Shaft opening and double balance disc type axial force balancing device for multistage liquid turbine pump

Abstract

The application provides a shaft opening and double-balancing disc type axial force balancing device for a multistage liquid turbine pump, which is used to solve the technical problem that the high back pressure type multistage liquid turbine pump cannot realize axial force self-balancing because the turbine inlet and outlet pressure is high and the pump body inlet and outlet pressure is low, and there is no reference axial force balancing device configuration. The axial force balancing device of the application is provided with first and second dynamic seals with adjustable axial gaps in the fluid flow path, and a radial through hole is formed in the turbine center shaft, which cooperates with the axial play of the bearing to change the axial gaps of the first and second dynamic seals when the turbine disc shaft moves axially, and further causes the change of the cavity pressure; the application limits the pore diameter of the radial through hole so that the flow resistance of the fluid passing through the radial through hole is small enough, and limits the average diameter of the first and second dynamic seals and the numerical value of the inlet side outer diameter of the turbine center shaft, which effectively ensures the axial force balance of the multistage liquid turbine pump.

Description

Technical Field

[0001] This invention relates to an axial force balancing device, and more particularly to an axial force balancing device with shaft opening and double balance disc for a multi-stage hydraulic turbine pump. Background Technology

[0002] The turbopump is one of the core components of a liquid rocket engine, and axial force balance plays a crucial role in the turbopump's lifespan and reliability, and can even affect the performance of the entire liquid rocket engine.

[0003] With the development of liquid rocket engine systems, the application of multistage liquid turbopumps is becoming increasingly common. Among them, the commonly used high back pressure multistage liquid turbopumps cannot achieve axial force self-balancing due to the high turbine inlet and outlet pressures and the low pump body inlet and outlet pressures. Currently, there is no reference axial force balancing device configuration for this type of multistage liquid turbopump, necessitating the development of a wide-range, highly reliable axial force balancing device to address this requirement. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problem that high back pressure multistage hydraulic turbine pumps cannot achieve axial force self-balancing due to the high turbine inlet and outlet pressures and the low pump body inlet and outlet pressures, and that there is currently no reference axial force balancing device configuration. The invention provides a shaft opening and double balance disc type axial force balancing device for multistage hydraulic turbine pumps.

[0005] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0006] A shaft opening and double-balance disc axial force balancing device for a multi-stage liquid turbine pump, the multi-stage liquid turbine pump including a multi-stage liquid turbine and a pump body, wherein the multi-stage liquid turbine includes a turbine disc shaft, a housing, and bearings; the turbine disc shaft has a hollow structure, including a turbine central shaft and a turbine disc disposed outside the turbine central shaft; one end of the turbine central shaft is connected to the drive shaft of the pump body, and the other end away from the pump body is an open structure; the housing is coaxially sleeved on the outside of the turbine disc shaft, and the bearing is disposed between the outer side wall of the turbine central shaft away from the pump body and the inner side wall of the housing at the corresponding position; the special feature is that the bearing has axial clearance;

[0007] A turbine high-pressure chamber is provided between the outer wall of the turbine disk near the pump body and the inner wall of the outer casing at the corresponding position; a first pressure regulating chamber is provided between the outer wall of the turbine central shaft near the pump body and the inner wall of the outer casing at the corresponding position; a first dynamic seal with adjustable axial clearance is provided between the turbine high-pressure chamber and the first pressure regulating chamber.

[0008] The turbine central shaft has multiple radial through holes along the circumferential direction on the side wall near the pump body, which connect the first pressure regulating chamber and the internal cavity structure of the turbine central shaft; the gap between the outer side wall of the turbine central shaft away from the pump body and the inner side wall of the outer shell at the corresponding position, and the internal cavity structure of the turbine central shaft, form the second pressure regulating chamber.

[0009] A turbine intermediate pressure chamber is provided between the outer wall of the turbine disk away from the pump body and the inner wall of the outer casing at the corresponding position; a second dynamic seal with adjustable axial clearance is provided between the second pressure regulating chamber and the turbine intermediate pressure chamber;

[0010] The diameter d4 of the radial through hole must satisfy the following formula:

[0011]

[0012] Where d2 is the average diameter of the first dynamic seal, c2 is the axial clearance value of the first dynamic seal, and z is the number of radial through holes;

[0013] The average diameter d2 of the first dynamic seal, the average diameter d7 of the second dynamic seal, and the outer diameter d9 of the turbine central shaft near the pump body must satisfy the following formula:

[0014]

[0015] Furthermore, the first dynamic seal is a non-contact dynamic seal; the second dynamic seal is a non-contact dynamic seal.

[0016] Furthermore, the first dynamic seal is an annular gap dynamic seal; the second dynamic seal is a stepped grate dynamic seal.

[0017] Furthermore, the minimum clearance c of the first dynamic seal 2min Satisfy the following formula:

[0018] 0.3mm≥c 2min ≥0.1mm

[0019] The minimum clearance c of the second dynamic seal 7min Minimum clearance c between the first dynamic seal and the first dynamic seal 2min The following formula applies between them:

[0020] c 2min =0.75c 7min .

[0021] Furthermore, the minimum clearance c of the first dynamic seal 2min The maximum clearance c of the first dynamic seal 2max The following formula must be satisfied between the bearing's axial clearance δ and the bearing's axial clearance δ:

[0022] c 2max=c 2min +δ;

[0023] The minimum clearance c of the second dynamic seal 7min The maximum clearance c of the second dynamic seal 7max The following formula must be satisfied between the bearing's axial clearance δ and the bearing's axial clearance δ:

[0024] c 7max =c 7min +δ.

[0025] The advantages of this invention compared to the prior art are as follows:

[0026] 1. This invention provides a shaft opening and double-balance disc axial force balancing device for a multi-stage hydraulic turbine pump. An adjustable first and second dynamic seal with axial clearance are provided in the fluid flow path to form two balance discs. Simultaneously, a radial through-hole is provided on the turbine central shaft, forming three flow resistance elements in the fluid flow path: the first dynamic seal, the radial through-hole, and the second dynamic seal. Combined with the axial clearance of the bearing, the axial clearance of the first and second dynamic seals can change with the axial movement of the turbine disc shaft, thereby causing changes in cavity pressure. This invention limits the diameter of the radial through-hole to allow fluid to pass through… The flow resistance through the radial through-hole is sufficiently small. At the same time, by limiting the average diameter of the first dynamic seal, the average diameter of the second dynamic seal, and the outer diameter of the turbine central shaft inlet side, the change in cavity pressure caused by the change in the axial clearance of the first and second dynamic seals can reduce the absolute value of the axial force until it approaches 0. This effectively ensures the axial force balance of the multi-stage hydraulic turbine pump. The structure is simple and easy to use. It can be widely used in high back pressure multi-stage hydraulic turbine pumps, filling the gap in axial force balancing devices for this type of turbine pump. It provides a foundation for this type of turbine pump to achieve wide-range variable operating condition adjustment and obtain high reliability margin.

[0027] 2. The present invention provides a shaft opening and double balance disc type axial force balancing device for a multi-stage liquid turbine pump. By setting the minimum gap of the first dynamic seal and the minimum gap of the second dynamic seal, it can ensure better axial force balancing capability of the multi-stage liquid turbine, and at the same time greatly reduce the risk of collision and wear between moving and stationary parts. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of an embodiment of the shaft opening and double balance disc type axial force balancing device for a multi-stage liquid turbine pump according to the present invention.

[0029] The specific labeling in the attached diagram is as follows:

[0030] 0-Outer shell, 1-High pressure chamber of turbine, 2-First dynamic seal, 3-First pressure regulating chamber, 4-Radial through hole, 5-Second pressure regulating chamber, 6-Bearing, 7-Second dynamic seal, 8-Intermediate pressure chamber of turbine, 9-Turbine disc shaft, 10-Turbine hub, 11-Turbine blade. Detailed Implementation

[0031] To make the advantages and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Multistage liquid turbine pumps typically include multistage liquid turbines and a pump body; in this embodiment, it is a two-stage liquid turbine pump. For example... Figure 1 As shown, the multi-stage liquid turbine includes a turbine disk shaft 9, a housing 0, and a bearing 6. The turbine disk shaft 9 is a hollow structure, comprising a turbine central shaft and a turbine disk integrally disposed on the outside of the turbine central shaft. One end of the turbine central shaft is connected to the drive shaft of the pump body, and the other end of the turbine central shaft away from the pump body is an open structure. The housing 0 is coaxially sleeved on the outside of the turbine disk shaft 9, and the bearing 6 is disposed between the outer wall of the turbine central shaft and the inner wall of the housing 0 at the corresponding position, for providing support to the turbine disk shaft 9. Turbine blades 11 are mounted on the turbine disk via a turbine hub 10. In this embodiment, the two-stage liquid turbine pump has two stages of turbine blades 11.

[0033] like Figure 1 As shown, this invention provides a shaft opening and double-balance disc axial force balancing device for a multi-stage liquid turbine pump. A turbine high-pressure chamber 1 is provided between the outer wall of the turbine disc near the pump body and the inner wall of the corresponding outer casing 0. A first pressure regulating chamber 3 is provided between the outer wall of the turbine central shaft near the pump body and the inner wall of the corresponding outer casing 0. A first dynamic seal 2 is provided between the turbine high-pressure chamber 1 and the first pressure regulating chamber 3. The first dynamic seal 2 is a non-contact dynamic seal with adjustable axial clearance. In this embodiment, an annular gap dynamic seal is used to make the fluid encounter resistance when flowing in the axial clearance of the first dynamic seal 2, thereby reducing fluid leakage from the turbine high-pressure chamber 1 to the first pressure regulating chamber 3, and simultaneously creating different chamber pressures between the turbine high-pressure chamber 1 and the first pressure regulating chamber 3.

[0034] Multiple radial through holes 4 are provided circumferentially on the side wall of the turbine central shaft near the pump body. One end of each radial through hole 4 is connected to the first pressure regulating chamber 3, and the other end is connected to the cavity structure inside the turbine central shaft. The gap between the outer side wall of the turbine central shaft away from the pump body and the inner side wall of the corresponding outer casing 0, and the cavity structure inside the turbine central shaft, form the second pressure regulating chamber 5.

[0035] A turbine intermediate pressure chamber 8 is provided between the outer wall of the turbine disk away from the pump body and the inner wall of the outer casing 0 at the corresponding position; a second dynamic seal 7 is provided between the second pressure regulating chamber 5 and the turbine intermediate pressure chamber 8. The second dynamic seal 7 is also a non-contact dynamic seal with adjustable axial clearance. In this embodiment, a stepped grate-type dynamic seal is used to make the fluid encounter resistance when flowing in the axial clearance of the second dynamic seal 7, thereby reducing the leakage of fluid from the second pressure regulating chamber 5 to the turbine intermediate pressure chamber 8, and at the same time making the second pressure regulating chamber 5 and the turbine intermediate pressure chamber 8 form different chamber pressures.

[0036] Since the turbine disk shaft 9 can move axially under the push of axial force when the multi-stage liquid turbine pump is working, it is also necessary to have axial clearance in the bearing 6. This allows the axial clearance of the first dynamic seal 2 and the axial clearance of the first dynamic seal 7 to change with the axial movement of the turbine disk shaft 9.

[0037] The flow direction of the fluid in the shaft opening and double balance disc type axial force balancing device of the multi-stage liquid turbine pump of the present invention, that is, the fluid flow path is: turbine high pressure chamber 1—second dynamic seal 2—first pressure regulating chamber 3—radial through hole 4—second pressure regulating chamber 5—second dynamic seal 7—turbine medium pressure chamber 8.

[0038] In the fluid flow path of this invention, there are three flow resistance elements: a first dynamic seal 2, a radial through hole 4, and a second dynamic seal 7. The gap between the first dynamic seal 2 and the second dynamic seal 7 is axial, forming two balance discs. The flow rate m in the fluid flow path satisfies the following formula:

[0039]

[0040] Wherein, c2 represents the axial clearance value of the first dynamic seal 2; d2 represents the average diameter of the first dynamic seal 2; μ2 represents the flow resistance coefficient of the first dynamic seal 2; ρ represents the density of the fluid; P1 represents the pressure of the turbine high-pressure chamber 1; P3 represents the pressure of the first pressure regulating chamber 3; z represents the number of radial through holes 4; d4 represents the diameter of the radial through holes 4; μ4 represents the flow resistance coefficient of the radial through holes 4; P5 represents the pressure of the second pressure regulating chamber 5; c7 represents the axial clearance value of the second dynamic seal 7; d7 represents the average diameter of the second dynamic seal 7; μ7 represents the flow resistance coefficient of the second dynamic seal 7; and P8 represents the pressure of the turbine intermediate pressure chamber 8.

[0041] Since the pressure P1 in the high-pressure chamber 1 and the pressure P8 in the intermediate-pressure chamber 8 of the turbine are fixed values, determined by the upstream and downstream conditions of the multi-stage liquid turbine pump, the pressure P3 in the first pressure regulating chamber 3 and the pressure P5 in the second pressure regulating chamber 5 can be obtained by combining formulas (1), (2), and (3).

[0042] Assuming the axial force is positive when it is directed to the right, the axial force F acting on the turbine disk shaft 9 can be expressed as follows:

[0043]

[0044] Where, d 10 d9 represents the diameter of turbine hub 10, d9 represents the outer diameter of the turbine central shaft near the pump body, and F p F represents the axial force on the side of the turbine's central shaft closest to the pump body. t This represents the axial force of turbine blade 11.

[0045] Based on the upstream and downstream conditions of the multi-stage hydraulic turbine pump, it can be determined that the pressure gradually decreases from upstream to downstream. This is also a necessary condition for the axial force balancing device to have the ability to adjust axial force.

[0046] P1 > P3 > P5 > P8 (5)

[0047] In this invention, to minimize the flow resistance of the fluid passing through the radial through-hole 4, the diameter of the radial through-hole 4 needs to be relatively large. The diameter of the radial through-hole 4 in this invention needs to satisfy the following formula:

[0048]

[0049] Formula (6) is a necessary condition for the axial force balancing device to have strong axial force adjustment capability. When formula (6) is satisfied, the flow resistance of the radial through hole 4 is much smaller than that of other flow resistance elements.

[0050] Since the flow resistance of the fluid through the radial through-hole 4 is small enough, that is, the pressure drop through the radial through-hole 4 is small enough, it can be approximated that P3≈P5. Therefore, the pressure P3 of the first pressure regulating chamber 3 can be used to replace the pressure P5 of the second pressure regulating chamber 5.

[0051] By making a simple transformation of formula (4), we can obtain formulas (7) to (10).

[0052] F = F1 + F3 + F8 + F p +F t (7)

[0053]

[0054] Wherein, F1 is the liquid force on the surface of the turbine disc shaft 9 in the region corresponding to the area between the turbine hub 10 and the first dynamic seal 2 upstream of the first dynamic seal 2; F3 is the liquid force on the surface of the turbine disc shaft 9 in the region corresponding to the area between the first dynamic seal 2 and the second dynamic seal 7; and F8 is the liquid force on the surface of the turbine disc shaft 9 in the region corresponding to the area between the second dynamic seal 7 and the turbine hub 10 downstream of the dynamic seal b.

[0055] Based on the aforementioned conditions, it can be known that the pressure P1 in the turbine high-pressure chamber 1, the pressure P8 in the turbine intermediate-pressure chamber 8, and the axial force F on the side of the turbine central shaft near the pump body are... pThe axial force F of turbine blade 11 t This can be considered a constant. During the design process, it is only necessary to ensure that the average diameter d2 of the first dynamic seal 2, the average diameter d7 of the second dynamic seal 7, and the outer diameter d9 of the turbine central shaft near the pump body satisfy formula (11) to achieve the balance adjustment of axial force.

[0056]

[0057] when At this time, the resultant force acting on the turbine disk shaft 9 by the first pressure regulating chamber 2 and the second pressure regulating chamber 7 is negative, i.e., F3 < 0. At this time, if the axial force F on the turbine disk shaft 9 is less than 0, the turbine disk shaft 9 will move to the left, the axial clearance c2 of the first dynamic seal 2 will decrease, and the axial clearance c7 of the second dynamic seal 7 will increase. According to formulas (1), (2), and (3), the pressure P3 of the first pressure regulating chamber 3 will decrease, the absolute value of F3 will decrease, and the axial force F on the turbine disk shaft 9 will increase. The reverse is also true.

[0058] Through the above process, the axial force F on the turbine disk shaft 9 is finally balanced within the range that the bearing 6 can withstand.

[0059] Furthermore, in order to ensure that the multi-stage hydraulic turbine pump has better axial force balance capability and control the risk of rubbing between moving and stationary parts, the minimum clearance c of the first dynamic seal (2) is [not specified]. 2min The minimum clearance c of the second dynamic seal (7) must satisfy formula (12). 7min The minimum gap c between the first dynamic seal (2) and the first dynamic seal (2) 2min The following conditions must be met: Formula (13)

[0060] 0.3mm≥c 2min ≥0.1mm (12)

[0061] c 2min =0.75c 7min (13)

[0062] The axial movement range of the turbine disk shaft 9 is determined by the axial clearance δ of the bearing 6 and the minimum clearance c of the first dynamic seal 2. 2min The maximum clearance c of the first dynamic seal 2 2max The axial clearance δ of bearing 6 must satisfy formula (14):

[0063] c 2max =c 2min +δ (14)

[0064] The minimum clearance c of the second dynamic seal 7 7min The maximum clearance c of the second dynamic seal 7 7max The axial clearance δ of bearing 6 must satisfy formula (15):

[0065] c 7max =c 7min +δ (15)

[0066] Correspondingly, the gap c2 of the first dynamic seal 2 and the minimum gap c 2min Maximum gap c 2max The gap c7 of the second dynamic seal 7, and the minimum gap c 7min Maximum gap c 7max The two satisfy formula (16):

[0067] c² + c⁷ = c 7max +c 2min =c 7min +c 2max (16)

[0068] The above description is only used to illustrate the technical solutions of the present invention, and is not intended to limit them. For those skilled in the art, modifications can be made to the specific technical solutions described in the above embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions protected by the present invention.

Claims

1. A shaft opening and double balance disc type axial force balancing device for a multi-stage liquid turbine pump, wherein the multi-stage liquid turbine pump includes a multi-stage liquid turbine and a pump body; the multi-stage liquid turbine includes a turbine disc shaft (9), a housing (0) and a bearing (6); the turbine disc shaft (9) is a cavity structure, including a turbine central shaft and a turbine disc disposed outside the turbine central shaft; one end of the turbine central shaft is connected to the drive shaft of the pump body, and the other end away from the pump body is an open structure; the housing (0) is coaxially sleeved on the outside of the turbine disc shaft (9), and the bearing (6) is disposed between the outer side wall of the turbine central shaft away from the pump body and the inner side wall of the housing (0) at the corresponding position; Its features are: The bearing (6) has axial clearance; A turbine high-pressure chamber (1) is provided between the outer wall of the turbine disk near the pump body and the inner wall of the outer shell (0) at the corresponding position; a first pressure regulating chamber (3) is provided between the outer wall of the turbine central shaft near the pump body and the inner wall of the outer shell (0) at the corresponding position; a first dynamic seal (2) with adjustable axial clearance is provided between the turbine high-pressure chamber (1) and the first pressure regulating chamber (3). The turbine central shaft has multiple radial through holes (4) along the circumferential direction on the side wall near the pump body, which connect the first pressure regulating chamber (3) and the internal cavity structure of the turbine central shaft; the gap between the outer side wall away from the pump body and the inner side wall of the corresponding housing (0) and the internal cavity structure of the turbine central shaft are connected to form the second pressure regulating chamber (5). A turbine intermediate pressure chamber (8) is provided between the outer wall of the turbine disk away from the pump body and the inner wall of the outer casing (0) at the corresponding position; a second dynamic seal (7) with adjustable axial clearance is provided between the second pressure regulating chamber (5) and the turbine intermediate pressure chamber (8); The diameter d4 of the radial through hole (4) must satisfy the following formula: Wherein, d2 is the average diameter of the first dynamic seal (2), c2 is the axial clearance value of the first dynamic seal (2), and z is the number of radial through holes (4); The average diameter d2 of the first dynamic seal (2), the average diameter d7 of the second dynamic seal (7), and the outer diameter d9 of the turbine central shaft near the pump body must satisfy the following formula:

2. The shaft opening and double-balance disc axial force balancing device for a multi-stage hydraulic turbine pump according to claim 1, characterized in that: The first dynamic seal (2) is a non-contact dynamic seal; The second dynamic seal (7) is a non-contact dynamic seal.

3. The shaft opening and double-balance disc axial force balancing device for a multi-stage hydraulic turbine pump according to claim 1, characterized in that: The first dynamic seal (2) is an annular gap dynamic seal; The second dynamic seal (7) is a stepped grate type dynamic seal.

4. The shaft opening and double-balance disc axial force balancing device for a multi-stage hydraulic turbine pump according to any one of claims 1-3, characterized in that: The minimum clearance c of the first dynamic seal (2) 2min Satisfy the following formula: 0.3mm≥c 2min ≥0.1mm The minimum clearance c of the second dynamic seal (7) 7min The minimum gap c between the first dynamic seal (2) and the first dynamic seal (2) 2min The following formula applies between them: c 2min =0.75c 7min 。 5. The shaft opening and double-balance disc axial force balancing device for a multi-stage hydraulic turbine pump according to claim 4, characterized in that: The minimum clearance c of the first dynamic seal (2) 2min The maximum clearance c of the first dynamic seal (2) 2max The axial clearance δ of bearing (6) must satisfy the following formula: c 2max =c 2min +d The minimum clearance c of the second dynamic seal (7) 7min The maximum clearance c of the second dynamic seal (7) 7max The axial clearance δ of bearing (6) must satisfy the following formula: c 7max =c 7min +d.

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