A single stage compressor rotor blade with a vent hole to reduce noise

Abstract

The application aims to provide a single-stage compressor rotor blade with a vent hole for noise reduction, comprising a blade body, the blade body comprising a blade tip, a blade root, a leading edge, a trailing edge, a suction surface and a pressure surface, a vent hole is arranged in the blade body, the inlet of the vent hole is located at the blade tip, the outlet of the vent hole is located at the trailing edge, the inlet of the vent hole is a straight line segment perpendicular to the blade tip and with a length of d2, the outlet is perpendicular to the trailing edge, the axis of the whole vent hole is a spatial curve distributed on a median surface, and the projection of the curve on a projection plane is a circular arc with a central angle of 60 degrees. A series of multi-channel vent holes are arranged in the rotor blade and pass through the blade tip and the trailing edge, which can reduce the generation of tip clearance leakage vortex and reduce the size of blade trailing edge shedding vortex, thereby reducing the vortex noise of the compressor. On the other hand, reducing the size of the blade trailing edge shedding vortex can also reduce the interference between the rotor blade and the static blade, thereby reducing the single-frequency discrete noise of the compressor.

Description

Technical Field

[0001] The present invention relates to a blade, specifically a single-stage compressor rotor blade. Background Technology

[0002] As early as the 1970s, aircraft noise pollution began to attract attention. With the development of the air transport industry, countries around the world have successively formulated strict airworthiness noise standards, such as the U.S. Federal Airworthiness Regulations (FAR) Part 36, the European Joint Airworthiness Standards Part 36, and the Chinese Civil Aviation Noise Regulations Part 36 (CCAR-36). With societal development, people's requirements for aircraft noise are becoming increasingly stringent, and how to more effectively reduce engine noise has become an urgent problem for the global aviation industry to solve.

[0003] The engines used in modern aircraft are highly complex noise systems, with four main noise sources: compressor noise, combustion noise, turbine noise, and jet noise. Among these, the compressor noise and jet noise are the primary noise sources of the engine.

[0004] Compressor noise includes single-frequency discrete noise and broadband eddy noise at the blade passage frequency. Single-frequency discrete noise is caused by the mutual interference between the rotor and stator during compressor operation: (1) interference between the rotor blade potential flow field and the stator; (2) interference between the stator blade potential flow field and the rotor; (3) interference between the stator blade cutting the rotor blade wake; (4) interference between the rotor blade cutting the stator blade wake. Broadband eddy noise mainly includes: (1) separation eddy noise formed by the separation of turbulent boundary layer at the blade suction surface; (2) noise generated by leakage eddies at the blade tip; (3) noise formed by eddies formed by the shedding of rotor blade trailing edges.

[0005] Among them, the generation of single-frequency discrete noise and broadband eddy current noise are closely related to the generation of trailing edge vortices. For eddy current noise, trailing edge vortices occupy a dominant position in the overall eddy current noise, while for single-frequency discrete noise, the increase of trailing edge vortices will lead to more severe interference between the rotor and the stator.

[0006] Current compressor noise reduction methods mainly include using serrated blade trailing edges and multi-curvature blade surfaces to disrupt trailing edge vortices, thereby achieving the purpose of compressor noise reduction. Summary of the Invention

[0007] The purpose of this invention is to provide a single-stage compressor rotor blade with ventilation holes for noise reduction, which can reduce compressor noise.

[0008] The objective of this invention is achieved as follows:

[0009] This invention discloses a single-stage compressor rotor blade with ventilation holes for noise reduction, characterized in that: it includes a blade body, which comprises a blade tip, blade root, leading edge, trailing edge, suction surface, and pressure surface. Ventilation holes are provided in the blade body, with the inlet of the ventilation hole located at the blade tip and the outlet of the ventilation hole located at the trailing edge. The inlet of the ventilation hole is a straight line segment perpendicular to the blade tip with a length of d2, and the outlet is perpendicular to the trailing edge. The axis of the entire ventilation hole is a spatial curve distributed on the mid-curved surface, and the projection of these curves on the projection surface is an arc with a central angle of 60°.

[0010] The present invention may also include:

[0011] 1. The perforation area at the vent tip of the blade accounts for 1.5%-2% of the blade tip area, and the perforation area at the trailing edge accounts for 5%-8% of the trailing edge area.

[0012] 2. The diameter D of the vent is 1.5%-2% of the leaf height h. Adjacent vents are equidistantly distributed at the leaf tip and at the trailing edge.

[0013] 3. The distance between adjacent vents at the blade tip is L2, the distance between the first vent and the trailing edge is L1, and the distance between the last vent and the leading edge is L3. L2 is 8%-10% of the centerline length, L1 is 1 / 12-1 / 9 of the centerline length, and L3 is 14%-16% of the centerline length.

[0014] 4. The distance between adjacent ventilation holes on the trailing edge is h2, the distance between the first ventilation hole and the leaf tip is h3, and the distance between the last ventilation hole and the leaf root is h1. h1 is 12%-14% of the leaf height h, h2 is 8%-10% of the leaf height h, and h3 is 12%-14% of the leaf height h.

[0015] 5. The straight line connecting the intersection of the tip arc and the trailing edge of the blade and the intersection of the root arc and the trailing edge of the blade is the first straight line. The plane formed by the chords of the tip and root blade profiles and the first straight line is the projection plane. A coordinate system is established on the projection plane, with the origin O located on the first straight line and a distance d2 from the tip of the blade. The straight line passing through the origin O and coinciding with the first straight line is set as the Y-axis. The straight line passing through the origin O and perpendicular to the Y-axis in the projection plane is set as the X-axis. The straight line passing through the origin O and perpendicular to the XOY plane is set as the Z-axis, with the positive direction of the Z-axis pointing towards the suction surface of the blade. The projection line of the vent axis on the projection plane is represented by the following equation:

[0016] x 2 +[y+h3-d2+(i-1)h2] 2 =4[h3-d2+(i-1)h2] 2

[0017] The mid-surface F1 is represented by the following equation:

[0018]

[0019] The axis of the vent is represented by the following equation:

[0020]

[0021] In the above formula, i represents the distance from the axis of the i-th vent at the blade tip; b is the chord length; and d1 is the distance between the point on the corresponding arc at b / 2 and the chord.

[0022] The advantages of this invention are as follows: First, in the vortex noise of a single-stage compressor, the noise generated by tip clearance leakage vortices accounts for a considerable proportion. Tip clearance leakage vortices occur because the static pressure on the blade pressure surface is greater than the static pressure on the blade suction surface during blade operation. Due to centrifugal force, gas on the blade pressure surface flows through the gap between the blade tip and the casing to the blade suction surface, forming vortices at the tip clearance and thus generating significant vortex noise. Furthermore, in compressor vortex noise, the noise caused by blade trailing edge shedding vortices plays a major role. According to boundary layer theory, when airflow passes over the blade surface, vortex shedding occurs after the boundary layer develops to a certain extent. This shedding often reaches a very severe stage at the blade trailing edge, forming numerous shedding vortices and generating significant vortex noise. The feature of this invention is the provision of a series of multi-channel ventilation holes penetrating the blade tip and trailing edge inside the rotor blade. Therefore, when airflow flows from the pressure side of the blade through the tip clearance to the suction side, some of the airflow will flow into the vent from the tip, thus minimizing the leakage vortex at the tip clearance. On the other hand, the airflow flowing into the vent will be ejected from the trailing edge of the blade, thereby dispersing the detached vortex at the trailing edge, breaking large vortices into smaller ones, and significantly reducing the vortex volume at the trailing edge. This can greatly reduce the vortex noise of a single-stage compressor.

[0023] Secondly, in the single-frequency discrete noise of the compressor, whether it is the discrete noise generated by the interference between the blade potential flow field and another blade, or the noise generated by the viscous wake of one blade cutting another, the size of the trailing edge shedding vortex has a significant impact on these single-frequency noises. The feature of this invention is that a series of ventilation holes penetrating from the blade tip to the trailing edge are opened inside the compressor rotor blade. Gas flowing into the ventilation holes from the blade tip is ejected from the trailing edge, thereby dispersing the trailing edge shedding vortex. After the size of the trailing edge shedding vortex is reduced, the noise generated when the stator blade cuts the rotor viscous wake is reduced; furthermore, the interference noise between the potential flow fields of the stator blade and the rotor blade also decreases.

[0024] In summary, this invention reduces compressor vortex noise by creating a series of multi-channel ventilation holes penetrating the blade tip and trailing edge inside the rotor blades. This reduces the generation of leakage vortices at the blade tip clearance and decreases the size of trailing edge vortices. Furthermore, reducing the size of trailing edge vortices also reduces interference between the rotor blades and the stationary blades, thereby lowering the compressor's single-frequency discrete noise. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the present invention and the stator blades installed on the compressor housing;

[0026] Figure 2 This is a schematic diagram of blade interference.

[0027] Figure 3 This is a schematic diagram of the structure of the present invention;

[0028] Figure 4 This is a schematic diagram of the leaf tip structure;

[0029] Figure 5 This is a schematic diagram of the trailing edge structure;

[0030] Figure 6 This is a schematic diagram of the axis projection. Detailed Implementation

[0031] The invention will now be described in more detail with reference to the accompanying drawings:

[0032] Combination Figure 1-6 This invention relates to a compressor rotor blade that reduces noise by incorporating multiple ventilation holes. For example... Figure 1 As shown, the overall structure of the present invention includes a compressor housing 1, rotor blades 2, stator blades 3, hub 4, blade tip clearance 5, and vent holes 6. Figure 3 and Figure 4 As shown, the blade includes a blade tip 9, a blade root 10, a leading edge 7, a trailing edge 8, a pressure surface 11, a suction surface 12, and multi-channel ventilation holes 6. Combined with... Figures 1-4 As the blades rotate with the hub, the static pressure on the pressure side of the blades is greater than that on the suction side due to the work done by the blades. Furthermore, the gas exhibits centrifugal force during rotation. Therefore, under the influence of the static pressure difference and centrifugal force, the gas flows from the pressure side through the blade tip gap to the suction side, forming vortices at the blade tip gap, thus generating considerable vortex noise. According to boundary layer theory, the airflow forms strong shedding vortices at the blade trailing edge, and the noise generated by these trailing edge shedding vortices constitutes a major portion of the total aerodynamic noise. This invention addresses this by creating a series of multi-channel ventilation holes inside the rotor blades, extending from the blade tip to the trailing edge. Figure 3As shown, the airflow passing through the blade tip gap flows directly into the vent, which greatly reduces the formation of leakage vortices in the blade tip gap. Furthermore, the gas flowing into the vent will be ejected from the trailing edge of the blade. This ejected airflow will directly impact the trailing edge shedding vortex, blowing the large trailing edge shedding vortex into smaller vortices, which will significantly reduce the vortex noise of the compressor, thereby achieving the purpose of compressor noise reduction.

[0033] like Figure 2 As shown, the compressor rotor blades interfere with the stator blades during rotation, resulting in discrete noise at a single frequency. The interference between the rotor and the stator includes: (1) interference between the rotor blade potential flow field and the stator; (2) interference between the stator blade potential flow field and the rotor; (3) interference between the stator blade cutting the rotor blade wake; and (4) interference between the rotor blade cutting the stator blade wake. The feature of this invention is that a series of ventilation holes penetrating the blade tip and trailing edge are provided inside the rotor blade. One of the functions of the ventilation holes is to disperse the large-sized shedding vortices at the trailing edge into smaller vortices. Reducing the size of the trailing edge shedding vortex can reduce the noise generated by the interference between the potential flow fields of the stator and rotor blades. On the other hand, the reduction of the vortex amount in the viscous wake of the rotor blade will also reduce the noise generated by the stator cutting the rotor blade wake.

[0034] Therefore, the present invention opens a ventilation hole inside the rotor blade that runs from the blade tip to the trailing edge, which greatly reduces the generation of broadband eddy noise and single-frequency discrete noise in the compressor.

[0035] like Figure 4 As shown, the blade tip structure includes the mid-arc line 13, the intersection point of the mid-arc line and the leading edge of the blade 14, the intersection point of the mid-arc line and the trailing edge of the blade 15, and the chord 16. The mid-arc line is the line connecting the centers of the inscribed circles of the blade, also known as the midline. The chord is the straight line connecting the mid-arc line to the intersection points of the leading and trailing edges of the blade; the length of the chord is called the chord length, denoted by the letter b. The surface that runs through the mid-arc line at the blade tip and the mid-arc line at the blade root is called the mid-surface. Figure 3 In this context, F1 represents the mid-curved surface.

[0036] Depend on Figure 4 It can be seen that the vents are equidistantly distributed along the mid-arc line on the blade tip, with a spacing of L2 between adjacent vents, a distance of L1 between the first vent and the trailing edge, and a distance of L3 between the last vent and the leading edge. L2 can be set to 8%-10% of the midline length, L1 can be set to 1 / 12-1 / 9 of the midline length, and L3 can be set to 14%-16% of the midline length.

[0037] Depend on Figure 5It can be seen that adjacent vents are equidistantly distributed on the trailing edge, with a spacing of h2 between adjacent vents on the trailing edge. The distance between the first vent and the leaf tip is h3, and the distance between the last vent and the leaf root is h1. h1 can be taken as 12%-14% of the leaf height h, h2 can be taken as 8%-10% of the leaf height h, and h3 can be taken as 12%-14% of the leaf height h.

[0038] Figure 6 The curves numbered ①-⑨ represent the spatial curves projected onto the projection plane by the axis of the vent. The position and shape of the vent axis at different locations can be obtained by taking different variable values ​​from the same equation.

[0039] The area of ​​the perforations at the 9th position of the leaf tip accounts for 1.5%-2% of the area of ​​the 9th position of the leaf tip, while the area of ​​the perforations at the 8th position of the trailing edge accounts for 5%-8% of the area of ​​the 8th position of the trailing edge.

[0040] The diameter D of the ventilation hole 6 can be taken as 1.5%-2% of the leaf height h. Each adjacent ventilation hole 6 is equidistantly distributed at the leaf tip 9 and also equidistantly distributed at the trailing edge 8.

[0041] The vent 6 is a straight line segment of length d2 perpendicular to the blade tip 9 at the inlet, and perpendicular to the blade trailing edge 8 at the outlet. The entire axis of the vent is a spatial curve distributed on the mid-curved surface. Furthermore, the projections of these spatial curves onto the projection plane are all arcs with a central angle of 60°.

[0042] like Figure 6 As shown, let point 15.1 be the intersection of the mid-arc line at the blade tip and the trailing edge, and point 15.2 be the intersection of the mid-arc line at the blade root and the trailing edge. The straight line connecting points 15.1 and 15.2 is called line 17. The chord of the blade tip airfoil is defined as line 16.1, and the chord of the blade root airfoil is defined as line 16.2. The plane formed by lines 16.1, 16.2, and 17 is the projection plane, and ①-⑨ are the projections of the vent axis onto the projection plane. Establish a coordinate system on the projection plane, with the origin O located on line 17 and a distance d2 from the blade tip, where d2 is the length of the straight line segment perpendicular to the blade tip at the vent inlet. The straight line passing through the origin O and coinciding with line 17 is defined as the Y-axis; the straight line passing through the origin O and perpendicular to the Y-axis in the projection plane is defined as the X-axis; and the straight line passing through the origin O and perpendicular to the XOY plane is defined as the Z-axis, with the positive direction of the Z-axis pointing towards the suction surface of the blade. The projection line of the vent axis onto the projection plane can be represented by the following equation:

[0043] x 2 +[y+h3-d2+(i-1)h2] 2 =4[h3-d2+(i-1)h2] 2

[0044] On the other hand, the mid-curved surface F1 can be represented by the following equation:

[0045]

[0046] Therefore, the axis of the vent can be represented by the following equation:

[0047]

[0048] In the above formula, i represents the distance from the i-th vent axis at the blade tip; h3, h2, and d2 are... Figure 5 and Figure 6 The structural parameters on; d1 and b are Figure 4 The structural parameters are: b is the chord length, and d1 is the distance between the point on the middle arc corresponding to b / 2 and the chord.

Claims

1. A single-stage compressor rotor blade with vent holes for noise reduction, characterized in that: The blade body includes a blade tip, blade root, leading edge, trailing edge, suction surface, and pressure surface. Ventilation holes are provided in the blade body. The inlet of the ventilation hole is located at the blade tip, and the outlet of the ventilation hole is located at the trailing edge. The inlet of the ventilation hole is a straight line segment with a length of d2 perpendicular to the blade tip, and the outlet is perpendicular to the trailing edge. The axis of the entire ventilation hole is a spatial curve distributed on the mid-curved surface. The projection of these curves on the projection surface is an arc with a central angle of 60°. The straight line connecting the intersection of the tip arc and the trailing edge of the blade and the intersection of the root arc and the trailing edge is the first straight line. The plane formed by the chords of the tip and root blade profiles and the first straight line is the projection plane. A coordinate system is established on the projection plane, with the origin O located on the first straight line and a distance d2 from the tip of the blade. The straight line passing through the origin O and coinciding with the first straight line is set as the Y-axis. The straight line passing through the origin O and perpendicular to the Y-axis in the projection plane is set as the X-axis. The straight line passing through the origin O and perpendicular to the XOY plane is set as the Z-axis, with the positive direction of the Z-axis pointing towards the suction surface of the blade. The projection line of the vent axis on the projection plane is represented by the following equation: The mid-surface F1 is represented by the following equation: The axis of the vent is represented by the following equation: In the above formula, i represents the distance from the axis of the i-th vent at the blade tip; b is the chord length; d1 is the distance between the point on the middle arc corresponding to b / 2 and the chord; h is the blade height. d2 is the length of the straight line segment perpendicular to the blade tip at the vent inlet; h2 is the distance between adjacent vents on the trailing edge; h3 is the distance between the first vent and the blade tip.

2. A single-stage compressor rotor blade with ventilation holes for noise reduction according to claim 1, characterized in that: in The perforation area at the blade tip accounts for 1.5%-2% of the blade tip area, while the perforation area at the trailing edge accounts for 5%-8% of the trailing edge area.

3. A single-stage compressor rotor blade with ventilation holes for noise reduction according to claim 1, characterized in that: The diameter D of the vent is 1.5%-2% of the leaf height h. Adjacent vents are equidistantly distributed at the leaf tip and at the trailing edge.

4. A single-stage compressor rotor blade with ventilation holes for noise reduction according to claim 1, characterized in that: The distance between adjacent vents at the blade tip is L2, the distance between the first vent and the trailing edge is L1, and the distance between the last vent and the leading edge is L3. L2 is 8%-10% of the centerline length, L1 is 1 / 12-1 / 9 of the centerline length, and L3 is 14%-16% of the centerline length.

5. A single-stage compressor rotor blade with ventilation holes for noise reduction according to claim 1, characterized in that: The distance between adjacent vents on the trailing edge is h2, the distance between the first vent and the leaf tip is h3, and the distance between the last vent and the leaf root is h1. h1 is 12%-14% of the leaf height h, h2 is 8%-10% of the leaf height h, and h3 is 12%-14% of the leaf height h.

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