Circumferential blade row for gas turbine engine with non-uniform blade pitch

Abstract

A circumferential blade row for a gas turbine engine, the circumferential blade row having a non-uniform pitch. The circumferential wheel blade row comprises a plurality of stator wheel blades circumferentially arranged around the inner ring. The plurality of stator vanes includes a first set of stator vanes having a first pitch between adjacent stator vanes of the first set of stator vanes and a second set of stator vanes having a second pitch between adjacent stator vanes of the second set of stator vanes. The second pitch is 2% to 11% greater than, or 2% to 11% less than, a nominal uniform vane pitch defined by a total number of the plurality of stator vanes. The engine includes a row of circumferential vanes.

Description

Technical Field

[0001] The present disclosure generally relates to a circumferential bucket row for a gas turbine having a non-uniform bucket spacing. Background Art

[0002] A turbine engine generally comprises a fan and a core section arranged in flow communication with each other. The core section comprises one or more turbines and one or more compressors. The turbine and the compressor comprise one or more stages, each stage comprising rotor blades and stator blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The foregoing and other features and advantages will be apparent from the following more particular description of various exemplary embodiments as illustrated in the drawings, in which like reference numerals generally indicate identical, functionally similar, and / or structurally similar elements.

[0004] Figure 1 A schematic cross-sectional view of a ducted indirect drive gas turbine engine according to the present disclosure, taken along the longitudinal centerline axis of the engine, is shown.

[0005] Figure 2A The invention is shown to be applicable to Figure 1 Schematic end view of a circumferential stator blade row in a turbine engine.

[0006] Figure 2B It shows that according to the present disclosure Figure 2A Schematic end view of an alternative orientation of circumferential stator blade rows.

[0007] Figure 3A It shows that according to the present disclosure Figure 2A or Figure 2B Graph of the harmonic offset of the circumferential stator blade row.

[0008] Figure 3B It shows that according to the present disclosure Figure 2A or Figure 2B Graph of the harmonic offset of the circumferential stator blade row. DETAILED DESCRIPTION

[0009] Additional features, advantages, and embodiments of the present disclosure will be set forth or apparent by consideration of the following detailed description, drawings, and claims. Furthermore, the foregoing overview and the following detailed description of the present disclosure are exemplary and are intended to provide further explanation without limiting the scope of the present disclosure as claimed.

[0010] Various embodiments of the present disclosure are discussed in detail below. Although specific embodiments are discussed, this is for illustrative purposes only. Those skilled in the relevant art will recognize that other components and configurations may be used without departing from the spirit and scope of the present disclosure.

[0011] As used herein, the terms “first” and “second” may be used interchangeably to distinguish one component from another, and are not intended to indicate the position or importance of each component.

[0012] The terms "upstream" and "downstream" refer to relative directions with respect to the flow of a fluid in a fluid path. For example, "upstream" refers to the direction from which the fluid is flowing, and "downstream" refers to the direction to which the fluid is flowing.

[0013] The terms "front" and "rear" refer to relative positions within a turbine engine or vehicle and refer to the normal operating attitude of the turbine engine or vehicle. For example, for a turbine engine, front refers to the position closer to the engine inlet, while rear refers to the position closer to the engine nozzle or exhaust.

[0014] As used herein, the terms "low," "medium" (or "medium"), and "high," or their corresponding comparatives (e.g., "lower" and "higher," as applicable), when used with a compressor, turbine, shaft, fan, or turbine engine component, each term refers to a relative pressure, relative speed, relative temperature, and / or relative power output within the engine, unless otherwise indicated. For example, a "low power" setting defines an engine that is configured to operate at a power output that is lower than a "high power" setting for the engine, and a "medium power" setting defines an engine that is configured to operate at a power output that is higher than the "low power" setting and lower than the "high power" setting. The terms "low," "medium" (or "medium"), or "high" in the foregoing terms may additionally or alternatively be understood as relative to a minimum allowable speed, pressure, or temperature, or relative to a minimum or maximum allowable speed, pressure, or temperature for normal, desired, steady-state, etc., operation of the engine.

[0015] The terms “coupled,” “fixed,” “attached,” “connected,” and the like refer to both direct coupling, fixing, attachment, or connection as well as indirect coupling, fixing, attachment, or connection through one or more intermediate components or features, unless otherwise indicated herein.

[0016] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0017] As used herein, the terms "axial" and "axially" refer to directions and orientations extending substantially parallel to the centerline of the turbine engine. Additionally, the terms "radial" and "radially" refer to directions and orientations extending substantially perpendicular to the centerline of the turbine engine. Additionally, as used herein, the terms "circumferential" and "circumferentially" refer to directions and orientations extending arcuately around the centerline of the turbine engine.

[0018] Turbine engines include rotor blades and stator vanes in turbines and compressors. Stator vanes are formed by airfoils, referred to herein as stator airfoils, which produce wakes or disturbances in the airflow downstream and upstream of the airfoils. The wakes or disturbances act as pulses on the airfoils (referred to herein as rotor airfoils) that form the rotor blades. The pulses acting on the rotor airfoils can excite the rotor airfoils to a vibration response frequency or vibration response state. The frequency or rate of the pulse depends on a variety of factors, including a combination of engine speed (also referred to as engine revolutions per minute (RPM)), the number of stator airfoils, and the spacing of the stator airfoils. The severity of the vibration response depends on a variety of factors, including but not limited to engine RPM and pulse frequency.

[0019] Uneven blade spacing is provided in the circumferential rows of the stator airfoils to reduce the severity of the vibration response. The uneven blade spacing provides multiple blade spacings within the same circumferential row of the stator airfoils. The use of uneven blade spacing can change the pulse frequency from a single frequency to a range of pulse frequencies, which in turn can change the RPM at which the rotor airfoils are excited, thereby reducing the severity of the vibration response. Depending on the uneven blade spacing provided, the pulse frequency can be increased or decreased. Reducing the pulse frequency increases the RPM at which the rotor airfoils are excited, while increasing the pulse frequency decreases the RPM at which the rotor airfoils are excited. Therefore, the uneven blade spacing reduces the severity of the vibration response, but does so at the expense of spreading the vibration response over a wider range of pulse frequencies, which is equivalent to spreading the vibration response over a wider range of engine speeds. Thus, the non-uniform blade spacing of the present disclosure achieves the aforementioned advantages, but addresses the dispersion of the vibration response over a wider range of pulse frequencies by providing a non-uniform blade spacing that forces most of the drive harmonics to occur only on one side (above or below) of the uniform drive frequency. More specifically, the non-uniform blade spacing of the present disclosure allows the pulse frequency to target or avoid specific predetermined harmonics.

[0020] The circumferential blade row with uneven blade spacing of the present disclosure disrupts the above-mentioned vibration response in multiple harmonic ranges. The circumferential blade row with uneven blade spacing of the present disclosure offsets the harmonic response relative to the driving harmonic (N) of the uniformly spaced circumferential blade row. That is, the circumferential blade row with uneven spacing of the present disclosure targets high-side harmonics (e.g., higher than N) or low-side harmonics (e.g., lower than N). This results in a harmonic response that is primarily on one side of the main driving harmonic N, and may result in N+1 or N-1 or more harmonic responses. Targeting the high-side or low-side harmonics allows a higher offset or a lower offset of the harmonic resonant speed. Targeting the harmonic response to only one side of the main driving harmonic can allow the pulse frequency discussed previously to occur at a predetermined speed. This speed can be outside the operating range of the engine or can be reduced so that the speed of the pulse frequency is independent of the engine operation, even if it is still within the operating range of the engine.

[0021] Thus, the circumferential blade row of the present disclosure with non-uniform pitch provides a non-uniform blade pitch divided into a first group of blades with a first pitch and a second group of blades with a second pitch. The pitch in the first group is not equal to the pitch in the second group. The second group accounts for twenty to forty percent of the total number of blades on the circumferential row, and the second group pitch is two to eleven percent greater or less than the nominal uniform blade pitch.

[0022] Figure 1 A schematic cross-sectional view of a ducted indirect drive gas turbine engine 100 (also referred to as turbine engine 100) is shown taken along a longitudinal centerline axis 102 of the turbine engine 100 according to an embodiment of the present disclosure. The turbine engine 100, also referred to herein as turbine engine 100, includes in downstream series flow relationship a fan section 104 including a fan 106, a compressor section 108 including a supercharger or low pressure (LP) compressor 110 and a high pressure (HP) compressor 112, a combustion section 114 including a combustor 116, a turbine section 118 including a high pressure (HP) turbine 120, a low pressure (LP) turbine 122, and an exhaust nozzle 124. Figure 1 As shown, the turbine engine 100 defines an axial direction A, a radial direction R, and a circumferential direction C.

[0023] The fan section 104 includes a fan casing 126 fixed to a nacelle (omitted for clarity) surrounding the fan 106. The fan 106 includes a plurality of fan blades 128 radially arranged about the longitudinal centerline axis 102. The HP compressor 112, the combustor 116, and the HP turbine 120 form an engine core 130 of the turbine engine 100, which produces combustion gases. The engine core 130 is surrounded by a core casing 132, which is coupled to the fan casing 126. The fan casing 126 is supported relative to the turbine by circumferentially spaced outlet guide vanes 134.

[0024] A high-speed shaft 136, also referred to herein as a high-pressure shaft 136, is coaxially disposed about the longitudinal centerline axis 102 of the turbine engine 100 and drivingly connects the HP turbine 120 to the HP compressor 112. A low-speed shaft 138, also referred to herein as a low-pressure shaft 138, is coaxially disposed about the longitudinal centerline axis 102 of the turbine engine 100 and is located within the larger diameter annular high-speed shaft 136, drivingly connecting the LP turbine 122 (either directly or indirectly through a gearbox assembly 140) to the LP compressor 110 and the fan 106. The high-speed shaft 136 and the low-speed shaft 138 are rotatable about the longitudinal centerline axis 102.

[0025] The LP compressor 110 and the HP compressor 112 include respective multiple compressor stages 142, 144, wherein respective sets of compressor blades 146, 148 rotate relative to respective sets of compressor vanes 150, 152 to compress or pressurize gas entering through an inlet 154. Each compressor stage 144 of the HP compressor 112 includes a plurality of compressor blades 148 (or blades and disks integrated together, referred to as blisks), also referred to herein as rotor compressor blades 148, disposed on a rotor disk 156. Each compressor blade 148 extends radially outward from a blade platform to a blade tip relative to the longitudinal centerline axis 102. Compressor vanes 152, also referred to herein as stator vanes 152, are positioned upstream / downstream of the rotor compressor blades 148 and adjacent to the rotor compressor blades 148. A rotor disk 156 for a stage of compressor blades 148 is mounted to the high-speed shaft 136. The compressor stage 144 of the HP compressor 112 may refer to a single disk rotor compressor blade 148 or may refer to both a single disk rotor compressor blade 148 and an adjacent single disk stator vane 152. Either meaning may be applied in the context of the present disclosure without loss of clarity.The same description applies to each compressor stage 142 of the LP compressor 110 (eg, each compressor stage 142 of the LP compressor 110 includes a plurality of rotor compressor blades 146 and stator compressor vanes 150 ).

[0026] The HP turbine 120 has one or two turbine stages 158. In a single turbine stage 158, turbine blades 160 are disposed on a rotor disk 162, referred to herein as rotor blades 160. Each turbine blade 160 extends radially outward from a blade platform to a blade tip relative to the longitudinal centerline axis 102. The HP turbine 120 may also include stator turbine buckets 164, also referred to as stator turbine nozzles. The HP turbine 120 may have an upstream nozzle adjacent to the outlet of the combustor 116 and a downstream nozzle behind the rotor (e.g., turbine blades 160), or the HP turbine 120 may have nozzles located upstream of the rotor blades (e.g., turbine blades 160) or downstream of the rotor blades.

[0027] Air exiting the HP turbine 120 enters the LP turbine 122, which has a plurality of turbine stages 166 of rotor blades 168. The LP turbine 122 may have three, four, five, or six stages. In a single LP turbine stage 166 (including a plurality of blades 168 coupled to the low-speed shaft 138), the blades 168, also referred to herein as rotor blades 168, are disposed on a rotor disk (connected to the low-speed shaft 138) and extend radially outward from a blade platform to a blade tip relative to the longitudinal centerline axis 102. The LP turbine 122 may also include stator turbine buckets 170, also referred to as stator turbine nozzles. The LP turbine 122 may have an upstream nozzle and a downstream nozzle behind the turbine stage 166, followed by an exhaust nozzle 124.

[0028] During operation of the turbine engine 100, a volume of air A1 enters the turbine engine 100 through the inlet 172 of the fan case 126. When the volume of air A1 passes through the fan section 104 and through the fan blades 128, a first portion of air A2 of the air A1 is directed or directed into the bypass air flow passage 174, and a second portion of air A3 of the air A1 is directed or directed into the inlet 154 at the upstream section of the core air flow passage 176. The ratio between the first portion of air A2 and the second portion of air A3 is generally referred to as the bypass ratio. Then, when the second portion of air A3 is directed through the HP compressor 112 and enters the combustion section 114, its pressure increases, and in the combustion section 114, the highly pressurized air is mixed with fuel and burned to provide combustion gases 178.

[0029] The combustion gases 178 are directed into and expanded through the HP turbine 120, wherein a portion of the thermal and / or kinetic energy from the combustion gases 178 is extracted via the sequential stages of turbine blades 164 of the HP turbine 120 and rotor blades 160 coupled to the high-speed shaft 136, thereby causing the high-speed shaft 136 to rotate, thereby supporting the operation of the HP compressor 112. The combustion gases 178 are then directed into and expanded through the LP turbine 122. Here, a second portion of the thermal and kinetic energy is extracted from the combustion gases 178 via the sequential stages of LP turbine 122 turbine blades 170 and LP turbine rotor blades 168 coupled to the low-speed shaft 138, thereby causing the low-speed shaft 138 to rotate. The rotation of the low-speed shaft 138 thereby supports the operation of the LP compressor 110 and the rotation of the fan 106 (via the gearbox assembly 140, when present).

[0030] Combustion gases 178 are then directed through exhaust nozzle 124 to provide propulsive thrust. At the same time, the pressure of first portion air A2 is significantly increased as it is directed through bypass air flow passage 174 before being discharged from fan nozzle exhaust 180, also providing propulsive thrust.

[0031] Turbine engine 100 is provided as an example only. In other embodiments, the gas turbine engine may have any other suitable configuration, including, for example, any other suitable number or configuration of shafts or spools, fan blades, turbines, compressors, or combinations thereof. The gearbox assembly may have any suitable configuration, including, for example, a star gear configuration, a planetary gear configuration, a single stage, a multi-stage, an epicyclic, a non-episodic, etc., as further described below. The gearbox may have a gear ratio in the range of 3:1 to 4:1, 3:5 to 4:1, 3.25:1 to 3.5:1, or 4:1 to 5:1. The fan assembly may be any suitable fixed pitch assembly or a variable pitch assembly. Turbine engine 100 may include Figure 1 Additional components not shown in the fan assembly, such as rotor blades, stator blades, etc., may be provided. The fan assembly may be configured in any other suitable manner (e.g., as a fixed pitch fan) and may also be supported using any other suitable fan frame configuration. Aspects of the present disclosure may be incorporated into any other suitable turbine engine, including, but not limited to, turbofan engines, propfan engines, turbojet engines, turboprop engines and turboshaft engines, aviation turbine engines, marine turbine engines, land-based turbine engines, industrial turbine engines, power generation turbine engines, etc.

[0032] As indicated, the high and low pressure compressors and turbines include one or more stages, each stage having stator vanes and rotor blades. Each of the stator vanes and rotor blades includes an airfoil. The airfoil, whether stator or rotor, is oriented about a longitudinal centerline axis 102 ( Figure 1) are arranged in a circumferential manner. That is, each stage of the compressor and turbine is associated with a ring or a circumferential row of stator airfoils and a ring or a circumferential row of rotor airfoils. The rotor airfoils or stator airfoils are axisymmetric about the longitudinal centerline axis 102.

[0033] Figure 2A A schematic end view from front to back of an exemplary circumferential row 200 of stator blades 202 is shown. The stator blades 202 of the circumferential row 200 have a non-uniform blade spacing (NUVS). Figure 2A As shown, stator blades 202 are associated with turbine engine 100 ( Figure 1 ) is axially symmetrical about the longitudinal centerline axis 102. Each stator vane 202 extends radially outward from an inner ring 204 extending circumferentially around the longitudinal centerline axis 102.

[0034] Circumferential row 200 can be used as a reference Figure 1 Any stator blades of the depicted turbine engine 100. For example, compressor blades 150 of the LP compressor 110, compressor blades 152 of the HP compressor 112, turbine blades 164 of the HP turbine 120, or turbine blades 170 of the LP turbine 122 may be formed from stator blades 202 in a circumferential row 200. Any single stage, combination of stages, or all stages of any or all of the LP compressor, LP turbine, HP compressor, or HP turbine may be formed from stator blades 202 in a circumferential row 200.

[0035] Reference Figure 2A The depicted circumferential row 200 has a non-uniform vane pitch defined by a pitch between at least two stator vanes 202 that is different than a pitch between at least two other stator vanes 202. Figure 2A In the example of , the circumferential row 200 is divided into two groups, a first group of stator blades 250 and a second group of stator blades 260. Each stator blade 202 in the first group of stator blades 250 and the second group of stator blades 260 can be identical. In the first group of stator blades 250, adjacent stator blades 202 have a first spacing S1. Adjacent stator blades 202 are defined as two stator blades 202 that are directly circumferentially adjacent to each other without an intervening stator blade 202. In the second group of stator blades 260, adjacent stator blades 202 have a second spacing S2. The spacing S1 is not equal to the spacing S2, so that the spacing between adjacent stator blades 202 in the first group of stator blades 250 is not equal to the spacing between adjacent stator blades 202 in the second group of stator blades 260.

[0036] The first group of stator blades 250 and the second group of stator blades 260 each include discrete groups of stator blades 202. In each of the first group of stator blades 250 and the second group of stator blades 260, the group extends between the first axis 201 and the second axis 203. The grouping is provided so that there are only two different groups of spacing between the stator blades 202, such as Figure 2A 2. The circumferential row 200 is a circumferential row of stators 200, which is a circumferential row of stators 200, which is a circumferential row of stators 200, which is a circumferential row of stators 200, which is a circumferential row of stators 200, which is a circumferential row of stators 200, 200, and 200. The circumferential row 20 ...

[0037] The circumferential row 200 may be viewed relative to a "clock" orientation having a twelve o'clock position 216, a three o'clock position 218, a six o'clock position 220, and a nine o'clock position 222. Although no reference numerals are provided, the clock orientation is understood to include all clock positions therebetween. Figure 2A In the orientation of , the first set of stator vanes 250 extends in a clockwise direction from approximately the six o'clock position 220 to approximately the three o'clock position 218. The second set of stator vanes 260 extends in a clockwise direction from approximately the three o'clock position 218 to approximately the six o'clock position 220.

[0038] Despite Figure 2A , but the stator vanes 202 may be rotated circumferentially to any clock position about the circumferential row 200. For example, Figure 2B A circumferential row 300 of stator blades is shown that rotates compared to the circumferential row 200. All aspects of the circumferential row 300 are identical to the circumferential row 200 except for the "clocking" of the circumferential row 300. In each of the first set of stator blades 350 (which is identical to the first set of stator blades 250 except for the clocking orientation) and the second set of stator blades 360 (which is identical to the second set of stator blades 260 except for the clocking orientation), the set extends between the first axis 301 and the second axis 303. As shown in FIG. Figure 2B As shown, the first set of stator vanes 350 extends from approximately the twelve o'clock position 216 to approximately the nine o'clock position 222. The second set of stator vanes 360 extends from approximately the nine o'clock position 222 to the twelve o'clock position 216. Figure 2A and Figure 2BThe orientation is merely exemplary, and the first set of stator blades 250, 350 and the second set of stator blades 260, 360 may be rotated to any clock position as long as only two sets of stator blades are provided.

[0039] Return to reference Figure 2A , the spacing S1 and the spacing S2 can be defined by angle measurements. The angle measurement is defined by the spacing measured relative to the angle created between adjacent stator blades 202. For example, an angle 206 can be defined between an axis 208 of a first stator blade 212 extending through and perpendicular to the longitudinal centerline axis 102 and an axis 210 of a second adjacent stator blade 214 extending through and perpendicular to the longitudinal centerline axis 102. Measuring the angle 206 defines the first spacing S1. Although the angle measurement in the first set of stator blades 250 is shown by way of example only to define the first spacing S1, the angle measurement is also used to determine the second spacing S2. The angle measurement of the second spacing S2 can be measured between the axes of adjacent stator blades, as described with respect to the first spacing S1.

[0040] exist Figure 2A In the example of , the number of stator blades 202 in the second set of stator blades 260 is 20 to 40 percent of the total number of stator blades 202 in the circumferential row 200. This is shown in the following relationship (1), where n is the total number of stator blades 202 in the circumferential row 200 and n 260 is the number of stator blades 202 in the second set of stator blades 260 .

[0041] 0.2*n≤n 260 ≤0.4*n(1)

[0042] The number of stator blades 202 in the second set of stator blades 260 may be any percentage between and including 20 percent and 40 percent. In some examples, the number of stator blades 202 in the second set of stator blades 260 is approximately one-third or thirty-three percent of the total number of stator blades 202 in the circumferential row 200. In some examples, the number of stator blades 202 in the second set of stator blades 260 is approximately 29 percent, for example Figure 3A and Figure 3B .

[0043] These percentages are approximate (e.g., referred to as "approximately" a particular percentage) because discrete percentages of the total number of stator vanes 202 may result in partial vanes being included in a group, whereas only complete vanes are included in the first group and the second group. For example, in an example having thirty-one vanes (e.g., Figure 3A and Figure 3B), exactly twenty-nine percent of the total number of thirty-one blades results in 8.99 blades in the second set of stator blades, however, as discussed herein, the second set of stator blades includes nine blades. Therefore, twenty-nine percent is an approximation. Therefore, in the context of the present disclosure, the terms "about" or "approximately" refer to rounded percentages to ensure that each of the first and second sets of stator blades includes a whole blade, rather than a partial blade.

[0044] The number of stator blades 202 in the first set of stator blades 250 is the number of stator blades remaining in the total stator blades after the percentage of stator blades in the second set of stator blades 260 is determined, as shown in relation (2), where n 250 is the number of stator blades 202 in the first set of stator blades 250 .

[0045] n 250 =n*n 260 (2)

[0046] Therefore, the number of stator blades 202 in the first group of stator blades 250 depends on the number of stator blades 202 in the second group of stator blades 260. Therefore, when the number of stator blades in the second group of stator blades 260 is approximately one-third, the number of stator blades in the first group of stator blades is two-thirds. Each stator blade 202 is included in only one of the two groups, i.e., the first group of stator blades 250 or the second group of stator blades 260.

[0047] exist Figure 2A In the example, the second spacing S2 is 2 to 11 percent smaller than the nominal uniform blade spacing S, as shown in the following relationship (3), or the second spacing S2 is 2 to 11 percent larger than the nominal uniform blade spacing S, as shown in the following relationship (4).

[0048] S*0.02*S≤S2≤S-0.11*S(3)

[0049] S+0.02*S≤S2≤S+0.11*S(4)

[0050] In some examples, the second spacing S2 is four to six percent less than the nominal uniform blade spacing S, or the second spacing S2 is four to six percent greater than the nominal uniform blade spacing S.

[0051] The nominal uniform blade spacing S is defined as the spacing between adjacent stator blades having a uniform (e.g., equal) distribution around the entire circumference of the circumferential row. That is, the nominal uniform blade spacing can be defined by the following relationship (5), where n is the total number of stator blades in the circumferential row:

[0052]

[0053] Once the second spacing S2 is determined based on the above description, the remaining number of blades (eg, the number of blades n) is obtained. 250 ) and dividing that number by the remaining degrees of the circumferential row 200 (eg, the remaining degrees out of the full three hundred and sixty degrees) to determine the first spacing S1.

[0054] refer to Figure 2A The depicted circumferential row 200 is shown as having thirty-one blades, however, any number of blades may be disposed in the circumferential row 200. The circumferential row 200 may be applied to any number of configured blades, and the exact features of the airfoils (e.g., size, angle, fixed or variable pitch) that form the stator blades 202 are not limited. As previously described, in addition to the clocked orientation of the first set of stator blades 350 and the second set of stator blades 360, Figure 2B The circumferential row of 300 and Figure 2A The circumferential row 200 is the same.

[0055] refer to Figure 3A and Figure 3B The effect of uneven blade spacing of the circumferential row 200 is described. As previously described, uneven blade spacing according to the present disclosure allows harmonic offsets around the main drive harmonics. For example, Figure 3A and Figure 3B An exemplary circumferential row including thirty-one vanes is shown. Figure 2A and Figure 2B As shown. Figure 3A and Figure 3B In the example of FIG. 1 , the first set of stator blades 250 ( Figure 2A and Figure 2B ) includes twenty-two blades, the second set of stator blades 260 ( Figure 2A and Figure 2B ) includes nine blades. In the case of uniform blade spacing also with a circumferential row of thirty-one blades, there is a main drive harmonic 400 occurring at the thirty-first harmonic, also referred to herein as a uniform main drive harmonic 400, and the blades have a nominal uniform spacing. In examples with a different number of blades, the main drive harmonic may be offset to align with the number of blades.

[0056] exist Figure 3A In the embodiment, the circumferential rows have uneven blade spacing, wherein the spacing of the second set of stator blades (e.g., spacing S2 ( Figure 2A and 2B )) is 2 to 11 percent smaller than the nominal uniform blade spacing (e.g., spacing S). Specifically, Figure 3AAn example of includes a second set of stator blades having a pitch S2 that is 4.3 percent less than the nominal blade pitch. As noted, both the non-uniform blade pitch and the uniform blade pitch are defined for a circumferential row having thirty-one blades. This results in the harmonics being biased toward higher harmonics. That is, Figure 3A As shown, the harmonic response 500 includes a main drive harmonic 501 appearing at the thirty-first harmonic and an N-1 harmonic 502 which is a harmonic one lower than the main drive harmonic 501. The harmonic response 500 has almost no response to harmonics 503 lower than the N-1 harmonic 502, and the harmonic response is biased to harmonics 504 higher than the main drive harmonic 501 (e.g., N+1 and greater harmonics). Almost no response means that the harmonic response of the harmonic 503 is smaller than the harmonic response of at least one of the harmonics 504 in the bias group. Figure 3A In the example of FIG. 5 , the harmonic responses of harmonic 503 are all smaller than the harmonic responses at four harmonics greater than the main drive harmonic 501 .

[0057] exist Figure 3B In the embodiment, the circumferential rows have uneven blade spacing, wherein the spacing of the second set of stator blades (e.g., spacing S2 ( Figure 2A and 2B )) is two to eleven percent greater than the nominal uniform blade spacing (e.g., spacing S). Specifically, Figure 3B An example of includes a pitch S2 of the second set of stator vanes that is 5.2 percent greater than the nominal vane pitch. As noted, both the non-uniform vane pitch and the uniform vane pitch are defined for a circumferential row having thirty-one vanes. This results in the harmonics being biased toward lower harmonics. That is, Figure 3B As shown, the harmonic response 600 includes a main drive harmonic 601 appearing at the thirty-first harmonic and an N+1 harmonic 602 which is one harmonic greater than the main drive harmonic 601. The harmonic response 600 has almost no response to harmonics 603 higher than the N+1 harmonic 602, and the harmonic response is biased to harmonics 604 lower than the main drive harmonic 601 (e.g., N-1 and lower harmonics). Almost no response means that the harmonic response of the harmonic 603 is less than the harmonic response of at least one of the harmonics 604 in the bias group. Figure 3B In the example of FIG. 6 , the harmonic responses of harmonic 603 are all smaller than the harmonic responses at three harmonics lower than the main drive harmonic 601 .

[0058] Figure 3A and Figure 3B An example with thirty-one blades is shown. In an example with a different number of blades, the main drive harmonic N can be shifted to align with the number of blades, and the N-1 and N+1 harmonics will be similarly shifted.

[0059] Therefore, if Figure 3A and Figure 3BAs shown, relative to Figure 2A The particular non-uniform blade spacing of the present disclosure described by circumferential row 200 and relationships (1) to (5) achieves a biasing of harmonics higher or lower than the main drive harmonics such that there is little response to the opposite side of the main drive harmonics.

[0060] Thus, the harmonic response of the blades of the circumferential row 200 of the present disclosure with non-uniform blade spacing biases the harmonic response relative to the drive harmonics. This is in contrast to other non-uniform blade spacings where the harmonic response is centered around the main drive harmonics (e.g., a bell curve type arrangement) such that the harmonic response is evenly distributed over the main drive harmonics N. That is, there are harmonic responses both higher and lower than the main drive harmonics. Both the higher and lower harmonic responses are greater than Figure 3A and Figure 3B . Outside the 2 to 11 percent range described herein, the harmonic response transitions to a harmonic response having a bell curve distribution or uniform distribution centered on the main drive harmonic, as previously described. That is, the offset harmonic response pattern decreases outside the 2 to 11 percent range described herein.

[0061] Targeting of the high side or low side harmonics allows for a higher or lower shift of the harmonic resonant speed. Targeting the harmonic response to only one side of the main drive harmonic can allow the engine to avoid higher or lower crossover speeds within the operating range and provide control of the resonant response placement within the operating range. The non-uniform blade spacing of the present disclosure allows for control of the resonant response placement within the engine operating range.

[0062] The non-uniform blade spacing of the present disclosure provides the aforementioned benefit of amplitude reduction compared to uniform blade spacing. The targeting of the high-side and low-side harmonics may show a reduction in the overall effectiveness of amplitude reduction compared to non-uniform blade spacing with spacing outside the two to eleven percent range. However, the biasing of the harmonics allows the harmonics to be truncated or severely reduced to one side of the main drive harmonics, and this makes up for the lower reduction in the overall amplitude of the harmonic response. That is, even though the amplitude of the harmonic response of the current design may be larger (compared to other non-uniform blade spacings), the effect of biasing the harmonics to one side of the main drive harmonics outweighs the inherently higher amplitude in the harmonic response. This is because the targeting of the harmonics described herein allows specific harmonics within the operating range of the engine to be avoided.

[0063] Further aspects are provided by the subject matter of the following clauses.

[0064] A circumferential blade row with non-uniform blade spacing, the circumferential blade row comprising a plurality of stator blades arranged circumferentially around an inner ring, the plurality of stator blades comprising a first group of stator blades and a second group of stator blades, the first group of stator blades having a first spacing between adjacent stator blades of the first group of stator blades, the second group of stator blades having a second spacing between adjacent stator blades of the second group of stator blades, the second spacing being two to eleven percent less than a nominal uniform blade spacing, or two to eleven percent greater than the nominal uniform blade spacing, the nominal uniform blade spacing being defined by the total number of the plurality of stator blades.

[0065] The circumferential blade row of the preceding clause, wherein the first pitch is uniform between the plurality of stator blades in the first set of stator blades and is based on the second pitch.

[0066] A circumferential blade row as in any preceding clause, wherein the plurality of stator blades comprises only the first set of stator blades and the second set of stator blades.

[0067] A circumferential blade row as in any preceding clause, wherein the number of stator blades in the first set of stator blades is equal to the total number of the plurality of stator blades minus the number of stator blades in the second set of stator blades.

[0068] A circumferential blade row as in any preceding clause, wherein the number of stator blades in the second set of stator blades is between twenty percent and forty percent of the total number of stator blades of the plurality.

[0069] A circumferential blade row as in any preceding clause, wherein the number of stator blades in the second set of stator blades is approximately one third of the total number of stator blades in the plurality.

[0070] A circumferential bucket row as in any preceding clause, wherein the second pitch is between two and eleven percent less than the nominal uniform bucket pitch.

[0071] A circumferential bucket row as in any preceding clause, wherein the second pitch is four to six percent less than the nominal uniform bucket pitch.

[0072] A circumferential bucket row as in any preceding clause, wherein said second pitch is 4.3 percent less than said nominal uniform bucket pitch.

[0073] A circumferential bucket row as in any preceding clause, wherein the second pitch is between two and eleven percent greater than the nominal uniform bucket pitch.

[0074] A circumferential bucket row as in any preceding clause, wherein the second pitch is four to six percent greater than the nominal uniform bucket pitch.

[0075] A circumferential bucket row as in any preceding clause, wherein said second pitch is 5.2 percent greater than said nominal uniform bucket pitch.

[0076] A circumferential blade row as in any preceding clause, wherein the plurality of stator blades provides a harmonic response defined by a total number of the plurality of stator blades, the first pitch, and the second pitch.

[0077] A circumferential blade row as in any preceding clause, wherein the second spacing is selected to bias the harmonic response to one or more harmonics above or below a uniform primary drive harmonic defined by the uniformly spaced circumferential blade row.

[0078] A circumferential blade row as in any preceding clause, wherein the harmonic response is biased to one or more harmonics above a uniform main drive harmonic defined by the uniformly spaced circumferential blade row.

[0079] A circumferential blade row as in any preceding clause, wherein the harmonic response is biased above the uniform main drive harmonic due to the second pitch being between two and eleven percent less than the nominal uniform blade pitch.

[0080] A circumferential blade row according to any preceding clause, wherein the harmonic response comprises a main drive harmonic occurring at the uniform main drive harmonic, a first harmonic lower than the main drive harmonic, and the one or more harmonics, and wherein the amplitude of the harmonics lower than the first harmonic is less than the amplitude of at least one of the one or more harmonics.

[0081] A circumferential blade row as in any preceding clause, wherein the harmonic response is biased to one or more harmonics below a uniform primary drive harmonic defined by the uniformly spaced circumferential blade row.

[0082] A circumferential blade row as in any preceding clause, wherein the harmonic response is biased below the uniform main drive harmonic due to the second pitch being two to eleven percent greater than the nominal uniform blade pitch.

[0083] A circumferential blade row according to any preceding clause, wherein the harmonic response comprises a main drive harmonic occurring at the uniform main drive harmonic, a first harmonic higher than the main drive harmonic, and the one or more harmonics, and wherein the amplitude of the harmonics higher than the first harmonic is less than the amplitude of at least one of the one or more harmonics.

[0084] An engine comprises a component having a plurality of rotor blades and a plurality of stator vanes arranged in circumferential rows according to any preceding clause.

[0085] An engine as claimed in any preceding clause, wherein the component is one or more of a high pressure compressor, a low pressure compressor, a high pressure turbine or a low pressure turbine.

[0086] Although the foregoing description is directed to the preferred embodiments of the present disclosure, other changes and modifications will be apparent to those skilled in the art, and other changes and modifications may be made without departing from the spirit or scope of the present disclosure. In addition, the features described in conjunction with one embodiment of the present disclosure may be used in conjunction with other embodiments, even if not explicitly stated above.

Claims

1. A circumferential blade row for a gas turbine engine, It is characterized in that The circumferential blade row has a non-uniform blade spacing and includes: A plurality of stator blades, the plurality of stator blades are arranged circumferentially around the inner ring, the plurality of stator blades comprising: a first set of stator blades having a first spacing between adjacent stator blades of the first set of stator blades; and A second group of stator blades has a second spacing between adjacent stator blades of the second group of stator blades, wherein the second spacing is two to eleven percent less than a nominal uniform blade spacing or two to eleven percent greater than the nominal uniform blade spacing, the nominal uniform blade spacing being defined by the total number of the plurality of stator blades.

2. The circumferential blade row according to claim 1, It is characterized in that Wherein the first pitch is uniform between the plurality of stator blades in the first set of stator blades and is based on the second pitch.

3. The circumferential blade row according to claim 1, It is characterized in that Wherein the plurality of stator blades includes only the first group of stator blades and the second group of stator blades.

4. The circumferential blade row according to claim 1, It is characterized in that The number of stator blades in the first group of stator blades is equal to the total number of the plurality of stator blades minus the number of stator blades in the second group of stator blades.

5. The circumferential blade row according to claim 1, It is characterized in that The number of the stator blades in the second group of stator blades is 20% to 40% of the total number of the plurality of stator blades.

6. The circumferential blade row according to claim 5, It is characterized in that The number of stator blades in the second group of stator blades is approximately one third of the total number of the plurality of stator blades.

7. The circumferential blade row according to claim 1, It is characterized in that The second pitch is between two and eleven percent smaller than the nominal uniform blade pitch.

8. The circumferential blade row according to claim 7, It is characterized in that The second pitch is four to six percent smaller than the nominal uniform blade pitch.

9. The circumferential blade row according to claim 8, It is characterized in that The second pitch is 4.3 percent less than the nominal uniform blade pitch.

10. The circumferential blade row according to claim 1, It is characterized in that The second pitch is two to eleven percent greater than the nominal uniform blade pitch.

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