A detection system and working method for hydrodynamic foil bearings lubricated by hydrocarbon fuel cracking gas.

Abstract

This invention relates to the field of dynamic pressure foil bearing performance testing technology under extreme and special working conditions, specifically to a dynamic pressure foil bearing testing system lubricated by hydrocarbon fuel cracking gas. The system includes: an oil reservoir containing aviation kerosene, the outlet of which is connected to the inlet of a fuel pump, and the outlet of the fuel pump connected to the inlet of an electric heater. The electric heater is used to crack the aviation kerosene, generating hydrocarbon fuel gas. A first valve body is located on the side of the electric heater away from the fuel pump. A pressure-resistant sealed chamber is connected to the outlet of the electric heater. A housing is located within the pressure-resistant sealed chamber, and a high-speed gas-driven turbine is located within the housing. A rotor passes through the high-speed gas-driven turbine, and a dynamic pressure foil bearing is sleeved on the rotor, with the dynamic pressure foil bearing installed at both ends inside the housing. This system solves the problem of excessive shaft frequency amplitude making it difficult to achieve high speeds during experiments, enabling the testing of dynamic pressure foil bearing characteristics under high-temperature hydrocarbon fuel conditions. It also allows for the testing of the dynamic characteristics of a single-sided cantilever rotor supported by the dynamic pressure foil bearing.

Description

Technical Field

[0001] This invention relates to the field of dynamic pressure foil bearing performance testing technology under extreme and special working conditions, specifically to a testing system and working method for dynamic pressure foil bearings lubricated by hydrocarbon fuel cracking gas. Background Technology

[0002] Currently, research on hypersonic vehicles is a hot topic in the military field worldwide, and turbine power generation systems using hydrocarbon fuel cracking gas as the working medium are the most promising applications in hypersonic vehicles. A key technical challenge is achieving stable turbine operation in the high-temperature, high-pressure hydrocarbon fuel cracking gas atmosphere, and adjusting power generation under different operating conditions during flight to match the power load, preventing insufficient or excessive power output. With the emergence of the concept of reusable hypersonic vehicles, higher demands are placed on turbine lifespan. The support structure of rotating components directly determines whether the turbine can reach the required speed and whether it can match the power generation to the vehicle's operating conditions in real time. High-speed operation of the support structure leads to frictional heat and wear; therefore, the reliability and durability of the support structure are crucial factors affecting turbine lifespan.

[0003] Available forms of bearing support include rolling bearings, electromagnetic bearings, foil bearings, etc. Among them, rolling bearing technology is the most mature. However, regardless of whether the rolling elements are steel balls or ceramic balls, their temperature resistance cannot meet the requirements for operation in hydrocarbon fuel cracking gas, and complex lubrication and cooling equipment is required. Conventional lubricants are prone to ignition when in contact with high-temperature hydrocarbon fuel cracking gas.

[0004] Electromagnetic bearings have become a popular support structure in the field of aircraft in recent years due to their controllability. However, their fundamental principle is to use electric current to control the magnetic field, and they will fail when the temperature exceeds 200°C.

[0005] The dynamic pressure foil bearing has a simple structure, and with the development of foil materials and high-temperature resistant coating materials, it can operate in an environment of 1000℃. Furthermore, after experimental testing, its number of repeated start-stop cycles can reach 100,000.

[0006] Initially, dynamic pressure foil bearings were used as lubricants in air at normal temperature and pressure. Due to their simple structure and excellent dynamic performance, the lubricant was gradually expanded to include SCO2, He-Xe mixtures, liquid nitrogen, and liquid oxygen. However, these working media generally have relatively simple compositions and low temperatures. Although foreign research institutions have conducted some research on dynamic pressure foil bearings in turbojet engines and other fields, they mainly focused on the bearing's temperature resistance and dynamic characteristics. They did not study the high-speed flow of special lubricants in small gaps and the thermal characteristics exhibited by the bearings. Furthermore, the composition of high-temperature hydrocarbon fuel cracking gas is different from that of turbojet engine exhaust gas, and the differences in physical properties are significant, making it not a valuable reference.

[0007] For experiments on dynamic pressure foil bearings, the widely used method at home and abroad is to use a high-speed motor to provide torque to the rotor to obtain the bearing characteristics under high-speed conditions. However, for performance tests of dynamic pressure foil bearings in high-temperature environments, the rotor-bearing system under test needs to be in a high-temperature environment above 500°C. The motor will demagnetize, and the harmonic components of the motor will seriously affect the analysis of the rotor vibration signal. If the motor is not used to provide torque to the rotor and a gas-driven turbine is used, there is a problem of difficulty in controlling the speed, especially when the dynamic balance accuracy is required, the gas drive cannot achieve a stable rotor speed. Summary of the Invention

[0008] Therefore, the technical problem to be solved by this invention is to overcome the lack of a dynamic characteristic testing method for dynamic pressure foil bearings under extreme and special working conditions in the existing technology, and to solve the problem that the shaft frequency amplitude is too large and it is difficult to achieve high speed during the experiment. Thus, a test scheme for the characteristics of dynamic pressure foil bearings using hydrocarbon fuel cracking gas as lubricating medium is provided, which can simulate the real working environment of dynamic pressure foil bearings more realistically, and eliminate the influence of rotor imbalance and motor harmonics on rotor-bearing performance testing to the greatest extent. The proposed test scheme takes into account the difficulty of high-pressure shaft sealing, and considers the influence of the single-sided impeller cantilever rotor structure on bearing performance during the experiment.

[0009] To address the aforementioned technical problems, this invention provides a detection system for a hydrodynamic foil bearing lubricated by hydrocarbon fuel cracking gas, comprising: an oil reservoir containing aviation kerosene, the outlet of which is connected to the inlet of a fuel pump, the outlet of which is connected to the inlet of an electric heater, the electric heater being used to crack the aviation kerosene to generate hydrocarbon fuel gas, and a first valve body located on the side of the electric heater away from the fuel pump; a pressure-resistant sealed chamber connected to the outlet of the electric heater, a housing within which a high-speed air-driven turbine is housed, a rotor passing through the high-speed air-driven turbine, a hydrodynamic foil bearing sleeved on the rotor, and the hydrodynamic foil bearing installed at both ends inside the housing; and a volute housing located within the pressure-resistant sealed chamber, the volute housing being connected to the rotor. The system delivers the hydrocarbon fuel cracked gas into the pressure-resistant sealed chamber and drives the rotor to rotate. An integrated starter-generator motor is located on one side of the pressure-resistant sealed chamber and is connected to one end of an overrunning clutch, the other end of which is connected to the rotor. A condenser is connected to the pressure-resistant sealed chamber, and a second valve body is located between the condenser and the pressure-resistant sealed chamber. The hydrocarbon fuel cracked gas enters the condenser through the second valve body. The condenser is used to condense the hydrocarbon fuel cracked gas and generate waste aviation kerosene. The outlet of the condenser is connected to the inlet of a vacuum pump, and the outlet of the vacuum pump is connected to a fuel recovery tank. A data acquisition mechanism is located within the pressure-resistant sealed chamber and is used to collect the internal temperature of the dynamic pressure foil bearing, the rotor speed, torque, and displacement.

[0010] Furthermore, the rotor, overrunning clutch, and starter motor are coaxially arranged.

[0011] Furthermore, the rotor includes: a simulated impeller disk, one end of which is provided with a drive impeller and the other end with a rotating shaft, and the dynamic pressure foil bearing is sleeved on the rotating shaft.

[0012] Furthermore, the simulated impeller disk is provided with a plurality of balancing holes, which are spaced apart along the center of the simulated impeller disk toward the outer edge of the simulated impeller disk.

[0013] Furthermore, the data acquisition mechanism includes: a first eddy current sensor and a second eddy current sensor, disposed on both sides of the housing, and the first eddy current sensor and the second eddy current sensor are connected to the vibration acquisition structure; a first thermocouple sensor and a second thermocouple sensor, disposed within the two dynamic pressure foil bearings, and the first thermocouple sensor and the second thermocouple sensor are connected to the temperature acquisition structure.

[0014] Furthermore, the data acquisition mechanism also includes a rotation speed sensor, which is located at the end of the rotating shaft away from the vortex shell, and the rotation speed sensor is connected to the vibration acquisition structure.

[0015] Furthermore, a first connecting pipe is provided between the first valve body and the pressure-resistant sealing chamber, and a first pressure sensor is provided on the first connecting pipe; a second connecting pipe is provided between the pressure-resistant sealing chamber and the second valve body, and a second pressure sensor is provided on the second connecting pipe.

[0016] Furthermore, it also includes a graphite sealing mechanism, which is disposed in the pressure-resistant sealing chamber and is used to seal the connection between the starter motor and the pressure-resistant sealing chamber.

[0017] Furthermore, the output shaft of the integrated starter motor is provided with a ceramic ball bearing, and a circulating cooling water mechanism is provided on the ceramic ball bearing.

[0018] This invention also provides a method for operating a dynamic pressure foil bearing detection system lubricated by hydrocarbon fuel cracking gas, comprising: matching the rotational speed of a high-speed gas-driven turbine; aviation kerosene being pumped by a fuel pump to an electric heater, where it undergoes a cracking reaction upon heating, generating a hydrocarbon fuel gaseous mixture with multiple components; the gaseous mixture entering the volute housing under the control of a first valve body, acting on the rotor inside the volute housing to provide driving torque to the rotor; the hydrocarbon fuel gas after the rotor has done work being discharged from the volute housing outlet into a pressure-resistant sealed chamber, gradually filling the entire pressure-resistant sealed chamber; a second valve body regulating the pressure inside the pressure-resistant sealed chamber and discharging the hydrocarbon fuel cracking gas inside the pressure-resistant sealed chamber into a condenser; a vacuum pump regulating the pressure inside the condenser; therefore, a first pressure sensor and a second pressure sensor respectively display the inlet pressure and back pressure of the high-speed gas-driven turbine; adjusting the pumping pressure of the fuel pump and the heating current of the electric heater can simulate different operating conditions, and in each operating condition... The different inlet pressures of the high-speed gas-driven turbine correspond to different valve openings, requiring different valve openings to achieve a stable speed. The high-speed gas-driven turbine is driven by an integrated starter-generator motor to reach takeoff speed. Adjusting the first and second valve bodies and the negative pressure in the condenser causes different driving torques to be applied to the high-speed gas-driven turbine. When the high-speed gas-driven turbine speed is higher than the integrated starter-generator speed under the drive of hydrocarbon fuel cracking gas, the turbine rotor disengages from the integrated starter-generator motor. When the torque sensor reading approaches zero, this corresponds to the opening of the first and second valve bodies corresponding to the inlet and outlet pressures required for stable operation of the high-speed gas-driven turbine under this condition. When the required inlet and outlet pressure difference is large under a certain condition, resulting in excessive pressure in the pressure-resistant sealed container, the pressure in the condenser is set to negative pressure using a vacuum pump to reduce the stress on the pressure-resistant sealed container. When the high-speed gas-driven turbine is running stably under the action of hydrocarbon fuel cracking gas, the integrated starter-generator motor disengages from the turbine rotor, returning the motor speed to zero.

[0019] The technical solution of this invention has the following advantages:

[0020] 1. The present invention provides a detection system for a hydrodynamic foil bearing lubricated by hydrocarbon fuel cracking gas, comprising: an oil reservoir containing aviation kerosene, the outlet of the oil reservoir being connected to the inlet of a fuel pump, the outlet of the fuel pump being connected to the inlet of an electric heater, the electric heater being used to crack the aviation kerosene to generate hydrocarbon fuel gas, and a first valve body being provided on the side of the electric heater away from the fuel pump; a pressure-resistant sealed chamber connected to the outlet of the electric heater, a housing being provided inside the pressure-resistant sealed chamber, a high-speed gas-driven turbine being provided inside the housing, a rotor passing through the high-speed gas-driven turbine, a hydrodynamic foil bearing being sleeved on the rotor, and the hydrodynamic foil bearing being installed at both ends inside the housing; and a volute housing located within the pressure-resistant sealed chamber, the volute housing being connected to the rotor to conduct the detection of the hydrocarbon fuel gas. Hydrogen fuel cracking gas is delivered to the pressure-resistant sealed chamber and drives the rotor to rotate. An integrated starter-generator motor is located on one side of the pressure-resistant sealed chamber and is connected to one end of an overrunning clutch, the other end of which is connected to the rotor. A condenser is connected to the pressure-resistant sealed chamber, and a second valve body is located between the condenser and the pressure-resistant sealed chamber. The hydrocarbon fuel cracking gas enters the condenser through the second valve body. The condenser is used to condense the hydrocarbon fuel cracking gas and generate exhaust aviation kerosene. The outlet of the condenser is connected to the inlet of a vacuum pump, and the outlet of the vacuum pump is connected to a fuel recovery tank. A data acquisition mechanism is located within the pressure-resistant sealed chamber and is used to collect the internal temperature of the dynamic pressure foil bearing, the rotational speed, torque, and displacement of the shaft.

[0021] The rotor of the dynamic pressure foil bearing detection system lubricated by hydrocarbon fuel cracking gas adopts a motorless structure and is directly driven by high-temperature hydrocarbon fuel cracking gas. On the one hand, it provides a real working environment for the dynamic pressure foil bearing in a pressure-resistant sealed container, and on the other hand, it avoids the problem that the motor cannot work in extreme high-temperature environments. At the same time, it eliminates the influence of motor harmonics on rotor vibration signal acquisition and analysis.

[0022] Furthermore, before the experiment began, the rotor was dynamically balanced at a stable speed by using the integrated starter motor. This solved the problem of difficult flow and pressure control when the gas-driven turbine was used, and avoided the excessive amplitude of the rotor shaft frequency caused by the change in the unbalance after rotor assembly and the optical axis state.

[0023] During the takeoff and shutdown phases of the rotor, the integrated starter motor controls the rotor speed through an overrunning clutch, avoiding the inability to achieve precise and continuous control of the high-speed air-driven turbine inlet and back pressure, which would cause large changes in rotor speed and result in continuous dry friction between the rotor and the hydrodynamic foil bearing.

[0024] During the takeoff phase of the rotor, the contact friction between the rotor and the dynamic pressure foil bearing changes to separation, meaning there is a gap between the rotor and the dynamic pressure foil bearing.

[0025] After the rotor under test takes off, the high-speed air-driven turbine is only subjected to air friction. When the speed of the rotor under test continues to increase, the starter motor can be used as a load to control the speed.

[0026] During the experiment, the volute, rotor, and housing were all in a pressure-resistant sealed chamber, and there were no high-pressure shaft seals or other structures, which greatly reduced the cost of the experiment and improved its safety.

[0027] By setting the pressure of the pressure-resistant sealing chamber to be less than atmospheric pressure using a vacuum pump, a large pressure difference can be achieved by reducing the pressure inside the pressure-resistant sealing chamber even with limited inlet pressure. This meets the high-speed requirements of the rotor under test, reduces the pressure resistance and sealing requirements of the experimental device, and improves the safety of the experiment.

[0028] 2. The hydrodynamic foil bearing detection system for hydrocarbon fuel cracking gas lubrication provided by this invention features a rotor, overrunning clutch, and integrated starter motor arranged coaxially. This method ensures the detection accuracy of the hydrodynamic foil bearing on the rotor and avoids errors.

[0029] The summary section is provided to present the chosen concepts in a simplified form, which will be further described in the detailed description below. The summary section is not intended to identify essential or indispensable features of this disclosure, nor is it intended to limit the scope of this disclosure. Attached Figure Description

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 A schematic diagram of the detection system for hydrodynamic foil bearings lubricated by hydrocarbon fuel cracking gas provided by the present invention;

[0032] Figure 2 A schematic diagram of the rotor structure in the hydrodynamic foil bearing detection system lubricated by hydrocarbon fuel cracking gas provided by the present invention.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. Fuel tank; 2. Fuel pump; 3. Electric heater; 4. First valve body; 5. First pressure sensor; 6. Second pressure sensor; 7. Second valve body; 8. Condenser; 9. Vacuum pump; 10. Fuel recovery tank; 11. Pressure-resistant sealed chamber; 12. Housing; 13. Rotor; 14. Dynamic pressure foil bearing; 15. Volute casing; 16. Starter motor; 17. Overrunning clutch; 18. Simulated impeller disk; 19. Drive impeller; 20. Shaft; 21. Balance hole; 22. First eddy current sensor; 23. Second eddy current sensor; 24. First thermocouple sensor; 25. Second thermocouple sensor; 26. Speed ​​sensor; 27. Temperature acquisition structure; 28. First connecting pipe; 29. ​​Shaft torque sensor; 30. Second connecting pipe; 31. Vibration acquisition structure; 32. Graphite sealing mechanism. Detailed Implementation

[0035] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this disclosure. Therefore, the drawings and description are to be considered exemplary in nature and not restrictive.

[0036] In the description of this disclosure, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this disclosure 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, and therefore should not be construed as a limitation of this disclosure. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0037] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joint" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or connections that allow for communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0038] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0039] The following disclosure provides numerous different embodiments or examples for implementing various structures of this disclosure. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this disclosure. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this disclosure, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0040] The preferred embodiments of this disclosure are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0041] Please see Figures 1 to 2As shown, this invention provides a detection system for a dynamic pressure foil bearing lubricated by hydrocarbon fuel cracking gas, comprising: an oil tank 1 containing aviation kerosene, the outlet of the oil tank 1 being connected to the inlet of a fuel pump 2, the outlet of the fuel pump 2 being connected to the inlet of an electric heater 3, the electric heater 3 being used to crack the aviation kerosene to generate hydrocarbon fuel gas, and a first valve body 4 being provided on the side of the electric heater 3 away from the fuel pump 2; a pressure-resistant sealed chamber 11 connected to the outlet of the electric heater 3, a housing 12 inside the pressure-resistant sealed chamber 11, a high-speed air-driven turbine inside the housing 12, a rotor 13 passing through the high-speed air-driven turbine, a dynamic pressure foil bearing 14 sleeved on the rotor 13, and the dynamic pressure foil bearing 14 installed at both ends inside the housing 12; and a volute 15 located inside the pressure-resistant sealed chamber 11, the volute 15 being connected to the rotor 13, and the system for detecting the dynamic pressure foil bearing 14 being installed at both ends inside the housing 12; and a volute 15 located inside the pressure-resistant sealed chamber 11, the volute 15 being connected to the rotor 13. The hydrocarbon fuel cracking gas is delivered to the pressure-resistant sealed chamber 11 and drives the rotor 13 to rotate. A starter-generator integrated motor 16 is located on one side of the pressure-resistant sealed chamber 11, and is connected to one end of an overrunning clutch 17, the other end of which is connected to the rotor 13. A condenser 8 is connected to the pressure-resistant sealed chamber 11, and a second valve body 7 is located between the condenser 8 and the pressure-resistant sealed chamber 11. The hydrocarbon fuel cracking gas enters the condenser 8 through the second valve body 7. The condenser 8 is used to condense the hydrocarbon fuel cracking gas and generate waste aviation kerosene. The outlet of the condenser 8 is connected to the inlet of a vacuum pump 9, and the outlet of the vacuum pump 9 is connected to a fuel recovery tank 10. A data acquisition mechanism is located inside the pressure-resistant sealed chamber 11 and is used to collect the internal temperature of the dynamic pressure foil bearing 14, the rotational speed, torque, and displacement of the rotor 13.

[0042] The rotor 13 of the dynamic pressure foil bearing detection system lubricated by hydrocarbon fuel cracking gas adopts a motorless structure and is directly driven by high-temperature hydrocarbon fuel cracking gas. On the one hand, it provides a real working environment for the dynamic pressure foil bearing 14 in a pressure-resistant sealed container, and on the other hand, it avoids the problem that the motor cannot work in extreme high-temperature environments. At the same time, it eliminates the influence of motor harmonics on the vibration signal acquisition and analysis of rotor 13.

[0043] Furthermore, before the experiment began, the rotor 13 was dynamically balanced at a stable speed by driving the integrated starter motor 16. This solved the problem of difficult flow and pressure control when the gas drives the turbine, and prevented the rotor 13 from having an excessively large amplitude corresponding to the shaft frequency due to the change in the unbalance between the assembled rotor 13 and the optical axis state.

[0044] During the takeoff and shutdown phases of rotor 13, the starter motor 16 controls the rotational speed of rotor 13 through overrunning clutch 17, avoiding the inability to achieve precise continuous control of the high-speed air-driven turbine inlet and back pressure, which would cause the rotational speed of rotor 13 to change drastically and result in continuous dry friction between rotor 13 and dynamic pressure foil bearing 14.

[0045] The take-off stage of rotor 13 is the rotation stage of rotor 13, and the dynamic pressure foil bearing 14 on rotor 13 gradually changes from contact friction to separation state, that is, there is a gap between rotor 13 and dynamic pressure foil bearing 14.

[0046] After the rotor 13 under test takes off, the high-speed air-driven turbine is only subjected to air friction. When the speed of the rotor 13 under test continues to increase, the starter motor 16 can be used as the load of the high-speed air-driven turbine to control the speed.

[0047] During the experiment, the volute 15, rotor 13, and housing 12 are all located in the pressure-resistant sealed chamber 11, and there are no high-pressure shaft seals or other structures, which greatly reduces the cost of the experiment and improves the safety of the experiment.

[0048] By setting the pressure of the pressure-resistant sealing chamber to less than atmospheric pressure using vacuum pump 9, a larger pressure difference can be achieved by reducing the pressure inside the pressure-resistant sealing chamber under limited inlet pressure, thus meeting the high speed requirements of the tested rotor 13, reducing the pressure resistance and sealing requirements of the experimental device, and improving the safety of the experiment.

[0049] In some optional embodiments, the rotor 13, the overrunning clutch 17, and the integrated starter motor 16 are coaxially arranged. This method can ensure the detection accuracy of the dynamic pressure foil bearing 14 on the rotor 13 and avoid errors.

[0050] In this embodiment, the rotor 13 includes a simulated impeller disk 18, with a drive impeller 19 at one end and a rotating shaft 20 at the other end. The dynamic pressure foil bearing 14 is sleeved on the rotating shaft 20. Furthermore, the simulated impeller disk 18 has a plurality of balancing holes 21, which are spaced apart along the center of the simulated impeller disk 18 toward its outer edge.

[0051] Among them, the balance holes 21 set on the simulated impeller disk 18 are M0.5 threaded holes, the interval between adjacent balance holes 21 is 20°, and they are distributed on two circumferences of different sizes according to different radii.

[0052] The driving impeller 19 is an axial flow type. Under the action of the guide vanes in the vortex casing 15, the axial force generated on the driving impeller 19 can be ignored. The blades of the driving impeller 19 are made of lightweight alloy material and the blade height is slightly larger than the outer diameter of the shaft 20. The rotational inertia generated during the experiment can be ignored.

[0053] The simulated impeller disk 18 and the rotating shaft 20 are machined as a single unit. After machining, M0.5 threaded holes are evenly distributed along the circumference at the outer edge of the simulated impeller disk 18 and at 0.5 times the radius of the driving impeller 19.

[0054] In some optional embodiments, the data acquisition mechanism includes a first eddy current sensor 22 and a second eddy current sensor 23, as well as a first thermocouple sensor 24 and a second thermocouple sensor 25.

[0055] The first eddy current sensor 22 and the second eddy current sensor 23 are disposed on both sides of the housing 12, and the first eddy current sensor 22 and the second eddy current sensor 23 are connected to the vibration acquisition structure.

[0056] The first eddy current sensor 22 and the second eddy current sensor 23 are each composed of four eddy current sensors that are perpendicular to each other. They are installed near the two dynamic pressure foil bearings 14 of the high-speed air-driven turbine, and can respectively test the shaft center trajectory of the rotor near the two dynamic pressure foil bearings 14. The shaft displacement acquired by the eddy current sensor is input into the vibration acquisition structure 31.

[0057] The first thermocouple sensor 24 and the second thermocouple sensor 25 are disposed in the two dynamic pressure foil bearings 14, that is, the first thermocouple sensor 24 and the second thermocouple sensor 25 are respectively installed on the back of the flat foil of the front and rear dynamic pressure foil bearings 14. The first thermocouple sensor 24 and the second thermocouple sensor 25 are connected to the temperature acquisition structure 27, that is, the temperature of the dynamic pressure foil bearing 14 is acquired and transferred to the temperature acquisition structure 27.

[0058] In some optional embodiments, the data acquisition mechanism further includes a speed sensor 26, which is located at the end of the rotating shaft 20 away from the volute 15 and is connected to the vibration acquisition structure. That is, the speed signal acquired by the speed sensor 26 is input to the vibration acquisition structure, thereby enabling the detection of the dynamic pressure foil bearing 14.

[0059] The driven end of the overrunning clutch 17 is connected to the end of the rotor 13 of the high-speed air-driven turbine, the driving end of the overrunning clutch 17 is connected to the output end of the shaft torque sensor, and the input end of the shaft torque sensor is fixed to the output shaft of the starter motor 16.

[0060] In some optional embodiments, a first connecting pipe 28 is provided between the first valve body 4 and the pressure-resistant sealing chamber 11, and a first pressure sensor 5 is provided on the first connecting pipe 28; a second connecting pipe 30 is provided between the pressure-resistant sealing chamber 11 and the second valve body 7, and a second pressure sensor 6 is provided on the second connecting pipe 30. The first pressure sensor 5 can display the inlet pressure of the high-pressure gas-driven turbine casing 15, and the second pressure sensor 6 can display the pressure inside the pressure-resistant sealing chamber 11.

[0061] A flange joint is provided at the outlet of the pressure-resistant sealed chamber 11, which is connected to the second connecting pipe 30. A second pressure sensor 6 is installed on the second connecting pipe 30 in the form of a pressure tapping pipe. The second pressure sensor 6 displays the pressure inside the pressure-resistant sealed chamber 11, and the outlet pressure is controlled by the second valve body 7. After the hydrocarbon fuel cracking gas is throttled and depressurized by the second valve body 7, it enters the condenser 8 for further cooling into a liquid state. The pressure in the condenser 8 can be adjusted by the vacuum pump 9. Finally, the liquid waste oil is discharged into the fuel recovery tank 10. Through the above steps, the pressure inside the pressure-resistant sealed chamber 11 can be regulated.

[0062] The first connecting pipe 28 and the second connecting pipe 30 are connected to the pressure-resistant sealed chamber 11 by argon arc welding. The first connecting pipe 28 and the second connecting pipe 30 are subjected to a 5.5MPa pressure test.

[0063] The first connecting pipe 28 is equipped with a fuel tank 1, a fuel pump 2, a first valve body 4, and a first pressure sensor 5; the second connecting pipe 30 is equipped with a fuel recovery tank 10, a vacuum pump 9, a condenser 8, a second valve, and a second pressure sensor 6; the first connecting pipe 28 and the second connecting pipe 30 are GH3128 pipes with a wall thickness of 3.5mm. The fuel pump 2 and the electric heater 3 are connected by a pressure-resistant metal hose, which isolates the fuel pump 2 from vibration during operation and prevents the first connecting pipe 28 from becoming loose due to vibration.

[0064] Aviation kerosene at normal temperature and pressure is stored in fuel tank 1. The fuel tank 1 is sealed, and the air inside the fuel tank 1 is discharged by filling it with nitrogen, so that the aviation kerosene is in an inert gas atmosphere, which prevents the aviation kerosene from igniting due to factors such as temperature rise or excessive current during the experiment.

[0065] The outer wall of the condenser 8 is equipped with circulating cooling water, and the condenser 8 is a pressure-resistant structure that can withstand pressure from both the inside and outside. There are three channels connecting the pressure-resistant sealed chamber 11 to the outside. The first is through the first connecting pipe 28 of the first pressure sensor 5 through the wall of the pressure-resistant sealed chamber 11. The second is through the second connecting pipe 30 of the second pressure sensor 6 connected by a flange. The third is through the output shaft of the starter motor 16 through the wall of the pressure-resistant sealed chamber 11. The wall thickness of the pressure-resistant sealed chamber 11 is increased here.

[0066] In some optional embodiments, the hydrodynamic foil bearing detection system lubricated by hydrocarbon fuel cracking gas further includes a graphite sealing mechanism 32, which is disposed in the pressure-resistant sealing chamber 11. The graphite sealing mechanism 32 is used to seal the connection between the starter motor 16 and the pressure-resistant sealing chamber 11. The gap between the graphite sealing mechanism 32 and the rotor 13 can be adjusted by an external clamping structure.

[0067] The graphite sealing mechanism 32 is equipped with a labyrinth seal and a carbon ring seal structure, and the local wall thickness is increased to 100mm at the junction of the output shaft of the starter motor 16 and the pressure-resistant sealing chamber 11.

[0068] The carbon ring sealing structure is a split structure. When the output shaft of the starter motor 16 is stationary, the gap between the carbon ring sealing surface and the surface of the rotating shaft 20 can be adjusted until the carbon ring and the surface of the rotor 13 are in contact.

[0069] A shaft torque sensor 29 is provided between the graphite sealing mechanism 32 and the overrunning clutch 17.

[0070] In some optional embodiments, the output shaft of the integrated starter motor 16 is provided with a ceramic ball bearing, and a circulating cooling water mechanism is provided on the ceramic ball bearing. The circulating cooling water mechanism can effectively reduce the temperature of the ceramic ball bearing.

[0071] This invention also provides a method for operating a dynamic pressure foil bearing detection system lubricated with hydrocarbon fuel cracking gas, comprising:

[0072] The high-speed gas-driven turbine is speed-matched. Aviation kerosene is pumped by fuel pump 2 to electric heater 3, where it undergoes a cracking reaction to generate a gaseous mixture of hydrocarbon fuels with multiple components. Controlled by the first valve body 4, the gaseous mixture enters the volute 15 and acts on the rotor 13 inside the volute 15, providing driving torque to the rotor 13. The hydrocarbon fuel gas after the rotor 13 has done work is discharged from the outlet of the volute 15 into the pressure-resistant sealed chamber 11, gradually filling the entire pressure-resistant sealed chamber 11. The second valve body 7 adjusts the pressure inside the pressure-resistant sealed chamber 11 and discharges the cracked hydrocarbon fuel gas in the pressure-resistant sealed chamber 11 into the condenser 8. The vacuum pump 9 adjusts the internal pressure of the condenser 8. Therefore, the first pressure sensor 5 and the second pressure sensor 6 display the inlet pressure and back pressure of the high-speed gas-driven turbine, respectively.

[0073] Adjusting the pumping pressure of fuel pump 2 and the heating current of electric heater 3 can simulate different operating conditions. Under each operating condition, there is a different inlet pressure of the high-speed gas turbine, which requires different valve openings to obtain a stable speed. The high-speed gas turbine is driven by the starter motor 16 to reach the takeoff speed. The first valve body 4, the second valve body 7 and the negative pressure value in the condenser are adjusted. The high-speed gas turbine is subjected to different driving torques. When the speed of the high-speed gas turbine is higher than the speed of the starter motor 16 under the drive of hydrocarbon fuel cracking gas, the high-speed gas turbine rotor 13 and the starter motor 16 are disengaged. When the torque sensor reading is close to zero, this is the opening of the first valve body 4 and the second valve body 7 corresponding to the inlet and outlet pressure required for the stable operation of the high-speed gas turbine under this operating condition.

[0074] When the required inlet and outlet pressure difference is large under a certain working condition, resulting in excessive pressure in the pressure-resistant sealed container, the pressure in the condenser 8 is set to negative pressure by the vacuum pump 9 to reduce the force on the pressure-resistant sealed container. When the high-speed gas-driven turbine is running stably under the action of hydrocarbon fuel cracking gas, the starter motor 16 is disengaged from the turbine rotor 13, and the speed of the starter motor 16 is returned to zero.

[0075] Pre-test debugging of the dynamic pressure foil bearing testing system for hydrocarbon fuel cracking gas lubrication: dynamic balancing and speed matching of the high-speed gas-driven turbine. Before the experiment, the top cover of the pressure-resistant sealed chamber 11 is opened, and the high-speed gas-driven turbine operates in the atmospheric environment. The speed of the starter-generator motor 16 is set so that the rotor 13 of the high-speed gas-driven turbine can smoothly and quickly reach the takeoff speed under the torque transmission of the overrunning clutch 17. During this process, the temperature of the dynamic pressure foil bearing 14 obtained by the two thermocouple sensors and the torque change obtained by the torque sensor are continuously observed. When the temperature and torque values ​​gradually rise to the maximum value and then fall and remain stable, it indicates that the rotor 13 is operating stably, and the next step of rotor 13 vibration test can be carried out. If the temperature and torque values ​​remain unchanged or increase, it indicates that the rotor 13 is in a dry friction state, and the machine needs to be stopped for inspection.

[0076] Once the rotor 13's speed stabilizes, the displacements measured by the two eddy current sensors are recorded. The displacement corresponding to the rotational frequency is considered to be caused by the unbalance of the rotor 13. The magnitude and angle of the rotor 13's unbalance are obtained through the phase signal of the speed sensor 26 and the measured displacement of the rotor 13. An M0.5 screw is installed in the balance hole 21 at the position where the unbalance is located plus 180°. When the unbalance is small, the screw is installed in the balance hole 21 near the center of the shaft 20. When the unbalance is large, the screw is installed in the unbalance hole 21 far from the center of the shaft 20. The above operation is repeated until the unbalance of the rotor 13 meets the G1 standard.

[0077] After dynamic balancing is completed, the speed matching of the high-speed gas-driven turbine can be performed. Aviation kerosene is pumped by fuel pump 2 to electric heater 3, where it undergoes a cracking reaction to generate a hydrocarbon fuel gaseous mixture with multiple components. Under the control of the first valve body 4, the gaseous mixture enters the volute 15 and acts on the drive impeller 19 inside the volute 15 to provide driving torque for the rotor 13. The hydrocarbon fuel gas after the drive impeller 19 has done work is discharged from the outlet of the volute 15 into the pressure-resistant sealed chamber 11, gradually filling the entire pressure-resistant sealed chamber 11. The second valve body 7 adjusts the pressure inside the pressure-resistant sealed chamber 11 and discharges the hydrocarbon fuel cracked gas inside the pressure-resistant sealed chamber 11 into the condenser 8. The vacuum pump 9 adjusts the internal pressure of the condenser 8. Therefore, the first pressure sensor 5 and the first pressure sensor 6 display the inlet pressure and back pressure of the high-speed gas-driven turbine, respectively.

[0078] Hypersonic vehicles experience varying engine wall temperatures and fuel supply rates under different operating conditions, leading to different products generated after the cracking reaction of aviation kerosene. These products exhibit significant differences in lubrication properties. Adjusting the pumping pressure of fuel pump 2 and the heating current of electric heater 3 can simulate different operating conditions. Each operating condition corresponds to a different inlet pressure of the high-speed gas turbine, requiring different valve openings to achieve a stable rotational speed. Therefore, the high-speed gas turbine is driven by the integrated starter motor 16 to reach the takeoff speed. Adjusting the first valve body 4, the second valve body 7, and the negative pressure in the condenser tank causes the high-speed gas turbine to experience different driving torques. When the high-speed gas turbine rotates faster than the integrated starter motor 16 under the drive of hydrocarbon fuel cracking gas, the high-speed gas turbine rotor 13 disengages from the integrated starter motor 16. When the torque sensor reading approaches zero, this corresponds to the opening of the first valve body 4 and the second valve body 7, which are the inlet and outlet pressures required for stable operation of the high-speed gas turbine under this operating condition.

[0079] When the required inlet and outlet pressure difference is large under a certain working condition, resulting in excessive pressure in the pressure-resistant sealed container, the pressure in the condenser 8 is set to negative pressure by the vacuum pump 9 to reduce the force on the pressure-resistant sealed container. When the high-speed gas-driven turbine is running stably under the action of hydrocarbon fuel cracking gas, the starter motor 16 is disengaged from the turbine rotor 13, the speed of the starter motor 16 is returned to zero, and the graphite seal at the shaft 20 is adjusted so that the graphite seal structure fits into the surface of the shaft 20.

[0080] The detection system for dynamic pressure foil bearings lubricated by hydrocarbon fuel cracking gas can effectively simulate the actual working state of the dynamic pressure foil bearing 14 in a hydrocarbon fuel environment, obtain the dynamic characteristics of the dynamic pressure foil bearing 14, and use high-pressure working fluid to drive a high-speed gas turbine, thus avoiding the limited temperature tolerance of the integrated starter motor 16 and eliminating the influence of motor harmonic components.

[0081] Before the experiment, the assembled rotor 13 was dynamically balanced by an external starter motor 16, which solved the problem of excessive shaft frequency amplitude making it difficult to achieve high speed during the experiment. At the same time, by using an overrunning clutch 17 to connect the external starter motor 16 and the rotor 13, the problem of rubbing caused by large speed fluctuations during the start and stop of the test bench was solved. The design of the rotor 13 structure verified the dynamic characteristics of the single-sided cantilever rotor 13 supported by the dynamic pressure foil bearing 14 under high temperature hydrocarbon fuel environment, and facilitated dynamic balancing operation. The vacuum pump 9 set at the outlet of the pressure-resistant sealed chamber 11 can provide a large pressure difference to maintain the high-speed operation of the rotor 13 under test even when the internal pressure of the chamber is relatively low.

[0082] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A detection system for hydrodynamic foil bearings lubricated by hydrocarbon fuel cracking gas, characterized in that, include: The oil storage tank (1) contains aviation kerosene. The outlet of the oil storage tank (1) is connected to the inlet of the fuel pump (2). The outlet of the fuel pump (2) is connected to the inlet of the electric heater (3). The electric heater (3) is used to crack the aviation kerosene. After cracking, hydrocarbon fuel gas is generated. The electric heater (3) is provided with a first valve body (4) on the side away from the fuel pump (2). Pressure-resistant sealed chamber (11) is connected to the outlet of electric heater (3). The pressure-resistant sealed chamber (11) is equipped with a housing (12). The housing (12) is equipped with a high-speed air-driven turbine. The rotor (13) passes through the high-speed air-driven turbine. The dynamic pressure foil bearing (14) is sleeved on the rotor (13) and is installed at both ends inside the housing (12). The vortex housing (15) is located in the pressure-resistant sealed chamber (11). The vortex housing (15) is connected to the rotor (13) to transport hydrocarbon fuel cracking gas to the pressure-resistant sealed chamber (11) and drive the rotor (13) to rotate. The starter motor (16) is located on one side of the pressure-resistant sealed chamber (11), and the starter motor (16) is connected to one end of the overrunning clutch (17), and the other end of the overrunning clutch (17) is connected to the rotor (13). The condenser (8) is connected to the pressure-resistant sealed chamber (11). The second valve body (7) is located between the condenser (8) and the pressure-resistant sealed chamber (11). The hydrocarbon fuel cracking gas enters the condenser (8) through the second valve body (7). The condenser (8) is used to condense the hydrocarbon fuel cracking gas and generate waste aviation kerosene. The outlet of the condenser (8) is connected to the inlet of the vacuum pump (9). The outlet of the vacuum pump (9) is connected to the fuel recovery tank (10). The data acquisition mechanism is located in the pressure-resistant sealed chamber (11). The data acquisition mechanism is used to collect the internal temperature of the dynamic pressure foil bearing (14), the rotor speed, torque and displacement; It also includes a graphite sealing mechanism (32), which is located in the pressure-resistant sealing chamber (11) and is used to seal the connection between the starter motor (16) and the pressure-resistant sealing chamber (11).

2. The detection system for hydrodynamic foil bearings lubricated by hydrocarbon fuel cracking gas according to claim 1, characterized in that, The rotor (13), overrunning clutch (17), and starter motor (16) are coaxially arranged.

3. The detection system for hydrodynamic foil bearings lubricated by hydrocarbon fuel cracking gas according to claim 1 or 2, characterized in that, The rotor (13) includes: A simulated impeller disk (18) is provided with a drive impeller (19) at one end and a rotating shaft (20) at the other end, with a dynamic pressure foil bearing (14) sleeved on the rotating shaft (20).

4. The detection system for hydrodynamic foil bearings lubricated by hydrocarbon fuel cracking gas according to claim 3, characterized in that, The simulated impeller disk (18) is provided with multiple balance holes (21), which are spaced apart along the center of the simulated impeller disk (18) toward the outer edge of the simulated impeller disk (18).

5. The detection system for hydrodynamic foil bearings lubricated by hydrocarbon fuel cracking gas according to claim 4, characterized in that, Data collection agencies include: The first eddy current sensor (22) and the second eddy current sensor (23) are disposed on both sides of the housing (12), and the first eddy current sensor (22) and the second eddy current sensor (23) are connected to the vibration acquisition structure. The first thermocouple sensor (24) and the second thermocouple sensor (25) are housed in two dynamic pressure foil bearings (14), and the first thermocouple sensor (24) and the second thermocouple sensor (25) are connected to the temperature acquisition structure (27).

6. The detection system for hydrodynamic foil bearings lubricated by hydrocarbon fuel cracking gas according to claim 5, characterized in that, The data acquisition mechanism also includes a speed sensor (26), which is located at the end of the rotating shaft (20) away from the volute (15) and is connected to the vibration acquisition structure (31).

7. The detection system for hydrodynamic foil bearings lubricated by hydrocarbon fuel cracking gas according to any one of claims 4-6, characterized in that, A first connecting pipe (28) is provided between the first valve body (4) and the pressure-resistant sealing chamber (11), and a first pressure sensor (5) is provided on the first connecting pipe (28); A second connecting pipe (30) is provided between the pressure-resistant sealing chamber (11) and the second valve body (7), and a second pressure sensor (6) is provided on the second connecting pipe (30).

8. The detection system for hydrodynamic foil bearings lubricated by hydrocarbon fuel cracking gas according to claim 7, characterized in that, The output shaft of the starter motor (16) is equipped with a ceramic ball bearing, and a circulating cooling water mechanism is provided on the ceramic ball bearing.

9. A method for operating a hydrodynamic foil bearing detection system lubricated with hydrocarbon fuel cracking gas as described in any one of claims 1-8, characterized in that, include: The high-speed gas-driven turbine is matched with the rotational speed. Aviation kerosene is pumped to the electric heater (3) by the fuel pump (2). It is heated in the electric heater (3) and undergoes a cracking reaction to generate a hydrocarbon fuel gaseous mixture with multiple components. Through the control of the first valve body (4), the gaseous mixture enters the volute (15) and acts on the rotor (13) inside the volute (15) to provide driving torque for the rotor (13). The hydrocarbon fuel gas after the rotor (13) does work is discharged from the outlet of the volute (15) into the pressure-resistant sealed chamber (11) and gradually fills the entire pressure-resistant sealed chamber (11). The second valve body (7) adjusts the pressure in the pressure-resistant sealed chamber (11) and discharges the hydrocarbon fuel cracked gas in the pressure-resistant sealed chamber (11) into the condenser (8). The vacuum pump (9) adjusts the pressure inside the condenser (8). Therefore, the first pressure sensor (5) and the second pressure sensor (6) display the inlet pressure and back pressure of the high-speed gas-driven turbine, respectively. Adjusting the pumping pressure of the fuel pump (2) and the heating current of the electric heater (3) can simulate different working conditions. Under each working condition, there are different inlet pressures of the high-speed gas turbine, and different valve openings are required to obtain a stable speed. The high-speed gas turbine is driven by the starter motor (16) to reach the takeoff speed. The first valve body (4), the second valve body (7) and the negative pressure value in the condenser are adjusted. The high-speed gas turbine is subjected to different driving torques. When the speed of the high-speed gas turbine is higher than the speed of the starter motor (16) under the drive of hydrocarbon fuel cracking gas, the high-speed gas turbine rotor (13) and the starter motor (16) are disengaged. When the torque sensor reading is close to zero, the opening degree of the first valve body (4) and the second valve body (7) corresponding to the inlet and outlet pressure required for the stable operation of the high-speed gas turbine under this working condition is: When the pressure difference between the inlet and outlet is large under a certain working condition, resulting in excessive pressure in the pressure-resistant sealed container, the pressure in the condenser (8) is set to negative pressure by the vacuum pump (9) to reduce the force on the pressure-resistant sealed container. When the high-speed gas-driven turbine is running stably under the action of hydrocarbon fuel cracking gas, the starter motor (16) is disengaged from the turbine rotor (13), and the speed of the starter motor (16) is returned to zero.

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