Grooving structure for improving turbine blade air film cooling efficiency

Abstract

The utility model relates to a novel slotting structure for improving the air film cooling efficiency of a turbine blade. The structure comprises a wall surface, an air film hole and a transverse slot. The air film holes are formed in the upstream area of the wall face, the air film holes are in an air film hole shape with the inlet expanded and the outlet flow direction gradually shrunk and expanded in the spanwise direction, the inlet expansion angle is 5-15 degrees, the outlet flow direction gradually shrunk angle is 5-10 degrees, the outlet is in a rounded rectangle shape, and the length of the outlet ranges from 1.5 D to 2D. The transverse groove is formed in the outlet position of the air film hole, the structure is arranged to be in a double-step shape on the downstream groove wall, the step close to the groove bottom is called as the first step, the appearance structure is rectangular, the height of the first step is 0.5 D to 1D, the width of the first step in the main flow direction is 0.5 D to 1D, the bottom of the first step is perpendicular to the groove bottom, the step close to the wall surface is called as the second step, and the outer surface is an arc surface; the tangent line of the highest point coincides with the wall face, the tangent line of the lowest point is perpendicular to the first step surface, and the radius of the arc is 0.5 D-1D. The flow channel design and the step-shaped structure in the cooling structure can effectively improve the air film cooling efficiency.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the category of turbine power device cooling technology, mainly relates to a new type of slotting structure of improving turbine blade gas film cooling efficiency. BACKGROUND

[0002] Gas turbine plays an important role in both energy field and military field, with the need of high thrust-to-weight ratio, the gas turbine turbine inlet temperature is higher and higher, the next generation engine inlet temperature is expected to exceed 2300K, which is far beyond the maximum tolerance temperature of blade high-temperature alloy. The development cycle of new high-temperature resistant material is long and the cost is high, which cannot solve the problem of high temperature of blade surface in a short time. Gas film cooling technology has become one of the important ways to solve this problem due to its high efficiency and low cost. Gas film cooling technology sprays cooling medium through small holes on the surface of high-temperature blade, which adheres to the blade surface under the pressure and friction of the main flow, isolates the high-temperature gas and reduces the heat transfer temperature.

[0003] The geometric conditions and aerodynamic parameters of the hole are two important factors affecting the gas film cooling efficiency, and the structure of the gas film hole can expand the space for improving the performance of the gas turbine. Studies have shown that the slot at the outlet of the gas film hole helps to weaken the influence of the change of jet aerodynamic parameters, while reducing the surface heat transfer coefficient and increasing the spanwise coverage area of the gas film, thereby improving the gas film cooling efficiency.

[0004] The Chinese invention patent with application number 202022258560.0 discloses a "new type of gas film cooling slotting structure", which is provided with a double-ladder structure on the downstream slot wall of the transverse slot, thereby increasing the coverage area of the downstream cooling gas film and improving the spanwise gas film cooling efficiency of the wall surface. Although this structure can improve the gas film cooling efficiency, it does not improve the flow channel of the hole. SUMMARY

[0005] In view of the shortcomings of the above structure, the utility model provides a new slotting structure for improving the turbine gas film cooling efficiency, which optimizes the flow channel and outlet of the jet at the same time, can improve the uniformity of the gas film spanwise coverage, make the gas film more easily adhere to the wall surface, thereby improve the gas film cooling efficiency, suitable for the gas film cooling technology of discrete hole with slotting structure, and the cooling effect is more obvious under higher blowing ratio.

[0006] To achieve the above purpose, the utility model provides a new slotting structure for effectively reducing the surface temperature of turbine blade, which comprises a gas film hole, a transverse slot and a wall surface, the gas film hole is arranged in the upstream area of the wall surface, and the internal reference circle is expanded by a certain angle in the transverse and longitudinal directions to the inlet direction α , the internal reference circle to the hole outlet part is expanded by an angle γThe tapering, the expanding in the spanwise direction, the inner reference circle is located at 1 / 2 of the hole center axis and is perpendicular to the hole center axis, the hole outlet is a rounded rectangle. A transverse slot is arranged at the outlet position of the film hole, and the structure is arranged as a double ladder structure at the downstream slot wall. The ladder close to the slot bottom is called the first ladder, and the outer shape structure is a rectangle. The surface along the slot height direction is perpendicular to the slot bottom. The ladder close to the incoming flow is called the second ladder, and the outer surface is a circular arc surface. The tangent line at the lowest point is perpendicular to the surface of the first ladder, and the tangent line at the highest point is coincident with the wall surface. The spanwise width of the ladder is the same as the spanwise width of the transverse slot, and the spanwise width of the structure is 2.5 D 3.5 D The upstream slot height is 1 D 2 D The downstream first ladder height is 0.5 D 1 D The first ladder width along the main flow direction is 0.5 D 1 D The radius of the second ladder circular arc is 0.5 D 1 D . Wherein D is the diameter of the film hole.

[0007] Further, the ladder structure is located in the downstream region of the corresponding slotted film hole.

[0008] Further, the ladder structure is a symmetrical structure in the spanwise width, and the spanwise width is the same as the spanwise width of the transverse slot.

[0009] Further, the film hole is a shaped hole with an inlet expansion.

[0010] Further, the film hole arranged on the wall surface is a shaped hole with an inlet expansion, and the expansion angle α is 5° ~ 15°, and the included angle β between the film hole and the main flow direction is 25° ~ 50°.

[0011] Further, the film hole flow direction tapering angle γ close to the slot side is 5° ~ 10°, the rounded rectangle length is 1.5 D 2 D , and the spanwise expansion angle is determined by the rounded rectangle length of the outlet.

[0012] Further, the circular arc of the second ladder is a quarter of a circle, and the tangent line at the highest point is coincident with the wall surface and smoothly transitions, and the tangent line at the lowest point is perpendicular to the surface of the first ladder.

[0013] As described above, the cooling structure involved in the utility model can achieve the following effects: the large inlet section can make the cooling airflow more easily flow into the hole, and the gradually tapered structure can accelerate the jet flow to some extent and improve its aerodynamic performance. The outlet is gradually tapered in the flow direction and gradually expanded in the spanwise direction. This structure can weaken the momentum of the jet flow in the lateral direction, reduce the mixing with the main flow, and maintain the aerodynamic performance under the condition of spanwise expansion of the flow passage. The stepped slot structure is arranged in the downstream area of the outlet position, which further increases the spanwise flow of the jet flow in the stepped slot structure. Under the pressure of the main flow, the spanwise distribution of the jet flow is more uniform, which increases the spanwise coverage area of the downstream gas film. At the same time, when the jet flow passes through the circular arc surface of the second step, the Coanda effect occurs, which reduces the upward lifting of the jet flow, weakens the mixing effect of the outlet flow of the gas film hole and the main flow, and effectively improves the stability of the downstream gas film, thereby improving the efficiency of the gas film cooling. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The structure of the gas film hole in the turbine blade in the utility model is shown in the figure

[0015] 1, end wall film hole 3, turbine end wall 4, turbine blade

[0016] 5, turbine blade internal cooling passage 6, blade pressure surface film hole 7, blade suction surface film hole

[0017] Figure 2 The arrangement of the stepped structure in the utility model is shown in the figure

[0018] 1, end wall film hole 2, transverse slot 3, turbine end wall

[0019] 81, first step 82, second step

[0020] Figure 3 The side view of the slotted film hole in the utility model is shown in the figure

[0021] 1, end wall film hole 2, transverse slot 3, turbine end wall

[0022] 81, first step 82, second step

[0023] Figure 4 The top view of the slotted film hole in the utility model is shown in the figure

[0024] 1, end wall film hole 2, transverse slot 3, turbine end wall DETAILED DESCRIPTION

[0025] The structure of the utility model will be further described below in combination with specific embodiments and drawings. Referring to Figures 1 to 4The utility model discloses gas film cooling stepped slot structure includes gas film hole 1, transverse slot 2 and wall 3, and gas film hole sets up in the upstream area of wall face, and the part close to hole import portion is expanded to the import direction with the flow direction by the inside reference circle with angle α 5°~15°, and the inside reference circle is located at the hole center axis 1 / 2 length and is perpendicular to hole center axis, and the part close to export portion is gradually reduced to the export direction by the inside reference circle with angle γ 5°~10°, and the hole export is the round rectangle of 1.5 D ~2 D long. The transverse slot 2 sets up in the export position of gas film hole 1, and the stepped structure is set up on the downstream slot wall of transverse slot 2, and the part close to the slot bottom of stepped structure is first step 81, and the outer surface is rectangle, and the part close to wall face of stepped structure is second step 82, and the outer surface is circular arc surface, and the height of first step is 0.5 D ~1 D , and the width of first step along the main flow direction is 0.5 D ~1 D , and the second step is the quarter circular arc of 0.5 D ~1 D radius and is tangent to blade wall surface, and the spanwise width of stepped structure is same with the spanwise width of transverse slot, and is 2.5 D ~3.5 D , and D the diameter of gas film hole 1 reference circle.

[0026] Specifically, referring to Figure 1 , the turbine blade 4 is provided with internal cooling channel 5, and the gas film hole set up on turbine blade 2 includes blade pressure surface gas film hole 6 and blade suction surface gas film hole 7, and the outlet of both is on the blade surface, and the end wall gas film hole 1 is set up on turbine end wall 3, and the outlet is on the wall surface of end wall 3.

[0027] The stepped cooling structure of the utility model discloses that the gas film hole set up on turbine blade 4 and turbine end wall 3 is multiple, and the size is not completely same, and the size specification of stepped structure is determined by its corresponding gas film hole, and the utility model discloses the entrance expansion special-shaped gas film hole.Gas film hole 1 is distributed in multiple rows in the transverse direction, and the included angle between gas film hole 1 and main flow direction is β 25°~50°.

[0028] The utility model discloses a turbine blade cooling structure, which comprises a turbine end wall, a plurality of turbine blades arranged on the turbine end wall, a plurality of gas film holes arranged on the turbine end wall, and a plurality of transverse grooves arranged on the turbine end wall.

[0029] The following is an embodiment of the utility model:

[0030] Referring to Figure 2 , the gas film holes 1 are arranged on the turbine end wall wall surface 3, the transverse grooves 2 are arranged at the outlet positions of the gas film holes, the ladder-shaped structures are arranged on the downstream groove walls of the transverse grooves 2, the gas film holes 1 are special-shaped holes inclined along the main flow direction, the expansion angle α =10°, the inclination angle β =35°, the taper angle γ =5°, the diameter of the gas film hole D =10 mm , the length of the round rectangle is 1.5 D =15 mm , the height of the gas film hole H =3 D= 30 mm , the height of the first ladder 81 is 0.5 h =0.5 D =5 mm , the width of the first ladder 81 along the main flow direction is 0.5 l =0.5 D =5 mm , the radius of the arc of the second ladder 82 is 0.5 R =0.5 D =5 mm , the highest point of the second ladder 82 is tangent to the wall surface, the depth of the transverse groove has a great influence on the gas film cooling efficiency and is not easy to be too deep, and the depth is taken as 1.2 D =12 mm here. The wider the transverse groove 2 is, the better the adhesion of the cooling jet is, the cooling gas film will cover the entire downstream area of the outlet position of the gas film hole 1, and the gas film cooling efficiency will also be improved, so that, in the embodiment, the total distance from the vertical wall surface upstream of the transverse groove to the gas film hole 1 and from the first ladder 81 to the gas film hole 1 is 2 D= 20 mm .

[0031] In the embodiment, high-temperature gas flows through the hot side surface, the cooling jet enters at the gas film hole entrance, flows into the stepped structure through the gas film hole 1, the slotted structure and the rounded rectangular outlet can increase the spanwise flow of the cooling jet, and the arc-shaped outer surface of the second step 82 is favorable to improve the wall adhesion of the cooling jet, thereby improving the gas film cooling efficiency.

[0032] In summary, the utility model overcomes the shortcomings in the prior art, combines the optimized gas film hole structure and the slotted structure, and can effectively improve the gas film cooling efficiency.

[0033] The above embodiment is only for illustrating the principle and function of the utility model, and professionals familiar with the technology can modify it on the basis.

Claims

1. A slotted structure for improving the effectiveness of film cooling of a turbine blade, comprising a film hole, a transverse slot, and a wall surface, characterized by The gas film hole passage structure is optimized, the inlet expanded gas film hole is arranged on the wall surface, the internal reference circle to the hole outlet part is tapered in the flow direction and expanded in the span direction, the transverse slot structure is arranged at the outlet position of the gas film hole, and the downstream slot wall of the transverse slot is arranged in a double-ladder structure, the first ladder shape structure is rectangular, the surface along the slot height direction is perpendicular to the slot bottom, the second ladder outer surface is a circular arc surface, the tangent line at the lowest point is perpendicular to the first ladder surface, and the tangent line at the highest point is coincident with the wall surface; the ladder span direction width is the same as the transverse slot span direction width, the span direction width is 2.5 D ~3.5 D , the upstream slot height is 1 D ~2 D , the first ladder height is 0.5 D ~1 D , the first ladder width along the main flow direction is 0.5 D ~1 D , and the radius of the second ladder circular arc is 0.5 D ~1 D , wherein D is the diameter of the gas film hole.

2. The slotted structure for improving the film cooling effectiveness of turbine blade according to claim 1, wherein The number of steps of the double-step structure is 2.

3. The slotted structure for improving the film cooling effectiveness of turbine blade according to claim 1, wherein The outer shape of the first step is rectangular, the surface along the groove height direction is perpendicular to the groove bottom, the height is 0.5 D ~1 D , and the width is 0.5 D ~1 D .

4. The slotted structure for improving the film cooling effectiveness of turbine blade according to claim 1, wherein The outer surface of the second step is a circular arc surface with a radius of 0.5 D ~1 D .

5. The slotted structure for improving the film cooling effectiveness of turbine blade according to claim 1, wherein The spanwise width of the transverse slot at the upstream end is 2.5 D ~3.5 D .

6. The slotted structure for enhancing the film cooling effectiveness of turbine blade according to claim 1, wherein The transverse slot is 1 upstream of the slot height D ~2 D .

7. The slotted structure for enhancing the film cooling effectiveness of turbine blade according to claim 1, wherein The gas film hole is a special-shaped gas film hole which is expanded by 5°-15° in the entrance direction of the reference circle located at 1 / 2 of the hole center axis.

8. The slotted structure for enhancing the film cooling effectiveness of turbine blade according to claim 1, wherein The gas film hole outlet shape is a 1.5 D ~2 D rounded rectangle, the gas film hole channel is tapered from a reference circle located at 1 / 2 of the hole center axis to the outlet direction at an angle of 5° ~10°, and the angle of expansion is determined by the length of the rounded rectangle at the outlet.

9. The slotted structure for enhancing the film cooling effectiveness of turbine blade according to claim 1, wherein The angle between the gas film hole and the main flow direction is 25°-50°.

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