A method for metal combustion testing of aerospace engines based on dynamic monitoring of combustion threshold values

Abstract

The present invention discloses a method for testing metal combustion of an aerospace engine based on dynamic monitoring of a combustion threshold value. The method comprises the following steps: driving the friction member to rotate, causing the friction structure to rotate at high speed; driving the simulated test piece of the characteristic component of the aerospace engine to make a linear displacement toward the friction structure, causing the friction structure and the friction end on the simulated test piece to rub against each other, and starting a timer; measuring the test parameters and the friction load of the friction end on the simulated test piece in real time during the friction between the friction structure and the simulated test piece; calculating the combustion threshold value in real time to predict the test trend and detecting the time signal of the timer, and terminating the test when the calculated combustion threshold value is greater than the critical value or the time signal of the detection timer is greater than the preset time. The method simulates the metal combustion test under the operating conditions of the aerospace engine according to the principles of operating condition matching, incoming flow environment matching, and fault characteristic matching. The test conditions are closely combined with the service environment to achieve targeted testing of different fault modes.

Description

Technical Field

[0001] The present invention relates to the technical field of aviation engines, and in particular to a metal combustion test method for an aerospace engine based on dynamic monitoring of a combustion threshold value. Background Art

[0002] Continuous breakthroughs in aerospace technology have enabled the rapid development of space planes. Space planes combine the advantages of traditional aircraft and spacecraft, employing horizontal takeoff and landing. They can reach speeds of 16,000 to 30,000 kilometers per hour within the atmosphere, reaching Mach 12 to 25 at altitudes of 30 to 100 kilometers. They can also accelerate directly into Earth orbit. Because they can fly both within and outside the atmosphere and are fully reproducible, space planes significantly reduce aerospace transportation costs.

[0003] Due to the unique operating environment, aerospace engines utilize a combination of engines, including a "supersonic combustion ramjet + rocket engine" and a "turbojet + ramjet + rocket engine" combination. The turbojet engine operates during horizontal takeoff, while the ramjet engine activates when the flight speed exceeds 2,400 kilometers per hour, enabling the spaceplane to reach speeds of 30,000 kilometers per hour at an altitude of 60 kilometers within the atmosphere. If the rocket engine is activated to accelerate the spaceplane directly into Earth orbit.

[0004] Turbojets in aerospace engines use a compressor to compress atmospheric air into a high-pressure flow. This air then burns with hydrocarbon fuel in the combustion chamber, producing high-temperature, high-pressure combustion gases that drive the turbine and are then ejected at high speed, generating thrust. Compressor blades are often made of titanium alloy. Due to the minimal clearance between the blade tips and the casing of high-performance compressors, friction between the titanium alloy blades and the casing can occur under extreme operating conditions, leading to combustion accidents.

[0005] The rocket engine in an aerospace engine uses its own high-purity oxygen, supplied through an extrusion or pump-type supply system, to combust with the propellant, generating high-temperature, high-pressure combustion gas that is ejected at high speed through the nozzle, generating thrust. In a highly oxygen-rich environment, adiabatic compression shocks or localized high temperatures can cause combustion in the rocket engine's high-temperature alloys, resulting in engine damage.

[0006] Currently, metal combustion is being tested both domestically and internationally using methods such as laser ignition, metal droplet ignition, and friction ignition. The laser ignition method uses a high-energy laser beam to target a narrow area of ​​a metal specimen, concentrating the energy. Using the laser energy as a benchmark, the initiation energy of metal combustion tests is highly repeatable. The metal droplet ignition method uses the energy of molten metal droplets as a benchmark, sequentially adding them to the test area of ​​the metal specimen until ignition occurs. The number of droplets used is used as an estimate of the metal initiation energy. However, this method has lower repeatability than the laser ignition method due to variations in droplet temperature, size, and droplet distribution. The friction method uses the same or different metal materials to form a friction pair, one serving as a simulated specimen and the other as an impactor. During the test, a rotary drive drives the impactor at a set speed. A feed mechanism gradually moves the simulated specimen closer to the impactor until a certain contact pressure is established. Simultaneously, parameters such as the temperature, rotational speed, and contact pressure of the friction surface are measured in real time until the simulated specimen ignites or the test ends after the set test time has elapsed. This method is close to the actual operating state in form, but the surface state of the friction pair, the degree of wear debris accumulation, and the friction intensity are widely dispersed, and the test reproducibility is low.

[0007] Further analysis shows that the various existing friction test systems and methods do not match and monitor the rubbing load in real time, nor do they match the rubbing power density in the test, resulting in a large dispersion of test results. Summary of the Invention

[0008] In response to the above-mentioned deficiencies in the existing technology, the present invention provides a metal combustion test method for aerospace engines based on dynamic monitoring of combustion threshold values. By closely integrating test conditions and dynamic monitoring with the service environment, the metal combustion test research and experimental verification of aerospace engines under various extreme working conditions and various fault modes are completed.

[0009] To achieve the above objectives, the present invention provides a method for testing metal combustion in an aerospace engine based on dynamic monitoring of a combustion threshold value. The method uses a friction piece to simulate the friction pair of a characteristic component of an aerospace engine, and uses a simulated test piece to simulate the characteristic component of an aerospace engine. The test method includes the following steps:

[0010] Step 1: Setting a ring-shaped friction structure on the friction member;

[0011] Step 2: driving the friction member to rotate so that the friction structure rotates at high speed around its own axis;

[0012] Step 3: driving the simulated specimen to perform linear displacement toward the rubbing structure, so that the rubbing structure and the rubbing end on the simulated specimen achieve rubbing strength simulation, and starting a timer;

[0013] Step 4: During the rubbing process between the rubbing structure and the simulated specimen, the test parameters and the rubbing load at the rubbing end of the simulated specimen are measured in real time;

[0014] Step 5: Calculate the combustion threshold value in real time based on the test parameters and the friction load to predict the test trend, and detect the time signal of the timer. The test is terminated when the calculated combustion threshold value is greater than the critical value or the time signal of the detection timer is greater than the preset time.

[0015] In one embodiment, in step 3, the rubbing structure and the rubbing end on the simulated specimen are simulated to achieve rubbing strength simulation, specifically:

[0016] The rubbing structure and the simulated specimen are caused to rub against each other until the rubbing power density is equivalent to the actual rubbing power density of the characteristic components under the operating conditions of the aerospace engine.

[0017] In one embodiment, in step 4, during the rubbing process between the rubbing structure and the simulated specimen, the rubbing end of the simulated specimen is also monitored in real time by a fire sensor and a temperature sensor;

[0018] When the rate of change of the output signals of the ignition sensor and the temperature sensor exceeds the set value, a high-speed photography operation is performed on the rubbing end of the simulated specimen.

[0019] In one embodiment, in step 5, when the real-time calculated combustion threshold value is less than the critical value and the time signal of the timer is less than the preset time, the output signals of the ignition sensor and the temperature sensor are detected to determine whether the rubbing end of the simulated specimen has reached the ignition state. If so, the test is terminated; otherwise, the test is terminated until the real-time calculated combustion threshold value is greater than the critical value or the time signal of the timer is greater than the preset time.

[0020] In one embodiment, in step 3, the friction simulation includes external scraping simulation and internal squeezing simulation;

[0021] When the rubbing simulation is an external scraping simulation, the simulated specimen is driven to perform a linear displacement toward the inner ring rubbing surface of the rubbing structure;

[0022] When the rubbing simulation is an internal extrusion simulation, the simulation specimen is driven to perform linear displacement toward the outer ring rubbing surface of the rubbing structure.

[0023] In one embodiment, in step 3, the rubbing structure and the simulated specimen are subjected to rubbing simulation, specifically:

[0024] This causes friction, collision, or friction + collision to occur between the rubbing structure and the simulated specimen.

[0025] In one embodiment, when the collision between the rubbing structure and the simulated specimen is simulated as friction, the rubbing structure includes a rubbing surface of an annular structure.

[0026] In one embodiment, when the collision between the rubbing structure and the simulated specimen is simulated as a collision, the rubbing structure includes a rubbing surface of an annular structure and a plurality of elastic beams and a matching mass block;

[0027] The elastic beams correspond to the matching mass blocks one by one, the head ends of the elastic beams are connected to the friction surface at equal intervals, and the tail ends are all facing the center of the friction surface. The matching mass blocks are arranged at the tail ends of the corresponding elastic beams.

[0028] In one embodiment, when the collision between the rubbing structure and the simulated specimen is simulated as friction + collision, the rubbing structure includes a rubbing surface of an annular structure, a friction ring, and a plurality of elastic beams and a matching mass block;

[0029] The friction ring is arranged inside the friction surface and is concentric with the friction surface. The head ends of the elastic beams are connected to the friction surface at equal intervals. The tail ends of the elastic beams are connected to an annular wall surface of the friction ring at equal intervals.

[0030] The elastic beams correspond to the matching mass blocks one by one, and the matching mass blocks are connected to the other annular wall surface of the friction ring at equal intervals. The matching mass blocks and the corresponding elastic beams are located in the same radial direction of the friction ring.

[0031] The present invention provides a metal combustion test method for an aerospace engine based on dynamic monitoring of combustion threshold values. The method simulates characteristic components of an aerospace engine through a simulated test piece, and simulates the friction pairs of characteristic components of an aerospace engine through a friction structure. The simulated friction test under the operating conditions of the aerospace engine is carried out according to the principles of operating condition matching, incoming flow environment matching, and fault characteristic matching. By closely combining the test conditions and dynamic monitoring with the service environment, the metal combustion test research and test verification under various extreme conditions and various fault modes of the aerospace engine are completed. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0033] Figure 1 Flowchart of the test method in the embodiment of the present invention;

[0034] Figure 2 A first axonometric view of a first embodiment of the friction member in an embodiment of the present invention;

[0035] Figure 3 A second isometric view of the first embodiment of the friction member in an embodiment of the present invention;

[0036] Figure 4 This is a first axonometric view of a simulated specimen in an embodiment of the present invention;

[0037] Figure 5 This is a first axonometric view of a second embodiment of the friction member in an embodiment of the present invention;

[0038] Figure 6 A second isometric view of the second and third implementation modes of the friction member in the embodiment of the present invention;

[0039] Figure 7 This is a second axonometric view of the simulated specimen in an embodiment of the present invention;

[0040] Figure 8 This is a first axonometric view of a third embodiment of the friction member in an embodiment of the present invention;

[0041] Figure 9 This is an axonometric view of a fourth embodiment of the friction member in an embodiment of the present invention;

[0042] Figure 10 This is an axonometric view of a fifth embodiment of the friction member in an embodiment of the present invention;

[0043] Figure 11 This is an axonometric view of a sixth embodiment of the friction member in an embodiment of the present invention.

[0044] Figure numbers: friction member 1, friction surface 101, friction groove 102, chip collecting groove 103, elastic beam 104, matching mass block 105, friction ring 106, simulation specimen 2, friction end 201, first simulation surface 202, second simulation surface 203, driving shaft 3.

[0045] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0047] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0048] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referenced. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this disclosure, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0049] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; it can mean mechanical connection, electrical connection, physical connection, or wireless communication connection; it can mean direct connection or indirect connection through an intermediate medium; it can mean internal communication between two elements or interaction between two elements, unless otherwise specified. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0051] This embodiment discloses a method for testing metal combustion of an aerospace engine based on dynamic monitoring of combustion threshold values. The method uses a simulated specimen to simulate a characteristic component of an aerospace engine, and a friction structure to simulate the friction pair of the characteristic component of an aerospace engine. The simulated specimen has a friction end with a sheet structure. The friction piece is made of the same material and processed by the same process as the friction pair of the characteristic component of the aerospace engine, and the simulated specimen is made of the same material and processed by the same process as the characteristic component of the aerospace engine. Figure 1 , the test method specifically includes the following steps:

[0052] Step 1: Setting a ring-shaped friction structure on the friction member;

[0053] Step 2: driving the friction member to rotate at high speed by a three-phase motor, so that the friction structure rotates at high speed around its own axis, and monitoring the torque of the friction member in real time by a friction torque sensor;

[0054] Step 3: Drive the simulated specimen to perform linear displacement toward the rubbing structure through a linear module, so that the rubbing structure and the simulated specimen realize rubbing strength simulation, and make the rubbing power density between the rubbing structure and the simulated specimen equivalent to the actual rubbing power density of the characteristic components under the operating conditions of the aerospace engine, and then detect the test parameters in real time and start the timer. In the process of the simulated specimen performing linear displacement toward the rubbing structure, the length direction of the rubbing end of the sheet structure on the simulated specimen is parallel to the radial direction of the rubbing structure, and the displacement of the simulated specimen is monitored in real time by a displacement sensor;

[0055] Step 4: During the rubbing between the rubbing structure and the simulated specimen, the rubbing load on the rubbing end of the simulated specimen is measured by mounting the simulated specimen on a triaxial load sensor, specifically including axial load, radial load, and tangential load. Furthermore, the rubbing end of the simulated specimen is monitored in real time by a fire sensor and a temperature sensor. When the rate of change of the output signals of the fire sensor and the temperature sensor exceeds a set value, a high-speed photographic operation is performed on the rubbing surface of the simulated specimen to complete image acquisition of the rubbing test.

[0056] Step 5: Detect the test parameters and friction load in real time, calculate the combustion threshold value and predict the test trend. Simultaneously, detect the time signal of the timer. When the calculated combustion threshold value is greater than the critical value or the detection timer time signal is greater than the preset time, terminate the test. When the time signal of the timer is less than the preset time and the real-time calculated combustion threshold value is less than the critical value, detect the output signals of the ignition sensor and the temperature sensor to determine whether the friction surface of the simulated specimen has reached the ignition state. If so, terminate the test. Otherwise, terminate the test until the time signal of the timer is greater than the preset time or the calculated combustion threshold value is greater than the critical value.

[0057] In step 3, the rubbing simulation mainly includes two forms: external scraping simulation and internal extrusion simulation. When the rubbing simulation is external scraping simulation, the simulated specimen is driven to make a linear displacement toward the inner ring rubbing surface of the rubbing structure; when the rubbing simulation is internal extrusion simulation, the simulated specimen is driven to make a linear displacement toward the outer ring rubbing surface of the rubbing structure. More specifically, the rubbing simulation between the rubbing structure and the simulated specimen can be implemented in three main ways: friction only, collision only, or both friction and collision.

[0058] In a specific implementation process, when the collision between the rubbing structure and the simulated specimen is simulated as friction, the rubbing structure includes a rubbing surface of an annular structure.

[0059] refer to Figure 2-3, is a friction member 1 that simulates external scraping with only friction. In this embodiment, the friction member 1 is a disc-shaped structure, and a drive shaft 3 connected to the motor drive end is provided at the axial center position of one end of the friction member 1, and a friction surface 101 is provided at the other end of the friction member 1. Specifically, the other end of the friction member 1 has a friction groove 102 with a circular ring structure, and the friction groove 102 is coaxial with the drive shaft 3. During the external scraping simulation of friction, the friction end 201 on the simulation specimen 2 can be embedded in the friction groove 102. Specifically, refer to Figure 4 The rubbing end 201 on the simulated specimen 2 has a first simulated surface 202 and a second simulated surface 203 that are perpendicular to each other, which are used to respectively simulate the rubbing end surface and the rubbing side surface of the rubbing end 201 of the characteristic component of the aerospace engine. The rubbing groove 102 also has two rubbing surfaces 101 that are perpendicular to each other, which are used to respectively simulate the end rubbing surface and the side rubbing surface of the rubbing pair of the characteristic component of the aerospace engine. During the rubbing test, when the rubbing end 201 on the simulated specimen 2 is embedded in the rubbing groove 102, one of the rubbing surfaces 101 is parallel to the first simulated surface 202 and friction is generated between them, which is used to simulate the internal extrusion friction of the friction pair of the characteristic component of the aerospace engine; the other rubbing surface 101 is parallel to the second simulated surface 203 and friction is generated between them, which is used to simulate the external scraping friction of the friction pair of the characteristic component of the aerospace engine, thereby realizing the simulation of the friction test during external scraping and rubbing. Preferably, the bottom of the friction groove 102 corresponds to the position between the two friction surfaces 101 and is also provided with a chip collecting groove 103 for collecting debris generated during the friction between the simulated specimen 2 and the friction member 1. During the rotation of the friction member 1, the debris will adhere to the friction surface 101 of the friction member 1, thereby being able to simulate the actual situation more realistically.

[0060] refer to Figure 5-6 , is a friction-only internal extrusion simulation friction member 1. In this embodiment, the friction member 1 is a cylindrical structure. A drive shaft 3 is provided at both ends of the friction member 1 along the axial direction of the friction member 1 for connecting to the drive motor. The friction surface 101 is the side wall surface of the friction member 1; Figure 7 The rubbing end 201 on the simulated specimen 2 is a plate-shaped structure, and the rubbing end 201 and the axis of the rubbing member 1 are located in the same plane. During the rubbing test, friction is generated between the rubbing end 201 on the simulated specimen 2 and the rubbing end of the rubbing member 1, thereby realizing the simulation of the friction test in the internal extrusion rubbing.

[0061] In a specific implementation, when the collision between the rubbing structure and the simulated specimen 2 is simulated as a collision, the rubbing structure includes an annular rubbing surface 101 and a plurality of elastic beams 104 and matching mass blocks 105. The elastic beams 104 correspond one-to-one with the matching mass blocks 105. The head ends of the elastic beams 104 are connected to the rubbing surface 101 at equal intervals, and the tail ends are all oriented toward the center of the rubbing surface 101. The matching mass blocks 105 are provided at the tail ends of the corresponding elastic beams 104.

[0062] refer to Figure 6 and Figure 8 , is a friction member 1 that only simulates external scraping of collision. In this embodiment, the friction member 1 is a disc-shaped structure. A drive shaft 3 connected to the motor drive end is provided at the axial center position of one end of the friction member 1. The other end of the friction member 1 has a friction groove 102 coaxial with the drive shaft 3. The friction groove 102 is a circular sunken groove structure, and the friction surface 101 is the side wall surface of the friction groove 102. There are four elastic beams 104 and four matching mass blocks 105, and the matching mass blocks 105 are fan-shaped columnar structures with the same curvature as that of the friction surface 101. The head ends of the four elastic beams 104 are connected to the friction surface 101 at equal intervals, and the tail ends are all facing the center of the friction groove 102. The center of the fan-shaped long arc wall of the matching mass block 105 is set at the tail end of the corresponding elastic beam 104, and the center of the fan-shaped short arc wall of the matching mass block 105 faces the center of the friction groove 102. Reference Figure 7 The rubbing end 201 on the simulated specimen 2 is a plate-like structure. During the rubbing test, after the simulated specimen 2 is embedded in the rubbing groove 102, it makes a linear displacement in the direction of the rubbing surface 101 until it collides with the matching mass block 105 but does not generate friction with the rubbing surface 101. The matching mass block 105 produces a small displacement after the collision and recovers under the action of the elastic beam 104, thereby realizing the simulation of the collision test in the external scraping rubbing.

[0063] refer to Figure 9 , is a friction member 1 that only simulates internal extrusion of collision. In this embodiment, the friction member 1 is a disc-shaped structure. The axial positions of both ends of the friction member 1 are provided with drive shafts 3 connected to the motor drive end. The friction surface 101 is the side wall surface of the friction member 1. There are four elastic beams 104 and four matching mass blocks 105, and the matching mass blocks 105 are fan-shaped columnar structures with the same curvature as that of the friction surface 101. The head ends of the four elastic beams 104 are connected to the friction surface 101 at equal intervals, and the tail ends are all located on the radial extension line of the friction member 1. The center of the fan-shaped short arc wall of the matching mass block 105 is located at the tail end of the corresponding elastic beam 104, and the center of the fan-shaped long arc wall of the matching mass block 105 is located on the radial extension line of the friction member 1. Reference Figure 7The rubbing end 201 on the simulated specimen 2 is a plate-shaped structure, and the rubbing end 201 is located in the same plane as the axis of the rubbing member 1. During the rubbing test, the rubbing end 201 on the simulated specimen 2 makes a linear displacement toward the rubbing surface 101 until it collides with the matching mass block 105 but does not generate friction with the rubbing surface 101. The matching mass block 105 produces a small displacement after the collision and recovers under the action of the elastic beam 104, thereby realizing the simulation of the collision test in the internal extrusion rubbing.

[0064] During the specific implementation process, when the collision between the rubbing structure and the simulated specimen 2 is simulated as friction + collision, the rubbing structure includes a rubbing surface 101 of an annular structure, a friction ring 106, and multiple elastic beams 104 and a matching mass block 105; the friction ring 106 is arranged in the ring of the rubbing surface 101 and is concentric with the rubbing surface 101, and the head end of each elastic beam 104 is connected to the rubbing surface 101 at equal intervals; the tail end of each elastic beam 104 is connected to the outer ring wall of the friction ring 106 at equal intervals; the elastic beams 104 correspond to the matching mass blocks 105 one by one, and each matching mass block 105 is connected to the inner ring wall of the friction ring 106 at equal intervals, and the matching mass block 105 and the corresponding elastic beam 104 are located in the same radial direction of the friction ring 106.

[0065] refer to Figure 10 , is a friction member 1 that simulates external scraping with both friction and impact. In this embodiment, the friction member 1 is a disc-shaped structure. A drive shaft 3 connected to the motor drive end is provided at the axial center position of one end of the friction member 1. The other end of the friction member 1 has a friction groove 102 that is coaxial with the drive shaft 3. The friction groove 102 is a circular sunken groove structure, and the friction surface 101 is the side wall surface of the friction groove 102. There are four elastic beams 104 and four matching mass blocks 105. The matching mass blocks 105 are fan-shaped columnar structures with the same curvature as the rubbing surface 101 and the friction ring 106. The head ends of the four elastic beams 104 are connected to the rubbing surface 101 at equal intervals, and the tail ends are all oriented toward the center of the rubbing groove 102 and are connected to the outer ring wall of the friction ring 106 at equal intervals, so that the friction ring 106 is concentric with the rubbing surface 101. The fan-shaped long arc wall of the matching mass block 105 is connected to the inner ring wall of the friction ring 106, and the center of the fan-shaped short arc wall of the matching mass block 105 is oriented toward the center of the rubbing groove 102. The matching mass block 105 and the corresponding elastic beam 104 are located in the same radial direction of the friction ring 106. Figure 7The rubbing end 201 on the simulated specimen 2 is a plate-shaped structure. During the rubbing test, after the simulated specimen 2 is embedded in the rubbing groove 102, it makes a linear displacement in the direction of the rubbing surface 101 until it collides with the matching mass block 105. At the same time, it can also generate friction with the inner ring wall of the friction ring 106. After the collision, the matching mass block 105 and the friction ring 106 produce a small displacement and recover under the action of the elastic beam 104, thereby realizing the simulation of both rubbing and friction tests in the external scraping rubbing.

[0066] refer to Figure 11 , is a friction member 1 that simulates internal extrusion with both rubbing and friction. In this embodiment, the friction member 1 is a disc-shaped structure, with drive shafts 3 connected to the motor drive end disposed at the axial centers of both ends of the friction member 1. The friction surface 101 is the side wall of the friction member 1. There are four elastic beams 104 and four matching masses 105, each of which is a fan-shaped columnar structure with the same curvature as the friction surface 101 and the friction ring 106. The leading ends of the four elastic beams 104 are connected to the friction surface 101 at equal intervals, and the trailing ends are all located on the radial extension line of the friction member 1 and connected to the inner ring wall of the friction ring 106 at equal intervals. The short fan-shaped arc wall of the matching mass 105 is connected to the outer ring wall of the friction ring 106, and the center of the long fan-shaped arc wall of the matching mass 105 is located on the radial extension line of the friction member 1. The matching mass 105 and the corresponding elastic beam 104 are located in the same radial direction of the friction ring 106. refer to Figure 7 The rubbing end 201 on the simulated specimen 2 is a plate-shaped structure, and the rubbing end 201 and the axis of the rubbing member 1 are located in the same plane. During the rubbing test, the rubbing end 201 on the simulated specimen 2 makes a linear displacement toward the rubbing surface 101 until it collides with the matching mass block 105. At the same time, it can also generate friction with the outer ring wall of the friction ring 106. After the collision, the matching mass block 105 and the friction ring 106 produce a small displacement and recover under the action of the elastic beam 104, thereby realizing the simulation of both rubbing and friction tests in the internal extrusion rubbing.

[0067] Taking titanium alloy materials as an example, the data characteristics of real-time data processing of working condition simulation and "titanium fire" early warning are further explained below.

[0068] First, in simulations, a database for the smoothness of friction-driven motors was established. By real-time monitoring of the three-phase motor's input voltage and current, the three-phase voltage and current imbalances, as well as the motor's input power, were determined. The motor's speed smoothness (or vibration intensity) was derived from the three-phase voltage and current imbalances. The motor's electric-to-electrical conversion efficiency was then derived from the input power and output data from the motor torque sensor, establishing an application database for the drive motors.

[0069] When the rubbing part and the simulated specimen rub, the simulated specimen acts as a "mechanical brake" on the rubbing part, causing the output of the rubbing torque sensor to change. In the non-rubbing state, the difference between the outputs of the three-phase motor's output torque sensor and the rubbing torque sensor is the effect of the coupling between the three-phase motor and the rubbing part. In the rubbing state, the difference between the outputs of the three-phase motor's output torque sensor and the rubbing torque sensor is the sum of the effect of the coupling and the effect transmitted to the simulated specimen. Because the simulated specimen is mounted on a triaxial load sensor, the load during the rubbing process is read by the triaxial load sensor, allowing the establishment of an application database related to torque, torque difference, rubbing load, and rubbing conditions during the rubbing process.

[0070] In addition, a database of the relationship between the mechanical performance parameters of the simulated specimens and the temperature is established. During the rubbing process, due to the increase in the specimen temperature and the effect of the load rate (strain rate), the stress-strain relationship of the simulated specimen will change (at this time, the strain remains unchanged, but the stress changes). The output data of the triaxial load sensor and the output data of the temperature sensor are identified and processed to obtain a database of the relationship between the mechanical performance parameters of the simulated specimens and the temperature and load rate (strain rate).

[0071] The modal identification process of the rubbing process is as follows: the real-time temperature of the rubbing end of the simulated specimen and the three-dimensional force parameters of the triaxial load sensor are collected in real time, and the rubbing modal parameters m are obtained through data processing. s (Temperature rise rate / strain rate of the simulated specimen), which can provide rough indicators for test progress indication and early warning.

[0072] In this embodiment, the combustion threshold value is obtained by real-time detection of test parameters (such as friction load, rotation speed, temperature, pressure, etc.), and querying the database to obtain the physical properties of the simulated specimen under the test conditions (such as heat transfer coefficient, thermal conductivity, density, elastic modulus, etc.). The real-time value of the combustion threshold value under the test condition is calculated according to the "combustion threshold value" model. When the combustion threshold value is greater than the critical value, it indicates that the "titanium fire" danger zone has been entered;

[0073] The identification process of the occurrence of "titanium fire" is: through real-time calculation of the combustion threshold value, when the combustion threshold value is greater than the critical value, the test process will enter the "titanium fire" danger zone; or the temperature gradient of the friction surface in the real-time collected data is greater than the critical value; or there are titanium combustion spectrum characteristics in the real-time collected data, the test system alarm enters the formation of "titanium fire" and starts fire extinguishing.

[0074] The calculation of the combustion threshold value is further explained below with reference to examples.

[0075] From the energy conservation equation of the rub-impact specimen 2, we can obtain:

[0076]

[0077] Where:

[0078] is the temperature rise rate of the simulated specimen rubbing test area, where:

[0079] m is the characteristic mass of the rubbing test area of ​​the simulated specimen, which is determined by the size of the test area. p is the specific heat of the simulated specimen material, which is obtained from the material physical parameters; T is the temperature of the simulated specimen friction test area, which is measured during the test process, and t is the test time. To simulate the temperature increase rate of the specimen rubbing test area, it can be calculated from the measured data.

[0080] λ is the thermal conductivity of the simulated specimen material, which is obtained from the material physical parameters. Taking TC4 material as an example, the relationship between its specific heat, thermal conductivity and temperature is:

[0081]

[0082]

[0083] To simulate the chemical reaction heat in the specimen rubbing test area, where:

[0084] ρ is the density of the simulated specimen material at the test temperature, which is corrected by the density ρ0 of the simulated specimen material under standard test conditions. The process is as follows:

[0085] ρ=ρ0*(1-γ m (T-T0))

[0086] In the formula, ρ0 is obtained from the material properties, such as ρ0 = 4500kg / m for a titanium alloy material. 3 ; γ m is the volume expansion coefficient of the material, which can be found from the material physical parameters, such as γ m =60*10 -6 ; T0 is the temperature value of standard test conditions.

[0087] q is the reaction heat per unit mass of the simulated specimen material, which is obtained from the material physical parameters. For example, for a titanium alloy, q = 24.7 MJ / kg. S is the reaction surface area of ​​the simulated specimen's rubbing test area, which is determined by the simulated specimen's shape, size, density, and characteristic mass. To simulate the reaction consumption rate of the specimen surface thickness, it is calculated by the Arrhenius formula as follows:

[0088]

[0089] Where K is the pre-exponential factor, which is obtained from the material properties. For example, for a titanium alloy material, K = 0.15 (kg / (m 2*s));

[0090] n O2 is the volume concentration of oxygen in the test environment, generally taken as 21%; h is the thickness of the surface reaction zone in the simulated specimen friction area; E is the activation energy of the chemical reaction, which can be obtained from the material physical properties, such as E = 190 / mol for a certain titanium alloy material; R is the gas constant, R = 8.314 (J / (mol*K)).

[0091] (α*T+β)F N *ω*R is the rubbing friction power, where:

[0092] α and β are the dynamic friction temperature correction coefficients, which can be obtained by looking up the table or by the engineering experience formula; F N is the contact normal stress of the rubbing pair, which can be measured during the test; ω and R are the rotation angular velocity and rotation radius of the rubbing rotor.

[0093] is the heat dissipation loss in the rubbing area of ​​the simulated specimen, where:

[0094] N u is the Nusselt number, which is determined by the Reynolds number and Prandtl number of the airflow in the rubbing test area according to the flow morphology; r is the surface characteristic size of the rubbing area of ​​the simulated specimen, which is determined by the test conditions.

[0095] In the calculation process of the combustion threshold value, or The initial value of the reference benchmark, the combustion threshold sensitivity coefficient is taken as 1.5 (determined by the test conditions), and and The curve changes with time and the inflection point appears suddenly. The ratio of the real-time value to the initial value is greater than the sensitivity coefficient (such as 1.5) and and When a sudden inflection point appears in the curve that changes with time, the current test parameters (including airflow pressure, temperature, friction rotor friction linear velocity, friction power and other combined parameters) are the current real-time combustion threshold values.

[0096] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for aerospace engine metal combustion test based on dynamic monitoring of combustion threshold value, characterized in that: The friction pair of a characteristic component of an aerospace engine is simulated by using a friction piece, and the characteristic component of an aerospace engine is simulated by using a simulated test piece. The test method includes the following steps: Step 1: Setting a ring-shaped friction structure on the friction member; Step 2: driving the friction member to rotate so that the friction structure rotates at high speed around its own axis; Step 3: driving the simulated specimen to perform linear displacement toward the rubbing structure, so that the rubbing structure and the rubbing end on the simulated specimen achieve rubbing strength simulation, and starting a timer; Step 4: During the rubbing process between the rubbing structure and the simulated specimen, the test parameters and the rubbing load at the rubbing end of the simulated specimen are measured in real time; Step 5: Based on the test parameters and the friction load, the combustion threshold value is calculated in real time to predict the test trend, and the time signal of the timer is detected. The test is terminated when the calculated combustion threshold value is greater than the critical value or the time signal of the detection timer is greater than the preset time; by and The curve changes with time and the inflection point appears suddenly. 、 The ratio of the real-time value to the initial value is greater than the sensitivity coefficient and and When the curve changes with time, a sudden inflection point appears. The combined parameters of the current airflow pressure, temperature, friction rotor linear velocity, and friction power are the current real-time combustion threshold value. is the temperature increase rate of the simulated specimen rubbing test area, To simulate the surface thickness reaction consumption rate of the specimen, the rubbing friction power is , α and β are dynamic friction temperature correction coefficients, is the normal contact stress of the rubbing pair, are the angular velocity and rotation radius of the rubbing rotor.

2. The aerospace engine metal combustion test method based on dynamic monitoring of combustion threshold value according to claim 1 is characterized in that: In step 3, the rubbing strength simulation between the rubbing structure and the rubbing end on the simulated specimen is realized by: The rubbing structure and the simulated specimen are caused to rub against each other until the rubbing power density is equivalent to the actual rubbing power density of the characteristic components under the operating conditions of the aerospace engine.

3. The aerospace engine metal combustion test method based on dynamic monitoring of combustion threshold value according to claim 1 is characterized in that: In step 4, during the rubbing process between the rubbing structure and the simulated specimen, the rubbing end of the simulated specimen is monitored in real time by the ignition sensor and the temperature sensor; When the rate of change of the output signals of the ignition sensor and the temperature sensor exceeds the set value, a high-speed photography operation is performed on the rubbing end of the simulated specimen.

4. The aerospace engine metal combustion test method based on dynamic monitoring of combustion threshold value according to claim 3 is characterized in that: In step 5, when the real-time calculated combustion threshold value is less than the critical value and the time signal of the timer is less than the preset time, the output signals of the ignition sensor and the temperature sensor are detected to determine whether the rubbing end of the simulated specimen has reached the ignition state. If so, the test is terminated; otherwise, the test is terminated until the real-time calculated combustion threshold value is greater than the critical value or the time signal of the timer is greater than the preset time.

5. The aerospace engine metal combustion test method based on dynamic monitoring of combustion threshold value according to any one of claims 1 to 4, characterized in that: In step 3, the friction simulation includes external scraping simulation and internal squeezing simulation; When the rubbing simulation is an external scraping simulation, the simulated specimen is driven to perform a linear displacement toward the inner ring rubbing surface of the rubbing structure; When the rubbing simulation is an internal extrusion simulation, the simulation specimen is driven to perform linear displacement toward the outer ring rubbing surface of the rubbing structure.

6. The aerospace engine metal combustion test method based on dynamic monitoring of combustion threshold value according to any one of claims 1 to 4, characterized in that: In step 3, the rubbing structure and the simulated specimen are subjected to rubbing simulation, specifically: This causes friction, collision, or friction + collision to occur between the rubbing structure and the simulated specimen.

7. The aerospace engine metal combustion test method based on dynamic monitoring of combustion threshold value according to claim 6 is characterized in that: When the collision between the rubbing structure and the simulated specimen is simulated as friction, the rubbing structure includes a rubbing surface of an annular structure.

8. The aerospace engine metal combustion test method based on dynamic monitoring of combustion threshold value according to claim 6 is characterized in that: When the collision between the rubbing structure and the simulated specimen is simulated as a collision, the rubbing structure includes a rubbing surface of an annular structure, a plurality of elastic beams and a matching mass block; The elastic beams correspond to the matching mass blocks one by one, the head ends of the elastic beams are connected to the friction surface at equal intervals, and the tail ends are all facing the center of the friction surface. The matching mass blocks are arranged at the tail ends of the corresponding elastic beams.

9. The aerospace engine metal combustion test method based on dynamic monitoring of combustion threshold value according to claim 6 is characterized in that: When the collision between the rubbing structure and the simulated specimen is simulated as friction + collision, the rubbing structure includes a rubbing surface of an annular structure, a friction ring, a plurality of elastic beams and a matching mass block; The friction ring is arranged inside the friction surface and is concentric with the friction surface. The head ends of the elastic beams are connected to the friction surface at equal intervals. The tail ends of the elastic beams are connected to an annular wall surface of the friction ring at equal intervals. The elastic beams correspond to the matching mass blocks one by one, and the matching mass blocks are connected to the other annular wall surface of the friction ring at equal intervals. The matching mass blocks and the corresponding elastic beams are located in the same radial direction of the friction ring.

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