Compressor blade capable of reducing flow separation

Abstract

The invention discloses a gas compressor blade capable of reducing flow separation, and relates to the technical field of gas turbines. Comprising a blade and a turbulent flow unit on the blade, the blade is provided with a blade front edge and a blade tail edge in the length direction and is provided with a pressure surface and a suction surface in the thickness direction, and the turbulent flow unit is arranged at one end, close to the blade front edge, of the suction surface. The turbulent flow unit extends in the height direction of the blade, the turbulent flow unit comprises a plurality of turbulent flow structures, the multiple turbulent flow structures are evenly distributed in an array mode, and the turbulent flow structures have various structural forms including knife patterns, grooves, bosses and the like. The turbulent flow unit is arranged on the suction surface of the blade close to the front edge of the blade, so that air flow at the front edge of the suction surface is transited in advance or the flow turbulence is increased, the momentum exchange strength of fluid at different speed layers is improved, the fluid separation resistance of the compressor blade is improved, and the power capability of the compressor blade is improved; and meanwhile, the method is suitable for stationary blades and movable blades of the gas compressor.

Description

Technical Field

[0001] The present invention relates to the technical field of gas turbines, and in particular to a compressor blade capable of reducing flow separation. Background Art

[0002] With the continuous advancement of gas turbine technology, the performance improvement of the compressor, one of its core components, plays a vital role in the overall efficiency and stability of the gas turbine. However, as gas turbine technical indicators become increasingly advanced, the requirements for compressor inlet flow and stage load are also constantly increasing, making the internal flow of the compressor more complex and unstable. Under high load conditions, flow separation is prone to occur on the suction surface of the compressor blades, resulting in increased blade losses and reduced performance, which in turn threatens the safe operation of the gas turbine.

[0003] At present, the existing compressor blade design usually adopts a smooth surface, without fully considering the impact of surface roughness on the development of turbulence of the suction side flow, and also lacks effective means to control turbulence to suppress flow separation. Under the condition of high blade load, this design is likely to cause flow separation on the suction side, which in turn affects the stable operation and overall performance of the compressor. In addition, the limitations of traditional compressor blade design theories and methods under high load conditions gradually become apparent, making it difficult to meet the high requirements of modern gas turbines for compressor performance. Therefore, how to effectively control flow separation in compressor blade design and improve the blade's anti-separation ability and overall performance has become an urgent problem to be solved in the current development of gas turbine technology.

[0004] Existing patent CN220285895U discloses a fixed guide vane for reducing boundary layer flow separation; it includes a fixed guide vane, which is a long strip structure with an arched cross-section, the arc surface of the fixed guide vane is the pressure surface, the bottom plane is the suction surface, the blade head of the pressure surface is provided with a strip hydrophobic belt, and the blade tail of the suction surface of the fixed guide vane is provided with a vortex generator; the hydrophobic belt is added to the head of the fixed blade to delay the transition of the upper layer flow at the head boundary to turbulent flow to a certain extent; the vortex generator is added to the tail of the blade to generate turbulence on the suction surface of the blade, and its wingtip vortex can move the position of the flow separation point on the suction surface of the guide vane, reduce the flow resistance of the guide vane, thereby reducing the external layer flow separation, and having the effect of reducing flow loss.

[0005] The existing patent CN111197612A discloses a spoiler mechanism for slowing down flow separation, which is mainly installed on the ratchet mechanism of the back flow surface of the blade and is hinged through the ratchet mechanism. The ratchet mechanism includes an outer wheel, an inner wheel and a pawl. The outer wheel is connected to the spoiler, and the inner wheel is connected to the balance plate. The flow field under the balance plate is connected to the flow field in front of the ratchet mechanism. The pawl is rotatably connected to the inner wheel and cooperates with the tooth groove of the outer wheel. A spring is provided between the pawl and the inner wheel. A baffle for limiting the rotation of the pawl is provided between the inner wheel and the outer wheel. The end of the blade corresponding to the balance plate is provided with an upper limit block and a lower limit block for limiting the rotation of the balance plate.

[0006] Both of the above-mentioned existing patents fail to solve the problem in the prior art that flow separation is prone to occur on the suction surface of the compressor blade, resulting in increased blade losses and decreased performance, which in turn threatens the operational safety of the gas turbine. Summary of the Invention

[0007] Based on the above technical problems, the present invention proposes a compressor blade that reduces flow separation, solving the problem in the prior art that flow separation is easily generated on the suction surface of the compressor blade, resulting in increased blade losses, decreased performance, and thus threatening the safe operation of the gas turbine. The specific technical solution is as follows:

[0008] A compressor blade for reducing flow separation comprises a blade and a spoiler unit on the blade, wherein the blade has a leading edge and a trailing edge in the length direction thereof, and the blade has a pressure surface and a suction surface in the thickness direction thereof, the spoiler unit is located at one end of the suction surface close to the leading edge of the blade, the spoiler unit extends along the height direction of the blade, and the spoiler unit comprises a plurality of spoiler structures distributed in an array.

[0009] Furthermore, the chord-wise length of the spoiler unit along the length direction of the blade is in a linear relationship with the chord length of the blade.

[0010] Furthermore, the chord-wise length of the spoiler unit along the length direction of the blade is w=Lc, where c is the chord length of the blade, and L is the dimensionless length coefficient of the spoiler unit, and the value range of L is 0.1-0.2.

[0011] Furthermore, the chord-wise length between the starting position of the spoiler unit and the leading edge of the blade is in a linear relationship with the chord length of the blade.

[0012] Furthermore, the chord length between the starting position of the spoiler unit and the leading edge of the blade is x=Xc, where c is the chord length of the blade, and X is the dimensionless starting position coefficient of the spoiler unit, and the value range of X is 0.05-0.8.

[0013] Furthermore, the spoiler structure includes knife marks, grooves or bosses.

[0014] Furthermore, the height or depth of the spoiler structure is linearly related to the thickness of the boundary layer on the blade wall.

[0015] Furthermore, the height or depth of the spoiler structure is h=Hδ, where δ is the thickness of the boundary layer on the blade wall, and H is the dimensionless height coefficient of the spoiler structure, and the value range of H is 3-5.

[0016] Furthermore, the width or diameter of the spoiler structure is in a linear relationship with the height or depth of the spoiler structure.

[0017] Furthermore, the width or diameter of the spoiler structure is d=Dh, where D is the dimensionless width coefficient of the spoiler structure, and the value range of D is 2-8.

[0018] Furthermore, a plurality of the spoiler structures are distributed in the spoiler unit in an array with the same structural form.

[0019] Based on the above technical solution, compared with the prior art, the present invention has at least the following beneficial effects:

[0020] 1. The present invention proposes a compressor blade for reducing flow separation. A turbulent unit is provided on the suction surface to promote early transition of the airflow at the front edge of the compressor suction surface or increase the flow turbulence, thereby improving the flow separation resistance of the compressor suction surface, reducing flow losses, and improving the aerodynamic efficiency of the compressor.

[0021] 2. The compressor blade for reducing flow separation proposed in the present invention can reduce the velocity loss at the trailing edge of the blade, reduce the total pressure loss, and improve the work capacity of the compressor blade, thereby improving the overall efficiency of the compressor.

[0022] 3. The present invention proposes a compressor blade for reducing flow separation. The spoiler unit can effectively suppress angular separation, allowing the compressor to operate stably within a wider angle of attack range, thereby widening the stable operating range of the compressor and reducing the number of compressor stages.

[0023] 4. The compressor blade for reducing flow separation proposed by the present invention has little impact on the compressor blade structure, is easy to process, and is applicable to both compressor stationary blades and moving blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0025] Figure 1This is a schematic structural diagram of a compressor blade for reducing flow separation proposed by the present invention;

[0026] Figure 2 1 is a schematic cross-sectional view of a compressor blade for reducing flow separation proposed by the present invention;

[0027] Figure 3 Schematic diagram of a turbulence unit of a compressor blade for reducing flow separation proposed by the present invention;

[0028] Figure 4 The flow separation phenomenon is a flow non-separation phenomenon when the compressor blade has a turbulent unit and a flow separation phenomenon when the compressor blade does not have a turbulent unit in the embodiment of the present invention.

[0029] Reference numerals: 1 - blade leading edge, 2 - pressure surface, 3 - blade trailing edge, 4 - suction surface, 5 - end wall, 6 - spoiler unit. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below with reference to specific examples. These examples should not be construed as limiting the scope of protection claimed in the present invention.

[0031] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0032] In order to solve the problem in the prior art that flow separation is prone to occur on the suction surface of the compressor blade, resulting in increased blade loss and performance degradation, which in turn threatens the operating safety of the gas turbine, the present invention proposes a compressor blade that reduces flow separation.

[0033] To achieve the above objectives, the present invention proposes a compressor blade that reduces flow separation. A flow disturbance element is provided at the front edge of the blade's suction surface to promote flow transition and increase turbulence at the suction surface, thereby improving flow separation resistance and reducing flow losses, thereby extending the compressor blade's stable operating range.

[0034] See Figures 1-4 As shown, this embodiment provides a specific implementation of a compressor blade for reducing flow separation. The compressor blade includes a blade and a spoiler unit on the blade.

[0035] See Figure 1As shown, the blade profile (i.e., the cross-section of the blade) is wing-shaped. The front end in the length direction of the blade is the leading edge 1 of the blade, which is the first position to come into contact with the gas flow. The rear end in the length direction of the blade is the trailing edge 3 of the blade, which is opposite to the leading edge 1 of the blade. The blade has two curved surfaces in its thickness direction. The concave surface is called the blade basin, which is the pressure surface 2 of the blade, and the convex surface is called the blade back, which is the suction surface 4 of the blade. The curvature of the suction surface 4 is greater than the curvature of the pressure surface 2, and the thickness of the front end of the blade is greater than the thickness of the rear end of the blade. The top and bottom ends of the blade are both connected to the end wall 5 (the top end wall is not drawn). A spoiler unit 6 is provided at one end of the suction surface 4 close to the leading edge 1 of the blade.

[0036] See Figure 2 As shown, the setting area of the spoiler unit on the suction surface 4 is a rectangular arc area, extending along the height direction of the blade. The specific starting position and occupied area of the spoiler unit on the suction surface 4 can be determined according to the chord-wise length corresponding to the spoiler unit in the length direction of the blade and the chord-wise length between the starting position of the spoiler unit and the leading edge 1 of the blade.

[0037] Among them, the chord length of the spoiler unit in the blade length direction is

[0038] w=Lc

[0039] In the above formula, L is the dimensionless length coefficient of the spoiler unit, the value range of L is 0.1-0.2, and c is the blade chord length.

[0040] The chord length between the starting position of the spoiler unit and the leading edge 1 of the blade is

[0041] x=Xc

[0042] In the above formula, X is the dimensionless starting position coefficient of the spoiler unit, the value range of X is 0.05-0.1, and c is the blade chord length.

[0043] See Figure 3 As shown, the spoiler unit 6 includes multiple spoiler structures, which are evenly distributed in an array. The spoiler structures have a variety of different structural forms, mainly including knife patterns, grooves and bosses. Among them, knife patterns are raised linear stripes on the surface of the suction surface. This embodiment provides three types of knife pattern structures. Figure 3 (a) shows the cross knife pattern. Figure 3 (b) shows an S-shaped knife mark. Figure 3 (c) shows the water wave pattern, among which the water wave pattern has the best turbulence effect. The groove is a concave groove on the surface of the suction surface. This embodiment provides three types of groove structures. Figure 3 (d) is a rectangular groove, Figure 3 (e) is an elliptical groove, Figure 3(f) is a hexagonal groove. The hexagonal grooves are arranged in a honeycomb pattern. The rectangular grooves have the best turbulence effect. The boss is a plurality of columnar protrusions on the surface of the suction surface. This embodiment provides two boss structures. Figure 3 (g) is a circular boss, Figure 3 (h) is a diamond-shaped boss, among which the circular boss has the best flow disturbance effect.

[0044] Specifically, the main influence range of the spoiler structure is on the boundary layer of the wall, so the height of the spoiler structure mainly depends on the thickness of the boundary layer of the incoming flow wall. Therefore, in order to reduce the influence of the spoiler structure on the mainstream flow, the relevant dimensions of each spoiler structure in the spoiler unit 6 are determined according to the thickness of the boundary layer of the wall at the inlet of the spoiler section. Among them, the height or depth of the spoiler structure is

[0045] h=Hδ

[0046] In the above formula, h is the height of the protrusion, groove depth or platform of the knife mark, H is the dimensionless height coefficient of the spoiler structure, the value range of H is 3-5, and δ is the boundary layer thickness of the inlet wall of the spoiler section.

[0047] The width or diameter of the spoiler structure is

[0048] d=Dh

[0049] In the above formula, D is the dimensionless width coefficient of the spoiler structure, and the value range of D is 2 to 8. d is the width of the knife pattern, the width of the groove, or the diameter of the circular boss.

[0050] The size of each turbulent structure can be determined based on the thickness of the boundary layer on the inlet wall of the turbulent section and the value of the dimensionless coefficient mentioned above. In a gas turbine, the flow state of the gas when it flows through the blades is usually turbulent. The calculation method of the turbulent wall boundary layer thickness is:

[0051]

[0052] In the above formula, v is the kinematic viscosity of the fluid, x is the distance along the flow direction, and U is the external mainstream velocity.

[0053] See Figure 4 As shown, Figure 4 (a) When the compressor blade load is relatively high, the airflow on the compressor suction side is prone to flow separation under a large adverse pressure echelon; Figure 4(b) After adding the spoiler unit to the suction surface 4, the flow separation phenomenon is suppressed due to the increase in turbulence. By adding the spoiler unit to the suction surface of the blade near the leading edge of the blade, the airflow at the leading edge of the suction surface of the compressor blade can be prompted to transition earlier or the flow turbulence can be increased, thereby increasing the momentum exchange intensity of the fluids in different velocity layers, suppressing the development of low-energy fluid regions, and improving the fluid separation resistance of the compressor blade, thereby improving the compressor blade's work capacity, expanding the compressor's stable operating range or achieving a higher-level load design, and reducing the number of compressor stages. The compressor blade with reduced flow separation proposed by the present invention has little impact on the compressor blade structure, is easy to process, and is applicable to both compressor stationary blades and moving blades.

[0054] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

[0055] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0056] It should be noted that, in the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

Claims

1. A compressor blade for reducing flow separation, characterized in that: The invention comprises a blade and a spoiler unit on the blade, wherein the blade has a leading edge and a trailing edge in the length direction thereof, the blade has a pressure surface and a suction surface in the thickness direction thereof, the spoiler unit is located at one end of the suction surface close to the leading edge of the blade, the spoiler unit extends along the height direction of the blade, and the spoiler unit comprises a plurality of spoiler structures distributed in an array.

2. The compressor blade for reducing flow separation according to claim 1, wherein: The chord-wise length of the spoiler unit along the length direction of the blade is in a linear relationship with the chord length of the blade.

3. The compressor blade for reducing flow separation according to claim 2, wherein: The chord length of the spoiler unit along the length direction of the blade is w=Lc, where c is the chord length of the blade, and L is the dimensionless length coefficient of the spoiler unit. The value range of L is 0.1-0.

2.

4. The compressor blade for reducing flow separation according to claim 1, wherein: The chord-wise length between the starting position of the spoiler unit and the leading edge of the blade is in a linear relationship with the chord length of the blade.

5. The compressor blade for reducing flow separation according to claim 4, characterized in that: The chord length between the starting position of the spoiler unit and the leading edge of the blade is x=Xc, where c is the chord length of the blade, and X is the dimensionless starting position coefficient of the spoiler unit, and the value range of X is 0.05-0.

8.

6. The compressor blade for reducing flow separation according to claim 1, wherein: The spoiler structure includes knife patterns, grooves or bosses.

7. The compressor blade for reducing flow separation according to claim 6, characterized in that: The height or depth of the flow-disturbing structure is linearly related to the thickness of the boundary layer on the blade wall.

8. The compressor blade for reducing flow separation according to claim 7, wherein: The height or depth of the flow-disturbing structure is h=Hδ, where δ is the thickness of the boundary layer on the blade wall, and H is the dimensionless height coefficient of the flow-disturbing structure. The value range of H is 3-5.

9. The compressor blade for reducing flow separation according to claim 8, characterized in that: The width or diameter of the spoiler structure is linearly related to the height or depth of the spoiler structure.

10. The compressor blade for reducing flow separation according to claim 9, wherein: The width or diameter of the spoiler structure is d=Dh, where D is the dimensionless width coefficient of the spoiler structure, and the value range of D is 2-8.

11. The compressor blade for reducing flow separation according to any one of claims 6 to 10, characterized in that: The plurality of spoiler structures are distributed in the spoiler unit in an array with the same structural form.

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