A clover-shaped turbine blade cooling unit and a turbine blade

Abstract

A clover-shaped turbine blade cooling unit and a turbine blade provided by the present invention. After cooling air enters the clover-shaped turbine blade cooling channel through a convergent air supply hole, it turns and flows from the center to the outside in a clockwise or counterclockwise direction. The cross-sectional area of the cold air flow path of the clover-shaped cooling structure of the present invention is substantially the same along the way, and there will be no sudden expansion or throttling of the flow. However, this structure will cause the flow direction of the air flow to continuously turn, resulting in mutual impact and mixing between air flow micro-groups. Therefore, this structure has relatively independent cold air channels, enabling the cooling air flow to flow a longer path therein, making more full use of the cooling air, and significantly enhancing the effect of internal convective heat transfer. On the other hand, the flow resistance along the path inside this structure is relatively large, which will cause a certain pressure loss of the cooling air flow, thereby effectively controlling the blowing ratio at the outlet of the film hole and enhancing the external film cooling effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of aero-engine turbine blades, and particularly relates to a clover-shaped turbine blade cooling unit and a turbine blade. Background Art

[0002] Increasing the turbine inlet temperature is an effective way to improve the thrust and efficiency of an aero-engine. However, the increase in the turbine inlet temperature will cause the turbine blades to bear a greater thermal load, and excessive temperature and thermal stress may lead to abnormal operation of the turbine blades. The turbine inlet gas temperature of modern high-performance aero-engines has far exceeded the temperature resistance limit of the materials used, and complex cooling technologies must be adopted to ensure the normal operation of the turbine under high-temperature conditions. The suction side of the turbine blade is a typical high-temperature part of the blade and is a part that is more easily damaged by heat corrosion. Especially for the suction side of the high-pressure turbine guide vane, the cooling problems faced are more severe. The cooling design of the suction side of the turbine blade is very difficult, mainly because the gas accelerates relatively fast on the suction side, and most of the gas is in the high-speed area. According to the external flow conditions of the suction side edge, the suction side cooling structure area can be roughly divided into the front suction side area (low Mach number area) and the middle and rear suction side areas (high Mach number area). The research results of the film cooling on the suction side of the turbine blade show that the film cooling coverage effect of the suction side film holes is mainly affected by the blowing ratio, density ratio, and mainstream Reynolds number on the film cooling effect; when the blowing ratio increases from 0.5 to 1.7, the film coverage area on the suction side first increases and then decreases, and the film coverage area is the largest when the blowing ratio is 1.2. When the blowing ratio exceeds 1.2, the film coverage width decreases, and it is obvious that the film detaches from the wall; the film cooling efficiency also increases first and then decreases with the increase of the blowing ratio, and the maximum film cooling efficiency corresponds to the blowing ratio of 1.0. If film holes are opened in the middle and rear suction side areas, due to the very low static pressure on the gas side of the main flow channel, the blowing ratio of the film holes often becomes too high, resulting in the film being easily detached from the wall after flowing out, causing a very poor film sticking and covering effect on the suction side, and it is difficult to form a good film coverage on the downstream area of the suction side, thus causing the phenomenon of insufficient cooling.

[0003] Therefore, it is urgent to seek a blade cooling structure suitable for the high-efficiency cooling structure of the suction side to ensure the stable operation of the turbine blade. Summary of the Invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a clover-shaped turbine blade cooling structure, specifically a clover-shaped high-efficiency cooling structure arranged in the middle and rear suction side areas of the turbine guide vane, so as to achieve the purpose of enhancing the internal convective heat transfer intensity while controlling the blowing ratio at the outlet of the film holes within the optimal range to enhance the external film cooling effect, thereby improving the blade cooling efficiency and the blade temperature-bearing capacity.

[0005] In order to achieve the above-mentioned objectives, the present invention provides the following technical solutions, providing a clover-shaped turbine blade cooling unit, wherein the cooling unit includes a cold air supply hole 1, an inlet rotary structure 2, a first folding structure 3, a first rotating structure 4, a second folding structure 5, a second rotating structure 6, a third folding structure 7, a third rotating structure 8, a transition structure 9 and an air film hole 10 connected in sequence; the inlet rotary structure 2, the first folding structure 3, the first rotating structure 4, the second folding structure 5, the second rotating structure 6, the third folding structure 7 and the third rotating structure 8 are smoothly connected to form a clover-shaped airflow cooling channel 11; the cooling airflow in the clover-shaped airflow cooling channel 11 flows from the cold air supply hole 1 to the air film hole 10.

[0006] The clover-shaped cooling unit provided by the present invention also has the following characteristics: the center lines of the inlet rotating structure 2, the first folding structure 3, the second folding structure 5 and the third folding structure 7 are clover-shaped rose lines, and the polar coordinate equation of the clover-shaped rose line is r=a*cos(3*θ) or r=a*sin(3*θ), where r is the radius coordinate in the plane polar coordinate system, θ is the angular coordinate in the plane polar coordinate system, and the coefficient a is 2.5mm-6.5mm.

[0007] The clover-shaped cooling unit provided by the present invention also has the following characteristics: the center lines of the first rotating structure 4, the second rotating structure 6 and the third rotating structure 8 are arc lines, the center line arc radius of the first rotating structure 4 is R1, the center line arc radius of the second rotating structure 6 is R2, and the center line arc radius of the third rotating structure 8 is R3, then R1=R2=R3=3.5mm-8.5mm.

[0008] The clover-shaped cooling unit provided by the present invention also has the following characteristics: the cross-section of the clover-shaped airflow cooling channel 11 is a rectangle with rounded corners, and the fillet radius r is 0.15mm-0.25mm, the channel width t is 0.4mm-2.0mm, and the channel thickness h is 0.3mm-0.75mm.

[0009] The cloverleaf-shaped cooling unit provided by the present invention also has the following feature: the cold air supply hole 1 is vertically connected to the cloverleaf-shaped airflow cooling channel 11 .

[0010] The clover-shaped cooling unit provided by the present invention also has the following characteristics: the cross section of the cold air supply hole 1 is a rectangular hole, and the flow area A is in It is 1.2*A-2.0*A, wherein A is the cross-sectional area of the clover-shaped airflow cooling channel.

[0011] The clover-shaped cooling unit provided by the present invention further has the following feature: the film holes adopt a film slit structure form, and the cross-section of the film holes 10 is the same as the cross-section shape of the clover-shaped air flow cooling channel 11.

[0012] The clover-shaped cooling unit provided by the present invention further has the following feature: the film holes 10 are inclinedly arranged at the end of the clover-shaped air flow cooling channel 11, and the inlet of the film holes 10 is smoothly connected to the end of the clover-shaped air flow cooling channel 11 through a transition structure 9, and the inclination angle γ of the film holes is 35°-50°.

[0013] The clover-shaped cooling unit provided by the present invention further has the following feature: the transition structure 9 is arc-shaped, and the arc radius R4 of the transition structure 9 is 0.35 mm - 0.85 mm.

[0014] The clover-shaped cooling unit provided by the present invention further has the following feature: the inner side of the connection between the end of the air supply hole 1 and the starting end of the clover-shaped air flow cooling channel 11 is rounded, and the rounding radius R5 is 0.20 mm - 0.35 mm.

[0015] Another object of the present invention is to provide a turbine blade with a clover-shaped blade cooling unit. A plurality of clover-shaped blade cooling units are arranged in an array in the back region of the turbine blade. The clover-shaped blade cooling unit is the cooling unit described in any one of the foregoing items. The radial distance S1 between the plurality of clover-shaped blade cooling units is 6.0 mm - 12.9 mm; the chordal distance S2 between the plurality of clover-shaped blade cooling units is 4.0 mm - 13.7 mm.

[0016] The turbine blade provided by the present invention further has the following feature: the plurality of clover-shaped blade cooling units include one or more selected from the clockwise clover-shaped blade cooling units in which the air flow flows from the center to the outside in the clockwise direction and the counterclockwise clover-shaped blade cooling units in which the air flow flows from the center to the outside in the counterclockwise direction.

[0017] Beneficial effects

[0018] A clover-shaped turbine blade cooling unit provided by the present invention. After the cooling air enters the clover-shaped turbine blade cooling channel through the convergent air supply holes, it turns and flows from the center to the outside in a clockwise or counterclockwise direction. The cross-sectional area of the cold air flow in the clover-shaped cooling structure of the present invention is substantially the same along the way, and there will be no sudden expansion and throttling of the flow. However, this structure will cause the flow direction of the air flow to continuously turn, resulting in mutual impact and mixing between air flow micro-groups. Therefore, this structure has relatively independent cold air channels, enabling the cooling air flow to flow a longer path therein, making more full use of the cooling air, and significantly enhancing the effect of internal convective heat transfer. On the other hand, the flow resistance along the way inside this structure is relatively large, which will cause a certain pressure loss of the cooling air flow, thereby effectively controlling the blowing ratio at the outlet of the film holes and enhancing the external film cooling effect.

[0019] The turbine blade provided by the present invention, without increasing the amount of cold air used, by arranging the clover-shaped turbine blade cooling unit provided by the present invention in the blade suction side area, can further increase the cooling efficiency by 4.6%, and greatly improve the temperature-bearing capacity of the turbine blade. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the following drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0021] Figure 1 It is a three-dimensional structure diagram of a clover-shaped turbine blade cooling unit with a counterclockwise air flow direction provided in an embodiment of the present invention;

[0022] Figure 2 For Figure 1 a two-dimensional cross-sectional schematic diagram of the provided cooling unit;

[0023] Figure 3 It is a two-dimensional cross-sectional schematic diagram of a clover-shaped turbine blade cooling channel with a counterclockwise air flow direction provided in an embodiment of the present invention;

[0024] Figure 4 It is a three-dimensional structure diagram of a clover-shaped turbine blade cooling unit with a clockwise air flow direction provided in an embodiment of the present invention;

[0025] Figure 5 It is a structural schematic diagram of the turbine blade provided in an embodiment of the present invention;

[0026] Figure 6 It is a structural schematic diagram of a second turbine blade provided in some embodiments of the present invention;

[0027] Figure 7 This is a schematic structural diagram of the third type of turbine blade provided by some embodiments of the present invention. Detailed implementation manners

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be noted, however, that these embodiments are not intended to limit the present invention. Any equivalent transformation or substitution in terms of function, method, or structure made by those of ordinary skill in the art based on these embodiments shall fall within the protection scope of the present invention.

[0029] In the description of the embodiments of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0030] In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0031] The terms "mounted", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, and it may be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] Such as Figures 1-7As shown, this embodiment provides a clover-shaped turbine blade cooling unit, which includes a cold air supply hole 1, an inlet rotating structure 2, a first folding structure 3, a first rotating structure 4, a second folding structure 5, a second rotating structure 6, a third folding structure 7, a third rotating structure 8, a transition structure 9 and an air film hole 10 connected in sequence; the inlet rotating structure 2, the first folding structure 3, the first rotating structure 4, the second folding structure 5, the second rotating structure 6, the third folding structure 7 and the third rotating structure 8 are smoothly connected to form a clover-shaped airflow cooling channel 11; the cooling airflow in the clover-shaped airflow cooling channel 11 flows from the cold air supply hole 1 to the air film hole 10.

[0033] In some embodiments, the center lines of the inlet rotating structure 2, the first folding structure 3, the second folding structure 5, and the third folding structure 7 are three-leaf rose lines, and the polar coordinate equation of the three-leaf rose line is r = a*cos(3*θ) or r = a*sin(3*θ), where r is the radius coordinate in the plane polar coordinate system, θ is the angular coordinate in the plane polar coordinate system, and the coefficient a is 2.5 mm-6.5 mm;

[0034] In some embodiments, the center lines of the first rotating structure 4, the second rotating structure 6 and the third rotating structure 8 are arc lines, the center line arc radius of the first rotating structure 4 is R1, the center line arc radius of the second rotating structure 6 is R2, and the center line arc radius of the third rotating structure 8 is R3, then R1=R2=R3=3.5mm-8.5mm.

[0035] In some embodiments, the cross section of the clover-shaped airflow cooling channel 11 is a rectangle with rounded corners, and the channel width t is 0.4 mm-2.0 mm, and the channel thickness h is 0.3 mm-0.75 mm.

[0036] In some embodiments, the cold air supply hole 1 is vertically connected to the clover-shaped airflow cooling channel 11 .

[0037] In some embodiments, the cross section of the cold air supply hole 1 is a rectangular hole with a flow area A. in It is 1.2*A-2.0*A, wherein A is the cross-sectional area of the clover-shaped airflow cooling channel.

[0038] In some embodiments, the air film hole adopts an air film seam structure, and the cross section of the air film hole 10 is the same as the cross section of the clover-shaped air flow cooling channel 11 .

[0039] In some embodiments, the film holes 10 are inclined and arranged at the end of the clover-shaped gas flow cooling channel 11, and the inlet of the film hole 10 is smoothly and transitionally connected to the end of the clover-shaped gas flow cooling channel 11 through a transition structure 9, and the inclination angle γ of the film hole is 35°-50°.

[0040] In some embodiments, the transition structure 9 is arc-shaped, and the arc radius R4 of the transition structure 9 is 0.35 mm - 0.85 mm.

[0041] In some embodiments, the four edges of the cooling unit are all rounded, and the rounding radius r is 0.15 mm - 0.25 mm.

[0042] In some embodiments, the inner side of the connection between the end of the air supply hole 1 and the starting end of the clover-shaped gas flow cooling channel 11 is rounded, and the rounding radius R5 is 0.20 mm - 0.35 mm.

[0043] In some embodiments, a turbine blade with a clover-shaped blade cooling unit is provided. The back region 13 of the turbine blade 12 is provided with a plurality of clover-shaped blade cooling units arranged in an array. The radial pitch S1 between the plurality of clover-shaped blade cooling units is 6.0 mm - 12.9 mm; the chordal pitch S2 between the plurality of clover-shaped blade cooling units is 4.0 mm - 13.7 mm.

[0044] In some embodiments, the plurality of clover-shaped blade cooling units include one or more selected from the clockwise clover-shaped blade cooling units in which the air flow flows from the center to the outside in a clockwise direction and the counterclockwise clover-shaped blade cooling units in which the air flow flows from the center to the outside in a counterclockwise direction. As Figure 5 shown, it is a turbine blade with clockwise clover-shaped blade cooling units. As Figure 6 shown, it is a second turbine blade whose cooling unit arrangement pitch is only different from that of the turbine blade shown in Figure 5 shown. As Figure 7 shown, it is a third turbine blade formed by alternately arranging clockwise clover-shaped blade cooling units and counterclockwise clover-shaped blade cooling units.

[0045] In some embodiments, the preparation steps of the turbine blade with a clover-shaped turbine blade cooling unit are as follows:

[0046] Step 1, referring to Figures 1-3, a three-leaf rose curve is drawn on the XOY plane with the origin O as the center. The polar coordinate equation of the three-leaf rose curve is r = a * cos(3 * θ), where a is taken as 3.5 mm. A vertical auxiliary line O - O1 is drawn through the origin O. Then, two more auxiliary lines O - O2 and O - O3 are drawn through the origin O at an angle of 120° with respect to O - O1. An arc with a radius of 5 mm and the center on the auxiliary line O - O1 is drawn to be tangent to the three-leaf rose curve at points A and B, and the arc intersects the auxiliary line O - O1 at point G. An arc with a radius of 5 mm and the center on the auxiliary line O - O2 is drawn to be tangent to the three-leaf rose curve at points C and D. Similarly, an arc with a radius of 5 mm and the center on the auxiliary line O - O3 is drawn to be tangent to the three-leaf rose curve at points E and F. After removing some contour lines, the center line O - A - M1 - B - C - M2 - D - E - M3 - F - G of the clover-shaped cooling channel is thus drawn, forming Figure 2 as shown;

[0047] Step 2: The center line O - A - M1 - B - C - M2 - D - E - M3 - F - G drawn in Step 1 is offset by 0.45 mm on each side respectively to form a two-dimensional plan view of the clover-shaped cooling channel, as shown in Figure 2 ; Then, the two-dimensional plan view thus formed is stretched along the Z direction by 0.35 mm to form a three-dimensional solid structure of the cooling unit. Then, all edges are rounded with a radius r of 0.15 mm. Air supply holes and air film holes are respectively set at the starting point O and the ending point G of the cooling unit, and finally a clover-shaped cooling unit is formed;

[0048] Step 3: The clover-shaped cooling units are arranged in an array with a radial pitch S1 of 7.2 mm and a chordal distance S2 of 8.25 mm. Then, a difference operation is performed with the blade model's suction side region to obtain a turbine blade with a clover-shaped cooling structure, as shown in Figure 5 as shown.

[0049] In another embodiment, the preparation steps of a turbine blade with a clover-shaped turbine blade cooling unit are as follows:

[0050] Step 1: Refer to Figures 1-3, a three-leaf rose curve is drawn on the XOY plane with the origin O as the center. The polar coordinate equation of the three-leaf rose curve is r = a * cos(3 * θ), where a is taken as 4.5 mm. A vertical auxiliary line O - O1 is drawn through the origin O, and then two more auxiliary lines O - O2 and O - O3 are drawn through the origin O at an angle of 120° with respect to O - O1. An arc with a radius of 6 mm and a center on the auxiliary line O - O1 is drawn to be tangent to the three-leaf rose curve at points A and B, and the arc intersects the auxiliary line O - O1 at point G. An arc with a radius of 6 mm and a center on the auxiliary line O - O2 is drawn to be tangent to the three-leaf rose curve at points C and D. Similarly, an arc with a radius of 6 mm and a center on the auxiliary line O - O3 is drawn to be tangent to the three-leaf rose curve at points E and F. After removing some contour lines, the center line O - A - M1 - B - C - M2 - D - E - M3 - F - G of the clover-shaped cooling channel is thus drawn, forming Figure 2 as shown;

[0051] Step Two: The center line O - A - M1 - B - C - M2 - D - E - M3 - F - G drawn in Step One is offset by 0.55 mm on each of the two sides to form a two-dimensional plan view of the clover-shaped cooling channel, as shown in Figure 2 . Then the two-dimensional plan view thus formed is stretched along the Z direction by 0.35 mm to form a three-dimensional solid structure of the cooling unit. Then, fillets with a radius r of 0.15 mm are made for all edges, and air supply holes and air film holes are respectively set at the starting point O and the ending point G of the cooling unit, finally forming a clover-shaped cooling unit.

[0052] Step Three: The clover-shaped cooling units are arranged in an array with a radial pitch S1 of 7.8 mm and a chordal distance S2 of 9.1 mm, and then the difference is taken with the blade model's suction side region to obtain the second type of turbine blade with a clover-shaped cooling structure, as shown in Figure 6 as shown.

[0053] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above is only the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and variations can be made, and these improvements and variations should also be regarded as within the protection scope of the present invention.

Claims

1. A clover-shaped turbine blade cooling unit, characterized in that, The cooling unit comprises a cold air supply hole (1), an inlet rotary structure (2), a first folding structure (3), a first rotary structure (4), a second folding structure (5), a second rotary structure (6), a third folding structure (7), a third rotary structure (8), a transfer structure (9) and an air film hole (10) connected in sequence; The inlet rotary structure (2), the first folding structure (3), the first rotary structure (4), the second folding structure (5), the second rotary structure (6), the third folding structure (7) and the third rotary structure (8) are smoothly transitioned and connected to form a clover-shaped airflow cooling channel (11); The cooling airflow in the clover-shaped airflow cooling channel (11) flows from the cold air supply hole (1) to the air film hole (10). The center lines of the inlet rotary structure (2), the first folding structure (3), the second folding structure (5) and the third folding structure (7) are three-leaf rose lines, and the polar coordinate equation expression of the three-leaf rose line is r=a*cos(3*θ) or r=a*sin(3*θ), wherein r is the radius coordinate in the plane polar coordinate system, θ is the angular coordinate in the plane polar coordinate system, and the coefficient a is 2.5mm-6.5mm. The center lines of the first rotating structure (4), the second rotating structure (6) and the third rotating structure (8) are arc lines. The centerline arc radius of the first rotating structure (4) is R1, the centerline arc radius of the second rotating structure (6) is R2, and the centerline arc radius of the third rotating structure (8) is R3, then R1=R2=R3=3.5mm-8.5mm, The cold air supply hole (1) is vertically connected to the clover-shaped air flow cooling channel (11). The transition structure (9) is in an arc shape, and the arc radius R4 of the transition structure (9) is 0.35 mm to 0.85 mm. The inner side of the connection between the end of the air supply hole (1) and the starting end of the clover-shaped air flow cooling channel (11) is rounded, and the rounded corner radius R5 is 0.20mm-0.35mm.

2. The clover-shaped turbine blade cooling unit according to claim 1, wherein The cross section of the clover-shaped airflow cooling channel (11) is a rectangle with rounded corners, and the rounded corner radius r is 0.15 mm to 0.25 mm, the channel width t is 0.4 mm to 2.0 mm, and the channel thickness h is 0.3 mm to 0.75 mm.

3. The clover-shaped turbine blade cooling unit according to claim 1, wherein, The cross-section of the cold air supply hole (1) is a rectangular hole with a flow area A in being 1.2*A - 2.0*A, where A is the cross-sectional area of the clover-shaped air flow cooling channel.

4. The clover-shaped turbine blade cooling unit according to claim 1, characterized in that, The air film hole adopts an air film seam structure, and the cross section of the air film hole (10) is the same as the cross section of the clover-shaped air flow cooling channel (11).

5. The clover-shaped turbine blade cooling unit according to claim 1, characterized in that, The air film hole (10) is tiltedly arranged at the end of the clover-shaped air flow cooling channel (11), and the inlet of the air film hole (10) is smoothly transitioned and connected to the end of the clover-shaped air flow cooling channel (11) through a transition structure (9), and the tilt angle γ of the air film hole is 35°-50°.

6. A turbine blade with a clover-shaped blade cooling unit, characterized in that, The back region of the turbine blade is provided with a plurality of clover-shaped blade cooling units arranged in an array, wherein the clover-shaped blade cooling units are the cooling units according to any one of claims 1 to 5. The radial pitch S1 between multiple clover-shaped blade cooling units is 6.0 mm - 12.9 mm; the chordwise pitch S2 between multiple clover-shaped blade cooling units is 4.0 mm - 13.7 mm.

7. The turbine blade according to claim 6, characterized in that The multiple clover-shaped blade cooling units include one or more selected from a clockwise clover-shaped blade cooling unit in which the air flow flows from the center outwards in the clockwise direction and a counterclockwise clover-shaped blade cooling unit in which the air flow flows from the center outwards in the counterclockwise direction.

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