Astroid dynamic pressure groove-backpressure self-drainage reinforced pressurization dry gas sealing structure

Abstract

The invention relates to an astroid dynamic pressure groove-backpressure self-drainage reinforced pressurization dry gas sealing structure, and belongs to the technical field of rotary fluid mechanical sealing. Main star-shaped line dynamic pressure grooves are formed in the sealing end face of the dry gas sealing moving ring and are uniformly arranged at intervals; secondary star-shaped dynamic pressure grooves are formed in the inner side directions of the main star-shaped dynamic pressure grooves; the secondary star-shaped dynamic pressure grooves are uniformly arranged at intervals along the circumferential direction of the dry gas sealing moving ring; an annular pressure equalizing groove is formed between the main star-shaped line dynamic pressure groove and the secondary star-shaped line dynamic pressure groove, and the pressure equalizing groove is communicated with the secondary star-shaped line dynamic pressure groove; and a backpressure drainage hole is formed in the pressure equalizing groove. The main star-shaped dynamic pressure groove and the secondary star-shaped dynamic pressure groove are arranged in series in the gas flowing direction, the groove root of each stage of star-shaped dynamic pressure groove is provided with a sealing dam structure, the leakage amount can be effectively limited, sealing back pressure is guided into a dam area of a sealing gap through the back pressure drainage hole, a secondary pressure peak is formed, and the radial pressure distribution condition of a gas film can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of rotary fluid mechanical seals, and in particular to a star-shaped linear dynamic pressure groove-back pressure self-drainage enhanced pressurized dry gas seal structure. Background Art

[0002] Mechanical seal is a key technology to prevent fluid leakage. It is mainly used in occasions where sealing is required at the dynamic and static junctions of rotating shafts and cavities. Mechanical seals are of various forms, among which non-contact seals are widely used in various low-speed, medium-speed and high-speed rotating machinery due to their unique advantages. The main working principle of non-contact mechanical seals is to use the static or dynamic pressure of the fluid to form a complete fluid film on the sealing end face, so that the sealing end faces are separated from each other to avoid contact. It has the characteristics of low leakage, low wear and long life.

[0003] In recent years, dry gas seal technology has continuously catered to the working conditions of the supporting main engine, and with the rapid development of the industrial process, the service environment of dry gas seals has gradually turned to extremes. The working conditions of high-pressure inlet and high-speed rotation have brought great challenges to the safe and stable operation of dry gas seals. In view of this, seal workers have carried out a lot of research on dry gas seal structural parameter optimization and fluid dynamic pressure groove design with the aim of improving the end face gas film characteristics.

[0004] For the working environment of high-pressure inlet, the dry gas seal is already in a high-pressure and heavy-load state (high inlet pressure leads to high closing force) at the beginning of startup. The conventional groove design and structural parameter optimization are based on strengthening the fluid dynamic pressure effect of the seal end face flow field, thereby ensuring the improvement of the bearing capacity of the seal during the stable operation stage. However, the seal speed is low in the initial stage of startup, and the fluid dynamic pressure effect is weak. This is an inherent defect of the dynamic pressure type dry gas seal. The groove design and structural parameter optimization alone cannot produce sufficient air film bearing capacity, and the separation of the dynamic and static rings of the seal will be delayed, causing long-term dry friction on the seal end face, inducing severe wear and a large temperature rise on the end face. Therefore, in order to ensure the normal opening and long-term stable operation of the dry gas seal, it is necessary to propose a new high-load dry gas seal structure, which can play a positive role in ensuring the long-term operation of the working equipment of the high-parameter power system and enhancing environmental protection. Summary of the invention

[0005] In order to solve or partially solve the problems existing in the related technology, the present invention provides a star-shaped linear dynamic pressure groove-back pressure self-drainage enhanced pressurized dry gas sealing structure, which aims to solve the technical problems of poor air film bearing capacity and slow opening speed of the existing dry gas sealing structure under the extreme dry gas sealing environment of high pressure and low speed.

[0006] The above-mentioned star-shaped linear dynamic pressure groove-back pressure self-drainage enhanced pressurized dry gas sealing structure comprises a dry gas sealing ring, and the sealing end surface of the dry gas sealing dynamic ring is provided with a main star-shaped linear dynamic pressure groove, and the main star-shaped linear dynamic pressure grooves are evenly spaced along the circumferential direction of the dry gas sealing dynamic ring, so that an active pressure groove platform is formed between two adjacent main star-shaped linear dynamic pressure grooves;

[0007] A secondary star-shaped linear dynamic pressure groove is provided on the inner side of the primary star-shaped linear dynamic pressure groove, and the secondary star-shaped linear dynamic pressure groove is not connected to the inner side surface of the dry gas sealing dynamic ring, so that a secondary sealing dam is formed between the inner side surface of the dry gas sealing dynamic ring and the groove root of the secondary star-shaped linear dynamic pressure groove; the secondary star-shaped linear dynamic pressure grooves are evenly spaced along the circumferential direction of the dry gas sealing dynamic ring, so that a secondary dynamic pressure groove platform is formed between two adjacent secondary star-shaped linear dynamic pressure grooves;

[0008] An annular pressure equalizing groove is provided between the primary star-shaped linear dynamic pressure groove and the secondary star-shaped linear dynamic pressure groove, the pressure equalizing groove is connected to the secondary star-shaped linear dynamic pressure groove, and is not connected to the primary star-shaped linear dynamic pressure groove, so that a main sealing dam is formed between the pressure equalizing groove and the groove root of the primary star-shaped linear dynamic pressure groove;

[0009] A back pressure drainage hole is arranged in the pressure equalizing groove, and the back pressure drainage hole penetrates the dry gas seal dynamic ring and corresponds one to one with the secondary star-shaped linear dynamic pressure groove.

[0010] In some embodiments, the main star-shaped linear dynamic pressure groove has an active pressure groove root and two main groove area side walls located on both sides of the active pressure groove root;

[0011] The root of the active pressure groove is in an arc shape; the side walls of the two main groove areas extend along a star-shaped line.

[0012] In some embodiments, the side walls of the two main groove areas are bent and extended in the same direction or are bent and extended relative to each other.

[0013] In some embodiments, the parametric equation of the star line is:

[0014] Among them, the constant a is the radial width of the main star-shaped linear dynamic pressure groove, and the constant b is 2a-3a.

[0015] In some schemes, the secondary star-shaped linear dynamic pressure groove has a secondary dynamic pressure groove root and two secondary groove area side walls located on both sides of the secondary dynamic pressure groove root;

[0016] The root of the secondary dynamic pressure groove is in an arc shape; the side wall of the secondary groove area extends along a star-shaped line.

[0017] In some embodiments, the side walls of the two secondary groove areas are bent and extended in the same direction or are bent and extended relative to each other.

[0018] In some embodiments, the parametric equation of the star line is:

[0019] Among them, the constant a is the radial width of the secondary star-shaped linear dynamic pressure groove, and the constant b is 2a-3a.

[0020] In some embodiments, the groove depth of the primary star-shaped linear dynamic pressure groove is 0.001mm-0.02mm; the groove depth of the secondary star-shaped linear dynamic pressure groove is 0.001mm-0.02mm; the groove depth of the equalizing pressure groove is 0.001mm-0.1mm;

[0021] The radial width of the primary sealing dam is 2 mm-10 mm; the radial width of the secondary sealing dam is 1 mm-5 mm.

[0022] In some embodiments, the cross-sectional shape of the back pressure drainage hole is square, circular or other shapes.

[0023] In some embodiments, the number of the primary star-shaped linear dynamic pressure grooves is 2-30; the number of the secondary star-shaped linear dynamic pressure grooves is 2-30.

[0024] The technical solution provided by the present invention may include the following beneficial effects:

[0025] 1. By setting a back pressure drainage hole in the pressure equalizing groove, the back pressure (inlet pressure) of the dry gas seal dynamic ring is introduced into the sealing dam area in the sealing gap to form a double pressure inlet, which realizes the inward shift of the high pressure area of ​​the sealing end face, reduces the pressure drop area, and thus improves the bearing capacity of the end face air film.

[0026] 2. A secondary star-shaped linear dynamic pressure groove-secondary sealing dam combination is set downstream of the back pressure drainage hole to construct a cascade dam area to further enhance the flow-blocking and pressurizing effect of the sealing dam. A secondary pressure peak can be formed near the outlet position, which can improve the sealing opening ability together with the back pressure drainage hole.

[0027] 3. By setting the main star-shaped line dynamic pressure groove and the secondary star-shaped line dynamic pressure groove, the dynamic and static pressures are mixed in series, and during the mechanical start and stop process, the sealing back pressure is introduced through the back pressure drainage hole, which can improve the radial pressure distribution of the air film, make the sealing end face open quickly or close slowly, avoid the occurrence of end face wear, extend the service life of the seal, and ensure the stable operation of the equipment.

[0028] 4. The groove shape used is a star-shaped linear dynamic pressure groove. A bidirectional star-shaped linear groove shape can be selected. The linear shapes on both sides of the star-shaped linear dynamic pressure groove are arranged symmetrically, which can realize the clockwise and counterclockwise rotation sealing of the dry gas sealing dynamic ring, broadening its application scenarios.

[0029] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0031] Figure 1 1 is a schematic structural diagram of a dry gas seal dynamic ring shown in Embodiment 1 of the present invention;

[0032] Figure 2 is another structural schematic diagram of a dry gas seal dynamic ring shown in the first embodiment of the present invention;

[0033] Figure 3 is a partial enlarged view of the dry gas seal dynamic ring shown in the first embodiment of the present invention;

[0034] Figure 4 is a schematic diagram of the dimensions of a dry gas seal dynamic ring shown in the first embodiment of the present invention;

[0035] Figure 5 1 is a schematic structural diagram of a back pressure drainage hole of a dry gas seal dynamic ring shown in Embodiment 1 of the present invention;

[0036] Figure 6 is a structural schematic diagram of a dry gas seal dynamic ring shown in the second embodiment of the present invention;

[0037] Figure 7 is a partial enlarged view of the dry gas seal dynamic ring shown in the second embodiment of the present invention;

[0038] Figure 8 is a structural schematic diagram of a dry gas seal dynamic ring shown in the second embodiment of the present invention;

[0039] Reference numerals:

[0040] 1. Main star-shaped linear dynamic pressure groove; 11. Active pressure groove root; 12. Side wall of main groove area; 2. Active pressure groove platform area; 3. Secondary star-shaped linear dynamic pressure groove; 31. Secondary dynamic pressure groove root; 32. Side wall of secondary groove area; 4. Secondary sealing dam; 5. Secondary dynamic pressure groove platform area; 6. Pressure balancing groove; 7. Main sealing dam; 8. Back pressure drainage hole;

[0041] R1-outer diameter of dry gas seal dynamic ring, R2-root radius of primary star-shaped linear dynamic pressure groove, R3-outer diameter of equalizing pressure groove, R4-inner diameter of equalizing pressure groove, R5-root radius of secondary star-shaped linear dynamic pressure groove, R6-inner diameter of dry gas seal dynamic ring. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the described contents.

[0043] Embodiment 1:

[0044] like Figures 1 to 4 As shown, the present application provides a star-shaped linear dynamic pressure groove-back pressure self-guiding enhanced pressurized dry gas sealing structure, including a dry gas sealing dynamic ring; the outer diameter of the dry gas sealing dynamic ring is the high-pressure air inlet side, and the inner diameter is the low-pressure air outlet side; the sealing end surface of the dry gas sealing dynamic ring is provided with a main star-shaped linear dynamic pressure groove 1, and the main star-shaped linear dynamic pressure groove 1 is evenly spaced along the circumferential direction of the dry gas sealing dynamic ring, so that an active pressure groove platform 2 is formed between two adjacent main star-shaped linear dynamic pressure grooves 1;

[0045] The main star-shaped linear dynamic pressure groove 1 has an active pressure groove root 11 and two main groove area side walls 12 located on both sides of the active pressure groove root 11;

[0046] The active groove root 11 is in an arc shape; the two main groove area side walls 12 extend along a star-shaped line.

[0047] The two main groove area side walls 12 are bent and extended in the same direction.

[0048] The parametric equation of the star line is: Among them, parameter a is 7.78 and parameter b is 15.56.

[0049] A secondary star-shaped linear dynamic pressure groove 3 is provided on the inner side of the main star-shaped linear dynamic pressure groove 1, and the secondary star-shaped linear dynamic pressure groove 3 is not connected to the inner side surface of the dry gas sealing dynamic ring, so that a secondary sealing dam 4 is formed between the inner side surface of the dry gas sealing dynamic ring and the groove root of the secondary star-shaped linear dynamic pressure groove 3; the secondary star-shaped linear dynamic pressure grooves 3 are evenly spaced along the circumferential direction of the dry gas sealing dynamic ring, so that a secondary dynamic pressure groove platform 5 is formed between two adjacent secondary star-shaped linear dynamic pressure grooves 3;

[0050] The secondary star-shaped linear dynamic pressure groove 3 has a secondary dynamic pressure groove root 31 and two secondary groove area side walls 32 located on both sides of the secondary dynamic pressure groove root 31;

[0051] The secondary dynamic pressure groove root 31 is in an arc shape; the secondary groove area side wall 32 extends along a star-shaped line.

[0052] The two secondary groove area side walls 32 are bent and extended in the same direction.

[0053] The parametric equation of the star line is: Among them, parameter a is 7.78 and parameter b is 15.56.

[0054] An annular pressure equalizing groove 6 is provided between the primary star-shaped linear dynamic pressure groove 1 and the secondary star-shaped linear dynamic pressure groove 3. The pressure equalizing groove 6 is connected to the secondary star-shaped linear dynamic pressure groove but is not connected to the primary star-shaped linear dynamic pressure groove 1, so that a primary sealing dam 7 is formed between the pressure equalizing groove 6 and the groove root of the primary star-shaped linear dynamic pressure groove;

[0055] The pressure equalizing groove 6 is provided with a back pressure drainage hole 8, and the back pressure drainage hole 8 is arranged through the dry gas seal dynamic ring and corresponds to the secondary star-shaped linear dynamic pressure groove 3 one by one. Figure 5 As shown, the back pressure drainage hole 8 can directly penetrate the dry gas sealing dynamic ring backwards, or penetrate the dry gas sealing dynamic ring from the outer side of the dry gas sealing dynamic ring. At the same time, the end of the back pressure drainage hole 8 can be widened to increase the air intake.

[0056] The cross-sectional shape of the back pressure drainage hole 8 is a slit shape.

[0057] Among them, the dimensions of the dry gas seal dynamic ring R1 are 77.78mm, and R6 is 58.42mm; the groove root R2 of the main star-shaped linear dynamic pressure groove 1 is 70mm; the equalizing pressure groove 6 is in the shape of a ring belt, and the groove width (R3-R4) is 2mm, and the secondary star-shaped linear dynamic pressure groove 3 starts at R4 and is 63mm; the width (R5-R6) of the secondary sealing dam 4 is 1.58mm.

[0058] The groove depth of each primary star-shaped linear dynamic pressure groove 1 is 5 μm, and the parameters a and b are 7.78 and 15.56 respectively; the groove depth of the equalizing groove 6 is 5 μm, and the groove depth of each secondary star-shaped linear dynamic pressure groove 3 is 5 μm, and the parameters a and b are 3 and 6 respectively. The number of primary star-shaped linear dynamic pressure grooves 1 is set to 12, and the groove-to-platform ratio (the ratio of the grooved area on the R1-R2 ring to the ungrooved area) is 1; the number of secondary star-shaped linear dynamic pressure grooves 3 is set to 24, and the groove-to-platform ratio (the ratio of the grooved area on the R4-R5 ring to the ungrooved area) is set to 1.

[0059] The slit aspect ratio of the back pressure drainage hole 8 is 25, and the length is 1 mm.

[0060] The dry gas seal dynamic ring of this example is compared with the classic spiral dynamic pressure groove dry gas seal dynamic ring which is the most widely used in the current industry through dry gas seal numerical simulation. The parameters of the traditional spiral dynamic pressure groove are helix angle of 15°, groove root radius of 70mm, and groove platform ratio of 1.

[0061] Working parameters: external pressure Po = 1MPa, internal pressure Pi = 0.1MPa, dry gas seal dynamic ring back pressure Po = 1MPa, speed w = 1087.08rad / s, working temperature T = 25℃, gas film thickness ho = 5μm. The numerical simulation results are shown in Table 1:

[0062] Table 1

[0063] structure Opening force(N) <![CDATA[Air film stiffness (10 8 N / m)]]> Traditional spiral dynamic pressure groove 5599.84 11.1996 This application 6764.76 13.5295

[0064] It can be seen from Table 1 that compared with the traditional spiral groove dry gas seal dynamic ring, the opening force of the dry gas seal dynamic ring of this embodiment is much greater than that of the traditional spiral groove dry gas seal structure, and the sealing end face can be quickly opened or slowly closed, thereby avoiding the occurrence of end face wear and extending the service life of the seal. The air film stiffness is also greater than that of the traditional spiral dynamic pressure groove, ensuring the stable operation of the equipment.

[0065] Embodiment 2:

[0066] like Figure 6 and Figure 7 As shown, based on Example 1, the differences are that the two secondary groove area side walls 32 are relatively bent and extended; the two main groove area side walls 12 are relatively bent and extended; the equalizing pressure groove 6 is fan-shaped and is arranged one-to-one with the secondary star-shaped linear dynamic pressure groove 3; the back pressure drainage hole 8 is in the shape of a circular hole.

[0067] The dimensions of the dry gas seal dynamic ring R1 are 48mm and R6 are 36mm; the groove root R2 of the main star-shaped linear dynamic pressure groove 1 is 43mm; the groove width of the equalizing pressure groove 6 is (R3-R4) 1.5mm, and the fan-shaped angle is the same as that of the secondary star-shaped linear dynamic pressure groove 3, which is 15°; the secondary star-shaped linear dynamic pressure groove 3 starts at R4 and is 39.5mm; the width of the secondary sealing dam 4 (R5-R6) is 1mm.

[0068] Each of the primary and secondary star-shaped linear dynamic pressure grooves 3 is symmetrically distributed, which can realize the clockwise and counterclockwise rotation sealing of the dry gas seal dynamic ring. The groove depth of the primary star-shaped linear dynamic pressure groove 1 is 5μm, and the parameters and are 5 and 15 respectively; the groove depth of the pressure equalization groove 6 is 5μm, and the groove depth of each secondary star-shaped linear dynamic pressure groove 3 is 5μm, and the parameters and are 2.5 and 7.5 respectively. The primary star-shaped linear dynamic pressure groove 1 is set to 8; the secondary star-shaped linear dynamic pressure groove 3 is set to 8. The outer diameter of the secondary star-shaped linear dynamic pressure groove 3 corresponds to an angle of 15°.

[0069] The circular hole diameter of the back pressure drainage hole 8 is 0.3 mm.

[0070] Embodiment three:

[0071] like Figure 8 As shown, based on the first embodiment, the difference is that:

[0072] The cross section of the back pressure drainage hole 8 is in the shape of a small hole, and its diameter is 0.2mm. The main star-shaped linear dynamic pressure groove 1 is still a star-shaped linear dynamic pressure groove, wherein the groove depth of each main star-shaped linear dynamic pressure groove 1 is 5μm, and the parameters and are 7.78 and 23.34 respectively; the groove depth of each secondary star-shaped linear dynamic pressure groove 3 is 5μm, and the parameters and are 3 and 9 respectively. The groove platform ratio is 0.5; the equalizing pressure groove 6 is an annular equalizing pressure groove 6, and its depth is 10μm.

[0073] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terms used herein are selected to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A star-shaped linear dynamic pressure groove-back pressure self-drainage enhanced pressurized dry gas sealing structure, including a dry gas sealing dynamic ring, characterized in that: The sealing end surface of the dry gas seal dynamic ring is provided with a main star-shaped linear dynamic pressure groove (1), and the main star-shaped linear dynamic pressure grooves (1) are evenly spaced along the circumferential direction of the dry gas seal dynamic ring, so that an active pressure groove platform (2) is formed between two adjacent main star-shaped linear dynamic pressure grooves (1); A secondary star-shaped linear dynamic pressure groove (3) is provided on the inner side of the primary star-shaped linear dynamic pressure groove (1), and the secondary star-shaped linear dynamic pressure groove (3) is not connected to the inner side surface of the dry gas sealing dynamic ring, so that a secondary sealing dam (4) is formed between the inner side surface of the dry gas sealing dynamic ring and the groove root of the secondary star-shaped linear dynamic pressure groove (3); the secondary star-shaped linear dynamic pressure grooves (3) are evenly spaced along the circumferential direction of the dry gas sealing dynamic ring, so that a secondary dynamic pressure groove platform (5) is formed between two adjacent secondary star-shaped linear dynamic pressure grooves (3); An annular pressure equalizing groove (6) is provided between the primary star-shaped linear dynamic pressure groove (1) and the secondary star-shaped linear dynamic pressure groove (3); the pressure equalizing groove (6) is connected to the secondary star-shaped linear dynamic pressure groove (3) but is not connected to the primary star-shaped linear dynamic pressure groove (1), thereby forming a main sealing dam (7) between the pressure equalizing groove (6) and the groove root of the primary star-shaped linear dynamic pressure groove (1); The pressure equalizing groove (6) is provided with a back pressure drainage hole (8), and the back pressure drainage hole (8) is arranged through the dry gas sealing dynamic ring and corresponds one to one with the secondary star-shaped linear dynamic pressure groove (3).

2. According to claim 1, a star-shaped linear dynamic pressure groove-back pressure self-drainage enhanced pressurized dry gas sealing structure is characterized by: The main star-shaped linear dynamic pressure groove (1) comprises an active pressure groove root (11) and two main groove area side walls (12) located on both sides of the active pressure groove root (11); The active pressure groove root (11) is in an arc shape; the two main groove area side walls (12) extend along a star-shaped line.

3. According to claim 2, a star-shaped linear dynamic pressure groove-back pressure self-drainage enhanced pressurized dry gas sealing structure is characterized by: The two main groove area side walls (12) are bent and extended in the same direction or are bent and extended relative to each other.

4. According to claim 2, a star-shaped linear dynamic pressure groove-back pressure self-drainage enhanced pressurized dry gas sealing structure is characterized by: The parametric equation of the star line is: Wherein, the constant a is the radial width of the main star-shaped linear dynamic pressure groove (1), and the constant b is 2a-3a.

5. According to claim 1, a star-shaped linear dynamic pressure groove-back pressure self-drainage enhanced pressurized dry gas sealing structure is characterized by: The secondary star-shaped linear dynamic pressure groove (3) comprises a secondary dynamic pressure groove root (31) and two secondary groove area side walls (32) located on both sides of the secondary dynamic pressure groove root (31); The secondary dynamic pressure groove root (31) is in an arc shape; the secondary groove area side wall (32) extends along a star-shaped line.

6. The star-shaped linear dynamic pressure groove-back pressure self-drainage enhanced pressurized dry gas sealing structure according to claim 5 is characterized by: The two secondary groove area side walls (32) are bent and extended in the same direction or are bent and extended relative to each other.

7. The star-shaped linear dynamic pressure groove-back pressure self-drainage enhanced pressurized dry gas sealing structure according to claim 5 is characterized by: The parametric equation of the star line is: Wherein, the constant a is the radial width of the secondary star-shaped linear dynamic pressure groove (3), and the constant b is 2a-3a.

8. The star-shaped linear dynamic pressure groove-back pressure self-drainage enhanced pressurized dry gas sealing structure according to claim 1 is characterized by: The groove depth of the primary star-shaped linear dynamic pressure groove (1) is 0.001 mm-0.02 mm; the groove depth of the secondary star-shaped linear dynamic pressure groove (3) is 0.001 mm-0.02 mm; the groove depth of the equalizing pressure groove (6) is 0.001 mm-0.1 mm; The radial width of the primary sealing dam (7) is 2 mm to 10 mm; the radial width of the secondary sealing dam (4) is 1 mm to 5 mm.

9. The star-shaped linear dynamic pressure groove-back pressure self-drainage enhanced pressurized dry gas sealing structure according to claim 1, characterized in that: The cross-sectional shape of the back pressure drainage hole (8) is square, circular or other shapes.

10. The star-shaped linear dynamic pressure groove-back pressure self-drainage enhanced pressurized dry gas seal structure according to claim 1, characterized in that: The number of the primary star-shaped linear dynamic pressure grooves (1) is 2-30; the number of the secondary star-shaped linear dynamic pressure grooves (3) is 2-30.

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