Composite sealing structure for turbine rim of gas turbine

Abstract

The invention discloses a composite sealing structure for a turbine rim of a gas turbine. Comprising a turbine static disc (1) and a turbine movable disc (2), a gap is formed between the turbine static disc (1) and the turbine movable disc (2), a static disc flange plate (3) and a static disc rib plate (6) are arranged in the rim area of the turbine static disc (1), and a movable disc flange plate (4), movable disc high-position fins (5) and movable disc low-position fins (7) are arranged in the rim area of the turbine movable disc (2). The movable disc flange plate (4) and the static disc flange plate (3) are opposite in the axial direction, the movable disc high-position fins (5) are located between the static disc flange plate (3) and the static disc rib plates (6) in the radial direction, and the movable disc low-position fins (7) are located below the static disc rib plates (6) in the radial direction. The efficient sealing effect is achieved under the condition that small cold air flow is introduced, interference loss caused by interaction between cold air flow and main flow at the rim is reduced, and the convective heat exchange performance at the rim is improved.

Description

Technical Field

[0001] The invention relates to the technical field of gas turbine turbine disk interstage wheel rim sealing, and in particular to a gas turbine turbine wheel rim composite sealing structure. Background Art

[0002] Among the many hot end parts of the turbine that need to be cooled, the cooling of the turbine disc cavity is an extremely critical link. Due to the gap between the turbine stator disc and the rotating disc, the mainstream high-temperature and high-pressure gas will invade the disc cavity through this gap. In order to achieve efficient cooling of the turbine disc cavity, the high-pressure cold air delivered by the compressor components is often introduced into the turbine disc cavity to increase the pressure in the disc cavity, thereby preventing the high-temperature gas in the mainstream channel of the turbine from invading the disc cavity and achieving a sealing effect at the wheel rim. This part of the cold air used to prevent the high-temperature gas from invading the disc cavity is called sealing cold air. The larger the injected cold air flow, the better the sealing effect, but a large cold air flow will lead to a decrease in turbine efficiency and cause complex flow changes in the mainstream channel of the turbine. According to research, a 1% increase in gas intrusion can reduce the life of the turbine disc by half, and a 50% reduction in the sealing flow can increase the turbine efficiency by 0.5%, and correspondingly reduce the fuel consumption rate by 0.9%. Regarding the phenomenon of gas intrusion, domestic and foreign research has found that its intrusion mechanism is mainly "rotation-induced intrusion", "outer ring-induced intrusion" and "mainstream and rotation combined induced intrusion". It is mainly manifested in the combined effect of the rotor disk pump effect, the turbine guide vane wake and the rotor blade leading edge potential field. The interstage flow field will form circumferential pressure non-uniformity at the rim gap. When a pressure difference is formed above and below the rim surface, gas intrusion or sealed outflow will generally occur.

[0003] Based on the above-mentioned gas intrusion characteristics at the wheel rim, Chinese patent CN105134306 sets a honeycomb structure on the raised fins of the moving disk to enhance the flow resistance, but the honeycomb structure it introduces is too complex and has the problem of great processing difficulty. Chinese patents CN109779696 and CN201610820605 add auxiliary jet holes on the basis of the fish mouth sealing structure to enhance the sealing and cooling effect at the wheel rim. The problem it brings is that an additional cold air path needs to be set up, which increases the complexity of the secondary air system of the gas turbine. Summary of the invention

[0004] The purpose of the present invention is to provide a composite sealing structure for a gas turbine wheel rim, which can achieve a high efficiency sealing effect when introducing a small cold air flow, reduce the interference loss caused by the interaction between the cold air flow and the main flow at the wheel rim, and improve the convective heat exchange performance at the wheel rim.

[0005] Technical solution. A gas turbine turbine rim composite sealing structure, comprising a turbine stator and a turbine rotor, wherein a gap is provided between the turbine stator and the turbine rotor, and characterized in that: the turbine stator rim region is provided with a stator flange plate and a stator rib plate, and the turbine rotor rim region is provided with a rotor flange plate, a rotor high-position fin, and a rotor low-position fin; the rotor flange plate is axially opposite to the stator flange plate, the rotor high-position fin is radially located between the stator flange plate and the stator rib plate, and the rotor low-position fin is radially located below the stator rib plate.

[0006] In the aforementioned gas turbine turbine wheel rim composite sealing structure, the lower edge corner of the stator disc flange plate is chamfered, and the upper edge corner of the moving disc flange plate is chamfered. After the chamfering treatment, the stator disc flange plate and the moving disc flange plate form a quasi-oblique 45° sealing structure, and the axial clearance α between the stator disc flange plate and the moving disc flange plate is set to D.

[0007] In the aforementioned gas turbine turbine wheel rim composite sealing structure, the moving disk high-position fin is L-shaped, and the moving disk high-position fin and the stationary disk flange plate form a high-position radial seal and form a groove cavity A, and the high-position radial gap β1 is set to D~1.5D.

[0008] In the aforementioned gas turbine turbine wheel rim composite sealing structure, the stator disk ribs are L-shaped, the stator disk ribs and the moving disk high-position fins form a mid-radial seal and form a buffer cavity B, and the mid-radial gap β2 is set to D~1.5D.

[0009] In the aforementioned gas turbine turbine wheel rim composite sealing structure, the low-position fins of the moving disk are arranged as inclined fins, and the inclination direction is directly opposite to the root of the static disk ribs. The low-position fins of the moving disk and the static disk ribs form a low-position radial gap β3, and form a cooling cavity C. The low-position radial gap β3 is set to D~1.5D.

[0010] In the aforementioned gas turbine turbine wheel rim composite sealing structure, the high-position fins of the moving disk are provided with axial convection holes at the L-shaped corners, the ribs of the stationary disk are provided with high-position radial jet holes at the L-shaped corners, and the low-position fins of the moving disk are provided with low-position radial jet holes at the roots.

[0011] In the aforementioned gas turbine turbine wheel rim composite sealing structure, the apertures of the axial convection holes and the high-position radial jet holes are set to 0.5D~D, and the aperture of the low-position radial jet holes is set to D~2D.

[0012] In the aforementioned gas turbine turbine rim composite sealing structure, the axial convection holes, high-position radial jet holes, and low-position radial jet holes are arranged at the same circumferential positions and are evenly distributed circumferentially, and the circumferentially opened cross-section is located in the high-pressure zone under the combined action of the turbine guide vane wake area and the turbine rotor blade leading edge potential field.

[0013] In the aforementioned gas turbine turbine wheel rim composite sealing structure, the circumferential number of axial convection holes, high-position radial jet holes, and low-position radial jet holes is set to 1 to 3 times the number of turbine guide vanes.

[0014] Beneficial effects: The present invention proposes a gas turbine turbine wheel rim composite sealing structure without introducing auxiliary cooling air and complex damping structure, which can achieve efficient sealing and cooling at the wheel rim.

[0015] The composite sealing structure of the turbine wheel rim of the gas turbine of the present invention achieves an efficient sealing effect when introducing a small amount of cold air flow, reduces the interference loss caused by the interaction between the cold air flow and the main flow at the wheel rim, and improves the convective heat exchange performance at the wheel rim. Specifically, the following beneficial effects are achieved:

[0016] 1. The chamfered corners of the flange plates of the dynamic and static disks constitute a quasi-oblique seal, which is simpler to process than traditional oblique seals, and the structural strength at the edge is reliable; after the sealing airflow flows out from the radial gap β1, the chamfered structure of the lower edge of the static disk increases the radial outflow velocity, which is beneficial to prevent the invasion of high-temperature and high-pressure combustion gas at the edge of the static disk; the expansion port at the chamfer of the upper edge of the dynamic disk weakens the radial outflow velocity, so that the outflow velocity of the sealing cold air is biased towards the axial direction of the mainstream, reducing the mixing effect between the sealing cold air and the mainstream, reducing the mixing loss, and improving the working efficiency of the turbine.

[0017] 2. The high-position fins of the moving disk form a groove cavity, so that most of the sealed cold air flow flows out from the radial gap β1 and forms a vortex in the groove cavity, cooling the rotor rim wall, while weakening the circumferential pressure unevenness caused by the stator wake and the moving blade leading edge potential field, improving the sealing effect at the rim in the circumferential range; the axial convection holes on the high-position fins of the moving disk play the role of connecting the buffer cavity, and the air flow in the groove cavity flows into the buffer cavity from the axial convection holes, avoiding the flow in the groove cavity from becoming a dead water area, thereby improving the convective heat exchange capacity of this area.

[0018] 3. The static disk ribs and the high-position fins of the moving disk form a buffer cavity. The high-temperature and high-pressure combustion gas invading from the rim side of the static disk and the sealed cold air flowing in from a low position merge in this area and form a counterclockwise rotating vortex in the buffer cavity. The existence of the vortex effectively inhibits the high-temperature combustion gas from invading the low-position disk cavity through the median radial gap β2; the high-position radial jet holes opened on the static disk ribs inject the sealed cold air into the buffer cavity, enhance the rotation speed of the vortex in the buffer cavity, effectively improve the convective heat exchange capacity of the area, and avoid the occurrence of local high-temperature areas on the high-position rim side of the static disk.

[0019] 4. The oblique fins of the moving disk and the low-position radial jet holes opened thereon guide the sealed cold air to impact the corner area of ​​the stationary disk ribs and the high-position fins of the moving disk, which greatly improves the radial velocity of the sealed cold air in this area, and can effectively prevent the high-temperature combustion gas from invading the low-position disk cavity from the radial gap. At the same time, it reduces the thermal stress at the dangerous section of the stationary disk ribs and the high-position fins of the moving disk, and effectively improves the working reliability of the rim sealing structure in a high-temperature environment.

[0020] 5. The composite sealing structure is set as an axial seal plus a triple radial seal. The overall structure has a large radial flow resistance. In the case of no sealing cold air, most of the mainstream high-temperature gas can be restricted to the wheel rim area by only using the "disc pump effect" of the rotor disk, effectively preventing the high-temperature gas from flowing back into the low-position disk cavity and reducing the thermal effect of the disk. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 This is a schematic diagram of a cross section of circumferentially uniform openings of the present invention;

[0023] Figure 3 It is a schematic diagram of circumferentially uniform opening of the present invention. DETAILED DESCRIPTION

[0024] Example 1. A gas turbine turbine wheel rim composite sealing structure, see Figure 1-Figure 3 ,like Figure 1 As shown, this embodiment introduces a gas turbine turbine rim composite sealing structure, including a turbine stator 1 and a turbine rotor 2, wherein a gap is arranged between the turbine stator 1 and the turbine rotor 2, and is characterized in that: a stator flange plate 3 and a stator rib plate 6 are arranged in the rim area of ​​the turbine stator 1, and a rotor flange plate 4, a rotor high-position fin 5 and a rotor low-position fin 7 are arranged in the rim area of ​​the turbine rotor 2.

[0025] The lower edge angle of the static disc flange plate 3 and the upper edge angle of the dynamic disc flange plate 4 are chamfered to form a quasi-oblique 45° sealing structure. The axial clearance α between the static disc flange plate 3 and the dynamic disc flange plate 4 is set to 3 mm.

[0026] The high-position fin 5 of the moving disk is set in an L shape. The high-position fin 5 of the moving disk and the flange plate 3 of the stationary disk form a high-position radial seal and form a groove cavity A. The high-position radial gap β1 is set to 3 mm.

[0027] The static disk rib plate 6 is set to be L-shaped, and the static disk rib plate 6 and the moving disk high-position fin 5 form a mid-position radial seal and form a buffer cavity B. The mid-position radial gap β2 is set to 3mm.

[0028] The moving disk low-position fin 7 is set as an inclined fin plate, and the inclined direction is directly opposite to the root of the static disk rib plate 6. The moving disk low-position fin 7 and the static disk rib plate 6 form a low-position radial gap β3 and form a cooling cavity C. The low-position radial gap β3 is set to 3mm.

[0029] The high-position fin 5 of the moving disk has an axial convection hole 8 at the L-shaped corner, the rib plate 6 of the stationary disk has a high-position radial jet hole 9 at the L-shaped corner, and the low-position fin 7 of the moving disk has a low-position radial jet hole 10 at the root. The apertures of the axial convection holes 8 and the high-position radial jet holes 9 are both set to 2 mm, and the aperture of the low-position radial jet holes 10 is set to 6 mm. The circumferential positions of the axial convection holes 8, the high-position radial jet holes 9, and the low-position radial jet holes 10 are consistent and evenly distributed circumferentially. The opening cross-section is located in the high-pressure area under the joint action of the wake area of ​​the turbine guide vane 11 and the leading edge potential field of the turbine rotor blade 12, and the circumferential opening number is set to twice the number of the turbine guide vanes 11.

Claims

1. A gas turbine turbine wheel rim composite sealing structure, comprising a turbine stator (1) and a turbine rotor (2), wherein a gap is provided between the turbine stator (1) and the turbine rotor (2), and characterized in that: The rim area of ​​the turbine stator (1) is provided with a stator flange plate (3) and a stator rib plate (6), and the rim area of ​​the turbine rotor (2) is provided with a rotor flange plate (4), a rotor high-position fin (5), and a rotor low-position fin (7); the rotor flange plate (4) and the stator flange plate (3) are axially opposed, the rotor high-position fin (5) is radially located between the stator flange plate (3) and the stator rib plate (6), and the rotor low-position fin (7) is radially located below the stator rib plate (6).

2. The gas turbine turbine rim composite sealing structure according to claim 1, characterized in that: The lower edge corner of the static disc flange plate (3) is chamfered, and the upper edge corner of the dynamic disc flange plate (4) is chamfered. After the chamfering, the static disc flange plate (3) and the dynamic disc flange plate (4) form a quasi-oblique 45° sealing structure, and the axial clearance α between the static disc flange plate (3) and the dynamic disc flange plate (4) is set to D.

3. The gas turbine turbine rim composite sealing structure according to claim 2, characterized in that: The moving disc high-position fin (5) is L-shaped, and the moving disc high-position fin (5) and the stationary disc flange plate (3) form a high-position radial seal and form a groove cavity A. The high-position radial gap β1 is set to D~1.5D.

4. The gas turbine turbine rim composite sealing structure according to claim 2, characterized in that: The static disk rib plate (6) is L-shaped, and the static disk rib plate (6) and the moving disk high-position fin (5) form a mid-position radial seal and form a buffer cavity B. The mid-position radial gap β2 is set to D to 1.5D.

5. The gas turbine turbine rim composite sealing structure according to claim 2, characterized in that: The moving disk low-position fin (7) is configured as an inclined fin plate, the inclination direction of which is directly opposite to the root of the stationary disk rib plate (6). The moving disk low-position fin (7) and the stationary disk rib plate (6) form a low-position radial gap β3 and form a cooling cavity C. The low-position radial gap β3 is configured to be D to 1.5D.

6. The gas turbine turbine rim composite sealing structure according to claim 2, characterized in that: The moving disk high-position fin (5) is provided with an axial convection hole (8) at the L-shaped corner, the stationary disk rib (6) is provided with a high-position radial jet hole (9) at the L-shaped corner, and the moving disk low-position fin (7) is provided with a low-position radial jet hole (10) at the root.

7. The gas turbine turbine rim composite sealing structure according to claim 6, characterized in that: The apertures of the axial convection holes (8) and the high-position radial jet holes (9) are both set to 0.5D to D, and the aperture of the low-position radial jet holes (10) is set to D to 2D.

8. The gas turbine turbine rim composite sealing structure according to claim 6, characterized in that: The axial convection holes (8), the high-position radial jet holes (9), and the low-position radial jet holes (10) are arranged at the same circumferential positions and are evenly distributed circumferentially, and the circumferentially opened cross section is located in the high-pressure area under the combined action of the wake area of ​​the turbine guide vane (11) and the leading edge potential field of the turbine rotor blade (12).

9. The gas turbine turbine rim composite sealing structure according to claim 8, characterized in that: The number of axial convection holes (8), high-position radial jet holes (9), and low-position radial jet holes (10) provided in the circumferential direction is set to be 1 to 3 times the number of turbine guide vanes (11).

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