Direct connection type stamping experiment table engine thrust calibration and measurement device and calibration and measurement method

Abstract

The invention provides a direct connection type stamping experiment table engine thrust calibration and measurement device and a calibration and measurement method. A pre-tightening device and a calibration device each comprise a weight, a rope, a pulley, a force bearing pier, a standard force sensor, a dowel bar, a working force sensor and a force transmission frame. According to the direct connection type stamping experiment table thrust measurement and calibration device and method, the integrated bearing pier design is adopted, the in-situ calibration device and the pre-tightening device are combined into one, the in-situ calibration device is the pre-tightening device, and the thrust measurement device is simple in structure. In the in-situ calibration process and the engine test process, the installation mode of the thrust measurement device is the same, the in-situ calibration device does not need to be removed after in-situ calibration, further thrust measurement can be carried out only by adjusting the number of weights after in-situ calibration, and the use process is simple.

Description

Technical Field

[0001] This invention relates to the field of engine thrust testing technology, specifically to a direct-connection ramjet test bench engine thrust calibration and measurement device and calibration and measurement method. Background Technology

[0002] In recent years, hypersonic flight technology has become the main battleground for near-space competition among major spacefaring nations. Ramjet engines, due to their simple structure, low flight cost, and ability to achieve hypersonic cruise, have become a relatively ideal power source for hypersonic flight. Currently, researchers have conducted a series of studies on ramjet engines, among which engine testing based on a direct-drive ramjet engine test rig is the primary research method due to its high economic efficiency.

[0003] A typical ramjet engine thrust measurement device based on a direct-drive ramjet test bench is shown in the attached instruction manual. Figure 1 As shown, the entire system is divided into a top movable section (the moving frame of the test bench and the heater and engine mounted on it, etc.) and a bottom fixed section (the fixed frame of the test bench and the sensors, guide rails, and calibration devices mounted on it, etc.). The heater and engine are mounted on the moving frame of the test bench, and the entire system is aligned along the engine's axial direction (see attached diagram). Figure 1 The guide rail has a degree of freedom in the left and right directions; the force sensor, fixed on the bottom platform, has no degree of freedom. The position of the force sensor is relatively free; it can be on the same horizontal plane as the guide rail or on the extension line of the engine thrust line. Figure 1 In the technical solution, the force sensor is located on the horizontal plane of the guide rail. In the horizontal direction, the forces on the moving parts of the test bench include the thrust generated by the heater and engine, the traction force of the auxiliary equipment, the preload force, the friction force of the guide rail, and the support force provided by the force sensor (which interacts with the compressive force received by the force sensor).

[0004] The thrust curve during engine testing is as follows: Figure 2 As shown, at the start of the test, the heater first starts working to generate a high-enthalpy gas flow, which passes through the engine and moves backward ( Figure 1 (From center to right) discharge, the heater and engine as a whole generate forward ( Figure 1 The thrust from the center to the left is canceled out by the thrust sensor located at the bottom. The thrust measured by the thrust sensor is F1, which is called cold thrust. After the heater stabilizes, the engine starts to work, and the thrust is further increased. The thrust measured by the thrust sensor reaches F2, which is called hot thrust.

[0005] To ensure the measurement accuracy and response speed of the engine thrust measurement device, a preload must be applied to the test bench moving frame to eliminate any misalignment between the moving frame and the force sensor in the engine thrust direction (see attached diagram). Figure 1The preload (in the left-right direction) is applied. Preload is typically applied using preload bolts, weights, or springs. For example, tightening the preload bolt applies preload to the moving frame of the test bench, ensuring a tight fit with the force sensor. Adjusting the tightness of the preload bolt allows for adjustment of the preload magnitude. However, during testing, the preload bolt may loosen due to vibration and impact loads, thus altering the preload. In existing technologies, the preload application device and the calibration device are separate sets of equipment (e.g.,...). Figure 1 The device is calibrated by applying pre-tightening force through fastening bolts and then by using weights. Pre-tightening force must be applied before calibration, and the in-situ calibration device must be removed during testing. The device structure and usage process are relatively complex.

[0006] It can be seen that factors such as engine thrust, guide rail friction, and preload can cause changes in the force sensor reading. To accurately measure the engine thrust during the test, the thrust measuring device must be calibrated in situ before the test. Generally, weights or hydraulic loading devices can be used as the calibration force source. Taking weights as an example, during calibration, weights are sequentially hung. The weight of the weights, after passing through the pulley, is converted into a horizontal pulling force, causing the entire moving frame of the test bench to press against the force sensor to the left. The force sensor then displays a reading due to the force. The thrust generated by the heater and the engine also causes the entire moving frame of the test bench to press against the force sensor to the left. Essentially, the pulling force of the weights and the engine thrust have the same effect on the force sensor. Therefore, during calibration, the pulling force of the weights can be used to replace the engine thrust, mapping the pulling force of the weights to the reading of the force sensor. During the engine test, the engine generates thrust, and the magnitude of the engine thrust can be obtained by inversely mapping the reading of the force sensor at this time. It should be noted that in the existing technical solutions, the in-situ calibration process must be carried out after the preload is applied, and the in-situ calibration device must be removed at the start of the test.

[0007] Current measurement methods have the following significant drawbacks: the preload application device and the calibration device are two separate sets, resulting in a complex structure for the engine thrust measurement device. Before engine testing, the preload device must be adjusted and preload applied before in-situ calibration. After calibration, the calibration device must be completely disengaged before engine testing. Overall, the preload and calibration process before engine testing is also quite cumbersome. Preload can be applied via spring preload, preload bolt preload, or weight preload. After applying preload, factors such as engine vibration and impact loads during the test may cause changes in the preload, directly affecting the force sensor readings, leading to inaccurate engine thrust measurements, or even calibration failure. However, existing technologies struggle to monitor changes in preload in real time.

[0008] Therefore, developing a direct-connection stamping test bench thrust measurement technology that integrates a pre-tensioning device and a calibration device and has a simple operating procedure is an urgent technical problem to be solved. Summary of the Invention

[0009] The purpose of this invention is to provide a ramjet engine thrust measurement device based on a direct-connection ramjet test bench, and to provide an integrated preload / calibration device and corresponding calibration method, solving the problems of structural complexity and cumbersome usage procedures caused by the separation of the preload and calibration devices in existing technologies. Through the design of an integrated load-bearing pier, while ensuring a relatively simple overall structure, this device achieves real-time measurement of preload and can correct the thrust measurement results based on changes in preload.

[0010] Specifically, to solve the above-mentioned technical problems, the present invention provides a direct-connection stamping test bench engine thrust calibration and measurement device. The device includes a fixed frame, a pre-tightening device, a calibration device, a heater, and an engine connected to the heater outlet. The pre-tightening device and the calibration device each include weights, ropes, pulleys, a load-bearing block, a standard force sensor, a force transmission rod, a working force sensor, and a force transmission frame. The heater and the engine are horizontally slidably mounted on the top of the fixed frame. A load-bearing block is fixed on the top of the fixed frame near the heater, and a working force sensor is fixed on the load-bearing block near the heater. A force transmission frame is fixed on the side of the heater near the load-bearing block, and a force transmission rod is detachably installed at the center of the force transmission frame.

[0011] Furthermore, the force transmission rod slides back and forth along its length relative to the working force sensor, and a standard force sensor is installed on the side of the force transmission rod away from the working force sensor. The end of the standard force sensor away from the force transmission rod is connected to a weight via a rope. A pulley for supporting the rope is rotatably installed on one side of the load-bearing block. The weight of the weight can be converted into a horizontal pulling force through the pulley to pull the standard force sensor to one side. The horizontal section of the rope and the axis of the force transmission rod are both located on the thrust line of the engine.

[0012] Through the integrated load-bearing pier design, both pre-tightening force application and in-situ calibration are achieved by hanging weights. This integrates the pre-tightening and calibration devices. After the weights are hung, their gravity is converted into a horizontal pulling force by the pulley. This pulls the standard force sensor, which in turn pulls the subsequent force transmission rod, force transmission frame, heater, and engine to the left, compressing the working force sensor. The internal force conditions of the device during pre-tightening and in-situ calibration are as described above. The weights, steel cables, pulleys, integrated load-bearing pier, standard force sensor, force transmission rod, working force sensor, force transmission frame, and fastening bolts constitute both the pre-tightening device and the in-situ calibration device, serving a dual purpose in one unit. This results in higher structural integration and a more streamlined structure.

[0013] Furthermore, a slide rail is provided at the top of the fixed platform, and a ball bearing support on the slide rail supports the engine. The heater and the engine are slidably mounted above the slide rail.

[0014] Furthermore, the engine can also be mounted using a spring suspension system.

[0015] Furthermore, the slide rail is equipped with a lifting component for adjusting the height of the heater and the engine, so that the center lines of the heater and the engine coincide with the axis of the force transmission rod.

[0016] Furthermore, the force transmission frame includes several parallel support rods and connecting plates and mounting parts respectively fixed at both ends of the support rod length. The center of the connecting plate is provided with a mounting hole for accommodating one end of the force transmission rod to pass through, and one end of the force transmission rod passes through the mounting hole and is threaded with a fastening nut. The mounting part is used for fixed connection with the heater.

[0017] Furthermore, the load-bearing pier includes a first support portion and a second support portion vertically arranged on both sides of the top of the load-bearing pier, and the height of the second support portion is higher than the height of the first support portion. The second support portion is provided with a clearance hole to accommodate the force transmission rod. The pulley is installed on one side of the first support portion through a bracket.

[0018] Furthermore, triangular reinforcing ribs are provided on the inner sides of both the first and second support portions.

[0019] The present invention also provides a method for calibrating and measuring engine thrust using the engine thrust calibration and measurement device of the direct-drive ramjet test bench as described above, comprising the following steps: Step S1: Fix the heater and engine to one side of the force transmission frame, and slide the heater and engine to the fixed frame. The heater and engine are in a non-working state. Step S2: Hang a weight on the rope and set the readings of the standard force sensor and the working force sensor to zero. Step S3: Add a weight to the rope and record the increment F of the standard force sensor reading. 标准 and the reading increment F of the working force sensor 实际 ; Step S4: Repeat S3 until the reading F of the working force sensor (8) is reached. 实际 The functional relationship F is obtained when the range is above 40% of the sensor's measurement range and below the sensor's measurement range. 标准 =f(F 实际 This serves as the calibration result for this calibration process; Step S5: Unload the weights until only one weight remains on the rope, and then set the readings of the standard force sensor and the working force sensor to zero. Step S6: Repeat steps S2-S5 to verify the calibration result F. 标准 =f i (F 实际 This continues until the repeatability flag is successfully calibrated, where i is the number of repetitions, and all F values ​​obtained during the calibration process are used. 标准 and F 实际 Functional relationship fitted to data points F 标准 =f 标定 (F 实际 This will be used as the final calibration result; Step S7: Hang some weights on the steel cable to provide preload, and measure the engine thrust after setting the readings of the standard force sensor and the working force sensor to zero; Step S8: With the heater or engine in operation, thrust measurement is performed, and the reading F of the working force sensor is recorded. 实际 The magnitude of the thrust can be calculated by substituting the obtained function relationship into the calibration.

[0020] Furthermore, the good repeatability criterion in step S6 is: the calibration results obtained after at least three calibrations. F 标准= f 标定( F 实际) At each sampling point, the absolute value of the error is less than 20N or the relative error is less than 5%.

[0021] Furthermore, the formula for calculating the thrust in step S8 is F. 推力 =f(F 实际 )-ΔF 预紧 ;where ΔF 预紧 This refers to the change in the reading of the standard force sensor during the thrust measurement process after the readings of the standard force sensor and the working force sensor are zeroed in step S7. This is due to the magnitude of the preload F. 预紧 It is measured in real time using a standard force sensor, and the change in preload ΔF during the test is caused by factors such as vibration. 预紧 It can be used to correct the magnitude of thrust.

[0022] Preload is applied using weights, and the standard force sensor is not removed during the test. The preload is measured in real time using the standard force sensor to obtain the change in preload ΔF. 预紧 According to the in-situ calibration result F 推力 =f(F 实际 The change in preload ΔF 预紧 It can be accessed via F 推力 =f(F 实际 )-ΔF 预紧 For the thrust measurement value F 推力 The corrections made the thrust measurement results more reliable and accurate.

[0023] Compared with the prior art, the beneficial effects of the present invention are: 1. The thrust measurement and calibration device and method for this direct-connection stamping test bench adopts an integrated load-bearing pier design, combining the in-situ calibration device and the pre-tightening device into one unit; the in-situ calibration device is also the pre-tightening device, resulting in a simplified thrust measurement device structure. The in-situ calibration process is the same as the thrust measurement device installation method during engine testing, eliminating the need to remove the in-situ calibration device after calibration. After in-situ calibration, only the number of weights needs to be adjusted for further thrust measurement, making the process simple.

[0024] 2. The standard force sensor is not removed during the engine test. The standard force sensor can be used to measure the preload in real time, and the thrust data can be corrected by the change in preload, making the thrust measurement results more reliable and accurate. Attached Figure Description

[0025] Figure 1 This refers to the existing technology of a ramjet engine thrust measurement device based on a direct-drive ramjet test bench. Figure 1 ; Figure 2 The thrust curve of the ramjet engine thrust measurement device during the engine test process of the existing direct-connection ramjet test bench; Figure 3 This is a schematic diagram of the structure of the present invention; Figure 4 This is a schematic cross-sectional view of the load-bearing pier of the present invention; Figure 5 This is a schematic diagram of the three-dimensional structure of the force transmission frame of the present invention; Figure 6 This is a repeatability verification curve from step S6 in Example 2; In the diagram: 1. Fixed platform; 2. Weight; 3. Rope; 4. Pulley; 5. Load-bearing block; 501. First support part; 502. Second support part; 5021. Clearance hole; 503. Reinforcing rib; 6. Standard force sensor; 7. Force transmission rod; 8. Working force sensor; 9. Force transmission frame; 901. Support rod; 902. Connecting plate; 9021. Mounting hole; 903. Mounting part; 10. Fastening nut; 11. Heater; 12. Engine; 13. Slide rail; 14. Lifting component. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. In this description, it should be noted that the terms "first," "second," etc., are used for descriptive purposes only and do not specifically refer to any order or sequence, nor are they intended to limit the present invention. They are merely used to distinguish components or operations described using the same technical terms, and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. The term "comprising" and any variations thereof in the specification, claims, and accompanying drawings are intended to cover non-exclusive inclusion.

[0027] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances. Furthermore, in the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0028] Example 1 This embodiment provides a direct-connection stamping test bench calibration and thrust measurement device. Please refer to [link to relevant documentation]. Figure 3-5 The device includes a fixed platform 1, a pre-tightening device, a calibration device, a heater 11, and an engine 12 connected to the outlet of the heater 11. The pre-tightening device and the calibration device each include a weight 2, a rope 3, a pulley 4, a load-bearing block 5, a standard force sensor 6, a force transmission rod 7, a working force sensor 8, and a force transmission frame 9. The heater 11 and the engine 12 are horizontally slidably mounted on the top of the fixed platform 1. A load-bearing block 5 is fixed on the top of the fixed platform 1 near the heater 11, and a working force sensor 8 is fixed on the side of the load-bearing block 5 near the heater 11. A force transmission frame 9 is fixed on the side of the heater 11 near the load-bearing block 5, and a force transmission rod 7 is detachably installed at the center of the force transmission frame 9.

[0029] refer to Figure 5The force transmission frame 9 includes four parallel support rods 901, connecting plates 902 and mounting parts 903 respectively fixed at both ends of the support rods 901. The four support rods 901 are fixed in a circular array at one end of the connecting plate 902. The center of the connecting plate 902 is provided with a mounting hole 9021 for one end of the force transmission rod 7 to pass through. One end of the force transmission rod 7 passes through the mounting hole 9021 and is threadedly connected to a fastening nut 10. One end of the force transmission rod 7 is provided with a positioning section that matches the mounting hole 9021. The size of the positioning section is smaller than the size of the force transmission rod 7. After the positioning section passes through the mounting hole 9021, it is rotated and fixed with the fastening nut 10, so that the force transmission rod 7 can be fixed to the connecting plate 902. The mounting part 903 specifically includes a ring connecting the four support rods 901 and four mounting blocks fixed at the edge of the ring. Each mounting block is provided with a through hole, which can be fixedly connected to the heater 11 by bolts.

[0030] The force transmission rod 7 can slide back and forth along its length relative to the working force sensor 8, and a standard force sensor 6 is installed on the side of the force transmission rod 7 that extends away from the force transmission frame 9. Specifically, the standard force sensor 6 has a measurement accuracy of not less than 0.5%FS and a range of not less than 2000N, while the working force sensor 8 has a measurement accuracy of not less than 1%FS and a range of not less than 2000N. It must be ensured that the standard force sensor 6 has a higher measurement accuracy and the same or wider range than the working force sensor 8.

[0031] The end of the standard force sensor 6 away from the force transmission rod 7 is connected to a weight 2 via a rope 3. A pulley 4 is rotatably installed on one side of the support block 5 to support the rope 3. The gravity of the weight 2 can be converted into a horizontal pulling force through the pulley 4 to pull the standard force sensor 6 to one side. The standard force sensor 6 can detect the change of preload in real time during the thrust detection process and is used to correct the magnitude of the thrust. The horizontal section of the rope 3 and the axis of the force transmission rod 7 are both located on the thrust line of the engine 12, that is, the horizontal section of the rope 3 and the axis of the force transmission rod 7 coincide with the center line of the heater 11 and the engine 12. During preload, the weight 2 pulls the force transmission rod 7, causing one end of the force transmission rod 7 to abut against the working force sensor 8. During detection, the thrust generated by the heater 11 and the engine 12 pushes the force transmission rod 7 to abut against the working force sensor 8.

[0032] refer to Figure 4The load-bearing pier 5 includes a first support part 501 and a second support part 502 vertically arranged on both sides of the top of the load-bearing pier 5. The height of the second support part 502 is higher than that of the first support part 501. The second support part 502 is provided with a clearance hole 5021 to accommodate the force transmission rod 7. The standard force sensor 6 and the working force sensor 8 are respectively located on both sides of the second support part 502. The second support part 502 is a steel plate with a thickness of not less than 30mm to ensure structural rigidity and strength. The smallest cross-sectional diameter of the force transmission rod 7 is not less than 12mm. The pulley 4 is installed on one side of the first support part 501 through a bracket.

[0033] In this embodiment, in order to improve the strength of the load-bearing pier 5, triangular reinforcing ribs 503 are provided on the inner sides of both the first support part 501 and the second support part 502.

[0034] In this embodiment, a slide rail 13 is provided at the top of the fixed platform 1. The heater 11 and the engine 12 are slidably mounted on the slide rail 13. A lifting component 14 is provided on the slide rail 13 to adjust the height of the heater 11 and the engine 12. The lifting component 14 can be any kind of threaded rod, electric push rod, etc. Its bottom end is slidably connected to the slide rail 13. By lifting it, the height of the heater 11 and the engine 12 is adjusted so that the axis of the heater 11 and the engine 12 coincides with the axis of the force transmission rod 7.

[0035] Example 2 This embodiment provides a method for thrust measurement and calibration using the direct-connection stamping test bench calibration and thrust measurement device described in Embodiment 1, including the following steps: Step S1: Fix the heater 11 and the engine 12 to one side of the force transmission frame 9, and slide the heater 11 and the engine 12 to the fixed frame 1. The heater 11 and the engine 12 are in a non-working state. Step S2: Hang a weight 2 on the rope 3 and set the readings of the standard force sensor 6 and the working force sensor 8 to zero. Step S3: Add a weight 2 to the rope 3 and record the increment F of the reading of the standard force sensor 6. 标准 and the reading increment F of the working force sensor 8 实际 ; Step S4: Repeat S3 until the reading F of the working force sensor (8) is reached. 实际 The thrust value exceeds the potential thrust value during subsequent experiments but is below the sensor's range, thus obtaining the functional relationship F. 标准 =f(F 实际 This serves as the calibration result for this calibration process; Step S5: Unload weight 2 until only one weight 2 remains on the rope 3, and set the readings of the standard force sensor 6 and the working force sensor 8 to zero at this time; Step S6: Repeat steps S2-S5 to verify the calibration result F. 标准= f i( F 实际) This continues until the repeatability flag is successfully calibrated, where i is the number of repetitions, and all F values ​​obtained during the calibration process are used. 标准 and F 实际 Functional relationship fitted to data points F 标准 =f 标定 (F 实际 This will be used as the final calibration result; Step S7: Hang some weights on the steel cable to provide preload, and measure the engine thrust after setting the readings of the standard force sensor 6 and the working force sensor 8 to zero; Step S8: With heater 11 or engine 12 in operation, thrust measurement is performed, and the reading F of working force sensor 8 is used. 实际 By substituting the function relationship obtained from the calibration, the magnitude of the thrust can be calculated. The formula for calculating the thrust is: F 推力 =f(F 实际 )-ΔF 预紧 ;where ΔF 预紧 The change in the reading of the standard force sensor 6 during the thrust measurement process after the readings of the standard force sensor 6 and the working force sensor 8 are set to zero in step S7.

[0036] The data involved in steps S2-S6 are shown in Table 1 and Figure 6 As shown. Figure 6 The results show that at each sampling point, the absolute thrust error is less than 20N or the relative error is less than 5%. That is, in actual use, the reading F of the working force sensor (8) is within acceptable limits. 实际 According to the final calibration result F 标准 =f 标定 (F 实际 The back-calculated thrust has a low error, and the thrust measurement results have good repeatability.

[0037] Table 1. Test data and calibration results of the four calibration processes.

[0038] *: The number of weights in the table is the number of weights added after the sensor reading is set to zero in step S2. N is the unit Newton.

[0039] The F obtained during the first calibration process 实际 and F 标准 The values ​​are fitted in Excel to obtain F. 标准 =1.0025F 实际 +2.0179, R 2=0.9997; The F obtained during the second calibration process 实际 and F 标准 The values ​​are fitted in Excel to obtain F. 标准 =1.0375F 实际 +15.26, R 2 =0.9993; The F obtained during the third calibration process 实际 and F 标准 The values ​​are fitted in Excel to obtain F. 标准 =1.012F 实际 +2.959, R 2 =1; The F obtained during the fourth calibration process 实际 and F 标准 The values ​​are fitted in Excel to obtain F. 标准 =1.0472F 实际 +12.286, R 2 =0.9997; All F values ​​measured during the first, second, third, and fourth calibration processes. 实际 and F 标准 The values ​​are fitted in Excel to obtain F. 标准 =1.0243F 实际 +8.5129, R 2 =0.9974; Figure 6 The calculation method for absolute and relative errors is as follows: using the calibration results Fstandard = fi(Factual) and the final calibration result Fstandard = fcalibration(Factual) obtained from each calibration process, the back-calculated thrust at each sampling point is calculated. Let Fstandard,i be the back-calculated thrust obtained according to Fstandard = fi(Factual), and Fstandard,final be the back-calculated thrust obtained according to Fstandard = fcalibration(Factual). The absolute error at a certain sampling point is the sum of the maximum absolute value of the difference between Fstandard,i and Fstandard,final at that sampling point and the sensor measurement error. The relative error is the percentage of the absolute error to the total absolute error. 标准，终 The ratio. In this example, the sensor measurement error is 1.96N, and the calculation results of the absolute error and relative error are shown in Table 2: Table 2 Calculation results of absolute and relative errors

[0040] During an engine test, at time 12.5s, ΔF 预紧 =16.3N, F 实际=406.6N, therefore, the thrust F after preload correction is... 推力 =1.0243×406.6+8.5129-16.3=408.7N, F without preload correction 推力 =1.0243×406.6+8.5129=425.0N, F before and after correction 推力 The difference is approximately 3.8%, after correction F 推力 More precise. In this embodiment, a preload is applied by hanging a weight, which serves as the standard force source during the calibration process. Alternatively, a hydraulic servo force source or a spring can be used as the force source.

[0041] In summary, this invention provides an integrated pre-tensioning / calibration device and corresponding calibration method, solving the problems of structural complexity and cumbersome usage procedures caused by the separation of pre-tensioning and calibration devices in existing technologies. Through the integrated load-bearing pier design, while ensuring a relatively simple overall structure, this device achieves real-time measurement of pre-tensioning force and can correct the thrust measurement results based on changes in pre-tensioning force.

[0042] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A direct-drive ramjet test bench engine thrust calibration and measurement device, characterized in that: The device includes a fixed frame (1), a pre-tightening device, a calibration device, a heater (11), and an engine (12) connected to the outlet of the heater (11). The pre-tightening device and the calibration device each include a weight (2), a rope (3), a pulley (4), a load-bearing block (5), a standard force sensor (6), a force transmission rod (7), a working force sensor (8), and a force transmission frame (9). The heater (11) and the engine (12) are horizontally slidably mounted on the top of the fixed frame (1). A load-bearing block (5) is fixed on the top of the fixed frame (1) near the heater (11), and a working force sensor (8) is fixed on the side of the load-bearing block (5) near the heater (11). A force transmission frame (9) is fixed on the side of the heater (11) near the load-bearing block (5), and a force transmission rod (7) is detachably installed at the center of the force transmission frame (9).

2. The direct-drive ramjet test bench engine thrust calibration and measurement device according to claim 1, characterized in that: The force transmission rod (7) slides back and forth along its length relative to the working force sensor (8), and a standard force sensor (6) is installed on the side of the force transmission rod (7) away from the force transmission frame (9). The end of the standard force sensor (6) away from the force transmission rod (7) is connected to a weight (2) through a rope (3). A pulley (4) for supporting the rope (3) is rotatably installed on one side of the bearing block (5). The weight (2) can be converted into a horizontal pulling force through the pulley (4) to pull the standard force sensor (6) to one side. The horizontal section of the rope (3) and the axis of the force transmission rod (7) are both located on the thrust line of the engine (12).

3. The direct-drive ramjet test bench engine thrust calibration and measurement device according to claim 1, characterized in that: The top of the fixed frame (1) is provided with a slide rail (13), and the heater (11) and the engine (12) are slidably mounted above the slide rail (13).

4. The direct-drive ramjet test bench engine thrust calibration and measurement device according to claim 1, characterized in that: The slide rail (13) is equipped with a lifting component (14) to adjust the height of the heater (11) and the engine (12), so that the center lines of the heater (11) and the engine (12) coincide with the axis of the force transmission rod (7).

5. The direct-drive ramjet test bench engine thrust calibration and measurement device according to claim 1, characterized in that: The force transmission frame (9) includes several parallel support rods (901) and connecting plates (902) and mounting parts (903) fixed at both ends of the length of the support rods (901). The center of the connecting plate (902) is provided with a mounting hole (9021) for accommodating one end of the force transmission rod (7) to pass through. One end of the force transmission rod (7) passes through the mounting hole (9021) and is threaded with a fastening nut (10). The mounting part (903) is used to fix it to the heater (11).

6. The direct-drive ramjet test bench engine thrust calibration and measurement device according to claim 1, characterized in that: The load-bearing pier (5) includes a first support part (501) and a second support part (502) vertically arranged on both sides of the top of the load-bearing pier (5), and the height of the second support part (502) is higher than the height of the first support part (501). The second support part (502) is provided with a clearance hole (5021) for accommodating the force transmission rod (7) to pass through. The pulley (4) is installed on one side of the first support part (501) by a bracket.

7. The direct-drive ramjet test bench engine thrust calibration and measurement device according to claim 5, characterized in that: The inner sides of the first support part (501) and the second support part (502) are provided with triangular reinforcing ribs (503).

8. A method for calibrating and measuring engine thrust using the calibration measuring device according to any one of claims 1-7, characterized in that, Includes the following steps: Step S1: Fix the heater (11) and the engine (12) on one side of the force transmission frame (9), and slide the heater (11) and the engine (12) with the fixed frame (1). The heater (11) and the engine (12) are in a non-working state. Step S2: Hang a weight (2) on the rope (3) and set the readings of the standard force sensor (6) and the working force sensor (8) to zero; Step S3: Add a weight (2) to the rope (3) and record the increment F of the standard force sensor (6) at this time. 标准 The reading increment F of the working force sensor (8) 实际 ; Step S4: Repeat S3 until the reading F of the working force sensor (8) is reached. 实际 The functional relationship F is obtained when the range is above 40% of the sensor's measurement range and below the sensor's measurement range. 标准 =f(F 实际 This serves as the calibration result for this calibration process; Step S5: Unload the weight (2) until only one weight (2) remains on the rope (3), and set the readings of the standard force sensor (6) and the working force sensor (8) to zero at this time; Step S6: Repeat steps S2-S5 to verify the calibration result F. 标准 =f i (F 实际 This continues until the repeatability flag is successfully calibrated, where i is the number of repetitions, and all F values ​​obtained during the calibration process are used. 标准 and F 实际 Functional relationship fitted to data points F 标准 =f 标定 (F 实际 This will be used as the final calibration result; Step S7: Hang some weights on the steel cable to provide preload, and measure the engine thrust after setting the readings of the standard force sensor (6) and the working force sensor (8) to zero; Step S8: With the heater (11) or engine (12) in operation, thrust measurement is performed, and the reading F of the working force sensor (8) is used. 实际 The magnitude of the thrust can be calculated by substituting the obtained function relationship into the calibration.

9. The method according to claim 8, characterized in that, The good repeatability criterion in step S6 is: after at least three calibrations, the obtained calibration result F 标准= f 标定( F 实际) At each sampling point, the absolute value of the error is less than 20N or the relative error is less than 5%.

10. The method according to claim 8, characterized in that, The formula for calculating the thrust in step S8 is F. 推力 =f(F 实际 )-ΔF 预紧 ;where ΔF 预紧 The change in the reading of the standard force sensor (6) during the thrust measurement process after the readings of the standard force sensor (6) and the working force sensor (8) are set to zero in step S7.

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