A single-stage compressor rotor blade for reducing noise by providing a vent hole

Abstract

The purpose of this invention is to provide a single-stage compressor rotor blade that reduces noise by incorporating vents. The blade includes a blade body comprising a tip, root, leading edge, trailing edge, pressure surface, and suction surface. Ventilation holes are provided within the blade body, extending from the pressure surface to the trailing edge. The angle α between the vent and the pressure surface at the inlet is 30°, and at the outlet it is perpendicular to the trailing edge. The axes of all vents are located in a plane parallel to the blade root. This invention, by creating a series of multi-channel vents extending from the pressure surface to the trailing edge within the rotor blade, reduces compressor vortex noise by decreasing the size of the trailing edge vortex. Furthermore, reducing the size of the trailing edge vortex also reduces interference between the rotor blade and the stator blade, thereby reducing the compressor's single-frequency discrete noise.

Description

Technical Field

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

[0002] 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.

[0003] 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.

[0004] 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.

[0005] 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

[0006] The purpose of this invention is to provide a single-stage compressor rotor blade that reduces noise by setting vent holes, thereby reducing the single-frequency discrete noise of the compressor.

[0007] The objective of this invention is achieved as follows:

[0008] The present invention discloses a single-stage compressor rotor blade for noise reduction by setting vent holes, characterized in that: it includes a blade body, the blade body including a blade tip, a blade root, a leading edge, a trailing edge, a pressure surface, and a suction surface, and vent holes are provided in the blade body that extend from the pressure surface to the trailing edge. The angle α between the vent holes and the pressure surface at the inlet is 30°, and the vent holes are perpendicular to the trailing edge at the outlet. The axes of each vent hole are all located in a plane parallel to the blade root.

[0009] The present invention may also include:

[0010] 1. The perforation area at the pressure surface accounts for 0.5%-0.8% of the pressure surface area, and the perforation area at the trailing edge accounts for 8%-10% of the trailing edge area.

[0011] 2. The diameter D of the vent is 1.8%-2.2% of the leaf height h.

[0012] 3. Adjacent ventilation holes are equidistantly distributed on the trailing edge with a spacing of d2. The distance between the first ventilation hole and the leaf root is d1, and the distance between the last ventilation hole and the leaf tip is d3. d1 is 5%-7% of the leaf height h, d2 is 8%-10% of the leaf height h, and d3 is 5%-7% of the leaf height h.

[0013] 4. Establish a coordinate system based on the leaf shape at the leaf root. The projection of the axis of each vent onto the plane of the leaf root is a curve. The starting point of the curve is the origin O, and the straight line connecting the starting and ending points of the curve is the X-axis. The straight line located in the plane of the leaf root, passing through the origin O and perpendicular to the X-axis is set as the Y-axis, and the straight line passing through the origin O and perpendicular to the XOY plane is set as the Z-axis. Let the distance between the two endpoints of the curve be L, and the distance between the point on the curve at L / 2 and the X-axis be d. Then the projection line of the vent axis on the plane of the leaf root is represented by the following equation:

[0014]

[0015] The plane containing each axis is represented by the following equation:

[0016] z = d1 + (i-1)d2

[0017] The axis of the vent is represented by the following equation:

[0018]

[0019] In the above formula, i represents the distance from the axis of the i-th vent at the leaf root.

[0020] The advantages of this invention are as follows: First, in the vortex noise of compressors, the noise caused by detached vortices at the blade trailing edge plays a major role. According to boundary layer theory, when airflow passes over the blade surface, vortex detachment occurs after the boundary layer develops to a certain extent. This detachment often develops to a very severe degree at the blade trailing edge, forming a large number of detached vortices, which in turn generate significant vortex noise. The feature of this invention is the provision of a series of multi-channel ventilation holes inside the rotor blade, connecting the middle of the pressure surface to the trailing edge. Part of the airflow flows into the ventilation holes from the blade pressure surface, and then this part of the airflow is ejected from the blade trailing edge, thus dispersing the detached vortices at the blade trailing edge, breaking down large vortices into smaller vortices, thereby significantly reducing the vortex volume at the trailing edge. This significantly reduces the vortex noise of a single-stage compressor.

[0021] 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 vents are opened inside the compressor rotor blades, penetrating the middle of the pressure surface and the trailing edge. Gas flowing into the vents from the pressure surface will be 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 will be reduced. Furthermore, the interference noise between the potential flow fields of the stator blade and the rotor blade will also decrease.

[0022] Therefore, this invention reduces compressor vortex noise by creating a series of multi-channel ventilation holes inside the rotor blades that connect the pressure surface and the trailing edge. This reduces the size of the trailing edge vortex and, conversely, reduces interference between the rotor blades and the stationary blades, thereby lowering the compressor's single-frequency discrete noise. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention and the stator blades installed in the compressor housing;

[0024] Figure 2 This is a schematic diagram of the structure of the present invention;

[0025] Figure 3 This is a schematic diagram of blade interference.

[0026] Figure 4 This is a schematic diagram of the trailing edge structure;

[0027] Figure 5 This is a schematic diagram showing the axial distribution of the vent holes;

[0028] Figure 6 This is a schematic diagram of the axis projection. Detailed Implementation

[0029] The invention will now be described in more detail with reference to the accompanying drawings:

[0030] 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, a hub 4, and a vent 5. Figure 2 and Figure 6As shown, the blade includes a blade tip 8, a blade root 9, a leading edge 6, a trailing edge 7, a pressure surface 10, a suction surface 11, and ventilation holes 5. According to boundary layer theory, airflow will form a relatively strong shedding vortex at the trailing edge of the blade, and the noise generated by the trailing edge shedding vortex accounts for a major position in the total vortex noise. This invention, however, opens a series of multi-channel ventilation holes inside the rotor blade, extending from the pressure surface to the trailing edge. Figure 2 As shown, some airflow flows into the vent from the middle of the pressure surface and is ejected from the trailing edge of the blade. This ejected airflow directly impacts the shedding vortex at the trailing edge of the blade, blowing the large trailing edge shedding vortex into smaller vortices, which in turn greatly reduces the vortex noise of the compressor, thereby achieving the purpose of compressor noise reduction.

[0031] Figure 5 The middle number is ①- The spatial curve used to represent the axis of the vent is obtained by taking different variable values ​​from the same equation for the position and shape of the vent axis at different locations.

[0032] The perforation area at pressure surface 10 accounts for 0.5%-0.8% of the area of ​​pressure surface 10, and the perforation area at tail edge 7 accounts for 8%-10% of the area of ​​tail edge 7.

[0033] The diameter D of the ventilation hole 5 can be taken as 1.8%-2.2% of the leaf height h, and adjacent ventilation holes 5 are equidistantly distributed at the trailing edge 7.

[0034] The angle α between the vent 5 at the inlet and the pressure surface 10 can be 30°. At the outlet, it is perpendicular to the trailing edge 7 of the blade. The axes of each vent are located in a plane parallel to the blade root 9, such as axis ⑥ located in plane F1.

[0035] like Figure 3 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 vent holes are provided inside the rotor blades, extending from the pressure surface to the trailing edge. The function of the vent holes is to disperse the large-sized shedding vortices at the trailing edge into smaller vortices. Reducing the size of the trailing edge shedding vortices 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 quantity in the viscous wake of the rotor blades will also reduce the noise generated by the stator cutting the rotor blade wake.

[0036] Therefore, the present invention opens a vent hole inside the rotor blade that runs through the pressure surface to the trailing edge, which greatly reduces the generation of broadband eddy noise and single-frequency discrete noise in the compressor.

[0037] Depend on Figure 4 It can be seen that adjacent vents are equidistantly distributed on the trailing edge with a spacing of d2. The distance between the first vent and the leaf root is d1, and the distance between the last vent and the leaf tip is d3. d1 can be taken as 5%-7% of the leaf height h, d2 can be taken as 8%-10% of the leaf height h, and d3 can be taken as 5%-7% of the leaf height h.

[0038] Since the axes of all vents are located in a plane parallel to the leaf root, to more easily describe the shape of the vent axes, such as... Figure 6 As shown, a coordinate system is established based on the blade shape at the blade root. Curve 12 is the projection of the axes of each vent onto the plane of the blade root. The origin O of the coordinate system is the starting point of curve 12; the straight line connecting the starting and ending points of curve 12 is the X-axis; the straight line located in the plane of the blade root, passing through the origin O and perpendicular to the X-axis is the Y-axis; and the straight line passing through the origin O and perpendicular to the XOY plane is the Z-axis. Let the distance between the two endpoints of curve 12 be L, and the distance between the point on curve 12 at L / 2 and the X-axis be d.

[0039] The projection of the vent axis onto the plane containing the blade root can be represented by the following equation:

[0040]

[0041] On the other hand, the plane containing each axis can be represented by the following equation:

[0042] z = d1 + (i-1)d2

[0043] Therefore, the axis of the vent can be represented by the following equation:

[0044]

[0045] In the above formula, i represents the distance from the axis of the i-th vent at the leaf root; d and L are... Figure 6 The structural parameters on; d1 and d2 are Figure 4 The structural parameters on.

Claims

1. A single-stage compressor rotor blade that reduces noise by providing vent holes, characterized in that: The blade body includes a blade tip, a blade root, a leading edge, a trailing edge, a pressure surface, and a suction surface. A vent is provided in the blade body that extends from the pressure surface to the trailing edge. The vent is at an angle α of 30° with the pressure surface at the inlet and perpendicular to the trailing edge at the outlet. The axis of each vent is located in a plane parallel to the blade root. Adjacent ventilation holes are equidistantly distributed on the trailing edge with a spacing of d2. The distance between the first ventilation hole and the leaf root is d1, and the distance between the last ventilation hole and the leaf tip is d3. d1 is 5%-7% of the leaf height h, d2 is 8%-10% of the leaf height h, and d3 is 5%-7% of the leaf height h. A coordinate system is established based on the blade shape at the blade root. The projection of the axis of each vent onto the plane of the blade root is a curve. The origin O is the starting point of the curve, and the straight line connecting the starting and ending points of the curve is the X-axis. The straight line located in the plane of the blade root, passing through the origin O and perpendicular to the X-axis is set as the Y-axis, and the straight line passing through the origin O and perpendicular to the XOY plane is set as the Z-axis. Let the distance between the two endpoints of the curve be L, and the distance between the point on the curve at L / 2 and the X-axis be d. Then, the projection line of the vent axis on the plane of the blade root is represented by the following equation: The plane containing each axis 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 leaf root.

2. A single-stage compressor rotor blade for noise reduction by providing vent holes according to claim 1, characterized in that: The perforation area at the pressure surface accounts for 0.5%-0.8% of the pressure surface area, and the perforation area at the trailing edge accounts for 8%-10% of the trailing edge area.

3. A single-stage compressor rotor blade for noise reduction by providing vent holes according to claim 1, characterized in that: The diameter D of the vent is 1.8%-2.2% of the leaf height h.

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