Flow control valve and method for low-temperature liquid rocket propellant

Abstract

The invention relates to the technical field of liquid rockets, in particular to a flow control valve and method for a low-temperature liquid rocket propellant. According to the technical scheme, the low-temperature compensation valve comprises a low-temperature compensation valve body, the low-temperature compensation valve body comprises a valve sleeve and a valve shell, the valve shell is inserted into the valve sleeve, the valve sleeve and the valve shell are fixed through evenly-distributed bolts, a spiral flow guide groove with the spiral angle being 35 degrees is formed in a valve element, honeycomb-shaped micropores are further formed in the valve element, and the valve element is fixedly connected with a valve rod. The flow guide cover is composed of a guide-in part and a pressure reduction part, the guide-in part is distributed along the wall of the end cover, the pressure reduction part is provided with three layers of stepped pressure reduction annular grooves which are in a stepped shape and sequentially enlarged, and an annular cavity is formed in the connecting position of the guide-in part and the pressure reduction part. The belleville spring sets are used for automatically compensating the thermal expansion difference of inner and outer layer materials, low-temperature clamping stagnation is avoided, the flow speed is reduced through the spiral flow guide grooves, the cavitation energy is collapsed through the honeycomb micropores, the pressure difference is dispersed through the annular pressure reduction cavity, the metal corrugated pipe bears main sealing, the elastic body ring compensates micro deformation, and dynamic sealing is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid rockets, and particularly to a flow control valve and method for cryogenic liquid rocket propellants. Background Art

[0002] In the aerospace propulsion system, cryogenic liquid rocket propellants (such as liquid hydrogen and liquid oxygen) are widely used due to their high energy density and environmental protection characteristics. However, traditional cryogenic valves have many defects during use, seriously affecting the reliability and performance of rocket engines.

[0003] In terms of the valve body, due to the significant difference in the thermal expansion coefficients of different materials in a cryogenic environment, when the temperature of the traditional cryogenic valve body drops suddenly, the clearance between components changes, easily leading to cryogenic jamming.

[0004] During the throttling process, when cryogenic fluid flows through the valve, the change in flow velocity will cause a local pressure drop, triggering the formation and collapse of cavities, i.e., cavitation. The powerful impact force generated by the collapse of cavities will cause cavitation damage to the valve core, reducing the service life and sealing performance of the valve. According to statistics, the failure ratio of the traditional cryogenic valve core due to cavitation is as high as 30% after frequent use. Summary of the Invention

[0005] The purpose of the present invention is to propose a flow control valve and method for cryogenic liquid rocket propellants in view of the problems in the background art.

[0006] The technical solution of the present invention: A flow control valve for cryogenic liquid rocket propellants includes a cryogenic compensation valve body, the cryogenic compensation valve body includes a valve sleeve and a valve housing, the valve housing is inserted into the valve sleeve, and the valve sleeve and the valve housing are fixed by evenly distributed bolts;

[0007] A valve core, the valve core is located in the valve housing, a spiral guide groove with a spiral angle of 35° is provided on the valve core, honeycomb micropores are also provided on the valve core, and the valve core is fixedly connected with a valve rod;

[0008] A flow guide cover, one end of the flow guide cover is flush with the end cover, and the other end extends into the valve housing to wrap the valve core. The flow guide cover is composed of an introduction part and a pressure reduction part. The introduction part is distributed along the end cover wall. The pressure reduction part is provided with three stepped pressure reduction annular grooves that are stepped and gradually expand. An annular cavity is provided at the connection between the introduction part and the pressure reduction part;

[0009] A sealing mechanism, the sealing mechanism includes a disc spring preloading assembly and a stainless steel bellows. A valve seat is provided in the valve housing. The disc spring preloading assembly is located on the valve seat. The valve core passes through the disc spring preloading assembly, and the stainless steel bellows is located between the valve seat and the valve rod.

[0010] Preferably, a counterbore is provided on the end face of the valve sleeve, and a disc spring group is installed in the counterbore. Each disc spring group of disc springs is formed by stacking and aligning disc springs with a guide cover sheet, and the disc spring group is fixed by an adjusting bolt.

[0011] Preferably, the guide cover further includes a mounting portion at the junction of the inlet portion and the pressure reducing portion. The valve housing is provided with a mating groove, and the mounting portion is installed in the mating groove and fixed axially with a snap ring. A copper gasket is installed between the valve housing and the mounting portion.

[0012] Preferably, the thickness of the single-piece aligned disc spring of the disc spring group is 2.5 mm, the stiffness coefficient is 85 N / mm, and the pre-tightening force realizes a ±10% dynamic compensation through the adjusting bolt.

[0013] Preferably, the depth of the honeycomb micropores is 2 times their pore diameter, the distance between adjacent pore walls is 0.4 mm, and the pore density is 22 pieces / cm 2 。

[0014] Preferably, the groove width ratio of the three-layer stepped pressure reducing ring groove is 1:1.6:2.7, and the groove depth ratio is 1:1.5:2.

[0015] Preferably, the inner wall surface of the guide cover is formed with a tungsten carbide-cobalt-based composite coating by laser cladding technology. The coating thickness is 150 - 250 μm, the hardness ≥1200 HV, and the porosity ≤0.5%.

[0016] Preferably, the cryogenic compensation valve body needs to be cryogenically pre-treated before assembly. The specific process is as follows: Immerse the valve housing and the valve sleeve separately in liquid nitrogen for 2 - 4 hours, then let them stand at room temperature for 12 hours to release the residual stress, repeat 3 cycles, and after treatment, the standard deviation σ of the cryogenic deformation of the valve body ≤0.01 mm.

[0017] Preferably, the valve sleeve is made of aluminum alloy material, and the valve housing is made of 316L stainless steel material.

[0018] A cryogenic flow control method includes the following steps:

[0019] S1: Cryogenic deformation compensation stage. The propellant flows in from the inlet pipe, passes through the annular cavity between the outer wall of the guide cover and the valve housing to form a pre-cooling circulation path. When the cryogenic fluid contacts the valve housing, heat will be quickly conducted, and a shrinkage difference will be generated between the valve sleeve and the valve housing due to the temperature difference, causing the disc spring group to deform.

[0020] S2: Cavitation energy hierarchical dissipation. When the fluid continuously flows into the cylinder, the fluid will distribute the differential pressure in proportion through the stepped pressure reducing ring groove, reduce the speed of the fluid through the spiral guide groove, and then cause the cavitation bubbles to collapse in advance through the honeycomb micropores;

[0021] S3: Dynamic seal compensation: As the temperature in the cylinder continuously decreases, the disc spring pre-tightening assembly outputs a compensation displacement to maintain the pressure of the sealing surface.

[0022] Compared with the existing technologies, the beneficial effects of the present invention are as follows:

[0023] 1. By providing a low-temperature compensation valve body, the present invention significantly improves the reliability and sealing life of the valve under extreme low temperatures. The valve sleeve of the low-temperature compensation valve body is made of aluminum alloy material, and the valve housing is made of 316L stainless steel material. Through the combination of different materials and a number of circumferentially evenly distributed disc spring groups, the self-adaptive compensation of the low-temperature shrinkage amount is achieved. In a low-temperature environment, the shrinkage difference caused by the difference in the thermal expansion coefficients of the inner and outer layer materials is accurately absorbed by the disc spring groups. Moreover, by setting the valve core to cooperate with the flow guide cover, the jamming problem caused by thermal deformation of the traditional integral valve body is solved.

[0024] 2. By providing spiral flow guide grooves on the surface of the main valve core, the fluid flow rate can be rapidly reduced, thereby reducing the kinetic energy loss by [X]; and by providing honeycomb micropores, cavitation bubbles are induced to collapse in the pores through the boundary layer separation effect, and the impact energy is absorbed by the pore walls, so that the cavitation damage area is significantly reduced compared with that of the traditional flat valve core. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of the present invention;

[0026] Figure 2 is a schematic structural diagram of the valve core of the present invention;

[0027] Figure 3 is a flow chart of the method of the present invention.

[0028] Reference numerals: 1. Low-temperature compensation valve body; 2. Valve core; 3. Flow guide cover; 4. Sealing mechanism; 5. Valve seat; 6. Valve rod; 10. Annular cavity; 11. Valve sleeve; 12. Valve housing; 21. Spiral flow guide groove; 22. Honeycomb micropore; 31. Introduction part; 32. Pressure reduction part; 33. Stepwise pressure reduction ring groove; 34. Installation part; 41. Disc spring pre-tightening assembly; 42. Stainless steel bellows; 100. Bolt; 200. Disc spring group; 300. Matching groove; 1000. End cover. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0030] Referring to Figure 1 and 2 , a flow control valve for cryogenic liquid rocket propellants includes:

[0031] Low-temperature compensation valve body 1, the low-temperature compensation valve body 1 includes a valve sleeve 11 and a valve housing 12. The valve housing 12 is inserted into the valve sleeve 11, and the valve sleeve 11 and the valve housing 12 are fixed by evenly distributed bolts 100;

[0032] A valve core 2, the valve core 2 is located inside the valve housing 12. A spiral guide groove 21 with a spiral angle of 35° is provided on the valve core 2, and honeycomb micropores 22 are also provided on the valve core 2. The valve core 2 is fixedly connected to a valve rod 6;

[0033] A flow guide cover 3, one end of the flow guide cover 3 is flush with the end cover 1000, and the other end extends into the valve housing 12 to wrap the valve core 2. The flow guide cover 3 is composed of an introduction part 31 and a pressure reduction part 32. The introduction part 31 is distributed along the wall of the end cover 1000. Three stepped pressure reduction annular grooves 33 that are stepped and gradually expand are provided on the pressure reduction part 32. An annular cavity 10 is provided at the connection between the introduction part 31 and the pressure reduction part 32;

[0034] A sealing mechanism 4, the sealing mechanism 4 includes a disc spring pre-tightening assembly 41 and a stainless steel bellows 42. A valve seat 5 is provided inside the valve housing 12. The disc spring pre-tightening assembly 41 is located on the valve seat 5. The valve core 2 passes through the disc spring pre-tightening assembly 41, and the stainless steel bellows 42 is located between the valve seat 5 and the valve rod 6.

[0035] In the present invention, the low-temperature compensation valve body 1 is divided into a split structure of a valve sleeve 11 and a valve housing 12. Between the two, the reliability at low temperatures can be improved. And the valve housing 12 is made of aluminum alloy material, which can reduce its own weight while ensuring the structural strength, and can solve the problem of valve body deformation and jamming caused by the difference in thermal expansion coefficients of different materials at low temperatures;

[0036] And through the valve core 2, with a specific spiral angle of 35° of the spiral guide groove 21, the flow velocity of the fluid when entering can be reduced. Specifically, the fluid velocity is reduced from 30 m / s to 12 m / s, and the kinetic energy is reduced by 64%. And it can induce the collapse of cavitation bubbles in the holes, protecting the surface of the valve core from cavitation damage.

[0037] Also due to the setting of the flow guide cover 3, when the fluid passes through, the flow guide cover 3 will play a guiding effect. And because three stepped pressure reduction annular grooves 33 that are stepped and gradually expand are provided, when the fluid passes through, its flow area will gradually expand, avoiding the flow field distortion caused by sudden expansion. And the spiral guide groove 21 of the structural valve core 2 can convert high-speed turbulent flow into laminar flow or orderly swirling flow, reducing flow separation and energy loss.

[0038] In this embodiment, a counterbore is provided on the end face of the valve sleeve 11, and a disc spring group 200 is installed in the counterbore. Each disc spring of the disc spring group 200 is formed by stacking and fitting disc springs of the flow guide cover 3. The disc spring group 200 is fixed by adjusting bolts, and the disc spring group 200 can absorb the shrinkage difference between the inner and outer layers in a low-temperature state.

[0039] In addition, the thickness of a single pair of mating disc springs in the disc spring group 200 is 2.5 mm, the stiffness coefficient is 85 N / mm, and the pre-tightening force realizes ±10% dynamic compensation through an adjusting bolt.

[0040] In this embodiment, the flow deflector 3 further includes a mounting portion 34 at the junction of the inlet portion 31 and the pressure reducing portion 32. The valve housing 12 is provided with a mating groove 300. The mounting portion 34 is installed in the mating groove 300 and is axially fixed by a snap ring. A copper gasket is installed between the valve housing 12 and the mounting portion 34.

[0041] In this embodiment, the depth of the honeycomb micropores 22 is twice its pore diameter, the distance between adjacent pore walls is 0.4 mm, and the pore density is 22 per cm. 2 , and the groove width ratio of the three-layer stepped pressure reducing ring groove 33 is 1:1.6:2.7, and the groove depth ratio is 1:1.5:2.

[0042] The inner wall surface of the flow deflector is formed with a tungsten carbide-cobalt-based composite coating by laser cladding process. The coating thickness is 150 - 250 μm, the hardness is ≥1200 HV, and the porosity is ≤0.5%.

[0043] The valve sleeve is made of aluminum alloy material, and the valve housing is made of 316L stainless steel material. The cryogenic compensation valve body needs to be cryogenically pre-treated before assembly. The specific process is as follows: Immerse the valve housing and the valve sleeve separately in liquid nitrogen for 2 - 4 hours, then let them stand at room temperature for 12 hours to release the residual stress, repeat 3 cycles, and the standard deviation σ of the low-temperature deformation amount of the valve body after treatment is ≤0.01 mm.

[0044] Specifically, when it comes to generating the assembly:

[0045] Installation of the cryogenic compensation valve body 1. The valve sleeve 11 is made of 316L stainless steel, the valve housing 12 is made of Al-2219 aluminum alloy, the number of disc spring groups 200 is 8, the inner diameter of the valve sleeve 11 is Φ76.50 ± 0.02 mm, the depth of the counterbore adapted to the disc spring group 200 is 10 mm, each disc spring group 200 is stacked by 3 pieces of the flow deflector in a mating manner, its outer diameter is Φ25 mm, thickness is 2.5 mm, stiffness is 85 N / mm, and the single-piece pre-compression amount δ = 0.5 mm;

[0046] When specifically installing the cryogenic compensation valve body 1:

[0047] First, embed the disc spring group into the counterbore, apply an initial pre-tightening force of 600 N and a torque value of 45 N·m through an adjusting bolt, and calibrate it with a digital display torque wrench;

[0048] Second, insert the valve housing 12 into the valve sleeve 11, evenly distribute 8 M12 flange bolts along the circumference, their strength grade is 12.9, tighten them in three times in a diagonal order to 80 N·m, and then use a coordinate measuring instrument to detect that the coaxiality of the inner and outer layers is ≤0.02 mm.

[0049] Installation of the valve core 2 and the flow guide cover 3. The outer diameter of the valve core 2 is Φ50.00 - 0.02 / -0.05 mm, the inner hole of the flow guide cover 3 is Φ50.03 + 0.01 / +0.03 mm, the clearance fit between the two is 0.05 - 0.08 mm, and 34 and 300 are interference fits.

[0050] The stepped pressure-reducing ring groove 33 is machined by a five-axis linkage CNC machine tool. The first stage: width 3 mm × depth 2 mm, fillet R0.2 mm; the second stage: width 5 mm × depth 3 mm, fillet R0.3 mm; the third stage: width 8 mm × depth 4 mm, fillet R0.5 mm, and the 10 MPa pressure difference is distributed as 4.5 / 3.3 / 2.2 MPa.

[0051] In addition, it should be noted that the formula for calculating the disc spring stiffness of the disc spring group 200:

[0052]

[0053] Among them, E = 206 GPa stainless steel, t = 2.5 mm, D = 25 mm, K1 = 0.69 rectangular cross-section coefficient, ν = 0.3;

[0054] The effective stroke of the stainless steel bellows 42 is S = 10 mm, the fatigue life N = 10 5 times, and the formula for calculating the pre-tightening force of 41:

[0055]

[0056] Among them, n is the number of disc spring sheets, δ = 0.5 mm, and the output F = 180 N.

[0057] The present invention automatically compensates for the thermal expansion difference between the inner and outer layer materials through the disc spring group to avoid low-temperature jamming. The spiral flow guide groove reduces the flow rate, the honeycomb micropores quench the cavitation energy, the annular pressure-reducing cavity disperses the pressure difference, the metal bellows undertakes the main seal, and the elastomer ring compensates for the microscopic deformation to achieve dynamic sealing.

[0058] The present invention also discloses a low-temperature flow control method, including the following steps:

[0059] S1: Low-temperature deformation compensation stage. The propellant flows in from the inlet pipeline, passes through the annular cavity 10 between the outer wall of the flow guide cover 3 and the valve housing 12, forms a pre-cooling circulation path. When the low-temperature fluid contacts the valve housing 12, the heat will be quickly conducted, and the valve sleeve 11 and the valve housing 12 generate a shrinkage difference due to the temperature difference, causing the disc spring group 200 to deform.

[0060] S2: Cavitation energy is dissipated in a graded manner. When the fluid continuously flows into the cylinder, the fluid will distribute the differential pressure proportionally through the stepped pressure-reducing annular groove 33, reduce the speed of the fluid through the spiral diversion groove 21, and then cause the cavitation bubbles to collapse in advance through the honeycomb micropores 22;

[0061] S3: Dynamic seal compensation: As the temperature in the cylinder continuously decreases, the disc spring pre-tightening assembly 41 outputs a compensation displacement to maintain the pressure on the sealing surface.

[0062] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0063] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined.

[0064] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A flow control valve for cryogenic liquid rocket propellant, characterized in that: include: Low temperature compensation valve body, the low temperature compensation valve body includes a valve sleeve and a valve shell, the valve shell is inserted in the valve sleeve, and the valve sleeve and the valve shell are fixed by evenly distributed bolts; The valve core is located in the valve housing, a spiral guide groove with a spiral angle of 35° is provided on the valve core, a honeycomb-shaped micropore is also provided on the valve core, and the valve core is fixedly connected to the valve stem; A flow guide cover, one end of which is flush with the end cover, and the other end extends into the valve housing to wrap the valve core. The flow guide cover is composed of an introduction part and a pressure reduction part. The introduction part is distributed along the end cover wall. The pressure reduction part is provided with three-layer stepped pressure reduction ring grooves that are stepped and expanded successively. An annular cavity is provided at the connection between the introduction part and the pressure reduction part; Sealing mechanism: The sealing mechanism includes a disc spring pre-tightening assembly and a stainless steel bellows. A valve seat is arranged in the valve housing. The disc spring pre-tightening assembly is located on the valve seat. The valve core passes through the disc spring pre-tightening assembly. The stainless steel bellows is located between the valve seat and the valve stem.

2. A flow control valve for cryogenic liquid rocket propellant according to claim 1, characterized in that: The end face of the valve sleeve is provided with a countersunk hole, in which a disc spring group is installed. The disc spring of each disc spring group is formed by overlapping a guide cover plate and a disc spring, and the disc spring group is fixed by an adjusting bolt.

3. A flow control valve for cryogenic liquid rocket propellant according to claim 1, characterized in that: The guide cover also includes a mounting portion at the junction of the inlet portion and the pressure reducing portion. The valve housing is provided with a matching groove, the mounting portion is mounted in the matching groove, and is fixed axially by a retaining ring. A copper gasket is installed between the valve housing and the mounting portion.

4. A flow control valve for cryogenic liquid rocket propellant according to claim 2, characterized in that: The thickness of the single disc spring of the disc spring group is 2.5mm, the stiffness coefficient is 85N / mm, and the preload force can be dynamically compensated by ±10% by adjusting the bolt.

5. A flow control valve for cryogenic liquid rocket propellant according to claim 1, characterized in that: The depth of the honeycomb micropores is twice their pore diameter, the distance between adjacent pore walls is 0.4 mm, and the pore density is 22 pores / cm 2 .

6. A flow control valve for cryogenic liquid rocket propellant according to claim 1, characterized in that: The groove width ratio of the three-layer stepped pressure-reducing ring groove is 1:1.6:2.7, and the groove depth ratio is 1:1.5:

2.

7. A flow control valve for cryogenic liquid rocket propellant according to claim 3, characterized in that: The inner wall surface of the fairing is formed with a tungsten carbide-cobalt-based composite coating by a laser cladding process, the coating thickness is 150-250 μm, the hardness is ≥1200 HV, and the porosity is ≤0.5%.

8. A flow control valve for cryogenic liquid rocket propellant according to claim 1, characterized in that: The cryogenic compensation valve body needs to be cryogenically pretreated before assembly. The specific process is: immerse the valve shell and valve sleeve separately in liquid nitrogen for 2-4 hours, then let it stand at room temperature for 12 hours to release residual stress, and repeat the cycle 3 times. After treatment, the standard deviation of the low-temperature deformation of the valve body σ≤0.01mm.

9. A flow control valve for cryogenic liquid rocket propellant according to claim 8, characterized in that: The valve sleeve is made of aluminum alloy and the valve shell is made of 316L stainless steel.

10. A cryogenic flow control method, based on a cryogenic liquid rocket propellant flow control valve according to any one of claims 1 to 9, characterized in that: The steps include: S1: In the low-temperature deformation compensation stage, the propellant flows in from the inlet pipe, passes through the annular cavity between the outer wall of the guide cover and the valve shell, and forms a pre-cooling circulation path. The low-temperature fluid contacts the valve shell, and the heat is quickly transferred. The valve sleeve and the valve shell shrink due to the temperature difference, causing the disc spring group to deform. S2: Cavitation energy is dissipated in stages. When the fluid continues to flow into the cylinder, the fluid will distribute the differential pressure proportionally through the stepped pressure reduction ring groove, and reduce the fluid speed through the spiral guide groove, and then the cavitation will be collapsed in advance through the honeycomb micropores; S3: Dynamic seal compensation: As the temperature in the cylinder continues to drop, the disc spring preload assembly outputs a compensating displacement to maintain the pressure on the sealing surface.

Images