JP2011149425A - Nonlinear unsymmetrical variable guide vane schedule - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the vibration stress of blades by changing an opening/closing schedule depending on a peripheral position. <P>SOLUTION: A variable inlet guide vane mechanism 30 for a compressor 18 includes a case 40 for defining the inlet of the compressor, at least one vane support arranged coaxially in the case, a plurality of vanes 38 each pivotally mounted between the case and at least one vane support, and arranged around the case in the peripheral direction, and actuator mechanisms 44, 46 configured to pivotally actuate at least some of the plurality of vanes around the case in an unsymmetrical pattern. A method for controlling the variable inlet guide vane mechanism for the compressor includes a step of pivotally actuating at least some of the plurality of vanes around the case in the unsymmetrical pattern. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a variable inlet guide vane used for controlling a flow flowing into a compressor such as a compressor of a gas turbine engine.

  Turbofan gas turbine engines that power a sailing aircraft typically include a fan, a low pressure compressor or booster, a high pressure compressor, a combustor, a high pressure turbine, and a low pressure turbine in fluid communication in series. The combustor produces combustion gas that is continuously directed to the high pressure turbine, where the combustion gas expands to drive the high pressure turbine and then is directed to the low pressure turbine where it expands further to drive the low pressure turbine. The high pressure turbine is drivingly connected to a high pressure compressor via a first rotor shaft, and the low pressure turbine is drivingly connected to both the fan and booster via a second rotor shaft.

  High pressure compressors often include a series of stator vane stages used for air compression in engine and aircraft applications. The first compressor stage adjacent to the booster is an inlet guide vane stage composed of a plurality of cantilevered inlet guide vanes arranged in the circumferential direction. The inlet guide vanes are actuated by the control system to optimize the air flow for the purpose of powering and avoiding stalls. The guide vane is held between the stator case and the internal vane shroud. The stator case is coupled to the engine case. The space between the stator case and the shroud determines the volume of air passing through the high pressure compressor. The shroud delimits the aerodynamic flow path of the high pressure compressor.

  In some engines, the inlet guide vane and other downstream stator vanes are variably actuated by operation of one or more controllable vane actuators. The trunnion or spindle outside the vane passes through the stator case and is coupled to the lever arm. The lever arm is coupled to an actuating ring connected to the vane actuator. One or more vane actuators move a series of stator vanes arranged in the circumferential direction of each compressor stage. The vane is held in the stator case by a combination of a bush, a washer, and a lock nut fitted in the outer trunnion.

  The variable guide vanes are used to control the flow into the compressor and are scheduled to open and close according to the flow demand. When the flow rate is low, the variable guide vanes operate in a separated flow state, and when the flow rate is relatively high, the variable guide vanes operate in a non-separated flow state. During operation of the variable guide vanes along the opening and closing schedule, there is an area where flow separation begins. This area is referred to as an “onset of separation” area. Due to inlet distortion, the flow rate is not uniform. This non-uniformity may cause a time difference for each vane to reach the separation start region. The circumferential pattern associated with this condition creates a strong harmonic stimulus that contributes to the vibration of the rotating blade that is susceptible to such excitation. Due to such stimulation, a strong harmonic portion is generated in a region where the blade resonance exists, and vibration stress is applied to the blade.

U.S. Patent No. 7223066B2

  A method for controlling a variable inlet guide vane mechanism for a compressor is provided.

  According to one embodiment of the present invention, a variable inlet guide vane mechanism for a compressor includes a case defining a compressor inlet, at least one vane support disposed coaxially within the case, and each vane comprising A plurality of vanes circumferentially arranged around the case pivotally mounted between the case and at least one vane support; and at least some of the plurality of vanes in an asymmetric pattern around the case And an actuator mechanism configured as described above.

  According to another embodiment of the invention, a case defining an inlet of the compressor, at least one vane support disposed coaxially within the case, each vane having a case and at least one vane support A plurality of vanes circumferentially disposed around the case, and an actuator mechanism configured to pivot at least some of the plurality of vanes in an asymmetric pattern around the case. A method of controlling a variable inlet guide vane mechanism for a compressor having a compressor is provided. The method includes the step of pivoting at least some of the plurality of vanes around the case in an asymmetric pattern.

1 is a partial schematic cross-sectional view of a turbofan engine to which an embodiment of an inlet guide vane control system is applied. FIG. 2 is a partially cutaway perspective view of a high pressure compressor portion of the engine of FIG. 1. FIG. 2 is a partially exploded perspective view of an inlet guide vane control system for the engine of FIG. 1. FIG. 6 is a side view of an inlet guide vane and a vane-shroud joint. FIG. 6 is a schematic view of an inlet guide vane mechanism and an actuator mechanism according to another embodiment of the present invention. FIG. 6 is a schematic view of an inlet guide vane mechanism and an actuator mechanism according to another embodiment of the present invention.

  Referring to the drawings in which like reference numbers indicate like elements, FIG. 1 shows a longitudinal cross-sectional view of a turbofan engine 10. Engine 10 includes a fan 14, a booster 16, a high-pressure compressor 18, a combustor 20, a high-pressure turbine 22, and a low-pressure turbine 24 that are in fluid communication in series axially around a longitudinal central axis 12. The high pressure turbine 22 is drivingly connected to the high pressure compressor 18 by a first rotor shaft 26, and the low pressure turbine 24 is a second rotor shaft 28 disposed within the first rotor shaft 26 and booster 16 and fan 14. Are connected in a driving manner.

  During operation of the engine 10, ambient air is continuously compressed through the fan 14, booster 16, and compressor 18. While some of the ambient air is extracted for auxiliary functions, the main pressurized air stream enters combustor 20 where it is mixed with fuel and burned to produce a high energy, hot combustion gas stream. provide. The high energy gas stream passes through the high pressure turbine 22 where it is further expanded to extract energy that drives the first rotor shaft 26. The gas stream then passes through the low pressure turbine 24 where the energy that drives the second rotor shaft 28 and thus the fan 14 is extracted. Combustion waste and unused gas are discharged from the engine 10 through an exhaust duct.

  Referring to FIGS. 2-4, the compressor 18 includes an inlet guide vane stage 30 followed by a set of variable vane stator stages 32, 34, and 36. The annular dimension of each stage 30, 32, 34, 36 gradually decreases to compress the air used in subsequent engine stages. Each stage of the compressor 18 includes a set of circumferentially arranged vanes 38 captured between a stator case 40 and a vane shroud 41 of the compressor 18. As shown in FIG. 3, the shroud 41 includes a set of shroud sections 42. Although a shroud is shown and described, the compressor 18 need not include a shroud, and the vane 38 includes a stator case 40 and a support such as an internal stator structure or casing, or ring, or a bearing support member of an engine, for example. May be supported in between.

  The vane 38 is variably actuated by a set of variable vane actuators 44, 46. The vane 38 is coupled to the actuators 44, 46 by a trunnion 48 outside the vane via the stator case 40. The outer trunnion 48 passes through the stator case port 50 and is held by an inner bushing 52 and an outer nut 54. A lever arm 56 is captured between the bushing 52 and the outer nut 54. The lever arm 56 is coupled to the vane actuators 44 and 46 via the link arm 58.

  With reference to FIGS. 3 and 4, rotation of the vane 38 is further enabled by coupling multiple sets of vanes 38 to each of the inner vane shroud sections 42. Each shroud section 42 includes a plurality of shroud ports 60, each port 60 configured to receive a trunnion 62 inside each vane 38. The inner trunnion 62 includes a contact shoulder or trunnion button 64 that resides in a shroud port groove 66 having a groove shoulder. The inner trunnion 62 is first captured in the port 60 using a shroud bushing 68 that matches the port 60. The shroud washer 70 forms an intermediate contact area between the bushing surface of the trunnion button 64 and the trunnion surface of the shroud bush 68. The washer 70 prevents the shroud section 42 from moving upward and significantly increases the capture contact area between its capture component and the inner trunnion 62. This extends the life of the guide vane system and reduces the maintenance burden.

  The shroud section 42 is further coupled to a shroud seal retainer 74. As shown in FIG. 3, the retainer 74 extends over approximately half of the entire inner circumference of the compressor 18 and effectively joins the group of shroud sections 42 and thus the group of vanes 38. As a result, a spoke effect occurs in the cantilever vanes 38 connected to each other. The span of the retainer 74 also makes it difficult for the shroud section 42 to move downward from the space inside the compressor 18. This reduces the effects of actuation and vibration on the shroud-vane boundary.

  With reference to FIGS. 5 and 6, a variable inlet guide vane mechanism according to another embodiment has an outer vane support 1 and an inner vane support 6. Each guide vane 4 includes a pinion 9 provided on the vane trunnion pivoted by the outer vane support 1. The rack 3 is connected to the surrounding support member 2, and engages with each pinion 9 of the guide vane mechanism as shown in FIG. The outer vane support 1 is connected to the stator case by a fastener member 7, and the inner vane support 6 is covered by an inner cover member 5.

  The surrounding support member 2 is connected to an actuator 8 configured to rotate the surrounding support member 2 so that the rack 3 pivots the inlet guide vane 4 via the pinion 9. Rack 3 is configured to change the vane opening / closing schedule asymmetrically. The rack 3 is non-uniform over the entire open / close range.

  By actuating the variable vane actuator and changing the opening / closing schedule of the vanes asymmetrically (circumferentially), the flow separation is initiated from the blades into a pattern that generates the desired harmonics and the stimulation on the rotating blades Can be reduced or eliminated if possible. The vane open / close schedule may use a non-linear schedule so that asymmetry is applied only to the separation start region. Alternatively, an alternating (different) linear schedule may be used to provide a bilinear schedule. Beyond the region of separation initiation, this asymmetry is not used, and the harmonics associated with these conditions are minimized by the vanes being located symmetrically in a completely separated or completely non-separated flow region. Can be suppressed.

  The start of separation can be controlled in the circumferential direction by changing the opening / closing schedule according to the position in the circumferential direction. The resulting harmonic stimulation is controlled using the separation pattern, eliminating the strong harmonic portion of the region where the blade resonance is, and thus reducing the vibration stress of the blade that is susceptible to this stimulation.

  The non-linearity of the vane open / close schedule causes the position of each vane to change circumferentially relative to other vanes in the stage, leading to a reduction in aerodynamic stimulation at frequencies close to the resonance frequency of the rotor blades. Is formed. The non-linearity of the schedule is applied over a narrow schedule region where the vane transitions from a fully attached flow to a completely separated flow, i.e. in the region of separation initiation. In other vane positions where the flow is completely separated (vanes are completely closed) or completely attached (vanes are fully open), the vane opening / closing schedule provides an axisymmetric pattern. It is linear and minimizes stimulation and maximizes operating efficiency in these more even conditions.

  The above embodiments include variable actuators connected to the inlet guide vanes by lever arms connected to individual inlet guide vanes connected to the variable actuators by linkages, but make the vane open / close schedule non-linear For this purpose, another vane opening / closing mechanism such as a gear mechanism or an elliptical cam may be used.

  Although the present invention has been described in connection with the most practical and preferred embodiments at the present time, the invention is not limited to the disclosed embodiments, but rather is various within the scope of the appended claims. Modifications and equivalent measures shall also be included.

DESCRIPTION OF SYMBOLS 1 Outer vane support body 2 Circumferential support member 3 Rack 4 Guide vane 5 Inner cover member 6 Inner vane support body 7 Fastening member 8 Actuator 9 Pinion 10 Turbofan engine 12 Longitudinal central axis 14 Fan 16 Booster 18 High pressure compressor 20 Combustor 22 High pressure turbine 24 Low pressure turbine 26 First rotor shaft 28 Second rotor shaft 30 Inlet guide vane stage 32 Variable vane stator stage 34 Variable vane stator stage 36 Variable vane stator stage 38 Vane 40 Stator case 41 Vane shroud 42 Shroud section 44 Variable vane actuator 46 Variable vane actuator 48 Trunnion outside vane 50 Stator case port 52 Inner bushing 54 Outer nut 56 Lever arm 58 link arm 60 shroud port 62 inner trunnion 64 contact shoulder / trunnion button 66 shroud port groove 68 shroud bush 70 shroud washer 74 shroud seal retainer

Claims (15)

A variable inlet guide vane mechanism (30) for a compressor (18), comprising:
A case (40) defining an inlet of the compressor;
At least one vane support (6; 41) arranged coaxially in the case;
A plurality of vanes (4; 38) circumferentially arranged around the case, each vane pivotally mounted between the case and the at least one vane support;
A variable inlet guide vane mechanism having an actuator mechanism (44, 46; 8) configured to pivot at least some of the plurality of vanes about the case in an asymmetric pattern.   The actuator mechanism (44, 46; 8) pivots the vanes according to a non-linear schedule or according to an alternating linear schedule while the vanes pivot from a fully closed position to a fully open position. The variable inlet guide vane mechanism of claim 1, wherein the variable inlet guide vane mechanism is configured to cause   The variable inlet guide vane mechanism according to claim 2, wherein the plurality of vanes (4; 38) are pivoted according to a non-linear schedule or an alternating linear schedule when flow begins to separate from the plurality of vanes.   The actuator mechanism (44, 46; 8) pivots the vanes according to a linear schedule when the flow is completely attached to the plurality of vanes or substantially separated from the plurality of vanes. The variable inlet guide vane mechanism according to claim 3, wherein the variable inlet guide vane mechanism is configured to form an axisymmetric pattern around the case.   The at least one vane support (41) includes a plurality of vane supports (42), and the plurality of vanes are pivotally mounted between the case and the plurality of vane supports, and the actuator mechanism ( 44, 46) pivot the plurality of vanes of the plurality of vane support subsets around the case in an asymmetric pattern and pivot the remaining vanes of the plurality of vane supports around the case. The variable inlet guide vane mechanism of claim 1, wherein the variable inlet guide vane mechanism is configured to pivot in a symmetrical pattern to form a flow separation pattern from the vane.   The variable inlet guide vane mechanism of claim 5, wherein the flow separation pattern is configured to produce less aerodynamic stimulation in the flow at a frequency near a resonance frequency of a turbofan engine rotor blade. The actuator mechanism (44, 46)
A plurality of lever arms (56), each lever arm connected to a vane;
A plurality of link arms (58), each link arm connected to a subset of the plurality of lever arms;
The variable inlet guide vane mechanism according to claim 1, comprising a plurality of actuators (44, 46), each actuator being connected to a link arm and pivoting the lever arm through the link arm. The actuator mechanism is
A gear (9) provided on each vane;
A rack (3) engaged with each gear;
The variable inlet guide vane mechanism according to claim 1, comprising an actuator (8) configured to move the rack relative to the gear to pivot the vane.   The variable inlet guide vane mechanism of claim 1, wherein the mechanism further comprises a compressor (18).   The variable inlet guide vane mechanism of claim 9, wherein the mechanism further comprises an engine. A case (40) defining an inlet of the compressor (18); at least one vane support (6; 41) disposed coaxially within the case; and each vane for the case and the at least one vane A plurality of vanes (4; 38) disposed circumferentially around the case, pivotally connected to a support, and an actuator configured to pivot at least some of the plurality of vanes A method for controlling a variable inlet guide vane mechanism (30) for a compressor (18) having a mechanism (44, 46; 8) comprising:
Pivoting at least some of the plurality of vanes in an asymmetric pattern around the case.   The step of pivoting the vanes in an asymmetric pattern is according to a non-linear schedule or an alternating linear schedule while at least some of the plurality of vanes are pivoting from a fully closed position to a fully open position. Pivoting at least some of the plurality of vanes, wherein at least some of the plurality of vanes pivot according to the non-linear schedule or an alternating linear schedule at a point in time when flow begins to separate from the plurality of vanes. 12. The method of claim 11, wherein the method is moved.   If the flow is completely attached to or substantially separated from the plurality of vanes, at least some of the plurality of vanes are pivoted according to a linear schedule to surround the case The method of claim 12, further comprising forming an axisymmetric pattern on the substrate. 12. The method of claim 11, wherein the at least one vane support comprises a plurality of vane shrouds (42), the plurality of vanes being pivotally mounted between the case and the plurality of vane shrouds. And
Pivoting the plurality of vanes of the plurality of vane shroud subsets in an asymmetric pattern around the case and pivoting the remaining vanes of the plurality of vane shrouds in an axisymmetric pattern around the case; A method further comprising forming a flow separation pattern from the plurality of vanes.   The method of claim 14, wherein the flow separation pattern is configured to produce less aerodynamic stimulation in the flow at a frequency close to a resonance frequency of a rotor blade of a turbofan engine (10).

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