Axial compressor rotor blade with tip guide vane structure and method of guiding thereof

Abstract

The application provides an axial-flow compressor rotor blade with a tip guide structure and a guide method thereof. The main structure of the blade is an axial-flow compressor rotor blade, and the blade has an oblique guide groove which is inclined to the trailing edge of the blade in the suction surface and the tip region of the blade. The oblique guide groove has a guide effect on the tip leakage flow, guides the tip leakage flow to the suction surface of the blade, reduces the air flow of the tip leakage vortex, effectively weakens the tip leakage vortex, reduces the pressure loss, and improves the efficiency of the compressor. In addition, under the guide effect, the pressure at the guide groove of the suction surface of the blade is reduced, the vortex line of the tip leakage vortex is closer to the surface of the suction surface of the blade, and the stable working margin of the compressor is also improved.

Description

Technical Field

[0001] The present invention relates to the field of impeller machinery, and in particular to an axial flow compressor rotor blade and a flow guiding method thereof. Background Art

[0002] At present, turbomachinery is facing the challenge of developing in the direction of high efficiency and low fuel consumption. Tip leakage flow exists in the compressor and turbine stages and is one of the important factors affecting the efficiency of turbomachinery. The tip leakage flow is generated due to a certain radial gap between the rotor blade tip and the inner wall of the casing. During the rotation of the rotor, driven by the pressure difference on both sides of the blade, part of the fluid will flow from the pressure side to the suction side through the tip gap. These fluids will mix and shear with the mainstream to form vortices, namely tip leakage vortices. For axial flow compressors, tip leakage vortices will cause flow loss and blockage, which will lead to a decrease in compressor efficiency and a reduction in stable operating margin.

[0003] Based on the significant influence of tip clearance flow on compressor performance, how to effectively control tip clearance flow and thus improve compressor efficiency and stability margin is one of the problems that need to be solved urgently. Summary of the Invention

[0004] The object of the present invention is to avoid the deficiencies of the prior art and provide an axial flow compressor rotor blade and a flow guiding method having a blade tip guide structure which has a simple structure and can effectively control the flow of the blade tip clearance and thereby improve the compressor efficiency and stability margin.

[0005] To achieve the above-mentioned object, the technical solution adopted by the present invention is as follows: an axial flow compressor rotor blade having a blade tip guide structure, wherein the blade tip guide structure is a guide groove provided at the blade tip of the blade suction surface, the guide groove being inclined from the blade tip toward the blade trailing edge and extending to the middle of the blade;

[0006] The ends of the guide grooves are located on a straight line, and the straight line is parallel to the blade tip cross section, so that when looking directly at the suction surface of the blade, the guide grooves form a parallelogram;

[0007] The opening of the guide groove at the blade tip is set on the blade tip cross section, and the opening is the blade tip leakage inlet into the guide groove, and the depth h1 of the guide groove opening end is (0.1~0.6)W, W=(0.01~0.06)c, where W is the guide groove width and 1 is the blade chord length;

[0008] The depth of the guide groove end h2 = (0~0.8) h1, that is, the depth of the guide groove (5) gradually decreases from the starting end at the tip section to the extended end extending toward the middle of the blade, which is used to promote the airflow guided out of the blade tip leakage flow by the guide groove to flow slowly back to the mainstream area, avoiding the introduction of additional losses due to excessive mixing; on the other hand, it is used to avoid the introduction of excessive turbulence due to the excessive depth of the guide groove near the middle of the blade, resulting in additional flow losses;

[0009] At the same time, the guide groove is located before the starting position of the blade tip leakage vortex in the blade tip section along the blade chord direction, and is used to guide the part of the blade tip leakage airflow, thereby reducing the blade tip leakage vortex.

[0010] Furthermore, the guide grooves are multiple grooves that are uniform and continuously arranged in parallel; and the interval w between two adjacent guide grooves is (0.1~0.5)W, where W is the width of the guide groove.

[0011] Furthermore, the guide groove height H is the distribution length along the span direction of the blade, and H=0.1~0.6c, where c is the chord length of the blade.

[0012] Furthermore, the cross section of the guide groove is a rectangle, a parallelogram, an inverted trapezoid, or an inverted triangle.

[0013] Furthermore, the cross section of the guide groove is an inverted right-angled trapezoid, the windward surface of the guide groove is perpendicular to the suction surface of the blade, and the leeward surface of the guide groove is an inclined surface with an inclination angle of β;

[0014] The windward surface of the guide groove is perpendicular to the blade surface, which can increase the guiding effect of the guide groove, thereby producing a sufficiently strong suppression and adsorption effect on the blade tip leakage vortex; the inclined surface of the leeward side of the guide groove can reduce the backflow on the leeward side of the guide groove, thereby reducing the additional loss introduced by the guide groove and maximizing the control effect of the guide groove.

[0015] Furthermore, the inclination angle β of the leeward side of the guide groove is 20-60°.

[0016] Furthermore, the inclination angle of the obliquely extending guide groove is α, and α is 20~60°.

[0017] Furthermore, the height of the guide groove along the span direction of the blade is H, the length of the guide groove from the starting end along the chord direction of the blade to the leading edge of the blade is L1, L1=0.1~0.3c; the length of the guide groove from the end end along the chord direction of the blade to the leading edge of the blade is L2, L2 =0.6~0.9c, where c is the chord length of the blade.

[0018] The present invention also provides a flow guiding method for the axial flow compressor rotor blade having the blade tip flow guiding structure, comprising the following steps:

[0019] When the tip leakage flow flows through the tip clearance and develops on the blade suction surface, a portion of the tip leakage flow enters the guide groove from the opening of the guide groove located at the blade tip section and is forced to be directed to the blade suction surface, reducing the airflow of the tip leakage vortex and thereby weakening the formation of the tip leakage vortex before the guide;

[0020] At the same time, under the guiding action of the guide groove, the pressure in the area where the guide groove is located on the suction surface of the blade is reduced, so that the blade tip leakage vortex before the guide is closer to the suction surface of the blade, which suppresses the vortex intensity of the blade tip leakage vortex in the guide groove guidance and makes the blade tip leakage vortex in the guide closer to the suction surface of the blade, thereby improving the stable operating margin of the compressor.

[0021] The beneficial effects of the present invention are:

[0022] 1. The inclined guide groove proposed in the present invention has a guiding effect, which can guide part of the tip leakage flow to the suction surface of the blade, reducing the airflow rate forming the tip leakage vortex, weakening the formation of the tip leakage vortex, and thus reducing the pressure loss of the compressor blade and improving the compressor efficiency.

[0023] 2. In addition, the guiding effect of the oblique guide groove will reduce the pressure at the guide groove on the suction side of the blade, making the vortex line of the tip leakage vortex closer to the suction surface of the blade, thereby improving the stable working margin of the compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the present invention;

[0025] Figure 2 This is a schematic structural diagram of the suction surface of the compressor blade proposed in the present invention;

[0026] Figure 3 This is a schematic diagram of the cross-sectional structure of the starting end of the inclined guide groove (located at the blade tip section) proposed by the present invention;

[0027] Figure 4 This is a schematic cross-sectional view of the end of the oblique guide groove proposed in the present invention (located in the middle of the blade along the blade height);

[0028] Figure 5 A schematic diagram of the working principle of the guide groove (5) proposed in the present invention;

[0029] Figure 6 This is a graph showing how the pressure loss reduction ratio of the guide groove changes with the Reynolds number at an incoming flow angle of 20° according to the present invention.

[0030] In the figure, 1 is the tip cross section, 2 is the suction surface of the blade, 3 is the leading edge of the compressor blade, 4 is the root of the compressor blade, 5 is the guide groove, 6 is the trailing edge of the blade, 7 is a straight line, 8 is the leeward side, 9 is the windward side, 10 is the blade tip leakage flow, 11 is the guided blade tip leakage flow, 12 is the blade tip leakage vortex before the guide, and 13 is the blade tip leakage vortex in the guide. DETAILED DESCRIPTION

[0031] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0032] In order to achieve the above object, the present invention provides the following specific implementation methods:

[0033] Example 1: Figure 1-4 As shown, an axial flow compressor rotor blade with a blade tip guide structure, the blade tip guide structure is a guide groove 5 set at the blade tip of the blade suction surface 2, as shown in FIG. Figure 1 As shown, the guide groove 5 is inclined from the blade tip to the blade trailing edge 6 and extends to the middle of the blade. The inclination angle α of the guide groove 5 is 20-60°.

[0034] like Figure 2 As shown, the guide groove 5 is a plurality of uniform, continuously parallel grooves. The height H of the guide groove 5 is distributed along the span direction of the blade with a length of 0.1~0.6c. The length of the guide groove 5 from the starting end along the chord direction of the blade to the leading edge of the blade is L1, L1=0.1~0.3c, and the length of the end along the chord direction of the blade from the leading edge of the blade is L2, L2 = 0.6~0.9c, where c is the chord length of the blade.

[0035] The end of the guide groove 5 is located on a straight line 7, and the straight line is parallel to the blade tip section 1, so that when looking directly at the blade suction surface 2, the guide groove 5 forms a parallelogram;

[0036] like Figure 3 As shown, the opening of the guide groove 5 at the blade tip is set on the blade tip cross section 1, and the opening is the inlet for the blade tip leakage flow into the guide groove, and the depth h1 of the opening end of the guide groove 5 is 0.1~0.6W, the width W=0.01~0.06c, and the interval w between two adjacent guide grooves 5 is 0.1~0.5W, where W is the guide groove width and c is the blade chord length;

[0037] like Figure 4As shown, the starting position of the guide groove 5 along the blade chord direction is 0.1~0.3c, and the ending position is 0.6~0.9c, where c is the blade chord length. The end depth h2 extending to the middle of the blade is 0~0.8h1, that is, the depth of the guide groove 5 gradually decreases from the starting end at the tip section to the end extending toward the middle of the blade. This is used to promote the airflow guided from the tip leakage flow by the guide groove 5 to flow slowly back to the mainstream area, avoiding additional losses due to excessive mixing. On the other hand, it is used to avoid excessive turbulence due to the excessive depth of the guide groove 5 near the middle of the blade, resulting in additional flow losses.

[0038] At the same time, the starting position of the guide groove 5 in the blade tip section along the blade chord direction is located before the starting position of the blade tip leakage vortex, which is used to guide part of the blade tip leakage airflow, thereby reducing the blade tip leakage vortex.

[0039] The cross section of the guide groove 5 is a rectangle, a parallelogram, an inverted trapezoid or an inverted triangle; Figure 3 The cross-section of the guide groove 5 is an inverted right-angled trapezoid. The windward surface 9 of the guide groove is perpendicular to the suction surface of the blade, and the leeward surface 8 of the guide groove is an inclined surface with an inclination angle β. The windward surface 9 of the guide groove is perpendicular to the blade surface, which can enhance the guide groove's guiding effect, thereby effectively suppressing and adsorbing the tip leakage vortex. The inclined surface of the leeward surface 8 of the guide groove can reduce backflow on the leeward side of the guide groove, thereby reducing the additional losses introduced by the guide groove and maximizing the control effect of the guide groove.

[0040] The inclination angle β of the leeward side of the guide groove 5 is 20-60°.

[0041] Example 2: Figure 1-4 and Figure 6 As shown, an axial flow compressor rotor blade with a blade tip guide structure, the blade tip guide structure is a guide groove 5 set at the blade tip of the blade suction surface 2, as shown in FIG. Figure 1 As shown, the guide groove 5 is inclined from the blade tip to the blade trailing edge 6 and extends to the middle of the blade. The inclination angle α of the guide groove 5 is 30°.

[0042] like Figure 2 As shown, the guide grooves 5 are multiple uniform, continuously parallel grooves. The height H of the guide grooves 5 is 32 mm along the span of the blade. The length of the guide grooves 5 from the starting end to the leading edge of the blade along the chord direction is L1 = 16 mm, and the length of the guide grooves 5 from the ending end to the leading edge along the chord direction is L2 = 144 mm, where c is the blade chord length. In this embodiment, the blade chord length c = 160 mm, so H = 0.2 c, L1 = 0.1 c, and L2 = 0.9 c.

[0043] The end of the guide groove 5 is located on a straight line 7, and the straight line is parallel to the blade tip section 1, so that when looking directly at the blade suction surface 2, the guide groove 5 forms a parallelogram;

[0044] like Figure 3 As shown, the opening of the guide groove 5 at the blade tip is located on the blade tip cross section 1. The opening serves as the inlet for tip leakage into the guide groove. The depth of the guide groove 5 at the open end is h1 = 0.5 mm, the width is W = 3 mm, and the spacing between two adjacent guide grooves 5 is w = 0.4 mm, where W is the guide groove width and c is the blade chord length. Therefore, h1 = 0.167W, W = 0.019c, and w = 0.133W.

[0045] At the same time, the cross section of the guide groove 5 is an inverted right-angled trapezoid, the windward surface 9 of the guide groove is perpendicular to the suction surface of the blade, and the leeward surface 8 of the guide groove is an inclined surface with an inclination angle β. Among them, the inclination angle β of the leeward surface of the guide groove 5 is 30°.

[0046] like Figure 4 As shown, the guide groove 5 extends to the end of the middle of the blade with a depth of h2 = 0.05 mm, so h2 = 0.1h1.

[0047] A high-precision numerical simulation study was conducted on this embodiment. The results show that the Reynolds number Re = 6×10 4 ~ 3.2×10 5 The results show that the guide groove can reduce the pressure loss at low Reynolds number and three inflow angles of attack. As the Reynolds number increases, the effect of the guide groove on reducing the pressure loss weakens and even loses the effect at inflow angles of attack of 10° and 15°. Figure 6 As shown in the figure, the pressure loss reduction ratio of the guide groove changes with the Reynolds number at a 20° incoming flow angle of attack. That is, at a higher incoming flow angle, such as when the incoming flow angle is 20°, as the Reynolds number increases, the effect of the guide groove on reducing the pressure loss will increase to a stable value. In this study, the pressure loss can be reduced by up to 30%.

[0048] Example 3: Figure 5 As shown, the present invention also provides a flow guiding method for the axial flow compressor rotor blade having the blade tip guide structure, comprising the following steps:

[0049] When the tip leakage flow 10 flows through the tip clearance and develops on the blade suction surface 2, a portion of the tip leakage flow 10 enters the guide groove 5 from the opening of the guide groove 5 located at the blade tip section and is forced to be directed onto the surface of the blade suction surface 2, reducing the airflow of the tip leakage vortex and thereby weakening the formation of the tip leakage vortex 12 before the guide.

[0050] At the same time, under the guiding action of the guide groove 5, the pressure in the area where the guide groove 5 is located on the surface of the blade suction surface 2 is reduced, so that the blade tip leakage vortex 12 before the guide is closer to the surface of the blade suction surface 2, which suppresses the vortex intensity of the blade tip leakage vortex 13 in the guide of the guide groove 5, and makes the blade tip leakage vortex 13 in the guide closer to the blade suction surface, thereby improving the stable operation margin of the compressor.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An axial flow compressor rotor blade with a blade tip guide structure, characterized in that: The blade tip guide structure is a guide groove (5) provided at the blade tip of the blade suction surface (2), wherein the guide groove (5) is inclined from the blade tip toward the blade trailing edge (6) and extends toward the middle of the blade; The end of the guide groove (5) is located on a straight line (7), and the straight line is parallel to the blade tip cross section (1), so that when looking directly at the blade suction surface (2), the guide groove (5) forms a parallelogram; The opening of the guide groove (5) at the blade tip is arranged on the blade tip cross section (1), and the opening is the blade tip leakage inlet into the guide groove, and the depth h1 of the opening end of the guide groove (5) is (0.1~0.6)W, W=(0.01~0.06)c, wherein W is the width of the guide groove and c is the chord length of the blade; The depth h2 of the end of the guide groove (5) is (0-0.8) h1, that is, the depth of the guide groove (5) gradually decreases from the starting end located at the tip section to the extended end extending toward the middle of the blade, so as to promote the airflow guided from the blade tip leakage flow of the guide groove (5) to slowly flow back to the main flow area; At the same time, the guide groove (5) is located before the starting position of the blade tip leakage vortex at the starting position of the blade tip cross section along the blade chord direction, and is used to guide part of the blade tip leakage flow; The guide grooves (5) are multiple grooves that are uniform and continuously arranged in parallel; and the interval w between two adjacent guide grooves (5) is (0.1~0.5)W, where W is the width of the guide groove.

2. The axial flow compressor rotor blade with a blade tip guide structure according to claim 1, characterized in that: The height H of the guide groove (5) is the distribution length along the blade span, and H=0.1~0.6c, where c is the blade chord length.

3. The axial flow compressor rotor blade with a blade tip guide structure according to claim 1, characterized in that: The cross section of the guide groove (5) is a rectangle, a parallelogram, an inverted trapezoid, or an inverted triangle.

4. The axial flow compressor rotor blade with a blade tip guide structure according to claim 1, characterized in that: The cross section of the guide groove (5) is an inverted right-angled trapezoid, the windward surface (9) of the guide groove is perpendicular to the suction surface of the blade, and the leeward surface (8) of the guide groove is an inclined surface with an inclination angle of β.

5. The axial flow compressor rotor blade with a blade tip guide structure according to claim 4, characterized in that: The inclination angle β of the leeward side of the guide groove (5) is 20-60°.

6. The axial flow compressor rotor blade with a blade tip guide structure according to any one of claims 1 to 5, characterized in that: The obliquely extending guide groove (5) has an inclination angle α, which is 20-60°.

7. The axial flow compressor rotor blade with a blade tip guide structure according to any one of claims 1 to 5, characterized in that: The length of the guide groove (5) from the starting end along the blade chord direction to the leading edge of the blade is L1, L1=0.1~0.3c; the length of the guide groove (5) from the ending end along the blade chord direction to the leading edge of the blade is L2, L2=0.6~0.9c, where c is the blade chord length.

8. A flow guiding method for an axial flow compressor rotor blade according to any one of claims 1 to 7, characterized in that: The steps include: When the blade tip leakage flow (10) flows through the blade tip gap and develops on the blade suction surface (2), a portion of the blade tip leakage flow (10) enters the guide groove (5) from the opening of the guide groove (5) located at the blade tip section and is forced to be directed to the surface of the blade suction surface (2), thereby reducing the airflow of the blade tip leakage vortex; At the same time, under the guiding action of the guide groove (5), the pressure in the area where the guide groove (5) is located on the surface of the blade suction surface (2) is reduced, thereby making the blade tip leakage vortex (12) before the guide flow closer to the surface of the blade suction surface (2), suppressing the vortex intensity of the blade tip leakage vortex (13) in the guide flow of the guide groove (5), and making the blade tip leakage vortex (13) in the guide flow closer to the blade suction surface.

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