A high-power two-stage pump axial force adjusting device with complex leakage channels

Abstract

The application provides a high-power two-stage pump axial force adjusting device with complex leakage channels, which comprises a primary pump and a secondary pump; further comprising a main shaft, wherein the main shaft is provided with a primary pump impeller; the primary pump impeller comprises a primary pump impeller front cover plate, and a primary pump front floating ring is coaxially sleeved outside the primary pump impeller front cover plate; the flow of a primary pump front leakage channel is adjusted to realize axial force adjustment through a radial sealing gap of the primary pump front floating ring; the primary pump impeller rear cover plate comprises a primary rear cover plate body, an integrated primary throttle shoulder is extended to the rear end surface of the primary rear cover plate body in an axial direction, and a primary pump rear floating ring is coaxially sleeved outside the primary throttle shoulder; the primary throttle shoulder divides a primary pump rear leakage channel into a floating ring leakage front high-pressure area and a floating ring leakage rear low-pressure area; the area distribution of the high-pressure area and the low-pressure area is changed to realize axial force adjustment. The device in the application solves the problem of axial force adjustment of a high-power two-stage pump with complex leakage channels, and improves the working reliability of an engine.

Description

Technical Field

[0001] This invention belongs to the field of fluid machinery technology and relates to axial force adjustment, specifically to an axial force adjustment device for a high-power two-stage pump with complex leakage channels. Background Technology

[0002] Liquid rocket engines typically employ centrifugal pumps to pressurize the fuel medium. To provide the necessary pressure for stable operation of the flow regulator and generator, the pressurization centrifugal pumps used in the staged combustion cycle liquid rocket engine fuel system are generally two-stage centrifugal pumps. The first-stage pump provides high-pressure fuel to the thrust chamber ignition circuit, while the second-stage pump uses an external conduit to draw a portion of the flow from the first-stage pump outlet to further pressurize the fuel. For high-thrust liquid rocket engines, the large impeller size, high pressure, and complex leakage channels of the two-stage pumps, coupled with the need to meet the system's wide range of variable operating conditions, pose significant challenges to adjusting the residual axial force of the rotor. Excessive residual axial force not only leads to bearing failure and rotor instability resulting in severe rubbing, but also transmits the axial force to the centrifugal pump in the oxygen system via the drive shaft, causing instability in the oxygen system rotor shaft system, potentially leading to rubbing explosions and severely impacting the reliability of the liquid rocket engine. Due to the unique structural constraints of the two-stage centrifugal pumps used in liquid rocket engines, it is difficult to effectively adjust the axial force using traditional methods such as balance pipes, back blades, and double-suction impellers. Therefore, it is necessary to provide a high-power two-stage pump axial force adjustment device with complex leakage channels to adjust the residual axial force of the two-stage fuel centrifugal pump rotor and improve the operational reliability of liquid rocket engines. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide an axial force adjustment device for a high-power two-stage pump with complex leakage channels, thereby solving the technical problem that the adjustment effect of the residual axial force of the rotor in a two-stage pump with complex leakage channels needs to be further improved in the existing technology.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A high-power two-stage pump axial force adjustment device with complex leakage channels includes a primary pump and a secondary pump arranged coaxially, wherein the inlet pressure of the secondary pump is the outlet pressure of the primary pump; it also includes a main shaft, on which the impeller of the primary pump is coaxially mounted, the impeller of the primary pump includes a front cover plate and a rear cover plate, the rear cover plate of the primary pump is arranged at the axial rear end of the front cover plate of the primary pump.

[0005] It also includes a primary pump pre-leakage channel and a primary pump post-leakage channel.

[0006] A floating ring is coaxially fitted on the outer wall of the front cover plate of the first-stage pump impeller. The flow rate of the leakage channel in front of the first-stage pump is adjusted by the radial sealing gap between the inner wall of the floating ring and the outer wall of the front cover plate of the first-stage pump impeller, thereby achieving the adjustment of the axial force.

[0007] The impeller rear cover plate of the first-stage pump includes a first-stage rear cover plate body. A first-stage throttling shoulder extends axially and rearward integrally from the axial rear end face of the first-stage rear cover plate body. A first-stage pump rear floating ring is coaxially fitted onto the outer wall of the first-stage throttling shoulder. The first-stage throttling shoulder and the first-stage pump rear floating ring work together to divide the leakage channel of the first-stage pump into a high-pressure zone before the floating ring leakage and a low-pressure zone after the floating ring leakage. The outer diameter of the first-stage throttling shoulder is the second sealing diameter D2. By adjusting the second sealing diameter D2, the area distribution of the high-pressure zone before the floating ring leakage and the low-pressure zone after the floating ring leakage is changed, thereby adjusting the axial force. The flow rate of the leakage channel of the first-stage pump is adjusted through the radial sealing gap between the inner wall of the first-stage pump rear floating ring and the outer wall of the first-stage throttling shoulder, thereby adjusting the axial force.

[0008] The secondary pump includes a secondary pump impeller and a radial bearing, which are coaxially mounted on the main shaft from front to back along the axial direction. A secondary pump floating ring is also coaxially mounted on the main shaft, located at the axial rear end of the radial bearing. The pump also includes a secondary pump rear leakage channel. The flow rate of the secondary pump rear leakage channel is adjusted by the radial sealing gap between the inner wall of the secondary pump floating ring and the outer wall of the main shaft, thereby achieving axial force adjustment.

[0009] The secondary pump impeller includes a secondary pump impeller front cover, which includes a secondary front cover body. A secondary throttling shoulder extends axially forward from the axial front face near the outer wall of the secondary front cover body. A channel inlet labyrinth is formed on the outer wall of the secondary throttling shoulder, and the outermost diameter of the channel inlet labyrinth is the labyrinth throttling diameter D3. The secondary pump also includes a secondary pump front housing. A balance piston chamber groove is formed on the axial rear end face of the secondary pump front housing. The axial front face near the axial center of the secondary front cover body extends axially forward. The axial clearance between the axial front face near the axial center of the secondary front cover body and the axial rear end face of the secondary pump front housing is the axial adjustment clearance X2. The axial adjustment clearance X2, the balance piston chamber groove, and the channel inlet labyrinth form a balance piston structure. The interior of the balance piston chamber groove of the balance piston structure is a constant pressure chamber. Pressure distribution and axial force are adjusted by adjusting the axial adjustment clearance X2 and the labyrinth throttling diameter D3.

[0010] The present invention also has the following technical features: Specifically, a thrust bearing is coaxially mounted on the main shaft, and a primary pump inlet housing is coaxially mounted outside the thrust bearing. The inner end face of the primary pump inlet housing limits the axial rear end face of the thrust bearing, and an axial compensation gap X1 is provided between the inner end face of the primary pump inlet housing and the axial rear end face of the thrust bearing.

[0011] The thrust bearing has a baffle and a clamping nut coaxially arranged at its axial front end from back to front. The clamping nut is sealed at its axial rear end and is connected to the inner wall of the primary pump inlet housing via an external thread. This allows for the axial rear end of the thrust bearing to be limited. When the axial front end of the thrust bearing is limited by the baffle, the axial compensation clearance X1 is at its maximum, i.e., the value of X1 is X1. max X1 max The axial clearance δ of the thrust bearing is increased by 0.1 mm.

[0012] Specifically, the complex leakage channels include a primary pump pre-leakage channel, a primary pump post-leakage channel, a primary pump internal main channel, a thrust bearing leakage channel, a secondary pump pre-leakage channel, a secondary pump post-leakage channel, and a secondary pump internal main channel.

[0013] Specifically, the inlet casing of the primary pump is located at the axial front end of the primary pump impeller. The exterior of the primary pump inlet casing and the middle of the front cover plate and the rear cover plate of the primary pump impeller form the main channel inside the primary pump.

[0014] The inlet housing of the primary pump is also provided with a branching through hole, and the axial rear end face of the baffle is also provided with a leakage groove. The branching through hole diverts the conveying medium entering the main channel of the primary pump to the leakage groove. The branching through hole, the leakage groove, the interior of the thrust bearing, and the interior of the inner side wall of the inlet housing of the primary pump form a thrust bearing leakage channel. The outlet end of the thrust bearing leakage channel is connected to the middle section of the main channel of the primary pump.

[0015] Specifically, the outer side of the front cover plate of the first-stage pump impeller and the floating ring in front of the first-stage pump form the leakage channel in front of the first-stage pump. The inlet end of the leakage channel in front of the first-stage pump is connected to the outlet end of the main channel inside the first-stage pump, and the outlet end of the leakage channel in front of the first-stage pump is connected to the middle section of the main channel inside the first-stage pump.

[0016] The primary pump impeller rear cover plate body is provided with a through-flow reflux hole near the hub. The outer side of the primary pump impeller rear cover plate, the radial sealing gap between the inner side wall of the primary pump rear floating ring and the outer side wall of the primary pump throttling shoulder, and the reflux hole constitute the primary pump rear leakage channel. The inlet end of the primary pump rear leakage channel is connected to the outlet end of the primary pump internal main channel, and the outlet end of the primary pump rear leakage channel is connected to the middle section of the primary pump internal main channel.

[0017] Specifically, the secondary pump impeller also includes a secondary pump impeller rear end cover, and the area between the secondary pump impeller rear end cover and the secondary pump impeller front end cover is the main channel inside the secondary pump. The inlet end of the main channel inside the secondary pump is connected to the outlet end of the main channel inside the primary pump.

[0018] The outer side of the impeller rear end cover of the secondary pump, the inner side of the radial bearing, and the radial sealing gap between the inner side wall of the floating ring of the secondary pump and the outer side wall of the main shaft form the rear leakage channel of the secondary pump. The inlet end of the rear leakage channel of the secondary pump is connected to the outlet end of the main channel inside the secondary pump, and the outlet end of the rear leakage channel of the secondary pump is connected to the front leakage channel of the primary pump in front of the return hole.

[0019] Specifically, the leakage channel before the secondary pump is a balanced piston structure. The inlet end of the leakage channel before the secondary pump is connected to the outlet end of the main channel inside the secondary pump, and the outlet end of the leakage channel before the secondary pump is connected to the middle section of the main channel inside the secondary pump.

[0020] Specifically, the value of the axial compensation clearance X1 is X1 max At that time, the value of the axial adjustment clearance X2 is at its maximum, which is X2. max .

[0021] The X2 mentioned max The value is (2δ+0.2)~(2δ+0.4) mm, where δ is the axial clearance of the thrust bearing.

[0022] Compared with the prior art, the present invention has the following technical effects: (I) The device in this invention solves the problem of axial force adjustment of a two-stage pump with high power and complex leakage channels, as well as the problem of poor adaptability to a wide range of changing working conditions, thereby improving the reliability of engine operation.

[0023] (II) The device in this invention solves the problem of ensuring that the remaining axial force on the thrust bearing is less than the axial design load of the thrust bearing when there is a large deviation in axial force or a wide range of working conditions during operation, thus ensuring stable operation of the rotor and improving the working stability and reliability of the liquid rocket engine. Attached Figure Description

[0024] Figure 1 This is a cross-sectional schematic diagram of the overall structure of the device in this invention.

[0025] Figure 2 for Figure 1 A proportionally enlarged schematic diagram of point A in the diagram.

[0026] Figure 3 for Figure 1 A scaled-up diagram of point B in the diagram.

[0027] The labels in the diagram represent the following: 1-First-stage pump, 2-Second-stage pump, 3-Main shaft, 4-First-stage pump impeller, 5-Floating ring before first-stage pump, 6-Leakage channel before first-stage pump, 7-Floating ring after first-stage pump, 8-Leakage channel after first-stage pump, 9-Second-stage pump impeller, 10-Radial bearing, 11-Floating ring after second-stage pump, 12-Leakage channel after second-stage pump, 13-First-stage pump housing, 14-Inner groove of balance piston chamber, 15-Leakage channel before second-stage pump, 16-Thrust bearing, 17-Inlet housing of first-stage pump, 18-Baffle, 19-Pressure nut, 20-Main channel inside first-stage pump, 21-Branch through hole, 22-Leakage groove, 23-Leakage channel of thrust bearing, 24-Main channel inside second-stage pump.

[0028] 401 - Front cover plate of the impeller of the first-stage pump; 402 - Rear cover plate of the impeller of the first-stage pump.

[0029] 801 - High-pressure zone before floating ring leakage; 802 - Low-pressure zone after floating ring leakage.

[0030] 901 - Front end cover of the impeller of the secondary pump; 902 - Rear end cover of the impeller of the secondary pump.

[0031] 40201 - Primary rear cover plate body, 40202 - Primary throttling shoulder, 40203 - Return hole.

[0032] 90101-Secondary front end cover body, 90102-Secondary throttling shoulder, 90103-Channel inlet labyrinth.

[0033] The specific content of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0034] It should be noted that, unless otherwise specified, all structures, components, materials, and methods in this invention adopt those commonly known in the art in the prior art. For example, the inner groove of the balance piston cavity adopts a known inner groove of the balance piston cavity, the inlet labyrinth of the channel adopts a known inlet labyrinth of the channel, the floating ring before the first-stage pump adopts a known floating ring before the first-stage pump, the radial bearing adopts a known radial bearing, the thrust bearing adopts a known thrust bearing, the clamping nut adopts a known clamping nut, the first-stage throttling shoulder adopts a known first-stage throttling shoulder, the conveying medium adopts a known conveying medium, and the accurate three-dimensional simulation model and calculation method for experimental correction adopt a known model and method.

[0035] In this invention, a high-power two-stage pump refers to a two-stage pump with a power greater than 20MW.

[0036] Following the above technical solution, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made on the basis of the technical solution of the present invention fall within the protection scope of the present invention.

[0037] Example: This embodiment provides an axial force adjustment device for a high-power two-stage pump with complex leakage channels, such as... Figure 1 As shown, it includes a primary pump 1 and a secondary pump 2 arranged coaxially, with the inlet pressure of the secondary pump 2 being the outlet pressure of the primary pump 1; it also includes a main shaft 3, on which the primary pump impeller 4 of the primary pump 1 is coaxially mounted. The primary pump impeller 4 includes a front cover plate 401 and a rear cover plate 402, with the rear cover plate 402 located at the axial rear end of the front cover plate 401.

[0038] It also includes a first-stage pump pre-leakage channel 6 and a first-stage pump post-leakage channel 8.

[0039] A floating ring 5 is coaxially fitted on the outer side wall of the front cover plate 401 of the first-stage pump impeller. The flow rate of the leakage channel 6 of the first-stage pump is adjusted by the radial sealing gap between the inner side wall of the floating ring 5 and the outer side wall of the front cover plate 401 of the first-stage pump impeller, thereby realizing the adjustment of the axial force.

[0040] The impeller rear cover plate 402 of the first-stage pump includes a first-stage rear cover plate body 40201. A first-stage throttling shoulder 40202 extends axially and rearwardly integrally on the axial rear end face of the first-stage rear cover plate body 40201. A first-stage pump rear floating ring 7 is coaxially fitted on the outer wall of the first-stage throttling shoulder 40202. Under the combined action of the first-stage throttling shoulder 40202 and the first-stage pump rear floating ring 7, the leakage channel 8 of the first-stage pump is divided into a high-pressure zone 801 before the floating ring leakage and a low-pressure zone 802 after the floating ring leakage. The outer diameter of the first-stage throttling shoulder 40202 is the second sealing diameter D2. By adjusting the second sealing diameter D2, the area distribution of the high-pressure zone 801 before the floating ring leakage and the low-pressure zone 802 after the floating ring leakage is changed, thereby realizing the adjustment of axial force. The flow rate of the leakage channel 8 of the first-stage pump is adjusted by the radial sealing gap between the inner wall of the first-stage pump rear floating ring 7 and the outer wall of the first-stage throttling shoulder 40202, thereby realizing the adjustment of axial force.

[0041] The secondary pump 2 includes a secondary pump impeller 9 and a radial bearing 10, which are coaxially mounted on the main shaft 3 from front to back along the axial direction. A secondary pump floating ring 11 is also coaxially mounted on the main shaft 3, and the secondary pump floating ring 11 is arranged at the axial rear end of the radial bearing 10. It also includes a secondary pump rear leakage channel 12. The flow rate of the secondary pump rear leakage channel 12 is adjusted by the radial sealing gap between the inner wall of the secondary pump floating ring 11 and the outer wall of the main shaft 3, thereby realizing the adjustment of the axial force.

[0042] like Figure 3As shown, the secondary pump impeller 9 includes a secondary pump impeller front cover 901, which includes a secondary front cover body 90101. A secondary throttling shoulder 90102 extends axially forward from the axial front face near the outer side wall of the secondary front cover body 90101. A channel inlet labyrinth 90103 is formed on the outer side wall of the secondary throttling shoulder 90102, and the outer diameter of the outermost end of the channel inlet labyrinth 90103 is the labyrinth throttling diameter D3. The secondary pump 2 also includes a secondary pump front housing 13, and a balance piston chamber is formed on the axial rear end face of the secondary pump front housing 13. The axial front face of the secondary front cover body 90101 near the axial center extends forward along the axial direction in an integral manner. The axial clearance between the axial front face of the secondary front cover body 90101 near the axial center and the axial rear face of the secondary pump front housing 13 is the axial adjustment clearance X2. The axial adjustment clearance X2, the inner groove 14 of the balance piston chamber, and the channel inlet labyrinth 90103 form a balance piston structure. The interior of the inner groove 14 of the balance piston structure is a constant pressure chamber. The pressure distribution and axial force are adjusted by adjusting the axial adjustment clearance X2 and the labyrinth throttling diameter D3.

[0043] In this embodiment, the inlet pressure of the secondary pump 2 is the outlet pressure P1 of the primary pump 1.

[0044] In this embodiment, a first-stage pump front floating ring 5 is provided on the outer wall of the first-stage pump impeller front cover plate 401 to seal the leakage channel 6 of the first-stage pump. The outer diameter of the first-stage pump impeller front cover plate 401 at the point of cooperation with the first-stage pump front floating ring 5 is the first sealing diameter D1. The first sealing diameter D1 is a key design parameter of the first-stage pump impeller 4, and the axial force is a non-adjustable parameter during the design.

[0045] In this embodiment, the conveying medium in the impeller 9 of the secondary pump is cooled by the leakage channel 12 after the secondary pump. A floating ring 11 of the secondary pump is set after the radial bearing 10 for sealing. The amount of cooling of the radial bearing 10 can be controlled by the radial sealing gap between the inner side wall of the floating ring 11 and the outer side wall of the main shaft 3, and the axial force can be adjusted at the same time.

[0046] In this embodiment, the inner groove 14 of the balance piston chamber has a circumferential stabilizing effect on the conveying medium in the leakage channel 15 before the secondary pump, and the interior of the inner groove 14 of the balance piston chamber is regarded as a constant pressure chamber.

[0047] In this embodiment, the axial forward and backward movement of the primary pump 1 is defined according to the flow direction of the medium transported in the main channel 20 of the primary pump 1; the axial forward and backward movement of the secondary pump 2 is defined according to the flow direction of the medium transported in the main channel 24 of the secondary pump 2.

[0048] As a preferred embodiment of this invention, such as Figure 2As shown, a thrust bearing 16 is coaxially mounted on the main shaft 3, and a primary pump inlet housing 17 is coaxially mounted outside the thrust bearing 16. The inner end face of the primary pump inlet housing 17 limits the axial rear end face of the thrust bearing 16, and an axial compensation gap X1 is provided between the inner end face of the primary pump inlet housing 17 and the axial rear end face of the thrust bearing 16.

[0049] A baffle 18 and a clamping nut 19 are coaxially arranged at the front end of the thrust bearing 16 from back to front. The rear end of the clamping nut 19 is sealed. The clamping nut 19 is connected to the inner wall of the inlet housing 17 of the first-stage pump through an external thread, which can limit the rear end of the thrust bearing 16. When the front end of the thrust bearing 16 is limited by the baffle 18, the axial compensation clearance X1 is at its maximum, that is, the value of X1 is X1. max X1 max The axial clearance δ of thrust bearing 16 is increased by 0.1 mm.

[0050] In this embodiment, the method for sealing the axial rear end of the compression nut 19 adopts a method commonly known in the art.

[0051] As a preferred embodiment, the complex leakage channels include a primary pump inlet leakage channel 6, a primary pump outlet leakage channel 8, a primary pump internal main channel 20, a thrust bearing leakage channel 23, a secondary pump inlet leakage channel 15, a secondary pump outlet leakage channel 12, and a secondary pump internal main channel 24.

[0052] As a preferred embodiment, the primary pump inlet housing 17 is arranged at the axial front end of the primary pump impeller 4. The exterior of the primary pump inlet housing 17 and the middle of the primary pump impeller front cover plate 401 and the primary pump impeller rear cover plate 402 form the primary pump internal main channel 20.

[0053] A branching through hole 21 is also provided on the inlet housing 17 of the primary pump, and a leakage groove 22 is also provided on the axial rear end face of the baffle 18. The branching through hole 21 diverts the conveying medium entering the main channel 20 of the primary pump to the leakage groove 22. The branching through hole 21, the leakage groove 22, the interior of the thrust bearing 16 and the interior of the inner side wall of the inlet housing 17 of the primary pump form the thrust bearing leakage channel 23. The outlet end of the thrust bearing leakage channel 23 is connected to the middle section of the main channel 20 of the primary pump.

[0054] As a preferred embodiment, the outer side of the front cover plate 401 of the first-stage pump impeller and the floating ring 5 of the first-stage pump form a leakage channel 6 in front of the first-stage pump. The inlet end of the leakage channel 6 in front of the first-stage pump is connected to the outlet end of the main channel 20 inside the first-stage pump, and the outlet end of the leakage channel 6 in front of the first-stage pump is connected to the middle section of the main channel 20 inside the first-stage pump.

[0055] A through-hole 40203 is provided on the main body 40201 of the first stage pump impeller near the hub. The radial sealing gap between the outer side of the first stage pump impeller impeller 402, the inner side wall of the first stage pump rear floating ring 7 and the outer side wall of the first stage throttling shoulder 40202, and the through-hole 40203 form the leakage channel 8 of the first stage pump. The inlet end of the leakage channel 8 of the first stage pump is connected to the outlet end of the main channel 20 inside the first stage pump, and the outlet end of the leakage channel 8 of the first stage pump is connected to the middle section of the main channel 20 inside the first stage pump.

[0056] As a preferred embodiment, the secondary pump impeller 9 further includes a secondary pump impeller rear end cover 902. The secondary pump impeller rear end cover 902 and the secondary pump impeller front end cover 901 form a secondary pump internal main channel 24. The inlet end of the secondary pump internal main channel 24 is connected to the outlet end of the primary pump internal main channel 20.

[0057] The outer side of the rear end cover 902 of the secondary pump impeller, the inner side of the radial bearing 10, and the radial sealing gap between the inner side wall of the floating ring 11 of the secondary pump and the outer side wall of the main shaft 3 form the rear leakage channel 12 of the secondary pump. The inlet end of the rear leakage channel 12 of the secondary pump is connected to the outlet end of the main channel 24 inside the secondary pump, and the outlet end of the rear leakage channel 12 of the secondary pump is connected to the front leakage channel 6 of the primary pump in front of the return hole 40203.

[0058] As a preferred embodiment, the pre-leakage channel 15 of the secondary pump is a balanced piston structure. The inlet end of the pre-leakage channel 15 of the secondary pump is connected to the outlet end of the main channel 24 inside the secondary pump, and the outlet end of the pre-leakage channel 15 of the secondary pump is connected to the middle section of the main channel 24 inside the secondary pump.

[0059] As a preferred embodiment, the value of the axial compensation clearance X1 is X1 max At that time, the value of the axial adjustment clearance X2 is at its maximum, which is X2. max .

[0060] X2 max The value is (2δ+0.2)~(2δ+0.4) mm, where δ is the axial clearance of the thrust bearing 16.

[0061] The device in this embodiment is used for a two-stage pump. The two-stage pump internally involves a thrust bearing leakage channel 23, a first-stage pump pre-leakage channel 6, a first-stage pump post-leakage channel 8, a first-stage pump internal main channel 20, a second-stage pump post-leakage channel 12, a second-stage pump pre-leakage channel 15, and a second-stage pump internal main channel 24, resulting in a complex leakage channel network. The rotor structure of the two-stage pump is characterized by two-point support. The thrust bearing 16, which bears axial force, is located on the inlet side of the lower-pressure first-stage pump 1, while the radial bearing 10, which does not bear axial force, is located on the rear side of the higher-pressure second-stage pump 2.

[0062] The principle by which the device in this embodiment achieves axial force adjustment is as follows: First, in the design: the axial force F1 of the first-stage pump 1 is generated by the axial force F on the rotor surface of the thrust bearing leakage channel 23. m An axial force F is generated on the rotor surface of the leakage channel 6 before the first-stage pump. 1q Axial force F is generated on the rotor surface in the leakage channel 8 after the first stage pump. 1h And the axial force F generated on the rotor surface of the main channel 20 inside the first-stage pump. 1L The sum of the four, i.e., F1 = F m +F 1L +F 1q +F 1h The axial force F2 of the secondary pump 2 is generated on the rotor surface of the leakage channel 12 after the secondary pump. 2h Axial force F is generated on the rotor surface of the leakage channel 15 before the secondary pump. 2q And the axial force F generated on the rotor surface of the main channel 24 inside the secondary pump. 2L The sum of the three, i.e., F2 = F 2L +F 2q +F 2h The resultant axial force F of primary pump 1 and secondary pump 2 is the vector sum of the axial force F1 of primary pump 1 and the axial force F2 of secondary pump 2, i.e., F = F1 + F2.

[0063] To reduce the axial load on the rotor shaft end clamping nut 19, and considering that the resultant axial force F of the first-stage pump 1 and the second-stage pump 2 cannot exceed the axial design load of the thrust bearing 16, the axial force F1 of the first-stage pump 1 is designed to point towards the second-stage pump 2 and has a magnitude of 0 to 50 kN, and the axial force F2 of the second-stage pump 2 is designed to point towards the first-stage pump 1 and has a magnitude of 0 to 50 kN; the resultant axial force F is designed to point towards the second-stage pump 2 and is less than the axial design load of the thrust bearing 16. The axial design load of the thrust bearing for the high-power fuel centrifugal pump of the rocket engine is 20 kN to 45 kN.

[0064] The above axial force calculation is performed using an accurate three-dimensional simulation model modified based on experiments. If the above requirements are not met, the axial force design adjustment can be achieved by adjusting the radial clearance of the three floating ring seals, the second seal diameter D2, the axial adjustment clearance X2, and the labyrinth throttling diameter D3 in the axial force adjustment device of this embodiment.

[0065] Secondly, during operation: Because both primary pump 1 and secondary pump 2 have large impeller sizes, high pressure, and complex leakage channels, significant cumulative axial force deviations may occur in each leakage channel during operation. Furthermore, during large-scale adjustments to varying operating conditions, the axial force changes with the operating conditions. Therefore, during operation, when the axial force deviation and changes are small, the axial adjustment clearance X2 is within (X2... max -X1 max -δ)~X2max Within the range of mm, the thrust bearing 16 is not under force, and the resultant axial force F is adjusted by the balance piston structure; when the axial force deviation and change are large, causing the resultant axial force F pointing towards the secondary pump 2 to increase, the rotor moves towards the secondary pump 2 under the action of the axial force, which reduces the axial adjustment clearance X2, enhances the adjustment capability of the balance piston structure, and the axial adjustment clearance X2 is in the range of 0 to (X2 max -X1 max When the axial force F is within the range of -δ) mm, the resultant axial force is shared by the thrust bearing 16 and the balance piston structure.

Claims

1. A high-power two-stage pump axial force adjustment device with complex leakage channels, comprising a primary pump (1) and a secondary pump (2) arranged coaxially, wherein the inlet pressure of the secondary pump (2) is the outlet pressure of the primary pump (1); and further comprising a main shaft (3), wherein a primary pump impeller (4) of the primary pump (1) is coaxially mounted on the main shaft (3), the primary pump impeller (4) comprising a primary pump impeller front cover plate (401) and a primary pump impeller rear cover plate (402), wherein the primary pump impeller rear cover plate (402) is arranged at the axial rear end of the primary pump impeller front cover plate (401); It also includes a pre-pump leakage channel (6) and a post-pump leakage channel (8), characterized in that: A floating ring (5) for the first-stage pump is coaxially fitted on the outer side wall of the front cover plate (401) of the first-stage pump impeller. The flow rate of the leakage channel (6) for the first-stage pump is adjusted by the radial sealing gap between the inner side wall of the floating ring (5) and the outer side wall of the front cover plate (401) of the first-stage pump impeller, thereby realizing the adjustment of the axial force. The impeller rear cover plate (402) of the first-stage pump includes a first-stage rear cover plate body (40201). A first-stage throttling shoulder (40202) extends axially and rearwardly integrally on the axial rear end face of the first-stage rear cover plate body (40201). A first-stage pump rear floating ring (7) is coaxially fitted on the outer side wall of the first-stage throttling shoulder (40202). Under the combined action of the first-stage throttling shoulder (40202) and the first-stage pump rear floating ring (7), the leakage channel (8) of the first-stage pump is divided into a high-pressure zone (801) before the floating ring leakage and a... After the floating ring leaks, the low-pressure area (802) has an outer diameter of the first-stage throttling shoulder (40202) equal to the second sealing diameter D2. By adjusting the second sealing diameter D2, the area distribution of the high-pressure area (801) before the floating ring leaks and the low-pressure area (802) after the floating ring leaks is changed, thereby adjusting the axial force. The flow rate of the leakage channel (8) after the first-stage pump is adjusted by the radial sealing gap between the inner wall of the floating ring (7) after the first-stage pump and the outer wall of the first-stage throttling shoulder (40202), thereby adjusting the axial force. The secondary pump (2) includes a secondary pump impeller (9) and a radial bearing (10). The secondary pump impeller (9) and the radial bearing (10) are coaxially mounted on the main shaft (3) from front to back along the axial direction. A secondary pump floating ring (11) is also coaxially mounted on the main shaft (3). The secondary pump floating ring (11) is arranged at the axial rear end of the radial bearing (10). It also includes a secondary pump rear leakage channel (12). The flow rate of the secondary pump rear leakage channel (12) is adjusted through the radial sealing gap between the inner wall of the secondary pump floating ring (11) and the outer wall of the main shaft (3), thereby realizing the adjustment of the axial force. The secondary pump impeller (9) includes a secondary pump impeller front end cover (901), which includes a secondary front end cover body (90101). A secondary throttling shoulder (90102) extends axially forward from the axial front end face of the secondary front end cover body (90101) near the outer side wall. A channel inlet labyrinth (90103) is provided on the outer side wall of the secondary throttling shoulder (90102). The outer diameter of the outermost end of the channel inlet labyrinth (90103) is the labyrinth throttling diameter D3. The secondary pump (2) also includes a secondary pump front housing (13). A flat surface is also provided on the axial rear end face of the secondary pump front housing (13). The axial front end face of the secondary front end cover body (90101) near the axial center extends forward along the axial direction. The axial gap between the axial front end face of the secondary front end cover body (90101) near the axial center and the axial rear end face of the secondary pump front housing (13) is the axial adjustment gap X2. The axial adjustment gap X2, the axial piston cavity inner groove (14), and the channel inlet labyrinth (90103) form a balance piston structure. The interior of the balance piston cavity inner groove (14) of the balance piston structure is a constant pressure chamber. The pressure distribution and axial force are adjusted by adjusting the axial adjustment gap X2 and the labyrinth throttling diameter D3.

2. The axial force adjustment device for a high-power two-stage pump with complex leakage channels as described in claim 1, characterized in that, The main shaft (3) is also coaxially fitted with a thrust bearing (16), and a primary pump inlet housing (17) is coaxially fitted outside the thrust bearing (16). The inner end face of the primary pump inlet housing (17) limits the axial rear end face of the thrust bearing (16), and an axial compensation gap X1 is provided between the inner end face of the primary pump inlet housing (17) and the axial rear end face of the thrust bearing (16). The thrust bearing (16) is provided with a baffle (18) and a clamping nut (19) coaxially from back to front along the axial front end. The clamping nut (19) is sealed at the axial rear end and is connected to the inner wall of the inlet housing (17) of the first-stage pump through an external thread. This can limit the axial rear end of the thrust bearing (16). When the axial front end of the thrust bearing (16) is limited by the baffle (18), the axial compensation clearance X1 is at its maximum, that is, the value of X1 is X1. max X1 max The axial clearance δ of the thrust bearing (16) is increased by 0.1 mm.

3. The axial force adjustment device for a high-power two-stage pump with complex leakage channels as described in claim 2, characterized in that, The complex leakage channels include a primary pump inlet leakage channel (6), a primary pump outlet leakage channel (8), a primary pump internal main channel (20), a thrust bearing leakage channel (23), a secondary pump inlet leakage channel (15), a secondary pump outlet leakage channel (12), and a secondary pump internal main channel (24).

4. The axial force adjustment device for a high-power two-stage pump with complex leakage channels as described in claim 3, characterized in that, The inlet housing (17) of the first-stage pump is arranged at the axial front end of the impeller (4) of the first-stage pump. The outside of the inlet housing (17) of the first-stage pump and the middle of the front cover plate (401) and the rear cover plate (402) of the first-stage pump impeller form the main channel (20) inside the first-stage pump. The inlet housing (17) of the primary pump is also provided with a branch through hole (21), and the axial rear end face of the baffle (18) is also provided with a leakage groove (22). The branch through hole (21) diverts the conveying medium entering the main channel (20) of the primary pump to the leakage groove (22). The branch through hole (21), the leakage groove (22), the interior of the thrust bearing (16) and the interior of the inner side wall of the inlet housing (17) of the primary pump form a thrust bearing leakage channel (23). The outlet end of the thrust bearing leakage channel (23) is connected to the middle section of the main channel (20) of the primary pump.

5. The axial force adjustment device for a high-power two-stage pump with complex leakage channels as described in claim 3, characterized in that, The exterior of the first-stage pump impeller front cover plate (401) and the first-stage pump front floating ring (5) form the first-stage pump front leakage channel (6). The inlet end of the first-stage pump front leakage channel (6) is connected to the outlet end of the first-stage pump internal main channel (20), and the outlet end of the first-stage pump front leakage channel (6) is connected to the middle section of the first-stage pump internal main channel (20). The first-stage rear cover plate body (40201) is provided with a backflow hole (40203) that runs through the front and rear. The outer side of the first-stage pump impeller rear cover plate (402), the radial sealing gap between the inner side wall of the first-stage pump rear floating ring (7) and the outer side wall of the first-stage throttling shoulder (40202), and the backflow hole (40203) form the first-stage pump rear leakage channel (8). The inlet end of the first-stage pump rear leakage channel (8) is connected to the outlet end of the first-stage pump inner main channel (20), and the outlet end of the first-stage pump rear leakage channel (8) is connected to the middle section of the first-stage pump inner main channel (20).

6. The axial force adjustment device for a high-power two-stage pump with complex leakage channels as described in claim 5, characterized in that, The secondary pump impeller (9) also includes a secondary pump impeller rear end cover (902), and the secondary pump impeller rear end cover (902) and the secondary pump impeller front end cover (901) are located in the middle of the secondary pump internal main channel (24), and the inlet end of the secondary pump internal main channel (24) is connected to the outlet end of the primary pump internal main channel (20); The outer side of the impeller rear end cover (902) of the secondary pump, the inner side of the radial bearing (10), and the radial sealing gap between the inner side wall of the floating ring (11) of the secondary pump and the outer side wall of the main shaft (3) form the secondary pump rear leakage channel (12). The inlet end of the secondary pump rear leakage channel (12) is connected to the outlet end of the main channel (24) inside the secondary pump, and the outlet end of the secondary pump rear leakage channel (12) is connected to the primary pump front leakage channel (6) in front of the return hole (40203).

7. The axial force adjustment device for a high-power two-stage pump with complex leakage channels as described in claim 3, characterized in that, The aforementioned secondary pump inlet leakage channel (15) is the aforementioned balanced piston structure. The inlet end of the secondary pump inlet leakage channel (15) is connected to the outlet end of the secondary pump inner main channel (24), and the outlet end of the secondary pump inlet leakage channel (15) is connected to the middle section of the secondary pump inner main channel (24).

8. The axial force adjustment device for a high-power two-stage pump with complex leakage channels as described in claim 3, characterized in that, The value of the axial compensation clearance X1 is X1 max At that time, the value of the axial adjustment clearance X2 is at its maximum, which is X2. max ; The X2 mentioned max The value is (2δ+0.2)~(2δ+0.4) mm, where δ is the axial clearance of the thrust bearing (16).

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