Large-expansion-ratio centripetal turbine blade and turbine engine with same

Abstract

The invention relates to the technical field of turbine blade structures, and discloses a large-expansion-ratio centripetal turbine blade and a turbine engine with the large-expansion-ratio centripetal turbine blade. The large-expansion-ratio centripetal turbine blade comprises a movable blade body, a damping groove is formed in the blade top of the movable blade body, the damping groove is formed in the extending direction of the blade top, a damping block is arranged in the damping groove, a bottom gap is reserved between the damping block and the bottom of the damping groove, and the bottom gap is formed between the damping block and the bottom of the damping groove. A pressure side gap and a suction side gap are formed in the two sides, perpendicular to the extending direction of the damping groove, of the damping block. A blade top gap is suitable for being reserved between the blade top of the movable blade body and an installation casing, and the blade top gap is communicated with the blade tip of the movable blade body. After blade top clearance flow enters the damping groove, the damping block can guide the flow direction of clearance secondary flow and prevent the clearance secondary flow from being rolled up in the damping groove to form a vortex structure, flow loss is reduced, the hindering effect of the clearance secondary flow on the clearance flow can be enhanced, and therefore the leakage flow is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of turbine blade structures, and particularly to a high-expansion-ratio centripetal turbine blade and a turbine engine having the same. Background Art

[0002] In a centripetal turbine blade, in order to avoid friction between the centripetal turbine blade and the casing, there is a clearance between the blade tip and the casing. Under the action of the pressure difference on both sides of the blade, the fluid flows from the pressure side to the suction side to generate leakage flow. The existence of the tip leakage flow not only reduces the blade load near the tip, blocks the mainstream of the channel, but also has an important impact on the aerodynamic performance of the turbine.

[0003] Currently, in the leakage flow suppression structure for centripetal turbines, in terms of the casing structure, there are mainly drag reduction-jet coupling structures, circumferential seal grooves, axial seal grooves, and honeycomb seals. In terms of the blade tip structure, there is mainly a concave slot structure. However, in a high-expansion-ratio and high-speed centripetal turbine, such structures may have a greater impact on the flow field structure, causing the actual operating conditions to deviate from the design point, resulting in an increase in flow loss while suppressing the leakage flow. Summary of the Invention

[0004] In view of this, the present invention provides a high-expansion-ratio centripetal turbine blade and a turbine engine having the same, so as to solve the problem that the leakage flow suppression structure of the centripetal turbine causes an increase in flow loss when applied to a high-expansion-ratio and high-speed centripetal turbine.

[0005] In a first aspect, the present invention provides a high-expansion-ratio centripetal turbine blade, comprising:

[0006] A moving blade body, at the tip of which there is a damping groove arranged along the extending direction of the blade tip. A damping block is arranged in the damping groove, and there is a bottom clearance reserved between the damping block and the bottom of the damping groove. Pressure-side clearances and suction-side clearances are arranged on both sides of the damping block perpendicular to the extending direction of the damping groove;

[0007] The tip of the moving blade body is adapted to have a tip clearance reserved with the installation casing, and the tip clearance communicates with the tip of the moving blade body.

[0008] In the axial clearance section at the inlet end of the centripetal turbine blade, the airflow in the tip clearance is mainly driven by the scraping flow, which to a certain extent inhibits the tip clearance leakage flow driven by the circumferential pressure difference between the suction surface and the pressure surface. A tip clearance is reserved between the tip of the rotor blade body and the mounting casing, and the tip clearance is connected to the blade tip, so that the tip leakage flow flows from the pressure side of the blade to the suction side through the tip clearance, and then enters the mainstream flow channel and mixes with the mainstream. In view of the leakage flow characteristics at the leading edge of the blade, damping grooves are arranged at the tip of the blade body of the centripetal turbine blade with a large expansion ratio. The damping grooves are arranged along the extension direction of the blade tip, and damping blocks are arranged in the damping grooves. A bottom clearance is reserved between the damping block and the groove bottom, and a pressure side clearance and a suction side clearance are arranged on both sides. When the tip clearance flow enters the damping groove, the damping block will guide the flow direction of the clearance secondary flow, prevent the clearance secondary flow from rolling up in the damping groove to form a vortex structure, reduce the flow loss, and further enhance the blocking effect of the clearance secondary flow on the clearance flow, thereby reducing the leakage flow rate.

[0009] In an alternative embodiment, a guiding portion is provided on the tip side of the trailing edge region of the rotor blade body, and a guiding deflection angle is provided between the extending direction of the guiding portion and the extending direction of the tip of the rotor blade body.

[0010] In the radial clearance at the outlet section of the rotor blade body, due to the reduction of the radius of the rotor blade body, the influence of the scraping flow gradually decreases, and the leakage flow dominates. In view of the leakage flow characteristics at the trailing edge, the direction of the leakage flow is changed by adopting a guiding groove, a guiding hole or other shaped guiding structures as the guiding portion, so as to reduce the included angle between the leakage flow and the mainstream, reduce the mixing loss, and improve the turbine efficiency.

[0011] In an alternative embodiment, a plurality of guiding portions are arranged at intervals along the extending direction of the tip of the rotor blade body. By arranging a plurality of guiding portions at intervals, the direction of the leakage flow can be guided more evenly. The plurality of guiding portions respectively guide the leakage flows at different positions, so that the direction of the leakage flow is gradually adjusted, thereby more effectively reducing the included angle between the leakage flow and the mainstream, reducing the mixing loss, and further improving the turbine efficiency.

[0012] In an alternative embodiment, the guiding portion is arranged at a position in the meridian chord length region of 80% - 100% on the tip side. Since the included angle between the leakage flow and the mainstream is relatively large near the trailing edge of the blade tip, arranging the guiding portion in this region can specifically change the direction of the leakage flow to make it closer to the flow direction of the mainstream, thereby reducing the mixing loss between the two and improving the operating efficiency of the turbine.

[0013] In an alternative embodiment, the depth of the damping groove is 1 to 5 times the height of the tip clearance. When the depth of the damping groove reaches a certain multiple of the height of the tip clearance, it can more effectively guide the flow direction of the secondary flow in the clearance, avoid the formation of vortex structures, enhance the obstruction to the clearance flow, thereby reducing the leakage flow rate and improving the aerodynamic performance of the turbine. Optimally, the depth of the damping groove is 2 times the height of the tip clearance.

[0014] In an alternative embodiment, the height of the bottom clearance is 0.3 to 0.8 times the depth of the damping groove. This ensures that there is enough space between the damping block and the bottom of the damping groove for the clearance flow to pass through, while not being too large to weaken the obstruction effect of the damping block on the clearance flow, maximizing the guiding effect of the damping block and reducing the leakage flow rate.

[0015] In an alternative embodiment, the rib width between the damping groove and the pressure side of the moving blade body is 0.5 to 1.5 times the height of the tip clearance. It can effectively control the flow direction of the secondary flow in the clearance, avoid the formation of vortex structures by the secondary flow in the clearance on the pressure side, thereby enhancing the obstruction effect of the damping groove on the clearance flow, reducing the leakage flow rate, and having a positive impact on the aerodynamic performance of the turbine.

[0016] In an alternative embodiment, the width of the damping block is not less than one-third of the width of the damping groove. This can ensure that the damping block has sufficient coverage area in the damping groove, thus more effectively guiding the flow direction of the secondary flow in the clearance, avoiding the formation of vortex structures, enhancing the obstruction effect on the clearance flow, and effectively reducing the leakage flow rate and improving the turbine efficiency.

[0017] In an alternative embodiment, the ratio of the width of the pressure side clearance to the width of the suction side clearance changes with the position of the airflow direction. According to the flow state and pressure distribution of the airflow at different positions at the blade tip, the flow velocity and flow direction of the secondary flow in the clearance are dynamically adjusted, so as to more effectively control the clearance flow in the entire blade tip region, reduce the leakage flow rate, and reduce the mixing loss, improving the overall performance of the turbine.

[0018] In a second aspect, the present invention also provides a turbine engine, including the large expansion ratio centripetal turbine blade of the present invention. Since the turbine engine includes the large expansion ratio centripetal turbine blade and has the same effects as the large expansion ratio centripetal turbine blade, it will not be elaborated here. Description of the Drawings

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 It is a schematic diagram of the air flow inside the centripetal turbine blade with a large expansion ratio in the embodiment of the present invention. The arrow direction in the figure is the air flow direction.

[0021] Figure 2 It is a schematic structural diagram of the moving blade body provided by the embodiment of the present invention.

[0022] Figure 3 It is a schematic structural diagram of the leading edge part of the moving blade body provided by the embodiment of the present invention.

[0023] Figure 4 is Figure 3 the sectional view in the A-A direction in

[0024] Figure 5 It is a schematic structural diagram of the moving blade body from another perspective provided by the embodiment of the present invention.

[0025] Figure 6 It is a schematic structural diagram of the trailing edge part of the moving blade body provided by the embodiment of the present invention.

[0026] Explanation of reference numerals: 1, guide vane; 2, mounting casing; 3, moving blade body; 4, mounting hub; 5, tip clearance; 6, back clearance; 7, damping groove; 8, damping block; 9, guide groove. Specific embodiments

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0028] The leakage flow loss caused by the gap between the centripetal turbine blade and the casing is mainly divided into two parts. One is that the existence of the leakage flow reduces the mainstream flow rate, resulting in less mainstream work. The other is that when the leakage flow mixes with the mainstream, mixing loss will occur, leading to a reduction in the mainstream energy. Approximately one-third of the flow loss in the centripetal turbine blade is caused by the leakage flow through the tip clearance 5.

[0029] The tip clearance 5 is affected by structural shape, deformation, vibration, machining accuracy, etc. The clearance size is not too small, and the leakage flow loss is still the main component of the turbine flow loss. Different from the axial-flow turbine where there is only a radial clearance at the tip, due to the characteristics of the centripetal impeller with radial inflow and axial outflow of the air flow, at the inlet section of the impeller, the clearance between the impeller and the casing is in the axial direction, and then gradually changes from axial to radial. At the outlet of the impeller, it shows the same radial clearance as the axial-flow turbine. This difference in structure leads to a large difference in the tip clearance leakage flow between the centripetal turbine and the axial-flow turbine. The leakage flow suppression structure applicable to the axial-flow turbine may not necessarily be applicable to the centripetal turbine.

[0030] In the common tip cavity structure, due to the existence of the cavity, the clearance flow is divided into two parts: the clearance main flow and the clearance secondary flow that flows into the cavity. The clearance secondary flow flows out from the rear of the cavity. Since this part of the fluid has an angle with the clearance main flow, it prevents the clearance flow from flowing out, thereby achieving the purpose of reducing the leakage flow. However, the entering cavity fluid will form vortex structures such as pressure-side corner vortices, suction-side corner vortices, and cavity vortices inside the cavity, weakening the obstructive effect of the cavity structure on the clearance flow. In addition, in the centripetal turbine with a large expansion ratio and high rotational speed, the pressure difference between the two sides of the blade in the axial clearance section at the inlet of the centripetal impeller is small, and the clearance flow is mainly driven by the scraping flow. This makes the internal flow direction of the conventional cavity structure opposite to the leakage flow direction, moving from the suction side to the pressure side, further reducing the inhibitory effect of the tip cavity structure on the clearance flow.

[0031] Based on this, the present invention provides a centripetal turbine blade with a large expansion ratio, including a tip leakage flow suppression structure applicable to the centripetal turbine blade with a large expansion ratio. Using this structure, the clearance secondary flow is guided to flow in the middle and front parts of the blade, avoiding it from rolling up to form vortex structures, and thus enhancing its obstructive effect on the clearance flow. At the tail of the blade, the angle between the leakage flow and the main flow is reduced, the mixing loss is reduced, and the turbine efficiency is improved. The numerical results show that this structure effectively reduces the leakage flow rate and improves the turbine efficiency.

[0032] The following combines Figures 1 to 6 , and describes the embodiments of the present invention.

[0033] According to an embodiment of the present invention, on the one hand, a centripetal turbine blade with a large expansion ratio is provided, wherein:

[0034] A damping groove 7 is provided at the tip of the moving blade body 3. The damping groove 7 is arranged along the extending direction of the tip. A damping block 8 is arranged in the damping groove 7. A bottom clearance is reserved between the damping block 8 and the bottom of the damping groove 7. Pressure-side clearances and suction-side clearances are provided on both sides of the damping block 8 perpendicular to the extending direction of the damping groove 7. The tip of the moving blade body 3 is adapted to leave a tip clearance 5 between it and the mounting casing 2, and the tip clearance 5 is communicated with the tip of the moving blade body 3.

[0035] In the axial clearance section at the inlet end of the centripetal turbine blade, the air flow in the tip clearance 5 is mainly driven by the scraping flow, which to a certain extent inhibits the tip clearance 5 leakage flow driven by the circumferential pressure difference between the suction surface and the pressure surface. A tip clearance 5 is reserved between the tip of the moving blade body 3 and the mounting casing 2, and the tip clearance 5 is communicated with the blade tip, so that the tip leakage flow flows from the pressure side of the blade to the suction side through the tip clearance 5, and then enters the mainstream flow channel and mixes with the mainstream. In view of the leakage flow characteristics at the leading edge of the blade, damping grooves 7 are arranged at the tip of the blade body of the high-expansion-ratio centripetal turbine blade. The damping grooves 7 are arranged along the extension direction of the blade tip, and damping blocks 8 are arranged in the damping grooves 7. A bottom clearance is reserved between the damping blocks 8 and the groove bottom, and a pressure-side clearance and a suction-side clearance are arranged on both sides. When the tip clearance 5 flow enters the damping grooves 7, the damping blocks 8 will guide the flow direction of the clearance secondary flow, prevent the clearance secondary flow from rolling up in the damping grooves 7 to form a vortex structure, reduce the flow loss, and further enhance the hindering effect of the clearance secondary flow on the clearance flow, thereby reducing the leakage flow rate.

[0036] In this embodiment, a guide part is arranged on the tip side of the trailing edge region of the moving blade body 3, and a guide deflection angle is arranged between the extension direction of the guide part and the extension direction of the tip of the moving blade body 3. In this embodiment, the guide part is selected as a guide groove. In the radial clearance at the outlet section of the moving blade body 3, due to the decrease in the radius of the moving blade body 3, the influence of the scraping flow gradually decreases, and the leakage flow dominates. In view of the leakage flow characteristics at the trailing edge, by adopting a guide groove, a guide hole or other shaped guide structures as the guide part to change the leakage flow direction, the included angle between the leakage flow and the mainstream can be reduced, the mixing loss can be reduced, and the turbine efficiency can be improved.

[0037] Furthermore, along the extension direction of the tip of the moving blade body 3, a plurality of guide parts are arranged at intervals. By arranging a plurality of guide parts at intervals, the leakage flow direction can be guided more evenly. The plurality of guide parts respectively guide the leakage flow at different positions, gradually adjust the leakage flow direction, so as to more effectively reduce the included angle between the leakage flow and the mainstream, reduce the mixing loss, and further improve the turbine efficiency.

[0038] In one embodiment, the guide part is arranged at the position of the 80% - 100% meridional chord length region on the tip side.

[0039] Since the included angle between the leakage flow and the mainstream is relatively large near the tip trailing edge, arranging the guide part in this region can specifically change the leakage flow direction to make it closer to the mainstream flow direction, thereby reducing the mixing loss between the two and improving the operating efficiency of the turbine.

[0040] In one embodiment, the depth of the damping groove 7 is 1 - 5 times the height of the tip clearance 5.

[0041] When the depth of the damping groove 7 reaches a certain multiple of the height of the tip clearance 5, it can more effectively guide the flow direction of the clearance secondary flow, avoid the formation of vortex structures, enhance the obstruction to the clearance flow, thereby reducing the leakage flow rate and improving the aerodynamic performance of the turbine. Optimally, the depth of the damping groove 7 is twice the height of the tip clearance 5.

[0042] In one embodiment, the height of the bottom clearance is 0.3 to 0.8 times the depth of the damping groove 7.

[0043] Ensure that there is enough space between the damping block 8 and the bottom of the damping groove 7 for the clearance flow to pass through, and at the same time, it is not too large to weaken the obstruction effect of the damping block 8 on the clearance flow, maximizing the guiding effect of the damping block 8 and reducing the leakage flow rate.

[0044] In one embodiment, the rib width between the damping groove 7 and the pressure side of the moving blade body 3 is 0.5 to 1.5 times the height of the tip clearance 5. It can effectively control the flow direction of the clearance secondary flow, avoid the formation of vortex structures by the clearance secondary flow on the pressure side, thereby enhancing the obstruction effect of the damping groove 7 on the clearance flow, reducing the leakage flow rate, and having a positive impact on the aerodynamic performance of the turbine.

[0045] In one embodiment, the width of the damping block 8 is not less than one-third of the width of the damping groove 7. It can ensure that the damping block 8 has sufficient coverage area in the damping groove 7, thereby more effectively guiding the flow direction of the clearance secondary flow, avoiding the formation of vortex structures, enhancing the obstruction effect on the clearance flow, and effectively reducing the leakage flow rate and improving the turbine efficiency.

[0046] In one embodiment, the ratio of the width of the pressure side clearance to the width of the suction side clearance changes with the airflow direction position. According to the flow state and pressure distribution of the airflow at different positions at the tip, the flow velocity and flow direction of the clearance secondary flow are dynamically adjusted, so as to more effectively control the clearance flow in the entire tip region, reduce the leakage flow rate, and reduce the mixing loss, improving the overall performance of the turbine.

[0047] The leakage flow suppression structure in the large expansion ratio centripetal turbine blade provided in this embodiment is arranged at the blade top for reducing the tip leakage flow rate. As Figure 1 shown, the centripetal turbine mainly includes a guide vane 1, a mounting casing 2, a moving blade body 3, and a mounting hub 4. A plurality of guide vanes 1 and moving blade bodies 3 are evenly distributed circumferentially to form a stator and a rotor, and their quantity, geometric shape, structural dimensions, etc. are determined by design parameters. The working fluid enters from the inlet of the guide vane 1, is accelerated and its flow direction is changed by the guide vane 1, and then enters from the inlet of the moving blade body 3, pushing the moving blade body 3 to rotate and do work. While the airflow does work in the impeller, its flow direction also changes.

[0048] The guide vane 1 is installed in the casing. The outlet end of the guide vane 1 is communicated with the moving blade body 3. A tip clearance 5 is provided between the tip of the moving blade body 3 and the inner cavity of the casing. The tip clearance 5 is communicated with the tip of the moving blade body 3. The mounting hub 4 is installed on the moving blade body 3. A back clearance 6 is provided between one side of the mounting hub 4 away from the moving blade body 3 and the casing. Both the tip clearance 5 and the back clearance 6 are communicated with the tip of the moving blade body 3.

[0049] In a radial inflow turbine, in addition to the mainstream fluid, there are two additional fluids inside the impeller, namely the back seal flow passing through the back clearance 6 and the tip leakage flow passing through the tip clearance 5. The back seal flow passes through the back of the mounting hub 4 and the back cavity of the mounting hub 4 and enters the tip through the back clearance 6. The tip leakage flow flows from the pressure side to the suction side of the blade through the tip clearance 5, and then enters the mainstream flow passage and mixes with the mainstream.

[0050] The losses caused by the leakage flow are mainly affected by the pressure difference between the pressure surface and the suction surface at the tip and the scraping flow generated by the relative movement between the tip and the mounting casing 2. The loss mechanisms of the two are not the same. Through experiments, it is found that in the axial clearance section at the inlet of the radial inflow impeller, the clearance flow is mainly driven by the scraping flow, which to a certain extent inhibits the tip clearance 5 leakage flow driven by the circumferential pressure difference between the suction surface and the pressure surface. In the radial clearance at the outlet of the impeller, due to the reduction of the impeller radius, the influence of the scraping flow gradually decreases, and the leakage flow dominates. In view of the different leakage flow characteristics of the leading edge and the trailing edge, the radial inflow turbine blade with a large expansion ratio provided in this embodiment adopts different leakage flow control structures at the leading edge and the trailing edge of the tip to reduce the leakage flow.

[0051] A tip flow damping structure is provided at the leading edge position of the tip, such as Figures 2 to 4As shown, the blade tip flow damping structure composed of the damping groove 7 and the damping block 8 guides the flow direction of the gap secondary flow in the blade tip gap 5, avoids the gap secondary flow from rolling up to form a vortex structure, and then enhances its blocking effect on the gap flow, so as to achieve the purpose of reducing the leakage flow. The blade tip flow damping structure is arranged at the blade tip in the 10%-70% meridian chord length area, and is mainly controlled by six parameters, namely the depth H1 of the damping groove 7, the height H2 of the bottom gap, the rib width W between the damping groove 7 and the pressure side of the moving blade body 3, the width W1 of the pressure side gap, the width W2 of the damping block 8, and the width W3 of the suction side gap. When the depth of the damping groove 7 is twice the height of the blade tip gap 5, the turbine aerodynamic performance is optimal. Further considering the aerodynamic characteristics of the structure of the present invention, it is recommended that the depth H1 of the damping groove 7 ranges from 1 to 5 times the height of the blade tip gap 5, and the height H2 of the bottom gap ranges from 0.3 to 0.8 times the depth of the damping groove 7. In the axial gap section at the inlet of the centrifugal impeller, the pressure difference on both sides of the blade is small, and the gap flow is mainly driven by the scraping flow, which makes the flow direction inside the damping device opposite to the leakage flow direction, moving from the suction side to the pressure side. In the gap flow, the jet in the separation bubble has a greater impact on the gap throat area, and the normalized separation bubble length is about 0.5-1.5. Therefore, in order to ensure that the structure has a good leakage flow suppression effect, the optimal value range of the rib width W between the damping groove 7 and the pressure side of the moving blade body 3 should be 0.5 to 1.5 times the height of the blade tip gap 5. It is recommended that the width W2 of the damping block 8 is not less than one-third of the width of the damping groove 7. The gap secondary flow velocity can be controlled by adjusting the width W1 of the pressure side gap and the width W3 of the suction side gap. Considering that the pressure ratio on both sides of the centrifugal turbine blade tip gradually increases along the flow direction, the ratio of W1 to W3 should change with the flow position to achieve the best suppression effect.

[0052] A blade tip guide structure is provided at the leading edge of the blade tip, such as Figure 5 and Figure 6 As shown, a guide groove is provided at the blade top position at the trailing edge of the moving blade body 3. The angle between the leakage flow and the mainstream is large near the trailing edge area of ​​the blade of the moving blade body 3, which causes more mixing losses. The use of guide grooves, guide holes or other shapes of guide structures can change the direction of the leakage flow, reduce the angle between the leakage flow and the mainstream, reduce the mixing loss, and improve the turbine efficiency. The guide groove structure is arranged at the blade top position in the 80%-100% meridian chord length area. The guide groove structure used in this embodiment is controlled by three parameters, namely the guide groove height H3, the guide groove depth W4 and the guide groove deflection angle θ. Among them, the guide groove height H3 and the guide groove depth W4 control the guide groove size, and the guide groove deflection angle θ controls the flow direction of the fluid in the guide groove.

[0053] The centripetal turbine tip leakage flow suppression structure provided by this embodiment can effectively reduce the leakage flow rate and improve the turbine efficiency by specifically treating the leakage flows at different positions. It guides the secondary flow in the clearance at the middle and front parts of the blade to avoid its rolling up to form a vortex structure, thereby enhancing its obstruction effect on the clearance flow. In the tail region of the blade, the included angle between the leakage flow and the mainstream is reduced to decrease the mixing loss and improve the turbine efficiency. The sub-region design is adopted, and different tip structures are designed according to different positions and flow mechanisms at the tip. In addition, this structural design has a large degree of freedom and strong adaptability to the geometric shape and operating conditions of a high-expansion-ratio centripetal turbine.

[0054] According to an embodiment of the present invention, on the other hand, a turbine engine is further provided, which includes the high-expansion-ratio centripetal turbine blade provided by this embodiment. By installing the high-expansion-ratio centripetal turbine blade provided by this embodiment, when the air flow moves inside the turbine engine to the position of the moving blade body 3, when the tip clearance 5 flow enters the damping groove 7, the damping block 8 will guide the flow direction of the secondary flow in the clearance, preventing the secondary flow in the clearance from rolling up to form a vortex structure in the damping groove 7, reducing the flow loss, and thus being able to enhance the obstruction effect of the secondary flow in the clearance on the clearance flow, thereby reducing the leakage flow rate. When the tip leakage flow flows into the guiding groove 9, the guiding groove can change the direction of the leakage flow, thereby reducing the included angle between the leakage flow and the mainstream, decreasing the mixing loss, and improving the turbine efficiency.

[0055] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A large expansion ratio centripetal turbine blade, characterized in that, Comprising: A rotor blade body (3), at the tip of which a damping groove (7) is provided. The damping groove (7) is arranged along the extending direction of the tip. A damping block (8) is arranged in the damping groove (7). A bottom gap is reserved between the damping block (8) and the bottom of the damping groove (7). Pressure-side gaps and suction-side gaps are provided on both sides of the damping block (8) perpendicular to the extending direction of the damping groove (7); A tip gap (5) is reserved between the tip of the rotor blade body (3) and the installation casing (2), and the tip gap (5) communicates with the tip of the rotor blade body (3).

2. The centripetal turbine blade with a large expansion ratio according to claim 1, characterized in that A guiding portion is provided on the tip side of the trailing edge region of the rotor blade body (3), and a guiding deflection angle is provided between the extending direction of the guiding portion and the extending direction of the tip of the rotor blade body (3).

3. The large expansion ratio centripetal turbine blade according to claim 2, characterized in that Along the extending direction of the tip of the rotor blade body (3), a plurality of the guiding portions are arranged at intervals.

4. The large expansion ratio centripetal turbine blade according to claim 2 or 3, characterized in that, The guiding portion is arranged at a position in the 80% - 100% meridional chord length region on the tip side.

5. The centripetal turbine blade with a large expansion ratio according to any one of claims 1 to 3, characterized in that The depth of the damping groove (7) is 1 - 5 times the height of the tip gap (5).

6. The large expansion ratio centripetal turbine blade according to any one of claims 1 to 3, characterized in that The height of the bottom gap is 0.3 - 0.8 times the depth of the damping groove (7).

7. The large expansion ratio centripetal turbine blade according to any one of claims 1 to 3, characterized in that The rib width between the damping groove (7) and the pressure side of the rotor blade body (3) is 0.5 - 1.5 times the height of the tip gap (5).

8. The large expansion ratio centripetal turbine blade according to any one of claims 1 to 3, characterized in that The width of the damping block (8) is not less than one-third of the width of the damping groove (7).

9. The centripetal turbine blade with a large expansion ratio according to any one of claims 1 to 3, characterized in that The ratio of the width of the pressure-side gap to the width of the suction-side gap changes with the position of the airflow direction.

10. A turbine engine, characterized in that, Comprising the large expansion ratio centripetal turbine blade according to any one of claims 1 to 9.

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