Semi-pear-shaped film hole structure for turbine blade and its design method

Abstract

A semi-pear-shaped film hole structure for a turbine blade and its design method, belonging to the technical field of gas turbine turbine blades. The semi-pear-shaped film hole structure for a turbine blade includes a divergent section, a connecting section, and a sunken outlet section. The design method of the semi-pear-shaped film hole structure for a turbine blade includes: determining the length L of the film hole, determining the blade inlet wall surface, determining the blade outlet wall surface, determining the outer contour line of the divergent section, determining the outer contour line of the sunken outlet section, determining the outer contour line of the connecting section, determining the two-dimensional model of the semi-pear-shaped film hole structure, and determining the three-dimensional model of the semi-pear-shaped film hole structure. The semi-pear-shaped film hole structure for a turbine blade and its design method can improve the cooling efficiency. The divergent structure of the hole gradually reduces the cold air velocity, enabling the cold air to better adhere to the wall surface. At the same time, when the air flow reaches the sunken outlet section, part of the cold air forms a vortex here, which is beneficial to cooling the entrained gas and improving the cooling effect.

Description

Technical Field

[0001] The present invention relates to the technical field of gas turbine turbine blades, and particularly relates to a semi-pear-shaped film hole structure for turbine blades and a design method thereof. Background Art

[0002] With the increase in the thrust-to-weight ratio of aero-engines, the gas temperature at the turbine inlet has become increasingly high, resulting in the development of high-temperature-resistant turbine blade materials being unable to meet the performance requirements of engine blades under the continuous increase of the temperature in front of the turbine. Therefore, in order to improve the performance of aero-engines, a more efficient film cooling technology needs to be adopted to cool the turbine blades.

[0003] Film cooling is to set film holes on the wall surface of an object, and the cooling gas is ejected from the film holes and adheres near the wall surface to form a cold gas film with a lower temperature, isolating the wall surface from the high-temperature gas, and at the same time taking away part of the high-temperature gas, thereby playing a good protective role for the wall surface.

[0004] At present, cylindrical film holes are mainly used for turbine blades. However, the jet of cylindrical holes is concentrated, and the spanwise area covered by the formed gas film is small. Moreover, at a large blowing ratio, the jet of cylindrical holes is prone to break through the wall surface and cannot form an effective gas film coverage. On the other hand, the shear action between the ejected cooling gas and the mainstream forms a kidney-shaped vortex, resulting in the cold gas detaching from the wall surface downstream, and the cooling effect is poor.

[0005] Therefore, in order to solve the shortcomings of cylindrical film cooling holes, it is necessary to improve the shape structure of the film holes to improve the film cooling efficiency. Summary of the Invention

[0006] In order to solve the technical problems existing in the prior art, such as low cooling efficiency of cylindrical film holes and large mixing loss of film cooling, the present invention provides a semi-pear-shaped film hole structure for turbine blades and a design method thereof, which can improve the film efficiency, the working reliability and the service life of the blades.

[0007] In order to achieve the above object, the technical solution of the present invention is:

[0008] A semi-pear-shaped film hole structure for turbine blades, comprising a diverging section, a connecting section and a sunken outlet section;

[0009] One end of the diverging section is located on the inlet wall surface of the blade, and the other end of the diverging section is smoothly connected to one end of the sunken outlet section through the connecting section, and the other end of the sunken outlet section is located on the outlet wall surface of the blade.

[0010] Furthermore, both the diverging section and the sunken outlet section are formed by rotating a quadratic curve 360° around the film hole rotation axis, and the included angle between the film hole rotation axis and the inlet wall surface of the blade is 30° to 60°.

[0011] Further, the connecting section is a structure formed by a fillet connection between the expansion section and the concave air outlet section, and the fillet radius r of the fillet is 4 to 6 mm.

[0012] Further, the length of the air film hole rotation axis between the blade inlet wall surface and the blade outlet wall surface is the air film hole length L, and the value range of the air film hole length L is 20 to 24 mm.

[0013] A design method for a semi-pear-shaped air film hole structure for a turbine blade includes the following steps:

[0014] S1. Determine the air film hole length L:

[0015] On the x-y plane of the three-dimensional coordinate system, draw a line segment AB through the origin A. The included angle between the line segment AB and the positive direction of the x-axis is α, and the length of the line segment AB is the air film hole length L;

[0016] S2. Determine the blade inlet wall surface:

[0017] On the x-y plane, the blade inlet wall surface is collinear with the x-axis;

[0018] S3. Determine the blade outlet wall surface:

[0019] On the x-y plane, the blade outlet wall surface passes through point B and is parallel to the x-axis;

[0020] S4. Determine the outer contour line of the expansion section:

[0021] On the x-y plane, the origin A is offset by L in the direction of the vector 1 to reach point C; the origin A is offset by L in the direction of the vector 2 to reach point D, and offset by L 3 to reach point E; respectively draw line segments CC 1 , DD 1 and EE 1 perpendicular to the line segment AB; using point C 1 as the starting point, point E 1 as the ending point, and point D 1 as the control point to obtain a quadratic curve, which is the outer contour line of the expansion section;

[0022] S5. Determine the outer contour line of the concave air outlet section:

[0023] On the x-y plane, draw a line segment BB 1 perpendicular to the line segment AB, and the length of the line segment BB 1 is d 3 ; point B is offset by L in the direction of the vector 4Reach point F at a distance; draw a line segment FF perpendicular to line segment AB 1 , the line segment FF 1 has a length of d 4 ; taking point E 1 as the starting point, point F 1 as the ending point, and point B 1 as the control point to obtain a quadratic curve, which is the outer contour line of the concave air outlet section;

[0024] S6. Determine the outer contour line of the connecting section:

[0025] On the x - y plane, set a fillet with a fillet radius of r at the connection of the outer contour line of the expansion section and the outer contour line of the concave air outlet section. The fillet intersects the outer contour line of the expansion section and the outer contour line of the concave air outlet section at point E 2 and point E 3 ;

[0026] S7. Determine the two - dimensional model of the semi - pear - shaped air film hole structure:

[0027] Curve C 1 E 2 E 3 F 1 is the two - dimensional model of the semi - pear - shaped air film hole structure;

[0028] S8. Determine the three - dimensional model of the semi - pear - shaped air film hole structure:

[0029] The axis of rotation of the air film hole is collinear with the line segment AB;

[0030] In the three - dimensional coordinate system, curve C 1 E 2 E 3 F 1 rotates 360° around the axis of rotation of the air film hole to obtain a rotating body;

[0031] Cut the rotating body along the z - axis direction by the blade inlet wall surface and the blade outlet wall surface to obtain the three - dimensional model of the semi - pear - shaped air film hole structure.

[0032] Furthermore, in the step S4, the L 1 = 0.1L, L 2 = 0.3L, L 3 = 0.75L, the length of the line segment CC 1 is d, the length of the line segment DD 1 d 1 = 5d, the length of the line segment EE 1 is d 2 = 6d, and the value range of d is 0.6 - 1.2 mm.

[0033] Further, in step S4, the curve fullness value Rho of the quadratic curve is 0.7.

[0034] Further, in step S5, d 3 = 14d, d 4 = 6d, L 4 = 0.51L.

[0035] Further, in step S5, the curve fullness value Rho of the quadratic curve is 0.6.

[0036] Advantages of the present invention:

[0037] 1) The semi-pear-shaped film hole structure of the present invention can improve the film efficiency and enhance the working reliability and lifespan of the blade;

[0038] 2) When the cooling gas enters the semi-pear-shaped film hole structure, the expansion structure of the semi-pear-shaped film hole structure causes the cold gas velocity to gradually decrease; when the air flow reaches the sunken outlet section through the connection section, part of the cold gas forms a vortex here, which is beneficial to cooling the entrained mainstream gas; at the same time, the vertical velocity component of the cold gas at the outlet is also reduced, enabling the cold gas to better adhere to the wall surface under the action of the mainstream gas and having a good cooling effect at different blowing ratios.

[0039] Other features and advantages of the present invention will be partially described in detail in the following specific embodiments. Description of the Drawings

[0040] Figure 1 is a schematic structural diagram of the semi-pear-shaped film hole structure for a turbine blade provided by an embodiment of the present invention;

[0041] Figure 2 is a front view of the semi-pear-shaped film hole structure for a turbine blade provided by an embodiment of the present invention;

[0042] Figure 3 is a design diagram of the semi-pear-shaped film hole structure for a turbine blade provided by an embodiment of the present invention.

[0043] The reference numerals in the drawings of the specification include:

[0044] 1 - expansion section, 2 - connection section, 3 - sunken outlet section, 4 - blade inlet wall surface, 5 - blade outlet wall surface, 6 - film hole rotation axis. Specific Embodiments

[0045] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0046] To solve the problems existing in the prior art, such as Figures 1 to 3 As shown, the present invention provides a semi-pear-shaped film hole structure for a turbine blade, including a divergent section 1, a connecting section 2, and a recessed outlet section 3;

[0047] One end of the divergent section 1 is located on the blade inlet wall surface 4, and the other end of the divergent section 1 is smoothly connected to one end of the recessed outlet section 3 through the connecting section 2, and the other end of the recessed outlet section 3 is located on the blade outlet wall surface 5.

[0048] In this embodiment, the semi-pear-shaped film hole structure is designed by the design method of the semi-pear-shaped film hole structure for a turbine blade of the present invention. The specific structure of the outer contour line of the semi-pear-shaped film hole structure in the x-y plane of the three-dimensional coordinate system includes: the divergent section 1, the connecting section 2, and the recessed outlet section 3 arranged in sequence along the positive y-axis direction of the three-dimensional coordinate system. And, the film hole rotation axis 6 is in the x-y plane of the three-dimensional coordinate system and passes through the origin, and the included angle α with the positive x-axis direction is 30°-60°. One end of the divergent section 1 is connected to the cooling gas inlet cavity, and the other end of the divergent section 1 is smoothly connected to the recessed outlet section 3 through the connecting section 2.

[0049] Both the divergent section 1 and the recessed outlet section 3 are formed by rotating a quadratic curve around the film hole rotation axis 6 by 360°, and the included angle between the film hole rotation axis 6 and the blade inlet wall surface 4 is 30°-60°.

[0050] The connecting section 2 is a structure formed by a fillet connection between the divergent section 1 and the recessed outlet section 3, and the fillet radius r of the fillet is 4-6 mm.

[0051] The length of the film hole rotation axis 6 between the blade inlet wall surface 4 and the blade outlet wall surface 5 is the film hole length L, and the value range of the film hole length L is 20-24 mm.

[0052] In this embodiment, the semi-pear-shaped film hole structure is similar to the outer contour line of a pear. The cooling gas diffuses to the blade surface through the semi-pear-shaped film hole structure to form a film. When the cooling gas enters the semi-pear-shaped film hole structure, the cold gas velocity gradually decreases due to the expansion structure; when the air flow passes through the connecting section 2 and reaches the recessed outlet section 3, part of the cold gas forms a vortex here, which is beneficial to cooling the entrained mainstream gas; at the same time, the vertical velocity component of the cold gas at the outlet is also reduced, so that the cold gas adheres to the wall surface better under the action of the mainstream gas, and the cooling efficiency decreases slowly along the flow direction. The semi-pear-shaped film hole structure improves the film efficiency and improves the working reliability and life of the blade.

[0053] Such as Figure 3 As shown, the present invention also provides a design method for a semi-pear-shaped film hole structure for a turbine blade, including the following steps:

[0054] S1. Determine the film hole length L:

[0055] On the xy plane of the three-dimensional coordinate system, draw a line segment AB through the origin A. The angle between the line segment AB and the positive direction of the x-axis is α, and the length of the line segment AB is the length L of the air film hole.

[0056] S2. Determine the blade inlet wall surface 4:

[0057] In the xy plane, the blade inlet wall surface 4 is collinear with the x-axis;

[0058] S3. Determine the blade outlet wall surface 5:

[0059] In the xy plane, the blade outlet wall surface 5 passes through point B and is parallel to the x-axis;

[0060] S4. Determine the outer contour line of expansion segment 1:

[0061] In the xy plane, the origin A is along the vector Direction bias L 1 Arrived at point C; origin A along vector Direction bias L 2 Arrival point D, offset L 3 Arrive at point E; draw line segments CC perpendicular to line segment AB 1 ,DD 1 and EE 1 ; Point C 1 As the starting point, point E 1 As the end point, point D 1 A quadratic curve is obtained as the control point, which is the outer contour line of the expansion segment 1;

[0062] In step S4, L 1 =0.1L,L 2 =0.3L,L 3 =0.75L, line segment CC 1 The length of line segment DD is d. 1 The length d 1 =5d, line segment EE 1 The length is d 2 =6d, d ranges from 0.6 to 1.2 mm;

[0063] In step S4, the curve fullness value Rho of the quadratic curve is 0.7;

[0064] S5, determine the outer contour line of the concave air outlet section 3:

[0065] In the xy plane, draw line segment BB perpendicular to line segment AB. 1 , line segment BB 1 The length is d 3 ; Point B along the vector Direction offset L 4 Reach point F at a distance; draw a line segment FF perpendicular to the line segment AB 1 The line segment FF 1 Has a length of d 4 ; Taking point E 1 As the starting point, point F 1 As the end point, and point B 1 As the control point to obtain a quadratic curve, which is the outer contour line of the concave air outlet section 3;

[0066] In step S5, d 3 = 14d, d 4 = 6d, L 4 = 0.51L;

[0067] In step S5, the curve fullness value Rho of the quadratic curve is 0.6;

[0068] S6. Determine the outer contour line of the connecting section 2:

[0069] On the x-y plane, set a fillet with a fillet radius of r at the connection of the outer contour line of the expansion section 1 and the outer contour line of the concave air outlet section 3. The fillets intersect the outer contour line of the expansion section 1 and the outer contour line of the concave air outlet section 3 at points E 2 And point E 3 ;

[0070] S7. Determine the two-dimensional model of the semi-pear-shaped air film hole structure:

[0071] Curve C 1 E 2 E a F 1 Is the two-dimensional model of the semi-pear-shaped air film hole structure;

[0072] S8. Determine the three-dimensional model of the semi-pear-shaped air film hole structure:

[0073] The air film hole rotation axis 6 is collinear with the line segment AB;

[0074] In the three-dimensional coordinate system, curve C 1 E 2 E 3 F 1 Rotates 360° around the air film hole rotation axis 6 to obtain a rotating body;

[0075] Cut the rotating body along the z-axis direction by the blade inlet wall surface 4 and the blade outlet wall surface 5 to obtain the three-dimensional model of the semi-pear-shaped air film hole structure.

[0076] Embodiment

[0077] In this embodiment, a design method for a semi-pear-shaped air film hole structure for a turbine blade includes the following steps:

[0078] S1. Determine the length L of the film hole:

[0079] Point A is the origin of the three-dimensional coordinate system. In the x-y plane of the three-dimensional coordinate system, draw a line segment AB from the origin A in the positive y-axis direction. The angle between the line segment AB and the positive x-axis direction is α = 30°. The length of the line segment AB is the length L of the film hole, and L = 20 mm;

[0080] S2. Determine the blade inlet wall surface 4:

[0081] In the x-y plane of the three-dimensional coordinate system, the blade inlet wall surface 4 is collinear with the x-axis;

[0082] S3. Determine the blade outlet wall surface 5:

[0083] In the x-y plane, the blade outlet wall surface 5 passes through point B and is parallel to the x-axis;

[0084] S4. Determine the outer contour line of the expansion section 1:

[0085] In the x-y plane of the three-dimensional coordinate system, the origin A is offset by a distance of L in the 1 direction to reach point C, the origin A is offset by a distance of L in the 2 direction to reach point D, and the origin A is offset by a distance of L in the 3 direction to reach point E; draw line segments CC 1 , DD 1 , EE 1 perpendicular to the line segment AB with lengths of d, d 1 = 5d, d 2 = 6d respectively; taking point C 1 as the starting point, point E 1 as the ending point, and point D 1 as the control point, a quadratic curve is obtained with a curve fullness value Rho of 0.7, which is the outer contour line of the semi-pear-shaped film hole structure expansion section 1; preferably, L 1 = 2 mm, L 2 = 6 mm, L 3 = 15 mm, d = 0.6 mm, d 1 = 3 mm, d 2 = 3.6 mm;

[0086] S5. Determine the outer contour line of the recessed outlet section 3:

[0087] In the x-y plane of the three-dimensional coordinate system, draw a line segment BB 1 perpendicular to the line segment AB with a length of d 3= 14d; Point B is offset along the vector by a distance of L 4 = 0.51L to reach point F; Draw a line segment FF 1 perpendicular to line segment AB and with a length of d 4 = 6d; Point E 1 is used as the starting point, point F 1 is used as the ending point, and point B 1 is used as the control point, and a quadratic curve is obtained with a curve fullness value Rho of 0.6, which is the outer contour line of the concave air outlet section 3. Preferably, d 3 = 8.4 mm, d 4 = 3.6 mm, L 4 = 10.2 mm;

[0088] S6. Determine the outer contour line of the connection section 2:

[0089] On the x-y plane of the three-dimensional coordinate system, a fillet structure with a fillet radius of r is set at the connection of the outer contour line of the expansion section 1 and the outer contour line of the concave air outlet section 3. The fillet structure intersects the outer contour line of the expansion section 1 and the outer contour line of the concave air outlet section 3 at point E 2 and point E 3 respectively; Preferably, r = 5 mm;

[0090] S7. Determine the two-dimensional model of the semi-pear-shaped air film hole structure:

[0091] The curves C 1 E 2 E 3 F 1 obtained in steps S4, S5 and S6 are the two-dimensional model of the semi-pear-shaped air film hole structure;

[0092] S8. Determine the three-dimensional model of the semi-pear-shaped air film hole structure:

[0093] The air film hole rotation axis 6 is collinear with the line segment AB;

[0094] In the three-dimensional coordinate system, the curve C 1 E 2 E 3 F 1 rotates 360° around the air film hole rotation axis 6 to obtain a rotating body;

[0095] The blade inlet wall surface 4 and the blade outlet wall surface 5 are used to cut the rotating body along the z-axis direction of the three-dimensional coordinate system, and the three-dimensional model of the semi-pear-shaped air film hole structure can be obtained.

[0096] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A design method for a semi-pear-shaped film hole structure for a turbine blade, the semi-pear-shaped film hole structure comprising a divergent section, a connecting section, and a sunken outlet section; One end of the divergent section is located on the inlet wall surface of the blade, the other end of the divergent section is smoothly connected to one end of the sunken outlet section through the connecting section, and the other end of the sunken outlet section is located on the outlet wall surface of the blade; It is characterized in that The following steps are included: S1. Determine the length L of the film hole: In the x-y plane of the three-dimensional coordinate system, draw a line segment AB through the origin A, the included angle between the line segment AB and the positive x-axis direction is α, and the length of the line segment AB is the length L of the film hole; S2. Determine the inlet wall surface of the blade: In the x-y plane, the inlet wall surface of the blade is collinear with the x-axis; S3. Determine the outlet wall surface of the blade: In the x-y plane, the outlet wall surface of the blade passes through point B and is parallel to the x-axis; S4. Determine the outer contour line of the divergent section: On the x-y plane, the origin A is offset by a distance L along the vector to reach point C. 1 ; The origin point A is offset along the vector by a direction offset L 2 to reach point D, and the offset L 3 is used to reach point E; perpendicular line segments CC 1 , DD 1 and EE 1 are respectively made to the line segment AB; with point C 1 as the starting point, point E 1 as the ending point, and point D 1 as the control point to obtain a quadratic curve, which is the outer contour line of the expansion section; S5. Determine the outer contour line of the sunken outlet section: In the xy plane, draw line segment BB perpendicular to line segment AB. 1 , line segment BB 1 The length is d 3 ; Point B along the vector Direction bias L 4 distance to reach point F; draw line segment FF perpendicular to line segment AB 1 , line segment FF 1 The length is d 4 ; Take point E 1 As the starting point, point F 1 As the end point, point B 1 A quadratic curve is obtained as the control point, which is the outer contour line of the concave air outlet section; S6. Determine the outer contour line of the connecting section: On the x-y plane, a fillet with a fillet radius of r is provided at the connection between the outer contour line of the expansion section and the outer contour line of the concave air outlet section, and the fillet intersects the outer contour line of the expansion section and the outer contour line of the concave air outlet section at points E 2 and point E 3 ; S7. Determine the two-dimensional model of the semi-pear-shaped film hole structure: Curve C 1 E 2 E 3 F 1 is a two-dimensional model of a semi-pear-shaped air film hole structure; S8. Determine the three-dimensional model of the semi-pear-shaped film hole structure: The rotation axis of the film hole is collinear with the line segment AB; In a three-dimensional coordinate system, curve C 1 E 2 E 3 F 1 Rotate 360° around the rotation axis of the air film hole to obtain a rotating body; Cut the rotating body along the z-axis direction with the inlet wall surface of the blade and the outlet wall surface of the blade to obtain the three-dimensional model of the semi-pear-shaped film hole structure.

2. The design method for a semi-pear-shaped film hole structure for a turbine blade according to claim 1, It is characterized in that Both the divergent section and the sunken outlet section are formed by a quadratic curve rotating 360° around the rotation axis of the film hole, and the included angle between the rotation axis of the film hole and the inlet wall surface of the blade is 30° to 60°.

3. The design method for a semi-pear-shaped film hole structure for a turbine blade according to claim 1, It is characterized in that The connecting section is a structure formed by a fillet connection between the divergent section and the sunken outlet section, and the fillet radius r of the fillet is 4 to 6 mm.

4. The design method for a semi-pear-shaped film hole structure for a turbine blade according to claim 1, It is characterized in that The length of the rotation axis of the film hole between the inlet wall surface of the blade and the outlet wall surface of the blade is the length L of the film hole, and the value range of the length L of the film hole is 20 to 24 mm.

5. The design method for a semi-pear-shaped film hole structure for a turbine blade according to claim 1, It is characterized in that In the step S4, the L 1 = 0.1L, L 2 = 0.3L, L 3 = 0.75L, the length of the line segment CC 1 is d, the length of the line segment DD 1 is d 1 = 5d, the length of the line segment EE 1 is d 2 = 6d, and the value range of d is 0.6 - 1.2 mm.

6. The design method for a semi-pear-shaped film hole structure for a turbine blade according to claim 1, It is characterized in that The curve fullness value Rho of the quadratic curve in step S4 is 0.

7.

7. The design method for a semi-pear-shaped film hole structure for a turbine blade according to claim 1, It is characterized in that In step S5, d 3 = 14d, d 4 = 6d, L 4 = 0.51L.

8. The design method for a semi-pear-shaped film hole structure for a turbine blade according to claim 1, It is characterized in that The curve fullness value Rho of the quadratic curve in step S5 is 0.6.

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