Liquid rocket engine ground inverted ignition test stand

Abstract

This invention discloses a ground-based inverted ignition test stand for a liquid rocket engine, along with its installation and maintenance methods. The stand includes at least two independent spherical propellant tanks, at least two tank mounting frames, an engine assembly, an engine mounting bracket, a positioning structure, and an installation pit. By installing the engine inverted, this invention simulates rocket recovery and reentry rocket braking scenarios, allowing for precise identification of specific issues such as thrust vector control and valve sealing in the inverted state. It also avoids ablation of the guide channel and backflow of the exhaust plume, eliminating the risk of the rocket body detaching from the test stand. The pre-embedded base plate of the engine mounting bracket is placed within the installation pit, and its upper surface is filled with sand for fixation. The elastic deformation of the sand absorbs the vibration force generated during the test, preventing structural damage. The sand filling within the installation pit incorporates existing guide channels, shock absorbers, and reaction walls, significantly reducing manufacturing and maintenance costs.

Description

Technical Field

[0001] This invention specifically relates to a test stand for rocket engines. Background Technology

[0002] In liquid rocket engine testing, the attitude difference between horizontal testing and actual rocket flight is significant. Core components such as the thrust chamber and turbopump of the rocket engine are designed for vertical operation. However, in a horizontal configuration, the distribution of lubricating oil and the stress state of the sealing surfaces differ from those in a vertical configuration. This can easily lead to insufficient lubricating oil supply and accelerated wear of the sealing surfaces, affecting the working efficiency and life test data of the turbopump. At the same time, the coolant flow in the thrust chamber's cooling channels becomes uneven in a horizontal configuration, and some cooling channels may experience insufficient coolant flow, leading to localized overheating of the thrust chamber. If a multi-engine parallel propulsion system is tested in a horizontal configuration, the problems will be even more pronounced. Furthermore, the propellant ejection becomes unbalanced in a horizontal configuration, resulting in strong excitation forces on the engine. These strong excitation forces also damage the concrete reaction wall, causing cracks, surface spalling of the concrete, and fatigue deformation of the internal steel reinforcement structure. Long-term strong excitation forces will reduce the structural strength of the reaction wall, affecting its lifespan. Repeated repairs or frequent construction of the reaction wall undoubtedly increase testing costs and impose huge R&D expenditures on the propulsion system.

[0003] While vertical flight testing most closely resembles actual flight, the vertically downward thrust of the exhaust plume during vertical tests causes severe impact and erosion to the test stand's guide channels and heat insulation structures. This increases testing costs and imposes significant R&D expenditures on the propulsion system. Furthermore, the high-temperature, high-pressure airflow generated by the exhaust plume may backflow and affect the rocket's bottom structure. The powerful vertical thrust generated during vertical tests can also easily cause structural failure at the connection between the rocket and the test stand, potentially leading to the rocket detaching from the stand.

[0004] In addition, in modern rocket applications, there are often scenarios of inverted flight / flight, such as the recovery phase of reusable rockets, the braking and deceleration phase of returnable rockets, and the deorbiting adjustment phase of the upper stage. In these scenarios, the rocket will be in an inverted state with its nose down and engine nozzles up, and the propulsion system needs to ignite and work in this state to complete the deceleration and attitude control operations.

[0005] When the rocket propulsion system is working normally, the propellant flows from the tank to the engine under the action of gravity. However, in the inverted state, the direction of gravity is completely opposite to that in the normal state. The flow direction of the propellant and the distribution of the propellant in the tank will change, which can easily lead to insufficient or unstable propellant supply, and thus cause abnormal engine operation.

[0006] In the inverted state, the rocket's attitude control logic and engine thrust vector control logic are completely different from those in normal vertical flight, and the force state of the propulsion system and rocket body structure will also change.

[0007] Many problems that would not occur in the normal orientation will be exposed in the inverted state. For example, propellant residue in the tank cannot be properly delivered, changes in the gas-liquid mixture in the pipeline can cause abnormal engine ignition, and valves may malfunction or fail to seal properly when inverted. These problems can only be discovered in advance through inverted testing, allowing for adjustments and optimizations to the power system design. Summary of the Invention

[0008] To overcome the shortcomings mentioned above, the present invention aims to provide a technical solution that can solve the above problems.

[0009] A ground-based inverted ignition test stand for a liquid rocket engine includes:

[0010] At least two independently arranged spherical propellant tanks, each of which has its outlet located in its bottom region, to accommodate the inertial convergence and pressure output of the propellant when the rocket is inverted and falling.

[0011] At least two tank mounting brackets, the top of which is connected to each of the spherical propellant tanks in a one-to-one correspondence;

[0012] The engine assembly is arranged in an inverted position with the nozzle facing upwards;

[0013] An engine mounting bracket is an integrally formed structure consisting of a load-bearing body, a positioning structure, a pre-embedded base plate, and at least four pre-embedded support trusses. The at least four pre-embedded support trusses are evenly arranged circumferentially along the outer side of the load-bearing body, and the pre-embedded base plate is located at the bottom of the pre-embedded support trusses and the load-bearing body.

[0014] The positioning structure is located on the top of the load-bearing body and is used for precise positioning, connection and fixation with the flange end of the engine assembly.

[0015] Preferably, a single tank mounting bracket includes an embedded base and at least four supports, the bottom of which is welded to the embedded base and the top of which is welded to the spherical propellant tank;

[0016] Preferably, the liquid rocket engine ground inverted ignition test stand further includes an installation pit, the embedded base plate and the embedded base are both placed in the installation pit, the installation pit is filled with compacted sand, and the lower section of the bracket, the lower section of the load-bearing body and the embedded support truss are all placed in the sand.

[0017] Preferably, the outer wall of the pre-embedded support truss is provided with anti-slip protrusions, the lower surface of the pre-embedded base plate is provided with anti-slip textures, and the pre-embedded base of the storage tank mounting frame is provided with anti-slip grooves.

[0018] Preferably, the outlet end of a single spherical propellant tank is connected to one end of a solenoid valve via a conduit, and the other end of the solenoid valve is connected to one of the propellant input ends of the engine assembly.

[0019] A method for installing a liquid rocket engine on a ground-based inverted ignition test stand includes the following steps:

[0020] S1. Excavate an installation pit at a preset location on the ground. The size of the installation pit is adapted to the overall space occupied by the embedded base plate and the embedded base.

[0021] S2. Hoist the engine mounting bracket into the mounting pit, so that the embedded base plate fits against the bottom of the mounting pit, and ensure that the positioning structure is facing upward and horizontal;

[0022] S3. Hoist the storage tank mounting bracket into the mounting pit, so that the pre-embedded base fits into the bottom of the mounting pit and maintains a preset distance from the engine mounting bracket;

[0023] S4. Weld and fix the spherical propellant tank to the top of the support bracket of the tank mounting frame, and accurately connect and fix the engine assembly to the positioning structure of the engine mounting frame;

[0024] S5. Fill the installation pit with sand in layers and compact it so that the sand completely covers the lower section of the support, the lower section of the load-bearing body and the pre-embedded support truss. The compaction of the sand will achieve the fixed positioning and vibration buffering of the test bench.

[0025] S6. After completing the backfilling with sand, mark the backfilling area on the top surface of all the backfilled sand.

[0026] S7: Connect the outlet of the spherical propellant tank to the solenoid valve via a conduit, and then connect the solenoid valve to the propellant input end of the engine assembly to complete the installation.

[0027] A maintenance method for a ground-based inverted ignition test stand for a liquid rocket engine includes the following steps:

[0028] S1. After the test, check the attitude of the engine mounting bracket. If it tilts or tilts slightly due to the excitation force, open the inverted ground ignition test stand for the liquid rocket engine for maintenance.

[0029] S2. Excavate the sand above the embedded base plate to expose the corresponding lower section of the load-bearing main body, the embedded support truss, and the embedded base plate;

[0030] S3. Adjust the horizontal and vertical alignment of the engine mounting bracket using mechanical supports until the preset mounting posture is restored;

[0031] S4. Refill the excavated area with sand in layers and compact it to ensure that the sand tightly wraps around the relevant components again. Use anti-slip protrusions, anti-slip textures, and anti-slip grooves to enhance the interlocking strength with the sand, restore the stability and shock absorption performance of the test bench, and complete the repair.

[0032] Compared with existing technologies, the advantages of this invention are:

[0033] This invention, through its inverted engine installation and upward-facing nozzle design, directly replicates real inverted scenarios such as reusable rocket recovery and return rocket braking, avoiding attitude deviations during horizontal / vertical testing, and can accurately identify specific issues such as thrust vector control and valve sealing in the inverted state.

[0034] The outlet of the spherical propellant tank of the present invention is located in the central area of ​​the bottom of the tank. When simulating the rocket falling upside down, the propellant naturally converges towards the outlet along the inner wall of the sphere under the combined action of inertial force and gravity.

[0035] The pre-embedded base plate of the engine mounting bracket of the present invention is placed in the mounting pit, and the upper surface of the pre-embedded base plate is filled with sand for fixation. The elastic deformation of the sand absorbs the excitation force generated during the test run, thus avoiding structural damage.

[0036] This invention replaces the existing diversion channel, shock absorption device and reaction wall with the design of filling the installation pit with sand. Installation and maintenance only require conventional tools, and the manufacturing cost and maintenance cost are greatly reduced.

[0037] The inverted test of this invention avoids the ablation of the guide channel and the backflow of the exhaust flame; the buffering effect of the sand reduces the impact of the vertical thrust on the connecting structure and eliminates the risk of "the rocket body leaving the test stand".

[0038] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the test stand of the present invention.

[0041] Figure 2 This is a structural diagram of the storage tank, storage tank mounting bracket, engine assembly, and engine mounting bracket.

[0042] Figure 3 This is a schematic block diagram of the installation method of the present invention.

[0043] Figure 4 This is a schematic block diagram of the repair method of the present invention. Detailed Implementation

[0044] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0046] Furthermore, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0047] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0048] Please see Figures 1-2 In this embodiment of the invention, a ground-based inverted ignition test stand for a liquid rocket engine includes at least two independent storage tanks 100, at least two storage tank mounting brackets 200, an engine assembly 300, an engine mounting bracket 400, and a mounting pit 600. Example

[0049] This invention features two independent storage tanks 100, which respectively hold oxidants (such as liquid oxygen) and fuels (such as kerosene and alcohol). The material used is conventional 5A06 aluminum alloy, which is low-cost, highly corrosion-resistant, and meets pressure requirements. The storage tank 100 of this invention is spherical. Compared with a cylindrical storage tank 100, the spherical shape has a lower center of gravity during commissioning and is easier to install.

[0050] Each tank 100 has an outlet 101 located in the central area of ​​the bottom of the tank 100. When the rocket is inverted and falling, the propellant naturally flows towards the outlet 101 along the inner wall of the sphere under the combined action of inertial force and gravity.

[0051] Each tank 100 is equipped with a tank mounting frame 200. The mounting frame of a single tank 100 consists of a pre-embedded base 210 and four supports 220. The pre-embedded base 210 is made of Q235 ordinary steel plate and cut into a square structure. Two annular anti-slip grooves (not shown in the attached figure) are stamped on the upper surface to enhance the interlocking friction with the sand 700. The four supports 220 are evenly distributed around the circumference of the pre-embedded base 210. The bottom of the supports 220 is fixed to the pre-embedded base 210 by manual arc welding. The top of the supports 220 is welded to the lower part of the outer wall of the tank 100 to form a stable four-corner support structure to ensure that the tank 100 does not shake when inverted and to avoid propellant supply fluctuations due to tank 100 displacement.

[0052] The engine assembly 300 is arranged in an inverted position with its nozzle facing upwards, simulating an inverted flight scenario of "nose down, nozzle up." This eliminates the need for indirect simulation via attitude conversion, accurately reproducing the engine's stress state and operating environment during recovery and braking deceleration. This facilitates the identification of issues specific to the inverted state, such as thrust vector control logic and valve sealing. The engine flange end has multiple positioning holes (not shown in the attached diagram) that precisely match the positioning pins of the positioning structure 420. These holes are detachably connected via bolts, allowing for easy replacement and testing of different engine models.

[0053] The engine mounting bracket 400 is an integrally formed structure consisting of a load-bearing main body 410, a positioning structure 420, an embedded base plate 430, and at least four embedded support trusses 440. The at least four embedded support trusses 440 are evenly arranged circumferentially along the outer side of the load-bearing main body 410. The embedded base plate 430 is located at the bottom of the embedded support trusses 440 and the load-bearing main body 410. The embedded base plate 430 forms a large-area load-bearing surface. Its lower surface is ground with transverse anti-slip textures (not shown in the attached diagram) to enhance friction with the sand 700 at the bottom of the pit. The upper surface is covered with sand 700. The sand 700 filling design replaces the dedicated shock absorption device, absorbing the excitation force through the elastic deformation of the sand 700, preventing damage to the surrounding structure. The ground directly bears the vertical thrust during engine ignition, replacing the load-bearing function of the "concrete reaction wall," eliminating the need for a complex reaction wall. This design, which uses 700 cubic meters of fully filled sand, reduces the manufacturing and maintenance costs of the test stand. If the engine assembly 300 is found to be tilted, only the 700 cubic meters of sand need to be dug up for readjustment. Compared to existing technologies using concrete reaction walls, both manufacturing and maintenance costs are significantly reduced.

[0054] The positioning structure 420 is installed on top of the load-bearing body 410 for precise positioning and connection with the flange end of the engine assembly 300. The flange end of the engine assembly 300 is adjustable to ensure the engine nozzle is vertical.

[0055] The ground-based inverted ignition test stand for liquid rocket engines also includes an installation pit 600, which is a square pit excavated from the ground using an excavator. The bottom of the pit utilizes the original soil without hardening treatment, and the pit walls maintain their natural soil shape. The embedded base plate 430 and embedded base 210 are both placed within the installation pit 600, which is filled with compacted sand 700. The lower section of the support 220, the lower section of the load-bearing main body 410, and the embedded support truss 440 are all placed within the sand 700. This invention's sand 700 filling design in the installation pit 600 replaces a dedicated shock absorption device. The elastic deformation of the sand 700 absorbs the excitation force, preventing damage to surrounding structures. The ground also bears the thrust generated by the engine assembly 300 during test ignition, reducing the manufacturing and maintenance costs of the test stand.

[0056] The outer side wall of the pre-embedded support truss 440 of the present invention is provided with anti-slip protrusions (not shown in the attached figure) to enhance the interlocking strength with the sand 700; the lower surface of the pre-embedded base plate 430 is provided with anti-slip texture to enhance the friction with the sand 700 at the bottom of the pit; the pre-embedded base 210 of the storage tank mounting frame 200 is provided with anti-slip grooves (not shown in the attached figure) to enhance the interlocking friction with the sand 700.

[0057] The outlet 101 of a single storage tank 100 is connected to one end of a solenoid valve 900 via a conduit 800, and the other end of the solenoid valve 900 is connected to one of the propellant input ends of the engine assembly 300. The solenoid valve 900 is remotely controlled and can be selected for stepless precise control of propellant flow or single-stage control of propellant flow. This is existing technology and will not be described in detail here. Example

[0058] like Figure 3 As shown, a method for installing a liquid rocket engine on a ground-based inverted ignition test stand includes the following steps:

[0059] S1. Excavate an installation pit 600 at a pre-set location on the ground. The size of the installation pit 600 is adapted to the overall space occupied by the pre-embedded base plate 430 and the pre-embedded base 210. The test site does not need to be hardened. Use an ordinary excavator to excavate a square installation pit 600. The size of the pit is to ensure that the pre-embedded base plate 430, the two storage tank mounting frames 200 and the pre-embedded base 210 can be laid flat and accommodated. The lower section of the bracket 220, the lower section of the load-bearing body 410 and the pre-embedded support truss 440 can be completely placed in the pit. After excavation, clean the loose soil at the bottom of the pit to ensure that the bottom of the pit is basically flat.

[0060] S2. Use a 25t truck crane to vertically lift the engine mounting bracket 400 to the center of the mounting pit 600, so that the embedded base plate 430 fits against the bottom of the pit. Place a level on the flange of the positioning structure 420 and manually adjust the position of the mounting bracket until the level shows horizontal, ensuring that the engine nozzle axis is vertical. At this time, the load-bearing body 410 and the embedded support truss 440 are naturally in a vertical stress state, which can effectively disperse the subsequent excitation force.

[0061] S3. Use the same crane to lift the two storage tank mounting brackets 200 into the installation pit 600 respectively, and arrange them symmetrically on both sides of the engine mounting bracket 400, so that the pre-embedded base 210 fits into the bottom of the pit, ensuring that there is no positional interference between the storage tank mounting bracket 200 and the engine mounting bracket 400, and reserving space for the connection of the conduit 800.

[0062] S4. Hoist the storage tank 100 above the storage tank mounting frame 200, adjust its position so that the liquid outlet 101 of the storage tank 100 faces downward, and weld the bottom of the storage tank 100 to the top of the bracket 220 by manual arc welding. Hoist the engine assembly 300 above the positioning structure 420, align the positioning hole of the engine flange end with the positioning pin and insert it, and tighten the connection with bolts to complete the fixation of the engine in the inverted position.

[0063] S5. Select ordinary building sand 700 from the surrounding area of ​​the site. No screening or special treatment is required. It is low-cost and readily available. Fill the installation pit 600 with the sand 700 in layers. Water can also be poured into the filling layer to ensure that the sand 700 tightly wraps the lower section of the support 220, the lower section of the load-bearing main body 410 and the pre-embedded support truss 440. Fill until the top surface of the sand 700 is flush with the ground. The dense wrapping of the sand 700 not only replaces the concrete reaction wall to fix the test bench, but also absorbs the excitation force through the elastic deformation of the sand 700 (replacing the special shock absorption device). At the same time, it solves the problem of "strong excitation force damaging the reaction wall" and avoids the "test bench" burning.

[0064] S6. After completing the sand 700, use white lime powder to mark the landfill boundaries of the engine mounting bracket 400 and the two storage tank mounting brackets 200 on the top surface of the sand 700.

[0065] S7. Seal and connect the outlet 101 of the storage tank 100 to the solenoid valve 900 through the conduit 800, and then seal and connect the other end of the solenoid valve 900 to the propellant input end of the engine assembly 300 to complete the installation. Example

[0066] like Figure 4 As shown, a maintenance method for a ground-based inverted ignition test stand for a liquid rocket engine includes the following steps:

[0067] S1. After each test run, place a level on the engine nozzle end face to check the levelness; at the same time, use a laser rangefinder to measure the distance between the four corners of the 420 flange of the positioning structure and the ground. If the mounting bracket tilts beyond the allowable deviation due to the engine ignition vibration force, it is determined that the liquid rocket engine ground inverted ignition test stand should be repaired.

[0068] S2. Use manual excavation or a small excavator to excavate the sand 700 above the pre-embedded base plate 430 along the boundary marked by lime powder until the lower section of the load-bearing main body 410, the pre-embedded support truss 440 and the pre-embedded base plate 430 are fully exposed. The excavation range is only for the area marked by the engine mounting bracket 400, which greatly reduces the amount of excavation work.

[0069] S3. Place two 50t jacks on the corresponding inclined side below the pre-embedded base plate 430, slowly lift the engine mounting bracket 400, and at the same time use a level to monitor the levelness of the flange in real time. Gradually adjust the height of the jacks until the level shows that it is horizontal and the engine nozzle axis is restored to vertical. At this time, the mounting bracket posture is restored to the preset state. There is no need to replace parts or complex calibration equipment, simplifying the maintenance process.

[0070] S4. Refill the excavated area with 700 layers of sand.

[0071] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A liquid rocket engine ground inverted point ignition test stand, characterized by, The application relates to a liquid rocket engine ground inversion ignition test bed. The application relates to a liquid rocket engine ground inversion ignition test bed. The application relates to a liquid rocket engine ground inversion ignition test bed. The application relates to a liquid rocket engine ground inversion ignition test bed. The application relates to a liquid rocket engine ground inversion ignition test bed. The application relates to a liquid rocket engine ground inversion ignition test bed. The application relates to a liquid rocket engine ground inversion ignition test bed. The application relates to a liquid rocket engine ground inversion ignition test bed. The application relates to a liquid rocket engine ground inversion ignition test bed. The application relates to a liquid rocket engine ground inversion ignition test bed. The application relates to a liquid rocket engine ground inversion ignition test bed. The application relates to a liquid rocket engine ground inversion ignition test bed. The application relates to a liquid rocket engine ground inversion ignition test bed. The application relates to a liquid rocket engine ground inversion ignition test bed. The application relates to a liquid rocket engine ground inversion ignition test bed. The application relates to a liquid rocket engine ground inversion ignition test bed.

2. The liquid rocket engine ground-inverted point ignition test stand of claim 1, wherein, The application relates to a liquid rocket engine ground inversion ignition test bed.

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The application relates to S2, dig the sand above the embedded bottom plate, expose the corresponding load-bearing main body lower section, embedded support truss and embedded bottom plate; S3, adjust the levelness and verticality of the engine mounting frame through mechanical support assistance until the preset installation posture is restored; S4, re-layered fill sand to the excavated area and compact, so that the sand tightly wraps the related components again, and the anti-slip protrusions, anti-slip patterns and anti-slip grooves enhance the engagement strength with the sand, restore the fixing and damping performance of the test bed, and complete the maintenance.

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