44as shown inFIG.4. The drum body40extends between a first axial end40A and a second axial end40B spaced apart axially from the first axial end40A. The drum body40defines an outer surface46that extends between the first and second axial ends40A,40B. The pair of pegs42,44each extend from one of the axial ends40A,40B of the drum body40to the case20to couple the respective drum26to the case20. The pair of pegs42,44extend axially from the first and second axial ends40A,40B of the drum body40to fit into peg holes42H,44H formed in the forward and aft sections32,34of the case20.

The drum body40is formed to define the slot28as shown inFIGS.3-6. The slot28extends entirely through the drum body40axially between the first and second axial ends40A,40B of the drum body40.

The drums26are rotatable between the closed position, the partially open positions, and the fully open position to control fluid communication between the gas path25and the plenum24. The drums26are rotated about the respective drum axis A to change the angle or position of slot28of the drums26relative to the gas path25, thereby exposing the slots28to the gas path25to direct flow into the plenum24.

In the closed position, the slot28of each drum26is positioned to extend circumferentially relative to the central axis or parallel to the inner surface21of the case20. In the fully open position, the slot28of each drum26is positioned to extend radially relative to the central axis or perpendicular to the inner surface21of the case20. In any one of the partially open positions, the slot28of each drum26extends radially and circumferentially so that the slot28is angled relative to the gas path25.

In the fully open position, the slot28is at the fully open angle26A as shown inFIG.8. In the illustrative embodiment, the fully open angle26A is about 90 degrees. In any one of the partially open positions, the slot28of each drum26is at an intermediate angle26B,26C. The intermediate angle26B,26C is anywhere between the position of the slot28in the closed position and the fully open angle26A of the slot28when in the fully opened position. The intermediate angle26B is the angle of the slot28when the slot28is angled in the first circumferential direction as shown inFIG.9and the intermediate angle26C is the angle of the slot28when the slot28is angled in the second circumferential direction as shown inFIG.10.

In the illustrative embodiment, the plurality of drums26may rotate in either direction about the drum axis A between the different positions. In some embodiments, the plurality of drums26may be configured to rotate in a first direction about the drum axis A from the closed position to one of the partially open positions or the fully open position. The drums26may be configured to rotate in a second direction about the drum axis A opposite the first direction to go back to the closed position. In some embodiments, the drums26may be configured to continue to rotate in the first direction to go back to the closed position.

The plurality of drums26may be configured to rotate in the second direction about the drum axis A from the closed position to one of the partially open positions or the fully open position. The drums26may be configured to rotate in the first direction about the drum axis A opposite the second direction to go back to the closed position. In some embodiments, the drums26may be configured to continue to rotate in the second direction to go back to the closed position.

In some embodiments, each of the drums26may be configured to rotate 180 degrees about the drum axis A. The plurality of drums26may configured to rotate in the first direction 180 degrees about the drum axis A from the closed position to another closed position with the drum26flipped. The plurality of drums26may configured to rotate in the second direction 180 degrees about the drum axis A from the closed position back to the original closed position with the drum26. In some embodiments, each of the drums26may be configured to rotate 360 degrees about the drum axis A in either the first direction and/or the second direction.

The control unit30includes at least one actuator60, a controller62, a memory64, and at least one sensor66as shown inFIGS.3and7-12. The actuator60is coupled to drums26. The actuator60is configured to drive the rotating motion of the drums26. The controller62is coupled to the actuator60to direct the actuator60to rotate the drums26between the different positions.

The actuator60is configured to rotate the drums26between the closed position as shown inFIG.7, the plurality of partially open positions as shown inFIGS.9and10, and the fully open position as shown inFIG.8. The controller62is configured to direct the actuator60to rotate the drums26between the different positions in response to preselected operating conditions. The preselected operating conditions include the plurality of preprogrammed aircraft maneuvers stored on the memory64included in the control unit30.

The controller62of the control unit30is configured to detect a preprogrammed aircraft maneuver included in the plurality of preprogrammed aircraft maneuvers on the memory64. Once the preprogrammed aircraft maneuver is detected, the controller62directs the actuator60to rotate some or all of the drums26to a corresponding position in response to detecting the preprogrammed aircraft maneuver.

An extension linkage or rod may be coupled to one of the pegs42,44at and end of each drum26that may be directly or indirectly coupled to the actuator60. A crank may be positioned outside of the fan case20, and may link the actuator60to the drums26. The drums26may be ganged together, for example, with gears, a curved rack, and/or a belt. Additionally or alternatively, a motor may be disposed at the end of each drum26for individual control of the drums26, and may be included in the fan case20.

In some embodiments, multiple drums26may be coupled together to sync movement of the drums26. The drums26may be coupled or linked together so that when the controller62directs the actuator60to rotate the drums26, the actuator60moves to simultaneously rotate the plurality of coupled drums26to the desired position.

In some embodiments, different sets of drums26may be coupled together. The control unit30may include multiple actuators60each coupled to a respective different set of coupled drums26to control the positions of the drums26in groups so that some of the drums26move together in unison, while other drums26are independently controlled from the first group.

In some embodiments, the control unit30includes a separate actuator60for each drum26. Each actuator60may be coupled to one of the respective drums26. In this way, the controller62independently controls the position of each drum26.

In some embodiments, the actuator60may include pneumatic or electric actuators, or combinations of hydraulic, pneumatic, and electric. Any other actuator known to a person skilled in the art could be utilized as well.

The controller62of the control unit30is configured to direct the actuator(s)60to rotate some or all of the drums26from the closed position to one of the partially open positions or to the fully open position based on the detected preprogrammed aircraft maneuver. As shown inFIG.8, the controller62has directed the actuator(s)60to rotate all of the drums26to the fully opened position. As shown inFIG.9, the controller62has directed the actuator(s)60to rotate all of the drums26to a first partially opened position to and direct gases flowing into the plenum24in the first circumferential direction. As shown inFIG.10, the controller62has directed the actuator(s)60to rotate all of the drums26to a second partially opened position to direct gases flowing into the plenum24in the second circumferential direction.

Depending on the preprogrammed aircraft maneuver, the controller62of the control unit30may direct certain actuators60to only rotate certain drums26to one of the partially open positions or to the fully open position, while keeping others in the closed position. As shown inFIG.12, the controller62has directed the actuator(s)60to rotate some of the drums26, or a first set of drums26′, to one of the partially open positions, while keeping other drums26, or a second set of drums26″, in the closed position. As shown inFIG.13, the controller62has directed the actuator(s)60to rotate some of the drums26, or the first set of drums26′, to one of the fully open position, while keeping other drums26, or a second set of drums26″, in the closed position.

In the illustrative embodiment, the first set of drums26′ is alternated between the second set of drums26″ as shown inFIGS.12and13. In some embodiments, the different sets26′,26″ are arranged in series. In some embodiments, the different sets26′,26″ are arranged in groups spaced apart circumferentially. In some embodiments, the different sets26′,26″ may have drums26located at different circumferential locations spaced about the axis11.

In the illustrative embodiment, the number of drums26in the first set of drums26′ is equal to the number of drums26in the second set of drums26″. In some embodiments, the number of drums26in one set26′,26″ may be less than or greater than the number of drums26in the other set26′,26″. In some embodiments, the controller62may not control the drums26in sets, but rather direct certain actuator(s)60to rotate certain drum(s)26to one of the partially open positions or to the fully open position, while keeping other drums26in the closed position.

Additionally, the controller62of the control unit30may direct the actuator(s)60to keep some of the drums26to in the closed position, while rotating some of the drums26to the fully opened position and others to a partially open position. The controller62of the control unit30is configured to direct the actuator(s)60to rotate some of the drums26to one partially open position while rotating others to another partially open position. In other words, the control unit30is configured to individual vary the angle of each of the slots28of the drums26.

The controller62of the control unit30may be configured to direct the actuator(s)60to rotate some of the drums26to one partially open position while rotating others to another partially open position, but keep the direction of the flow in the same circumferential direction. The controller62of the control unit30may be configured to direct the actuator(s)60to rotate some of the drums26to one partially open position to direct flow into the plenum24while rotating others to another partially open position so that the drums direct flow out of the plenum24.

As shown inFIG.11, the controller62has directed the actuators60to rotate some of the drums26′, or a first set of drums26′, to the first partially opened position, some of the drums26″, or a second set of drums26″, to the second partially opened position, and other drums26′″, or a third set of drums26′″, to the closed position. In the illustrative embodiment, the plurality the second set of drums26″ is spaced apart circumferentially from the first set of drums26′ and the third set of drums26′″ is arranged circumferentially between the two sets of drums26′,26″ as shown inFIG.11.

In the illustrative embodiment, the first set of drums26′ are arranged in series on one side of the third set of drums26′″, while the second set of drums26″ are arranged in series on the other side of the third set of drums26′″ as shown inFIG.11. The third set of drums26′″ is kept in the closed position to block flow into the plenum24, while the first26′ and second set of drums26′″ are positioned to one of the partially open positions or to the fully open position, as show inFIG.11. The first set of drums26′ allow air to flow into the plenum24while the second set of drums26″ direct air to flow out of the plenum24as shown inFIG.11.

In some embodiments, the third set of drums26″″ may be replaced with a portion of the case20. The first set of drums26′ may be arranged in series on one side of the partition, while the second set of drums26″ are arranged in series on the other side of the partition. The partition would block flow into or out of the plenum24between the two sets.

In some embodiments, the control unit30may control the plurality of rotatable drums26in more than three sets. In some embodiments, the plurality of drums26may have more than three sets of drums. In some embodiments, may have less than three sets of drums.

The preselected operating conditions may further include a sensor input from the sensor66or sensors66included in the control unit30. The sensor66is configured to measure one of pressure, air speed, and acceleration. The sensor66is also configured to detect distortion, fan stall, and/or other aeromechanical issues. In some embodiments, the control unit30includes a plurality of sensors66each configured to measure one of pressure, air speed, and acceleration and/or detect distortion, fan stall, and/or other aeromechanical issues.

The sensor66may include one of or a combination of dynamic sensors, static wall pressure sensors, altitude sensors, sensors configured to detect the angle of attack of the plurality of fan blades14, sensors configured to detect the tip timing of the plurality of fan blades14, and air speed sensors. In some embodiments, the sensor66may be a dynamic pressure transducer. The sensor66may also be a sensor configured to measure a rotational speed of the fan blades14, which could be used along with an additional sensor that is a dynamic pressure transducer. In some embodiments, the sensor66may be a sensor configured to measure a rotation speed of another section of the engine110.

The controller62of the control unit30is configured to receive a measurement from the sensor66or sensors66and direct the actuator60to rotate some or all of the drums26to a corresponding position in response to the measurement of the at least one sensor66. The controller62of the control unit30may be configured to direct actuator60to rotate some or all of the drums26to the closed position when the measurements from the sensor66are within a predetermined threshold.

Then, when the measurement from the sensor66is outside of the predetermined threshold, the controller62directs the actuator60to rotate some or all of the drums26to one of the partially open positions or the fully open position. Based on the difference of the measurement from the sensor66compared to the predetermined threshold, the controller62may vary the position of the drums26to control the amount of fluid communication between the gas path25and the plenum24through the slots28.

In some embodiments, the controller62of the control unit30may be configured to use a combination of the sensor measurements and the detected preprogrammed aircraft maneuver to control the position of the drums26. For example, when the controller62of the control unit30detects a preprogrammed aircraft maneuver and the measurement is outside of the predetermined threshold, the controller62directs the actuator60to rotate some or all of the drums26to one of the partially open positions or to the fully open position.

In some embodiments, the controller62of the control unit30is configured to use the measurements from the sensor66to anticipate the aircraft maneuver. The controller62of the control unit30is configured to direct the actuator60to rotate some or all of the drums26to one of the partially open positions or to the fully open position in response to the measurement from the sensor66even though no preprogrammed aircraft maneuver is detected.

Alternatively, there may be a delay in the measurements from the sensor66. Therefore, the controller62of the control unit30is also configured to direct the actuator60to rotate some or all of the drums26to one of the partially open positions or to the fully open position when the one of the preprogrammed aircraft maneuvers is detected, even though the measurements from the sensor66are within the predetermined thresholds.

In some embodiments, the controller62of the control unit30may detect one of the preprogrammed aircraft maneuvers, but the measurements from the sensors66are within the predetermined threshold. If so, the controller62of the control unit30may direct some or all of the drums26to remain in the current position.

A method of operating the inlet distortion mitigation system22may include several steps. During normal cruise conditions, the controller62directs the actuator60to locate the rotatable drums26in the closed position. If the controller62detects one of a preselected operating condition other than the cruise condition, the controller62directs the actuator60to rotate the drums26to one of the fully open position or one of the partially open positions depending on the operating condition detected to minimize the negative effects of pressure and swirl distortions to improve stall margin.

The method further includes continually adjusting the position of some or all of the drums26based on the preselected operating condition of the engine110. If the controller62detects the cruise condition, the controller62directs the actuator60to rotate the drums26back to the closed position. In other instances, the controller62may direct the actuator60to control the position of the drums26as discussed above based on the preprogrammed aircraft maneuvers and/or the measurements from the sensors.

When dealing with embedded inlet distortion, there may be a steep trade between stall margin and performance of the engine. There may be points during a mission or moments with maneuvers where it may be desirable to incorporate a different available stall margin or to be able to more evenly distribute flows. Attempting to solve the worst stall condition, while maintaining performance over all of the cycle or flight conditions may be difficult and result in compromised efficiency or a limited flight envelope.

Another embodiment of a fan case assembly210in accordance with the present disclosure is shown inFIGS.14and15. The fan case assembly210is substantially similar to the fan case assembly10shown inFIGS.1-13and described herein. Accordingly, similar reference numbers in the200series indicate features that are common between the fan case assembly10and the fan case assembly210. The description of the fan case assembly10is incorporated by reference to apply to the fan case assembly210, except in instances when it conflicts with the specific description and the drawings of the fan case assembly210.

The fan case assembly210includes, among other components, a case220and an inlet distortion mitigation system222as shown inFIGS.14and15. The case220extends circumferentially at least partway about the axis11to define the outer boundary of the gas path25of the gas turbine engine110. The case220is formed to define a plenum224that extends circumferentially at least partway about the axis11and is open to the gas path25of the gas turbine engine110. The inlet distortion mitigation system222is configured to control fluid communication between the plenum224and the gas path25of the gas turbine engine110.

The inlet distortion mitigation system222includes a plurality of rotatable drums226and a control unit230as shown inFIGS.14and15. The plurality of drums226are rotatably coupled to the case220in the plenum224to rotate about a drum axis A. The plurality of drums226are configured to rotate between the closed, partially open, and fully open positions like as shown inFIGS.7-13. The control unit230is configured to move the plurality of drums226between the different positions in response to preselected operating conditions to control fluid communication between the plenum224and the gas path25.

The drums226and the plenum224may extend over an along a portion of the fan blades14at the leading edge16of the fan blades. The case220includes a forward section232, an aft section234, and a partition238as shown inFIGS.14and15. The aft section234is configured to be coupled to the forward section232to trap the plurality of drums226axially therebetween in the plenum224. The forward section232may include the cavity forming the plenum224. The forward section232and the aft section234may meet at a central or mid-span of the fan blades112.

Each of the drums226includes a drum body240and a pair of pegs242,244as shown inFIG.15. The drum body240extends between a first axial end240A and a second axial end240B spaced apart axially from the first axial end240A. The drum body240defines an outer surface246that extends between the first and second axial ends240A,240B. The pair of pegs242,244each extend from one of the axial ends240A,240B of the drum body240to the case220to couple the respective drum226to the case220.

The drum body240is formed to define the slot228as shown inFIG.15. The slot228extends entirely through the drum body240axially between the first and second axial ends240A,240B of the drum body240.

In the illustrative embodiment, the plenum224and the plurality of drums226are located closer to the leading edge16of the fan blades14as shown inFIGS.14and15. The plenum224and the plurality of drums226are disposed at or near the leading edge16of the fan blades14so that the slot228is located at or near the leading edge16of the fan blades14.

The drums226are rotatable between the closed position, the partially open positions, and the fully open position to change the angle of each slot228formed in the drums226relative to the gas path25, thereby controlling fluid communication between the gas path25and the plenum224. The control unit230is configured to rotate the drums226between the different positions in response to preselected operating conditions. The control unit230is configured to control the position of the drums226similar to the control unit30inFIGS.1-13.

The preselected operating conditions include a plurality of preprogrammed aircraft maneuvers stored on a memory included in the control unit330. The plurality of preprogrammed aircraft maneuvers include banks, turns, rolls, etc.

The control unit230is configured to detect a preprogrammed aircraft maneuver included in the plurality of preprogrammed aircraft maneuvers. Once the preprogrammed aircraft maneuver is detected, the control unit230directs each of the drums226to rotate to a corresponding position in response to detecting the preprogrammed aircraft maneuver.

For example, the drums226may normally be in the closed position during a cruise condition so that no additional stall margin is created, but performance is not compromised. Then, when the control unit230detects a preprogrammed aircraft maneuver, i.e. banks, turns, rolls, the control unit230directs the drums226to rotate to one of the partially open positions or the fully open position so that flow is permitted into the plenum224. This permits air pressure and flows to better equalize circumferentially around the fan112to improve stall margin of the gas turbine engine110.

Conversely, when the control unit230detects the cruise condition after a preprogrammed aircraft maneuver, the control unit230directs the drums226to rotate to the closed position. Therefore, once the aircraft maneuver is completed, the drums226move to the closed position to performance is not compromised and the additional stall margin is removed during the cruise condition.

The control unit230is configured to direct some or all of the drums226to rotate from the closed position to one of the partially open positions or the fully open position based on the detected preprogrammed aircraft maneuver. Depending on the preprogrammed aircraft maneuver, the control unit230may directly only certain drums226to move to one of the partially open positions or the fully open position, while keeping others in the closed position.

Additionally, the control unit230may direct some of the drums226, to remain in the closed position, while directing some of the drums226to rotate to the fully opened position and others to a partially open position. The control unit230is configured to direct some of the drums226to rotate to one partially open position while others are rotated to another partially open position. In other words, the control unit230is configured to individual vary the angle of each slot228of each of the drums226.

Similarly, the control unit230is configured to receive a measurement from the at least one sensor or sensors and direct the drums226to rotate to a corresponding position in response to the measurement like as discussed above with respect to the embodiment ofFIGS.1-3. In some embodiments, the control unit230may be configured to use a combination of the sensor measurements and the detected preprogrammed aircraft maneuver to control the position of the plurality of drums226.

Another embodiment of a fan case assembly310in accordance with the present disclosure is shown inFIGS.16and17. The fan case assembly310is substantially similar to the fan case assembly10shown inFIGS.1-13and described herein. Accordingly, similar reference numbers in the300series indicate features that are common between the fan case assembly10and the fan case assembly310. The description of the fan case assembly10is incorporated by reference to apply to the fan case assembly310, except in instances when it conflicts with the specific description and the drawings of the fan case assembly310.

The fan case assembly310includes, among other components, a case320and an inlet distortion mitigation system322as shown inFIGS.16and17. The case320extends circumferentially at least partway about the axis11to define the outer boundary of the gas path25of the gas turbine engine110. The case320is formed to define a plenum324that extends circumferentially at least partway about the axis11and is open to the gas path25of the gas turbine engine110. The inlet distortion mitigation system322is configured to control fluid communication between the plenum324and the gas path25of the gas turbine engine110.

The inlet distortion mitigation system322includes a plurality of rotatable drums326and a control unit330as shown inFIGS.16and17. The plurality of drums226are rotatably coupled to the case320in the plenum324to rotate about a drum axis A. The plurality of drums326are configured to rotate between the closed, partially open, and fully open positions like as shown inFIGS.7-13. The control unit330is configured to move the plurality of drums326between the different positions in response to preselected operating conditions to control fluid communication between the plenum324and the gas path25.

The drums326and the plenum324may extend over an along a portion of the fan blades14at the trailing edge18of the fan blades. The case320includes a forward section332, an aft section334, and a partition336as shown inFIGS.16and17. The aft section334is configured to be coupled to the forward section332to trap the plurality of drums326axially therebetween in the plenum224. The aft section334may include the cavity forming the plenum224. The forward section232and the aft section334may meet at a central or mid-span of the fan blades112.

Each of the drums326includes a drum body340and a pair of pegs342,344as shown inFIG.17. The drum body340extends between a first axial end340A and a second axial end340B spaced apart axially from the first axial end340A. The drum body340defines an outer surface346that extends between the first and second axial ends340A,340B. The pair of pegs342,344each extend from one of the axial ends340A,340B of the drum body340to the case320to couple the respective drum326to the case320.

The drum body340is formed to define the slot328as shown inFIG.17. The slot328extends entirely through the drum body340axially between the first and second axial ends340A,340B of the drum body340.

In the illustrative embodiment, the plenum324and the plurality of drums326are located closer to the trailing edge18of the fan blades14as shown inFIGS.16and17. The plenum324and the plurality of drums326are disposed at or near the trailing edge18of the fan blades14so that the slot328is located at or near the trailing edge18of the fan blades14.

The drums326are rotatable between the closed position, the partially open positions, and the fully open position to change the angle of each slot328formed in the drums326relative to the gas path25, thereby controlling fluid communication between the gas path25and the plenum324. The control unit330is configured to rotate the drums326between the different positions in response to preselected operating conditions. The control unit330is configured to control the position of the drums326similar to the control unit30inFIGS.1-13.

The preselected operating conditions include a plurality of preprogrammed aircraft maneuvers stored on a memory included in the control unit330. The plurality of preprogrammed aircraft maneuvers include banks, turns, rolls, etc.

The control unit330is configured to detect a preprogrammed aircraft maneuver included in the plurality of preprogrammed aircraft maneuvers. Once the preprogrammed aircraft maneuver is detected, the control unit330directs each of the drums326to rotate to a corresponding position in response to detecting the preprogrammed aircraft maneuver.

For example, both the drums326may normally be in the closed position during a cruise condition so that no additional stall margin is created, but performance is not compromised. Then, when the control unit330detects a preprogrammed aircraft maneuver, i.e. banks, turns, rolls, the control unit330directs the drums326to rotate to one of the partially open positions or the fully open position so that flow is permitted into the plenum324. This permits air pressure and flows to better equalize circumferentially around the fan112to improve stall margin of the gas turbine engine110.

Conversely, when the control unit330detects the cruise condition after a preprogrammed aircraft maneuver, the control unit330directs the drums326to rotate to the closed position. Therefore, once the aircraft maneuver is completed, the drums326move to the closed position to performance is not compromised and the additional stall margin is removed during the cruise condition.

The control unit330is configured to direct some or all of the drums326to rotate from the closed position to one of the partially open positions or the fully open position based on the detected preprogrammed aircraft maneuver. Depending on the preprogrammed aircraft maneuver, the control unit330may directly only certain drums326to move to one of the partially open positions or the fully open position, while keeping others in the closed position.

Additionally, the control unit330may direct some of the drums326, to remain in the closed position, while directing some of the drums326to rotate to the fully opened position and others to a partially open position. The control unit330is configured to direct some of the drums326to rotate to one partially open position while others are rotated to another partially open position. In other words, the control unit230is configured to individual vary the angle of each slot328of each of the drums326.

Similarly, the control unit330is configured to receive a measurement from the at least one sensor or sensors and direct the drums326to rotate to a corresponding position in response to the measurement like as discussed above with respect to the embodiment ofFIGS.1-3. In some embodiments, the control unit330may be configured to use a combination of the sensor measurements and the detected preprogrammed aircraft maneuver to control the position of the plurality of drums326.

Another embodiment of a fan case assembly410in accordance with the present disclosure is shown inFIGS.18A and18B. The fan case assembly410is substantially similar to the fan case assemblies10,210,310shown inFIGS.1-17and described herein. Accordingly, similar reference numbers in the400series indicate features that are common between the fan case assembly10,210,310and the fan case assembly410. The description of the fan case assembly10,210,310is incorporated by reference to apply to the fan case assembly410, except in instances when it conflicts with the specific description and the drawings of the fan case assembly410.

The fan case assembly410includes, among other components, a case420and an inlet distortion mitigation system having a plurality of rotatable drums. One of the rotatable drums426is shown inFIGS.18A and18B.

The rotatable drum426has a substantially cylindrical shape as shown inFIGS.18A and18B. The drum426has an outer surface446with flattened surface sections450,452as shown inFIGS.18A and18B. The flattened surfaces450,452are configured to align with an inner surface421of the fan case420when the drum426is in the closed position as shown inFIG.18Aand the fully open position as shown inFIG.18B. The first flattened surface450of the drum426is aligned with the inner surface421of the fan case420when the drum426is in the closed position. The second flattened surface452of the drum426is aligned with the inner surface421of the fan case420when the drum426is in the fully open position. In this way, the drum426is flush with the inner surface421of the fan case420at the different positions.

Another embodiment of a fan case assembly510in accordance with the present disclosure is shown inFIGS.19A and19B. The fan case assembly510is substantially similar to the fan case assemblies10,210,310shown inFIGS.1-17and described herein. Accordingly, similar reference numbers in the500series indicate features that are common between the fan case assembly10,210,310and the fan case assembly510. The description of the fan case assembly10,210,310is incorporated by reference to apply to the fan case assembly510, except in instances when it conflicts with the specific description and the drawings of the fan case assembly510.

The fan case assembly510includes, among other components, a case520and an inlet distortion mitigation system having a plurality of rotatable drums. One of the rotatable drums526is shown inFIGS.19A and19B.

The rotatable drum526has a substantially cylindrical shape as shown inFIGS.19A and19B. The drum526has an outer surface546with flattened surface sections550,552and a rounded or shaved section554as shown inFIGS.19A and19B. The flattened surfaces550,552are configured to align with an inner surface521of the fan case520when the drum526is in the closed position as shown inFIG.19Aand the fully open position as shown inFIG.19B. The rounded or shaved surface554prevents the drum526from protruding past the fan case521and into the flow path when the drum526rotates between the different positions.

The first flattened surface550of the drum526is aligned with the inner surface521of the fan case520when the drum526is in the closed position. The second flattened surface550of the drum526is aligned with the inner surface521of the fan case520when the drum526is in the fully open position. In this way, the drum526is flush with the inner surface521of the fan case520at the different positions.

The fan112includes an inlet distortion mitigation system22,222,322which includes a plurality of rotatable drums26,226,326configured to control fluid communication between the plenum24,224,324and the gas path25. The plurality of rotatable drums26,226,326may be rotated all together or in sets/groups to expose the tips of the fan blades14to the plenum24,224,324radially outward of the drums26,226,326.

The flow path or gas path25between the drums26,226,326is a static flow path or has partitions38so when the slots28,228,328are rotated away from the gas path25, the gas path25is relatively smooth. Then the drums26,226,326may be rotated to expose the slots28,228,328to the gas path25and direct flow into the plenum24,224,324.

In the illustrative embodiment, the partitions38may block part of the slot28in certain positions to vary the size of the opening to the slot28thereby modulating the flow therethrough. In some embodiments, the partitions38do not block the opening to the slot28such that in the fully open and partially open positions the slots28are completely open to the gas path25.

The rotating drums26,226,326may be incorporated into the fan case20,220,320or into liners and operated via a variable geometry system similar to variable vanes. The actuator(s)60may be similar to the variable geometry system used with variable vanes.

In the first condition, or the closed position, any opening to the plenum24,224,324would be closed so no additional stall margin is created, but performance is not compromised. In a second condition, or the fully open position or partially open positions, the plurality of drums26,226,326rotates to permit flows into the plenum24,224,324. This permits air pressure and flows to better equalize circumferentially and provides additional stall margin benefit. The angle of the slots28,228,328of the drums26,226,326may be adjusted to tune the arrangement to particular needs or conditions.

The plurality of drums26,226,326permit the fan112to optimize efficiency at a cruise point with limited distortion, while being able to maintain adequate stall margin at another condition. By activating the rotatable drums26,226,326to trade efficiency for stall margin improvement, but not have to live with that trade at all times, the inlet distortion mitigation system22,222,322allows optimization of the fan112.

The plenum24,224,324uses rotating of the drums26,226,326to open or close the passage of air to the plenum24,224,324. The slots28,228,328of the drums26,226,326may be rotated to a range of angles between 0 to about 90 degrees.

This may be done with all drums26,226,326controlled the same, or with different angles for different sectors via ganging. The channel or plenum24,224,324itself may have different cross-sections when viewed in the circumferential direction. In some embodiments, the cross-section of the plenum24,224,324is a forward-leaning cross-sectional shape outboard of the space for the drums26,226,326. In some embodiments, the cross-section of the plenum24,224,324may have different shape. In the illustrative embodiment, the cross-section of the plenum24,224,324is rectangular when viewed circumferentially about the axis11.

In some embodiments, the drums26,226,326may be ganged by sectors and have some drums26,226,326at different circumferential locations be open to flow into the plenum24,224,324and other drums26,226,326to help flow out of the plenum. Other drums26,226,326in the middle may be closed. While all drums26,226,326may be in one direction as inFIGS.7-10, the air would have to flow past the drums26,226,326and then between it and a neighboring to flow out.

The drums26,226,326may be any suitable shape capable of controlling a flow or air between the gas path25and the plenum24,224,324when rotated or actuated. In the illustrative embodiments, the drums26,226,326are cylindrical. In some embodiments, the drums26,226,326may have a substantially cylindrical shape like drums426,526as shown inFIGS.18-19A.

In some embodiments, as shown inFIGS.18A and18B, the drums426, and/or the surface446of the drum426may have one or more flattened surfaces or portions450,452. The flattened portions450,452may allow for the drums426to be aligned with the inner surface421of the fan case when the drum426is in the closed position or fully open position, so that the outer surface446of the drum426sits flush with the fan case421and does not protrude into the flow path.

In some embodiments, as shown inFIGS.19A and19B, the drums526, and/or the outer surface546of the drum526may have one or more rounded or shaved portions554and/or one or more flattened portions550,552. The flattened portions550,552may be aligned with the inner surface521of the fan case when the drum526is in the closed position or fully open position, so that the outer surface546of the drums526sits flush with the fan case521and does not protrude into the flow path. The rounded or shaved portions554may be between the flattened portions550,552, and may prevent the drums526, from protruding past the fan case521and into the flow path. In some embodiments, the slot528may be open to flowpath25, but air may not be able to flow into the plenum, as shown inFIG.19A.

The control unit30is configured to use sensor inputs from a sensor66to control operation of the drums26,226,326. The sensor66may include one of or a combination of a static wall pressure sensor, an altitude sensor, sensors configured to detect twisting of the fan blades14, sensors configured to detect the tip timing of the fan blades14, sensors configured to measure a rotational speed of the fan blades14, a dynamic pressure transducer sensor. The combination of some sensors may provide data to engage mitigation of the effects of distortion, while other sensors may detect the maneuvers or mission phase.

For example, altitude and fan speed may provide data to engage mitigation, while also providing maneuver detection or regime/mission phase framing of control logic. Additionally, static wall pressure, dynamic pressure transducers, blade tip timing, blade untwist as well as fan speed and altitude may be used in distortion/effect detection for the control logic.

While the disclosure has been illustrated and described in detail in the foregoing drawings and description, the same is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments thereof have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.