A helical grate gear turbine interstage sealing structure and gas turbine

Abstract

The present invention relates to a helical grate turbine interstage sealing structure and a gas turbine, which belong to the field of gas turbines; it includes a turbine stator and a turbine rotor, a gap being provided between the turbine stator and the turbine rotor; a sealing module is provided between the turbine stator and the turbine rotor, and the sealing module includes two stages of annular helical grate teeth provided on the turbine stator; the first stage of helical grate teeth is provided circumferentially along the inner wall surface of the convex shoulder of the turbine stator, and the second stage of helical grate teeth is provided circumferentially along the inner end surface of the turbine stator, and the chamber inlets of the two stages of helical grate teeth are both oriented toward the direction of high-temperature fuel gas flow, so as to increase fuel gas flow resistance. In the sealing structure of the present invention, the high-temperature mainstream generates a strong vortex in the chamber formed by the helical grate teeth, which strengthens the airflow mixing and energy dissipation inside the grate seal, increases fuel gas flow resistance, and thus achieves the effect of suppressing fuel gas intrusion.

Description

Technical Field

[0001] The present invention belongs to the field of gas turbines, and in particular relates to a helical grate gear turbine interstage sealing structure and a gas turbine. Background Art

[0002] In rotating machinery such as gas turbines, the turbine components are arranged alternately in the form of rotors and stators due to their inherent characteristics, which leads to a certain gap between the two, where air can "enter and exit". Due to material and process limitations, the temperature resistance limit that the turbine disk can withstand is lower than that of other components, especially the rotor. Working in a harsh environment of high temperature and high speed for a long time, it is subjected to extremely high thermal stress and centrifugal tensile stress. If it works at overtemperature for too long, serious accidents such as turbine disk rupture may occur. Therefore, it is necessary to draw some cold air from the compressor to prevent high-temperature fuel gas from invading deep into the disk cavity. If the seal is insufficient, the mainstream high-temperature fuel gas will erode the turbine disk, greatly reducing the life of the turbine. However, too much bleed air will reduce the overall efficiency of the gas turbine.

[0003] In the article "Progress in Gas Turbine Disc Cavity Gas Intrusion and Sealing Technology" published by Jia Xingyun et al. in the sixth issue of "Thermal Energy and Power Engineering" in June 2021, it was pointed out that if the sealing gap is blindly reduced, while the gas intrusion is weakened, the cold air outflow is also suppressed. If a more complex structure is added to the wheel rim seal, it will bring good sealing effect, but it will bring a series of new problems such as difficulty in processing and assembly.

[0004] Therefore, the novel oblique grate tooth sealing structure provided by the present invention, which can reduce the minimum sealing flow rate, has very important engineering application value.

[0005] Compared with the traditional interstage sealing structure, the helical grate gear turbine interstage sealing structure can greatly damp the intrusion of mainstream combustion gas, thus having good sealing characteristics. At the same time, it also ensures that collision and scraping between the moving and static disks can be prevented even under high-speed rotation. Summary of the Invention

[0006] Technical issues to be solved:

[0007] In order to avoid the shortcomings of the prior art, the present invention provides a helical grate turbine interstage sealing structure and a gas turbine, in which the high-temperature mainstream generates a strong vortex in the chamber formed by the helical grate teeth. Combined with the tooth tip boss, the airflow mixing and energy dissipation inside the grate seal are enhanced, and the gas flow resistance is increased. At the same time, since the first profile of the helical grate teeth is set as an inclined section, it is also easy for cold air to flow out, thereby achieving the purpose of reducing the gas intrusion phenomenon from two aspects.

[0008] The technical solution of the present invention is: a helical grate turbine interstage sealing structure, comprising a turbine stator and a turbine rotor, with a gap provided between the turbine stator and the turbine rotor; a sealing module provided between the turbine stator and the turbine rotor, the sealing module comprising two stages of annular helical grate teeth provided on the turbine stator;

[0009] The first-stage bevel grate teeth are arranged circumferentially along the inner wall surface of the shoulder of the turbine stator, and the second-stage bevel grate teeth are arranged circumferentially along the inner end surface of the turbine stator. The chamber inlets of the two-stage bevel grate teeth are both facing the direction of the high-temperature gas flow, which is used to increase the gas flow resistance.

[0010] A further technical solution of the present invention is as follows: the beveled grate teeth include an inclined section, a straight section, and a tooth tip boss; the root of the inclined section is fixed to the turbine stator; one end of the straight section is connected to the inclined section, and the other end is provided with a tooth tip boss; the tooth tip boss is located inside the straight section, opposite to the turbine stator; the inlet of the annular chamber formed by the inclined section, the straight section, and the tooth tip boss faces the direction of the high-temperature combustion gas flow;

[0011] The angle between the inclined section and the incoming flow of high-temperature fuel gas is α, and the angle between the inclined section and the incoming flow of sealed cold air is β; the cross-sectional width of the inclined grate teeth is W.

[0012] A further technical solution of the present invention is that the angle α between the inclined section and the incoming flow of high-temperature fuel gas is 45°, and the angle β between the inclined section and the incoming flow of sealed cold air is 135°.

[0013] A further technical solution of the present invention is: the straight section of the first-stage bevel grate teeth is parallel to the inner wall surface of the turbine stator shoulder, the straight section of the second-stage bevel grate teeth is parallel to the inner end surface of the turbine stator shoulder, and the distance between the two-stage bevel grate teeth and the inner wall surface and inner end surface of the turbine stator shoulder respectively is the grate tooth height d.

[0014] A further technical solution of the present invention is: the relationship between the cross-sectional width W of the bevel grate teeth and the height d of the grate teeth is: W=0.4d.

[0015] A further technical solution of the present invention is that the relationship between the height d of the grate teeth and the width h of the flow channel is: h=3d, so as to prevent collision and scraping between the dynamic and static disks under high-speed rotation.

[0016] A further technical solution of the present invention is: the distance X1 from the root of the first-stage oblique grate teeth to the upper left vertex of the disc cavity and the relationship with the flow channel width h is: X1=h; the distance X2 from the root of the second-stage oblique grate teeth to the upper left vertex of the disc cavity and the relationship with the flow channel width h is: X2=1.8h.

[0017] A further technical solution of the present invention is: the cross-section of the tooth tip boss is triangular, with the sharp corner facing the turbine stator, and the radial height of the tooth tip boss is l.

[0018] A further technical solution of the present invention is that the relationship between the radial height l of the tooth tip boss and the height d of the comb teeth is: l=0.2d.

[0019] A gas turbine comprises a stator and a rotor, wherein the stator is mounted on a turbine stator disk, and the rotor is mounted on a turbine rotor disk; a sealing module is provided between the turbine rotor disk and the turbine stator disk, and the sealing module comprises two stages of annular beveled grate teeth provided on the turbine stator disk; the chamber inlets of the two stages of beveled grate teeth are both oriented towards the direction of high-temperature fuel gas flow, so as to increase the resistance to fuel gas flow.

[0020] Beneficial effects

[0021] The beneficial effects of the present invention are as follows: in the sealing structure of the present invention, the high-temperature mainstream generates a strong vortex in the chamber formed by the oblique grate teeth, which strengthens the airflow mixing and energy dissipation inside the grate seal, increases the gas flow resistance, and thus achieves the effect of suppressing gas intrusion. The present invention can achieve a good sealing effect even at a low sealing cold air flow rate, greatly reducing the minimum sealing flow rate (the minimum cold air flow rate required for the disc cavity to prevent gas intrusion), thereby reducing the amount of bleed air from the compressor, and thus improving the overall efficiency of the gas turbine. The specific advantages are as follows:

[0022] 1. Because gas intrusion occurs between turbine stages, the intrusion flow primarily flows along the surface of the stator disc into the depths of the disc cavity. Therefore, both stages of beveled grates are mounted on the turbine stator disc. The cavity inlet formed by the beveled grates and the stator disc wall faces the direction of the incoming high-temperature gas flow, increasing gas flow resistance and thus suppressing gas intrusion. Furthermore, the inclined design of the first profile of the beveled grates facilitates the outflow of cool air in the direction of incoming cool air.

[0023] 2. The inclined section, straight section, tooth tip boss and turbine stator wall of the beveled grate teeth together form a chamber with large chamber capacity, which strengthens the air flow mixing and energy dissipation inside the grate tooth seal.

[0024] 3. The relationship between the height d of a single grate tooth and the width h of the flow channel is: h = 3d, to prevent collision and scraping between the moving and static discs under high-speed rotation.

[0025] 4. The tips of the bevel teeth are provided with regular triangular prism-shaped bosses to enhance the energy dissipation of the gas entering the chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a meridian view of a single-stage turbine;

[0027] Figure 2 This is a schematic diagram of the flow characteristics at the interstage seal with oblique grate teeth;

[0028] Figure 3 It is an enlarged schematic diagram of the interstage sealing structure with oblique grate teeth.

[0029] Explanation of the accompanying symbols: 1-turbine moving disk, 2-turbine static disk, 3-interstage sealing structure, 4-cross-sectional width W of the inclined grate teeth, 5-height d of the grate teeth, 6-flow channel width h, 7-angle α between the inclined section and the high-temperature combustion gas flow, 8-angle β between the inclined section and the sealed cold air flow, 9-distance X1 from the root of the first-stage inclined grate teeth to the upper left vertex of the disk cavity, 10-distance X2 from the root of the second-stage inclined grate teeth to the upper left vertex of the disk cavity, 11-radial height l of the tooth tip boss. DETAILED DESCRIPTION

[0030] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0031] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0032] See also Figure 1-3 As shown, this embodiment provides a helical grate turbine interstage seal structure, achieved by adding two stages of helical grate teeth to the interstage seal. The structure comprises a turbine stator 1, a turbine rotor 2, and two stages of helical grate teeth arranged between the rotor and stator disks. The first stage of helical grate teeth is circumferentially arranged along the inner wall surface of the turbine stator's shoulder, while the second stage of helical grate teeth is circumferentially arranged along the inner end surface of the turbine stator. The chamber inlets of both stages of helical grate teeth face the direction of the high-temperature gas flow, thereby increasing gas flow resistance and preventing gas from intruding into the chamber.

[0033] The beveled grate teeth include an inclined section, a straight section and a tooth tip boss, the root of the inclined section is fixed on the turbine stator; one end of the straight section is connected to the inclined section, and the other end is provided with a tooth tip boss; the tooth tip boss is located on the inner side of the straight section, opposite to the turbine stator; the inlet of the annular chamber formed by the inclined section, the straight section and the tooth tip boss faces the direction of the high-temperature combustion gas flow; the angle between the inclined section and the high-temperature combustion gas flow is α, and the angle between the inclined section and the sealed cold air flow is β; the cross-sectional width of the beveled grate teeth is W.

[0034] The sealing effectiveness of this sealing structure has been verified through numerical simulations, comparing the sealing effects with and without the beveled grate structure. By setting identical mainstream and sealing flow conditions, the sealing efficiency of the disc cavity with and without the beveled grate structure was calculated and compared as a function of the sealing flow rate. The dimensions and installation positions of the two-stage beveled grate are defined.

[0035] The sealing efficiency with and without beveled grate teeth obtained through numerical calculation is shown in Table 1:

[0036] Sealing flow g / s 2.03 4.5 10.65 No oblique teeth 0.24 0.52 0.65 With oblique comb teeth 0.35 0.6 0.71

[0037] As shown in Table 1, the sealing efficiency is maximized at a low sealing flow rate (2.03 g / s), with an improvement of 45.8%. At a high sealing flow rate (10.65 g / s), the improvement is lower, at 9.2%. The numerical results show that at all sealing flow rates, the sealing efficiency is improved compared to the original structure.

[0038] In this embodiment, the first profile is an inclined section, which is inclined at 45° toward the direction of the high-temperature gas flow and 135° to the direction of the sealed cold air flow. The second profile is a straight section, which is parallel to the engine axis. The chamber formed by the two profiles has a large capacity, which enhances the airflow mixing and energy dissipation inside the comb seal. The overall configuration not only suppresses the intrusion of mainstream gas, but also enhances the outflow of cold air.

[0039] Since when gas intrusion occurs between turbine stages, the intrusion flow mainly flows along the surface of the stator disk into the deep part of the disk cavity, both stages of bevel grate teeth are installed on the turbine stator disk.

[0040] In this embodiment, the relationship between the height d of a single comb tooth and the width h of the flow channel is: h=3d=4 mm.

[0041] In this embodiment, the cross-sectional width W of a single oblique grate tooth and the height d of a single grate tooth are in the following relationship: d=1.33 mm, W=0.4d=0.52 mm.

[0042] In this embodiment, the tooth tips of the oblique comb teeth are provided with regular triangular prism-shaped bosses, and the relationship between the radial height l of the tooth tip bosses and the height d of a single comb tooth is: l=0.2d=0.26mm.

[0043] In this embodiment, the relationship between the distance X1 from the root of the first-level comb teeth to the upper left vertex of the disc cavity and the flow channel width h is: X1=h=4mm, and the relationship between the distance X2 from the root of the second-level comb teeth to the upper left vertex of the disc cavity and the flow channel width h is: X2=1.8h=7.2mm.

[0044] See also Figure 2The present invention enables the high-temperature mainstream to generate strong vortexes in the chamber formed by the oblique grate teeth, thereby strengthening the airflow mixing and energy dissipation inside the grate seal and increasing the gas flow resistance. At the same time, due to the design of the first profile of the oblique grate teeth, it is also easy for cold air to flow out, thereby achieving the purpose of reducing the gas intrusion phenomenon from two aspects, so that a better sealing effect can be achieved even under low sealing cold air flow.

[0045] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A helical grate turbine interstage sealing structure, comprising a turbine stator and a turbine rotor, with a gap provided between the turbine stator and the turbine rotor, characterized in that: A sealing module is provided between the turbine stator and the turbine rotor, and the sealing module comprises two stages of annular beveled grate teeth provided on the turbine stator; The first stage of beveled grate teeth is arranged along the circumference of the inner wall surface of the shoulder of the turbine stator, and the second stage of beveled grate teeth is arranged along the circumference of the inner end surface of the turbine stator. The chamber inlets of the two stages of beveled grate teeth are both oriented towards the direction of the high-temperature gas flow, which is used to increase the gas flow resistance; The bevel grate teeth include an inclined section, a straight section and a tooth tip boss. The root of the inclined section is fixed to the turbine stator. One end of the straight section is connected to the inclined section, and the other end is provided with a tooth tip boss. The tooth tip boss is located on the inner side of the straight section, opposite to the turbine stator. The inlet of the annular chamber formed by the inclined section, the straight section and the tooth tip boss faces the direction of the high-temperature gas flow. The angle between the inclined section and the high-temperature gas flow is α , and the angle between the sealed cold air flow is β ; The cross-sectional width of the bevel grate teeth is W ; The angle between the inclined section and the high-temperature gas flow α =45°, the angle with the sealed air flow β =135°; The straight section of the first-stage bevel grate is parallel to the inner wall of the turbine stator shoulder, and the straight section of the second-stage bevel grate is parallel to the inner end face of the turbine stator. The distance between the two-stage bevel grate and the inner wall and inner end face of the turbine stator shoulder is the grate height. d ; The cross-sectional width of the bevel grate teeth W Height of grate teeth d The relationship is: W =0.4 d ; The grate tooth height d and channel width h The relationship is: h =3 d .

2. The helical grate gear turbine interstage sealing structure according to claim 1, characterized in that: The distance from the root of the first-stage bevel grate teeth to the upper left vertex of the disc cavity is X 1 and flow channel width h The relationship is: X 1= h The distance from the root of the second-stage bevel grate teeth to the upper left vertex of the disc cavity is X 2 and flow channel width h The relationship is: X 2=1.8 h .

3. The helical grate gear turbine interstage sealing structure according to claim 1, characterized in that: The cross section of the tooth tip boss is triangular, with the sharp corner facing the turbine stator, and the radial height of the tooth tip boss is l .

4. The helical grate gear turbine interstage sealing structure according to claim 1, characterized in that: The radial height of the tooth tip boss l Height of grate teeth d The relationship is: l =0.2 d .

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