A kind of aero-engine shaft vibration graphite seal structure leakage measurement experimental device and method

Abstract

The application discloses an experimental device and method for measuring leakage of a graphite sealing structure during shaft vibration of an aero-engine, and belongs to the technical field of aero-engine rotating shafts. The technical scheme points of the application are as follows: the device comprises an installation experiment device, a calibration graphite sealing structure and a rotating shaft compression force, a calibration shaft vibration parameter, a verification of whether the graphite sealing structure compression force on the rotating shaft has an influence on the shaft vibration parameter, a verification of whether the graphite sealing structure vibration reduction air bag pressure pulsation range is within the design range, and an experimental study on the rotating shaft vibration on the leakage characteristics of the graphite sealing structure. The experimental device and method for measuring the leakage of the graphite sealing structure during the shaft vibration of the aero-engine can solve the influence of the vibration of the aero-engine rotating shaft on the leakage of the sealing structure in the sealing experiment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aero-engine rotating shafts, and particularly relates to a graphite sealing structure leakage measurement experimental device and method for aero-engine shaft vibration. BACKGROUND

[0002] An aero-engine combines the most advanced technologies in various industrial fields, has a delicate structure, and generates very powerful power, so that it makes it possible for an aircraft to fly in the air. As a power source of an aircraft, the aero-engine is indispensable like a heart for a human. The aero-engine determines basically all important performance indexes on an aircraft and also measures the technological level, industrial strength and national defense strength of a country. At present, only a few countries such as the United States, Russia, Britain and France in the world can independently develop high-performance aero-engines, and the requirements in the technical field are very harsh. In an aero-engine, a compressor, a combustion chamber and a turbine constitute a core engine of the aero-engine. The turbine drives the compressor to rotate at a high speed of thousands of revolutions per second, air entering the aero-engine is pressurized in the compressor, and the pressurization ratio of the multi-stage compressor can be up to 25 or more. Therefore, the inter-stage and rotating shaft high-temperature and high-pressure air sealing of the aero-engine is one of the methods for improving the performance of the aero-engine.

[0003] At present, the development of the graphite sealing technology of the aero-engine rotating shaft is changing rapidly, and the experimental measurement of the leakage of the shaft graphite sealing is also required to be higher and higher, and it is required to simulate the sealing performance of the coupled graphite sealing of the aero-engine rotating shaft under the condition of multiple parameters. The main experimental measurement technologies of the leakage of the graphite sealing structure at present are the influences of different graphite sealing structures and different pre-tightening forces on the sealing, the influences of the graphite sealing structure on the leakage with the increase of the wear amount, the influences of different air pressures and temperatures on the leakage and wear of the graphite sealing structure, and the like. The aero-engine rotating shaft vibration is only used as a monitoring signal, and the parameter change is easy to break the graphite sealing element, so the aero-engine rotating shaft vibration is not used as a change parameter for experimental research.

[0004] But now, the sealing characteristic experiment of the aero-engine rotating shaft graphite seal structure mainly studies the leakage characteristic of the graphite seal structure with the change of the gas parameter, and generally has a relative requirement for the vibration of the rotating shaft in the experiment, the amplitude of the shaft vibration cannot exceed a certain value, otherwise the sealing characteristic experiment cannot be carried out, therefore the influence of the shaft vibration on the leakage cannot be quantitatively characterized, that is, the influence of the shaft vibration on the leakage is not considered, and in addition, the monitoring of the shaft vibration signal in the experiment of the aero-engine rotating shaft graphite seal with different air parameters is only used to measure the concentricity, coaxiality and assembly precision of the experimental device, and is not a parameter for correcting the experimental data in the experimental results, therefore the influence of the shaft vibration on the leakage of the graphite seal structure is mixed in the measurement results, the influence of other parameters on the leakage of the graphite seal structure is amplified, the design deviation of the graphite seal structure is easily caused, and adverse consequences are formed, in addition, in the sealing characteristic experiment of the graphite seal structure, the vibration of the experimental system is required due to the strength problem of the graphite seal structure, and a flexible structure is arranged in the graphite seal structure, such as an air bag and a spring, to protect the graphite seal structure, so as to prevent the vibration of the aero-engine rotating shaft from damaging the graphite seal structure, therefore the influence of the vibration of the rotating shaft on the leakage of the graphite seal is also not reduced by a better damping method, and the vibration of the rotating shaft is reduced as much as possible in the experiment, but the vibration is dynamically changed with the change of the rotating speed, and it is not appropriate to ignore the influence of the vibration, and in addition, the shaft jumping amount of the aero-engine rotating shaft is within a certain range in the process of high-speed rotation, and the graphite seal structure is a contact seal, and a certain contact force is required to control the leakage of the high-temperature and high-pressure gas, therefore the preset compression force of the graphite seal structure in the graphite seal structure experiment should be constant as a fixed parameter, so as to study the influence of other parameters.

[0005] The present application solves the influence of the vibration of the aero-engine rotating shaft on the leakage of the sealing structure in the sealing experiment of the graphite seal structure, takes the vibration parameter as a variable parameter required to be changed in the experiment, studies the leakage characteristic law of the graphite seal structure under the parameter, corrects the influence of other parameters in the sealing experiment, reduces the experimental error, and improves the reliability of the experiment. SUMMARY

[0006] To address the problems existing in the prior art, the present invention aims to provide an experimental device and method for measuring the leakage of a graphite sealing structure during shaft vibration in an aero-engine, thereby solving the problems mentioned in the background art.

[0007] The above-mentioned technical objective of the present invention is achieved through the following technical solution: an experimental device for measuring the leakage of a graphite sealing structure during shaft vibration of an aero-engine, comprising:

[0008] Shaft;

[0009] The speed control system is used to drive the shaft to rotate and adjust the shaft speed. The speed control system is equipped with a tachometer for monitoring the shaft speed and an acceleration sensor for measuring the vibration amplitude of the shaft.

[0010] The experimental sealed chamber includes a front chamber, a middle chamber, and a rear chamber. A graphite sealing structure is provided inside the middle chamber, an airbag is provided outside the graphite sealing structure, an outer ring is provided outside the airbag, a tension and compression sensor is provided outside the outer ring of the airbag, and an exhaust port is provided in the rear chamber.

[0011] The airbag constant pressure system includes a cylinder and a piston located inside the cylinder. A sealed space is formed between the bottom of the piston and the cylinder. The sealed space is filled with dry air. The piston can be compressed by placing a weight on top of the piston. The sealed space is connected to the airbag through a cylinder-airbag connecting tube.

[0012] The air supply system, connected to the front chamber of the sealing chamber, is used to supply adjustable-pressure air to the front chamber of the sealing chamber and to detect air leakage.

[0013] In some embodiments, the speed control system includes a motor and coupling for driving the shaft to rotate, a speed regulator for adjusting the shaft speed, and a bearing housing for supporting the shaft.

[0014] In some embodiments, a temperature and pressure sensor is provided on the front cavity of the sealed chamber.

[0015] In some embodiments, the air supply system includes an air compressor unit for generating high-pressure air, an air storage tank for storing air, a shut-off valve and a pressure regulating valve for regulating air flow and pressure, a flow meter for detecting air flow, and a pipe running through the entire system for transmitting air.

[0016] An experimental method for measuring the leakage of a graphite sealing structure during shaft vibration in an aero-engine includes the following steps:

[0017] Step 1: Install and debug the experimental apparatus, and obtain the maximum theoretical clamping force F and the maximum experimental clamping force F of the rotating shaft according to its specifications. max Maximum experimental rotational speed n max And the maximum allowable amplitude of vibration S, where Fmax = 120% * F;

[0018] Step two: measure the compression force between the shaft and the graphite sealing structure by the tension sensor, after the shaft is installed, ensure that the compression force on the shaft is zero, then increase the same weight of the weight on the piston to adjust the pressure in the air bag several times, until the compression force on the shaft is increased to F max , record the compression force data after each time the weight is placed;

[0019] Step three: restore to the state after completing step one, screw the counterweight bolt into the shaft, and tighten the counterweight bolt completely, measure the height of the counterweight bolt protruding from the shaft and record it, place the weight on the piston, the weight of the weight is 60% F max of the weight in step two, control the shaft speed to 80 n max , during which the vibration amplitude of the shaft is measured by the acceleration sensor and recorded, then adjust the depth of the counterweight bolt several times, and record the height of the counterweight bolt relative to the shaft after each adjustment, during which the shaft speed is kept at 80 n max , until the vibration amplitude of the shaft is increased to 200% of the maximum allowable amplitude S of the shaft vibration, record the vibration amplitude of the shaft after each adjustment of the depth of the counterweight bolt;

[0020] Step four: verify whether the compression force of the graphite sealing structure on the shaft has an impact on the shaft vibration parameters, restore to the state after completing step one, screw the counterweight bolt into the shaft, adjust the height of the counterweight bolt relative to the shaft according to the data recorded in step three, ensure that the vibration amplitude of the shaft at this time is 100% S, and control the shaft speed to 80 n max , then increase the same weight of the weight on the piston to adjust the pressure in the air bag several times, until the compression force on the shaft is increased to F max , during which the vibration amplitude of the shaft is observed to see if it has an impact;

[0021] Step five: verify whether the pressure pulsation range of the graphite sealing structure damping air bag is within the design range, restore to the state after completing step one, screw the counterweight bolt into the shaft, adjust the height of the counterweight bolt relative to the shaft according to the data recorded in step three, ensure that the vibration amplitude of the shaft at this time is 100% S, control the shaft speed to 80 n max , and place the weight on the piston until the compression force on the shaft is F max , then record the pulsation change value of the compression force within 60 s by the tension sensor, the minimum pulsation compression force recorded is N min , the maximum pulsation compression force recorded is N max , use the formula The specific value of the stability coefficient μ is calculated, and when the stability coefficient μ is within 0.005, it is determined that the pressure pulsation range of the graphite sealing structure shock absorber is within the design range;

[0022] Step six: restore to the state just after step one, remove the counterweight bolt, use the filling nut to block the threaded hole adapted to the original counterweight bolt, and control the rotating shaft speed to be 80 n max , and adjust the pressing force on the rotating shaft to 25%*F by adjusting the weight on the piston max , 50% F max , 75% F max , and adjust the air pressure in the front cavity of the sealing chamber through the air supply system under different pressing forces, detect the air leakage of the graphite sealing structure under different air pressures, and record the data.

[0023] Step seven: restore to the state just after step one, screw the counterweight bolt into the threaded hole on the rotating shaft, and control the rotating shaft speed to be 80 n max , and adjust the pressing force on the rotating shaft to 25%*F by adjusting the height of the counterweight bolt relative to the rotating shaft max , and adjust the rotating shaft vibration amplitude to 120% S, 140% S, 160% S, 180% S, and 200% S by adjusting the height of the counterweight bolt relative to the rotating shaft, and adjust the air pressure in the front cavity of the sealing chamber through the air supply system under different rotating shaft vibration amplitudes, detect the air leakage of the graphite sealing structure under different air pressures, and record the data.

[0024] Step eight: compare and analyze the leakage characteristics of the graphite sealing structure under the condition that the rotating shaft vibration parameters change by comparing the data measured in steps six and seven, obtain the regular curve atlas, and use it as a correction reference for the leakage characteristics of the graphite sealing structure under other different working conditions.

[0025] In some embodiments, the specific operation of step one is as follows:

[0026] A threaded hole is formed on the rotating shaft, one end of the rotating shaft is installed on a rotating speed control system, the threaded hole is filled with a filling nut, the rotating speed control system is debugged to ensure that the rotating shaft vibration amplitude is less than 0.003 mm when the rotating speed is 80 n max , after debugging, the other end of the rotating shaft is externally penetrated into the rear cavity of the sealing chamber, and then penetrates into the front cavity of the sealing chamber, during which the rotating shaft penetrates through the graphite sealing structure and the two are in contact, and it is ensured that the air in the front cavity of the sealing chamber can only enter the rear cavity of the sealing chamber through the gap between the rotating shaft and the graphite sealing structure.

[0027] In some embodiments, in step two, the mass of the weight placed on the piston each time is 1 kg.

[0028] In some embodiments, in step five, the rotation frequency of the rotating shaft is f=0.8n within 60s max / 60, the response frequency of the tension-compression sensor is not less than 1.5f, and the acquisition frequency is not less than 2.5f.

[0029] In summary, the present application has the following beneficial effects:

[0030] 1. The speed of the rotating shaft of the aero-engine is generally very high, and the vibration problem of the shaft is directly related to the leakage characteristics of the graphite sealing structure. At the same time, the vibration of the shaft can also cause damage to the graphite sealing structure. Therefore, the protection of the graphite sealing structure is also a problem that needs to be considered in practice. The constant pressure air bag of the present application can reduce the vibration of the graphite sealing structure and also provide a constant compression force, thereby protecting the safe and reliable operation of the graphite sealing structure and generating a constant compression force, which is beneficial to improving the service life and performance of the graphite sealing structure.

[0031] 2. The present application standardizes the pressure of the constant pressure air bag and verifies and evaluates the compression force generated by the rotating shaft in the dynamic working process, realizes the change of the compression force from variable parameters to constant, and thereby improves the reliability of the experimental data.

[0032] 3. The present application takes the vibration parameter as a variable parameter that needs to be changed in the experiment, studies the leakage characteristics of the graphite sealing structure under this parameter, and is used to correct the influence of other parameters in the sealing experiment, thereby reducing the experimental error and improving the reliability of the experiment. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a structural schematic view of the experimental device of the present application;

[0034] Figure 2 is a structural schematic view of the experimental sealing cavity in the experimental device of the present application.

[0035] In the figure: 1 - air compressor unit, 2 - gas storage tank, 3 - stop valve, 4 - pipeline, 5 - pressure regulating valve, 6 - flow meter, 7 - front cavity of sealing chamber, 8 - temperature and pressure sensor, 9 - counterweight bolt, 10 - rotating shaft, 11 - weight, 12 - piston, 13 - air cylinder, 14 - dry air, 15 - air cylinder air bag connecting pipe, 16 - middle cavity of sealing chamber, 17 - tension-compression sensor, 18 - air bag outer ring, 19 - air bag, 20 - graphite sealing structure, 21 - rear cavity of sealing chamber, 22 - acceleration sensor, 23 - exhaust hole, 24 - bearing seat A, 25 - bearing seat B, 26 - tachometer, 27 - shaft coupling, 28 - motor, 29 - speed regulator. DETAILED DESCRIPTION

[0036] Embodiments of the present application are described below in detail with reference to the accompanying drawings, wherein the same or similar components are denoted by the same or similar reference numerals throughout the drawings. The embodiments described below by reference to the drawings are exemplary and are intended to explain the present application, and are not to be understood as limiting the present application.

[0037] In the description of the present application, it needs to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0038] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features referred to. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0039] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] An experimental device for measuring the leakage of a graphite sealing structure during shaft vibration of an aero-engine, comprising a rotating speed control system, an experimental sealing cavity, a gas bag constant pressure system, a gas source system and a rotating shaft 10 (i.e. an aero-engine shaft) as one of the experimental objects.

[0041] The rotating speed control system is used to drive the rotating shaft 10 to rotate and adjust the rotating speed of the rotating shaft 10. The rotating speed control system is provided with a rotating speed meter 26 for monitoring the rotating speed of the rotating shaft 10 and an acceleration sensor 22 for measuring the vibration amplitude of the rotating shaft 10. In some embodiments, the rotating speed control system can include a motor 28 and a coupling 27 for driving the rotating shaft 10 to rotate, a speed regulator 29 for adjusting the rotating speed of the rotating shaft 10, and a bearing seat for supporting the rotating shaft 10. The bearing seat can be provided with two groups of bearing seats A 24 and bearing seats B 25.

[0042] The experimental sealed cavity includes a front cavity 7, a middle cavity 16 and a rear cavity 21, the middle cavity 16 is provided with a graphite sealing structure 20, the graphite sealing structure 20 is provided with an air bag 19, the air bag 19 is provided with an air bag outer ring 18, the air bag outer ring 18 is provided with a tension sensor 17, the rear cavity 21 is provided with an exhaust hole 23, and a temperature and pressure sensor 8 is arranged on the front cavity 7 to monitor the temperature and pressure in the front cavity 7.

[0043] The air bag constant pressure system includes a cylinder 13 and a piston 12 arranged in the cylinder 13, a sealing space is formed between the bottom of the piston 12 and the cylinder 13, dry air 14 is filled in the sealing space, the piston 12 can compress the dry air 14 by placing a weight on the top of the piston 12, and the sealing space is connected with the air bag 19 through a cylinder air bag connecting pipe 15.

[0044] The air source system is connected with the front cavity 7 of the sealed chamber, and is used for providing air with adjustable air pressure to the front cavity 7 of the sealed chamber and detecting the air leakage amount, the air source system includes an air compressor set 1 for generating high-pressure air, an air storage tank 2 for storing air, a stop valve 3 and a pressure regulating valve 5 for adjusting air flow and air pressure, a flow meter 6 for detecting air flow, and a pipeline 4 penetrating through the whole system for transmitting air, wherein the flow meter 6 can be used to detect the air leakage amount of the front cavity 7 of the sealed chamber.

[0045] The following will be described with reference to the accompanying drawings:

[0046] Figure 1The application discloses a structure diagram of an experimental device, which shows a leakage characteristic experimental device of a graphite sealing structure of an aero-engine rotating shaft vibration parameter change. The whole experimental device can be divided into three parts: 1) a rotating speed control part; 2) a high-pressure air source part; and 3) an experimental sealing cavity and a constant-pressure damping air bag part. The rotating speed control part: the rotating shaft 10 is supported by bearing seats A and B and can rotate under the drive of a motor 28 through a connecting shaft 27, so that the required rotating speed is realized; the rotating speed is realized by a speed regulator 29; and the feedback monitoring of the rotating speed relies on a rotating speed instrument 26. The high-pressure air source part: the part is used for providing controllable pressure high-pressure air for a front cavity of the experimental sealing chamber, so as to simulate the front and back pressure difference of the graphite sealing structure of the aero-engine. A compressed high-pressure dry air is stored into a gas storage tank 2 by an air compressor set 1, so as to provide stable and reliable high-pressure air for the experiment. The flow of the high-pressure air is provided by the opening and closing of a stop valve 3, and the high-pressure air passes through a pipeline 4 to a pressure regulating valve 5; the pressure regulating valve 5 can adjust the pressure of the high-pressure air, so that the air pressure entering into the sealing chamber front cavity 7 meets the experimental requirements. The flow of the air can be measured by a flowmeter 6; after entering into the sealing chamber front cavity 7, the opening of the pressure regulating valve 5 is controlled by a temperature and pressure sensor 8, so as to realize the pressure control of the sealing chamber front cavity 7. The experimental sealing cavity and the constant-pressure damping air bag part: the experimental sealing cavity is divided into three parts, namely, a sealing chamber front cavity 7, a sealing chamber middle cavity 16 and a sealing chamber rear cavity 21. The sealing chamber front cavity 7 is mainly used for storing high-pressure air; the sealing chamber middle cavity 16 is used for installing a graphite sealing structure 20, an air bag 19, an air bag outer ring 18 and the like. The graphite sealing structure 20 is in close contact with the rotating shaft 10 and seals the high-pressure air through the contact. The graphite sealing structure 20 can rotate relative to the rotating shaft 10. The air bag 19 protects the graphite sealing structure 20 from vibration. The air bag 19 can absorb the vibration of the rotating shaft 10, and the constant pressure in the air bag 19 can guarantee the constant pressure of the graphite sealing structure 20. The constant pressure of the air bag 19 is realized by connecting the air bag 19 and a cylinder 13 through a cylinder air bag connecting pipe 15; the cylinder 13 has a piston 12, the internal space is sealed with dry air 14, a standard mass weight 11 is arranged on the piston 12, the constant pressure of the air bag 19 is provided by the pressure of the weight 11, the pressure in the air bag 19 is related to the weight of the weight 11, the pressure in the air bag 19 is constant when the weight of the weight 11 is constant. Therefore, the pressing force of the graphite sealing structure and the rotating shaft is constant. The air bag outer ring 18 is used for longitudinally restraining the air bag 19, and the pressing force of the graphite sealing structure and the rotating shaft 10 is measured through a tension and pressure sensor 17 connected with the air bag outer ring 18. The vibration parameter adjustment of the rotating shaft is realized by the depth of the screwing of a shaft head counterweight bolt 9 into the rotating shaft 10.

[0047] Figure 2This is a schematic diagram of the experimental sealed chamber in the experimental apparatus of the present invention. It illustrates the high-pressure air flow path in the experiment on the leakage characteristics of the graphite sealing structure when the vibration parameters of the aero-engine shaft change. As shown in the figure, high-pressure air enters the front chamber 7 of the sealing chamber through the pressure regulating valve 5. The entire sealing chamber is sealed, so the only place where the airflow can leak is the gap between the graphite sealing structure 20 and the shaft 10. Because the airbag 19 applies pressure to the graphite sealing structure 20 by relying on the constant pressure of the internal gas, the graphite sealing structure 20 is in close contact with the shaft 10. It is also based on this principle that the high-pressure gas behind the aero-engine shaft is sealed. The high-pressure gas enters the rear chamber 21 of the sealing chamber through the gap and is discharged from the exhaust port 23. The purpose of the experiment is to measure the leaked high-pressure gas using the flow meter 6, thereby evaluating the leakage characteristics of this type of graphite sealing structure 20.

[0048] An experimental method for measuring the leakage of a graphite sealing structure during shaft vibration in an aero-engine includes the following steps:

[0049] Step 1: Install and debug the experimental setup. Specifically, drill a threaded hole on the rotating shaft 10, install one end of the rotating shaft 10 onto the speed control system, and fill the threaded hole with a filler nut. Debug the speed control system to ensure that the vibration amplitude of the rotating shaft 10 is within 80% of its maximum value. max When the pressure is less than 0.003 mm, after adjustment, the other end of the rotating shaft 10 is passed through from the outside into the rear cavity 21 of the sealing chamber, and then from the rear cavity 21 into the front cavity 7 of the sealing chamber. During this process, the rotating shaft 10 passes through the graphite sealing structure 20, and the two are in contact with each other. It is ensured that the air in the front cavity 7 of the sealing chamber can only enter the rear cavity 21 of the sealing chamber through the gap between the rotating shaft 10 and the graphite sealing structure 20. Then, the maximum theoretical clamping force F and the maximum experimental clamping force F of the rotating shaft 10 are obtained according to the specifications of the rotating shaft 10. max Maximum experimental rotational speed n max And the maximum allowable amplitude of vibration S, where F max =120% * F;

[0050] Step 2: Measure the clamping force between the rotating shaft 10 and the graphite sealing structure 20 using the tension / compression sensor 17. Immediately after installing the rotating shaft 10, ensure that the clamping force on the rotating shaft 10 is zero. Then, repeatedly adjust the pressure inside the airbag 19 by continuously adding weights 11 of the same weight to the piston 12 until the clamping force on the rotating shaft 10 increases to F. max During this process, the clamping force data is recorded after each placement of weight 11. In this step, the mass of weight 11 placed on piston 12 each time can be 1KG.

[0051] Step 3: Return to the state immediately after completing Step 1. Screw the counterweight bolt 9 onto the rotating shaft 10 and tighten it completely. Measure and record the height of the counterweight bolt 9 protruding from the rotating shaft 10. Place a weight 11 on the piston 12. The weight of weight 11 is 60% of F from Step 2. max The weight 11 is at its maximum weight, and the rotation speed of the control shaft 10 is set to 80% at this time. max During this process, the vibration amplitude of the rotating shaft 10 was measured and recorded using the accelerometer 22. The screwing depth of the counterweight bolt 9 was then adjusted multiple times, and the height of the counterweight bolt 9 relative to the rotating shaft 10 was recorded after each adjustment. The rotational speed of the rotating shaft 10 was maintained at 80% of its maximum speed throughout this process. max Until the vibration amplitude of the rotating shaft 10 increases to 200% of the maximum allowable vibration amplitude S of the rotating shaft 10, the vibration amplitude of the rotating shaft 10 is recorded after each adjustment of the screwing depth of the counterweight bolt 9.

[0052] Step 4: Verify whether the clamping force of the graphite seal structure 20 on the rotating shaft 10 affects the shaft vibration parameters. Return to the state immediately after completing Step 1, and screw the counterweight bolt 9 onto the rotating shaft 10. Adjust the height of the counterweight bolt 9 relative to the rotating shaft 10 according to the data recorded in Step 3, ensuring that the vibration amplitude of the rotating shaft 10 is 100%S at this time, and control the rotation speed of the rotating shaft 10 to 80%n. max Then, by continuously adding weights 11 of the same weight to the piston 12, the pressure inside the airbag 19 is adjusted multiple times until the clamping force on the rotating shaft 10 is increased to F. max During this period, observe the vibration amplitude of the rotating shaft 10 to see if it has any impact;

[0053] Step 5: Verify that the pressure pulsation range of the graphite sealing structure 20 and the vibration damping airbag 19 is within the design range. Return to the state immediately after completing Step 1. Screw the counterweight bolt 9 onto the rotating shaft 10. Adjust the height of the counterweight bolt 9 relative to the rotating shaft 10 according to the data recorded in Step 3, ensuring that the vibration amplitude of the rotating shaft 10 is 100%S at this time, and control the rotation speed of the rotating shaft 10 to 80%n. max And by placing weights 11 on piston 12 until the clamping force on shaft 10 is F. max Then, the tension / compression sensor 17 records the pulsating change value of the clamping force within 60 seconds. The minimum pulsating clamping force recorded is N. min The recorded maximum pulsating clamping force was N. max Using the formula The specific value of the stability coefficient μ is calculated. If the stability coefficient μ is within 0.005, then the pressure pulsation range of the graphite sealing structure 20 and the vibration damping airbag 19 is determined to be within the design range, and the rotational frequency of the shaft 10 is f = 0.8n within 60s. max / 60, When selecting the tension / compression sensor 17, its response frequency should be no less than 1.5f and its acquisition frequency should be no less than 2.5f;

[0054] Step Six: Return to the state immediately after Step One, remove counterweight bolt 9, and use a filler nut to plug the threaded hole that originally fitted the counterweight bolt 9. Control the rotation speed of shaft 10 to 80%. max The clamping force on the rotating shaft 10 is adjusted to 25%*F by adjusting the number of weights 11 on the piston 12. max 50% F max 75% F max The air pressure in the front chamber 7 of the sealing chamber is adjusted by the air source system under different clamping forces. The air leakage of the graphite sealing structure 20 under different air pressures is detected and the data is recorded.

[0055] Step 7: Return to the state immediately after completing Step 1, and screw the counterweight bolt 9 onto the rotating shaft 10 to control the rotation speed of the rotating shaft 10 to 80%. max Adjust the clamping force on the rotating shaft 10 to 25%*F max The vibration amplitude of the rotating shaft 10 was adjusted sequentially to 120%S, 140%S, 160%S, 180%S, and 200%S by adjusting the height of the counterweight bolt 9 relative to the rotating shaft 10. Under different vibration amplitudes of the rotating shaft 10, the air pressure in the front chamber 7 of the sealing chamber was adjusted by the air source system. The air leakage of the graphite sealing structure 20 under different air pressures was detected and the data was recorded.

[0056] Step 8: Compare and analyze the leakage characteristics of the graphite sealing structure 20 under varying vibration parameters by measuring the data in Steps 6 and 7. 1) Leakage characteristics with increasing vibration amplitude under the same clamping force and gas pressure; 2) Leakage characteristics with increasing vibration amplitude under different clamping forces and gas pressures. A predictive curve can be obtained, which can serve as a reference for correcting the leakage characteristics of the graphite sealing structure 20 under other different operating conditions.

[0057] Based on the above experimental setup and procedures, the following experiments were conducted:

[0058] 1. The outer diameter of the shaft of a certain aero-engine is 168mm, and the maximum experimental rotational speed n max The maximum theoretical clamping force F is 20N, and the maximum experimental clamping force F is 12000rpm. The graphite sealing structure has an inner diameter of 168mm, an outer diameter of 184mm, and a length of 15mm. max =120% * F = 24N, and the maximum allowable vibration amplitude S is 0.01mm; when the rotational speed is set to 80% * 12000 = 9600rpm, the vibration amplitude of the shaft is adjusted to 0.002mm, which is less than 0.003mm, and this meets the experimental requirements.

[0059] 2. Calibrate the compression force of the graphite seal structure on the rotating shaft. First, adjust the air pressure in the air bag so that the force of the outer ring of the air bag on the tension and compression sensor is zero. At this time, seal the air cylinder, add weights to the piston, and record the data of the tension and compression sensor:

[0060]

[0061]

[0062] 3. Calibrate the vibration parameters of the rotating shaft: the rotating speed of the rotating shaft is 0.8*12000=9600 rpm, and the compression force is 24*0.6=14.4 N. Therefore, add 3.2 Kg weights to the piston, and screw all the counterweight bolts to a height of 8 mm. The maximum requirement for the vibration of the aero-engine rotating shaft is 0.01 mm. Therefore, the vibration parameter calibration is 200%*0.01=0.02 mm. Record the calibration data as:

[0063] Bolt height mm 8 9.6 11.1 12.4 13.6 14.6 15.4 Vibration amplitude mm 0.008 0.010 0.012 0.014 0.016 0.018 0.020

[0064] 4. Verify the effect of the compression force of the graphite seal structure on the amplitude of the rotating shaft. The rotating speed is 0.8*12000=9600 rpm, and the amplitude is adjusted to 100%*0.01=0.01 mm, i.e. the counterweight bolt is adjusted to a height of 11 mm. At this time, gradually increase the weight from 0 to 6 Kg, and the measured vibration amplitude is 0.0108, which has no effect.

[0065] 5. Verify the pressure pulsation range of the vibration reduction air bag of the graphite seal structure. The rotating speed is 0.8*12000=9600 rpm, and the amplitude is adjusted to 100%*0.01=0.01 mm, i.e. the counterweight bolt is adjusted to a height of 11 mm. The compression force is set to 24 N, the rotating frequency of the rotating shaft is f=9600 / 60=160 HZ, the response frequency of the tension and compression sensor is 1 KHZ, the collection frequency is 5 KHZ, and the collection time is 60 s. max 24.05 N, N min 23.96 N, μ=0.002, the stability coefficient is within 0.005, which is qualified.

[0066] 6. Perform the leakage characteristic experiment of the graphite seal structure in the zero state of the rotating shaft vibration. The rotating speed is 9600 rpm, and the compression force of the graphite seal structure on the rotating shaft is set to 6 N. Set the high-pressure air pressure in the front cavity of the graphite seal structure, and measure the leakage of the graphite seal structure under different air pressures:

[0067] Air pressure Mpa 0.2 0.4 0.6 0.8 1.0 Leak flow m 3 / s]] 0.0045 0.0054 0.0062 0.007 0.0081

[0068] 7. Conduct leakage characteristic tests on the graphite seal structure under shaft vibration conditions. The shaft vibration amplitude was set to five parameters: 120%S, 140%S, 160%S, 180%S, and 200%S, corresponding to 0.012mm, 0.014mm, 0.016mm, 0.018mm, and 0.02mm respectively. The rotational speed was 9600rpm. The clamping force of the graphite seal structure on the shaft was set to 6N. The high-pressure air pressure in the front cavity of the graphite seal structure was set, and the leakage of the graphite seal structure under different air pressures was measured.

[0069] 120% S data table (only one example is listed):

[0070] Air pressure Mpa 0.2 0.4 0.6 0.8 1.0 Leak flow m 3 / s]] 0.0048 0.0057 0.0066 0.0074 0.0085

[0071] 8. By comparing the data results in 6 and 7, the influence of shaft vibration on the graphite sealing structure can be obtained, which can be used as a correction factor for other experiments.

[0072] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. An experimental method for measuring the leakage of a graphite sealing structure during shaft vibration in an aero-engine, the experimental apparatus used in this method comprising: Shaft; A speed control system is used to drive the shaft to rotate and adjust the shaft speed. The speed control system includes a tachometer for monitoring the shaft speed and an acceleration sensor for measuring the shaft vibration amplitude. An experimental sealed chamber includes a front chamber, a middle chamber, and a rear chamber. A graphite sealing structure is located inside the middle chamber, an airbag is located outside the graphite sealing structure, an outer ring is located outside the airbag, and a tension / compression sensor is located outside the outer ring. An exhaust port is located in the rear chamber. An airbag constant pressure system includes a cylinder and a piston located inside the cylinder. A sealed space is formed between the bottom of the piston and the cylinder, and the sealed space is filled with dry air. The piston can be compressed by placing a weight on top of it. The sealed space is connected to the airbag via a cylinder-airbag connecting pipe. An air source system is connected to the front chamber of the sealed chamber and is used to provide adjustable-pressure air to the front chamber and detect air leakage. The method is characterized by the following steps: Step 1: Install and debug the experimental apparatus, and obtain the maximum theoretical clamping force F and the maximum experimental clamping force F of the rotating shaft according to its specifications. max Maximum experimental rotational speed n max And the maximum allowable amplitude of vibration S, where F max =120%*F; Step Two: Measure the clamping force between the rotating shaft and the graphite seal structure using a tension / compression sensor. Immediately after installation, ensure the clamping force on the shaft is zero. Then, repeatedly adjust the pressure inside the airbag by continuously adding weights of the same weight to the piston until the clamping force on the shaft increases to F. max During this period, the clamping force data was recorded after each weight was placed; Step 3: Return to the state immediately after completing Step 1. Screw the counterweight bolt onto the rotating shaft and tighten it completely. Measure and record the height of the counterweight bolt protruding from the rotating shaft. Place a weight on the piston, the weight of which is 60% of F in Step 2. max The weight of the weight at that time, and the rotation speed of the shaft is controlled at 80%n. max During this process, the vibration amplitude of the rotating shaft was measured and recorded using an accelerometer. The screwing depth of the counterweight bolts was then adjusted multiple times, and the height of the counterweight bolts relative to the rotating shaft was recorded after each adjustment. The rotating shaft speed was maintained at 80% of its maximum rotational speed throughout this process. max Until the shaft vibration amplitude increases to 200% of the maximum allowable amplitude S of the shaft vibration, the shaft vibration amplitude is recorded each time the counterweight bolt is tightened. Step 4: Return to the state immediately after completing Step 1. Screw the counterweight bolts onto the shaft. Adjust the height of the counterweight bolts relative to the shaft according to the data recorded in Step 3, ensuring that the shaft vibration amplitude is 100%S and controlling the shaft speed to 80%n. max Then, by continuously adding weights of the same weight to the piston, the pressure inside the airbag is adjusted multiple times until the clamping force on the rotating shaft is increased to F. max During this period, observe the vibration amplitude of the rotating shaft to see if it has any impact; Step 5: Return to the state immediately after completing Step 1. Screw the counterweight bolts onto the shaft. Adjust the height of the counterweight bolts relative to the shaft according to the data recorded in Step 3, ensuring that the shaft vibration amplitude is 100%S and the shaft speed is controlled at 80%n. max And by placing weights on the piston until the clamping force on the shaft is F. max Then, the pulsating change value of the clamping force was recorded over 60 seconds using a tension / compression sensor. The minimum pulsating clamping force recorded was... The recorded maximum pulsating compressive force was Using the formula Calculate the stability coefficient Specific values, stability coefficient If the value is within 0.005, then the pressure pulsation range of the graphite sealing structure vibration damping airbag is determined to be within the design range. Step Six: Return to the state immediately after Step One, remove the counterweight bolts, and use filler nuts to plug the threaded holes that originally fitted the counterweight bolts. Control the shaft speed to 80% of its maximum speed. max The clamping force on the rotating shaft is adjusted to 25%*F by adjusting the number of weights on the piston. max 50%F max 75%F max The air pressure in the front chamber of the sealing chamber was adjusted by the air source system under different clamping forces. The air leakage of the graphite sealing structure under different air pressures was detected and the data was recorded. Step 7: Return to the state immediately after completing Step 1, and screw the counterweight bolts onto the shaft to control the shaft speed at 80%. max Adjust the clamping force on the rotating shaft to 25%*F. max The vibration amplitude of the rotating shaft was adjusted sequentially to 120%S, 140%S, 160%S, 180%S, and 200%S by adjusting the height of the counterweight bolt relative to the rotating shaft. Under different vibration amplitudes of the rotating shaft, the air pressure in the front cavity of the sealing chamber was adjusted by the air source system. The air leakage of the graphite sealing structure under different air pressures was detected and the data was recorded. Step 8: By comparing and analyzing the data measured in Steps 6 and 7, the leakage characteristics of the graphite sealing structure under the condition of changing vibration parameters are obtained, and a regular curve spectrum is obtained as a reference for correcting the leakage characteristics of the graphite sealing structure under other different working conditions.

2. The experimental method for measuring the leakage of a graphite sealing structure during shaft vibration of an aero-engine, as described in claim 1, is characterized in that: The specific steps for step one are as follows: Drill a threaded hole on the shaft, install one end of the shaft onto the speed control system, and fill the threaded hole with a filler nut. Adjust the speed control system to ensure the shaft's vibration amplitude is within 80% of its maximum value. max When the thickness is less than 0.003mm, after debugging, the other end of the rotating shaft is passed through from the outside into the rear cavity of the sealing chamber, and then from the rear cavity of the sealing chamber into the front cavity of the sealing chamber. During this process, the rotating shaft passes through the graphite sealing structure and the two are in contact with each other, ensuring that the air in the front cavity of the sealing chamber can only enter the rear cavity of the sealing chamber through the gap between the rotating shaft and the graphite sealing structure.

3. The experimental method for measuring the leakage of a graphite sealing structure during shaft vibration of an aero-engine, as described in claim 1, is characterized in that: In step two, the mass of the weight placed on the piston each time is 1KG.

4. The experimental method for measuring the leakage of a graphite sealing structure during shaft vibration of an aero-engine, as described in claim 1, is characterized in that: In step five, the rotational frequency of the shaft is f = 0.8 MHz within 60 seconds. max / 60, the response frequency of the tension / compression sensor is not less than 1.5f, and the acquisition frequency is not less than 2.5f.

5. The experimental method for measuring the leakage of a graphite sealing structure during shaft vibration of an aero-engine according to claim 1, characterized in that: The speed control system includes a motor and coupling for driving the shaft to rotate, a speed regulator for adjusting the shaft speed, and a bearing housing for supporting the shaft.

6. The experimental method for measuring the leakage of a graphite sealing structure during shaft vibration of an aero-engine, as described in claim 1, is characterized in that: A temperature and pressure sensor is installed on the front cavity of the sealed chamber.

7. The experimental method for measuring the leakage of a graphite sealing structure during shaft vibration of an aero-engine, as described in claim 1, is characterized in that: The air supply system includes an air compressor unit for generating high-pressure air, an air storage tank for storing air, shut-off valves and pressure regulating valves for regulating air flow and pressure, a flow meter for detecting air flow, and pipes running through the entire system for transmitting air.

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