Vertical position micro turbojet engine thrust measuring device

Abstract

The invention relates to a thrust measuring device for a vertical-position micro turbojet engine. The device is used for measuring the thrust when a micro turbojet engine with a vector nozzle is vertically mounted, and mainly comprises two parts, namely a static frame and a movable frame. The static frame is composed of adjustable horizontal bottom feet and a static support, and an installation flat plate is arranged on the top of the static frame. A rotating shaft is fixed on one side of the static frame mounting flat plate, and the movable frame can tilt around the rotating shaft. The engine is vertically installed on the sliding rail of the movable frame and connected with the tension and compression sensor. A pressure sensor is fixed to the position, opposite to the rotating shaft, of the static frame installation flat plate, and the movable frame is supported on the pressure sensor. Through the design, the weight of the movable frame is larger than the maximum thrust of the engine, and it is guaranteed that the movable frame does not tilt in the engine test process. The thrust in the vertical direction of the engine can be calculated according to the torque relation by using the pressure value measured by the pressure sensor. And the measured value of the tension and compression sensor is the horizontal thrust generated by the vector nozzle. The device is simple in structure, convenient to install and small in measurement error.

Description

Technical Field

[0001] The present invention belongs to a thrust measurement device for a micro turbojet engine and belongs to the field of micro turbojet engine testing. Technical Background

[0002] Micro turbojet engines can be used to provide power for aircraft such as model airplanes, fixed-wing unmanned aerial vehicles, and vertical takeoff and landing flight platforms. Their thrust is an important parameter characterizing the engine performance and needs to be measured through bench tests. Traditional thrust measurement devices for micro turbojet engines are for engines installed in the horizontal position, and there is no report in the open literature on thrust measurement devices for engines installed in the vertical position, which belongs to a technical blank field. Summary of the Invention

[0003] The present invention proposes a thrust measurement device for a vertical-position micro turbojet engine. Its purpose is to accurately measure the horizontal and vertical forces generated by the engine for a vertical-position micro turbojet engine equipped with a vector nozzle and obtain the input-output characteristics of the engine. This thrust measurement device meets the requirements of simple structure, strong reusability, convenient movement, and low cost.

[0004] Technical Solution of the Present Invention:

[0005] A thrust measurement device for a vertical-position micro turbojet engine, the structure of which includes two parts: a static frame and a moving frame. The static frame includes a base foot 1, a bracket 2, a static frame mounting flat plate 3, a bearing seat 6, a pressure sensor fixing sleeve 9, and a pressure sensor 8. The base foot 1 can be used to adjust the horizontal level of the static frame, making the static frame mounting flat plate 3 parallel to the horizontal plane, and further making the engine axis perpendicular to the horizontal plane; the bracket 2 is the support of the entire force measurement device and keeps the engine at a certain height from the ground to prevent the high-temperature exhaust gas generated by the engine from burning the ground; the static frame mounting flat plate 3 serves to fix the bearing seat 6 and the pressure sensor fixing sleeve 9. The pressure sensor fixing sleeve 9 is installed on the static frame mounting flat plate 3, opposite to the position of the rotating shaft 4, for fixing the pressure sensor 8; the pressure sensor 8 is installed on the top of the pressure sensor fixing sleeve 9, for measuring the vertical thrust generated by the micro turbojet engine 10. The moving frame is composed of a moving frame mounting flat plate 5, a rotating shaft 4, a shaft support seat 7, a tension and compression sensor mounting seat 17, a tension and compression sensor 16, a tension and compression sensor connecting piece 14, a fixing seat 13, a slider 15, a slide rail 12, and a force transmission rod 11. The rotating shaft 4 is fixed to the bearing seat 6; a shaft support seat 7 is installed below the moving frame mounting flat plate 5, and the shaft support seat 7 is fixedly connected to the rotating shaft 4, enabling the moving frame mounting plate to rotate around the rotating shaft 4; the tension and compression sensor mounting seat 17 is located above the moving frame mounting flat plate 5, for fixing one end of the tension and compression sensor 16; the tension and compression sensor connecting piece 14 is located between the tension and compression sensor 16 and the micro turbojet engine 10, serving to transmit the horizontal force; the micro turbojet engine 10 is installed on two fixing seats 13, and further fixedly connected to the slider 15 through the fixing seats 13, and can slide horizontally on the slide rail 12; the tension and compression sensor 16 is used to measure the horizontal thrust generated by the vector nozzle; the tension and compression sensor connecting piece 14 is connected to the two fixing seats 13, and the horizontal thrust generated by the micro turbojet engine 10 is sequentially transmitted to the tension and compression sensor 16 through the fixing seats 13 and the tension and compression sensor connecting piece 14; the force transmission rod 11 is on the side of the moving frame mounting flat plate 5 opposite to the rotating shaft 4, located above the pressure sensor 8, supporting the moving frame to keep it in a balanced state, and transmitting the pressure generated by the moving frame and the micro turbojet engine 10 to the pressure sensor 8. The weight of the moving frame of the thrust measurement device is greater than the maximum thrust of the engine, thus ensuring that the moving frame does not tilt during the engine test. During the operation of the engine, the magnitude of the vertical thrust of the engine is calculated based on the reading of the pressure sensor 8 and the relationship of the balance moment of the moving frame. And the magnitude of the horizontal force generated by the vector nozzle of the engine can be directly measured by using the tension and compression sensor 16.

[0006] Advantages of the present invention:

[0007] 1) It can be used for measuring the horizontal thrust and vertical thrust of a micro turbojet engine with a vector nozzle installed in the vertical position;

[0008] 2) It has strong reusability and is suitable for measuring the vertical thrust of various models of micro turbojet engines.

[0009] 3) Simple structure, easy to install, less space occupied, and low cost.

[0010] 4) The static frame can be adjusted horizontally, and the moving frame reduces the influence of friction through bearings and slide rails, with high measurement accuracy. Description of the Drawings

[0011] Appendix Figure 1 is the structural diagram of the vertical thrust measurement device for a micro turbojet engine.

[0012] Appendix Figure 2 is the top view of the upper part of the bracket.

[0013] Appendix Figure 3 is the right view of the upper part of the bracket.

[0014] Appendix Figure 4 is the rear view of the upper part of the bracket.

[0015] Appendix Figure 5 is the structural diagram of the upper part of the bracket.

[0016] Appendix Figure 6 is the vertical thrust calculation relationship diagram of the engine without installing the vector nozzle.

[0017] Appendix Figure 7 is the horizontal thrust measurement diagram.

[0018] Appendix Figure 8 is the vertical thrust calculation relationship diagram of the engine with the vector nozzle installed.

[0019] In the figure: 1, foot; 2, bracket; 3, static frame mounting plate; 4, rotating shaft; 5, moving frame mounting plate; 6, bearing seat; 7, shaft support seat; 8, pressure sensor; 9, pressure sensor fixing sleeve; 10, micro turbojet engine; 11, force transmission rod; 12, slide rail; 13, fixed seat; 14, tension and compression sensor connecting piece; 15, slider; 16, tension and compression sensor; 17, tension and compression sensor mounting seat. Specific Embodiments

[0020] Measure the vertical thrust of the engine without installing the vector nozzle:

[0021] As Figure 2 shown, represent the vertical thrust of the micro turbojet engine 10 as F, the total gravity of the moving frame (including the micro turbojet engine) as G, the pressure N measured by the pressure sensor, the horizontal distance from the engine axis to the axis of the rotating shaft 4 as L1, and the horizontal distance from the axis of the pressure sensor 8 to the axis of the rotating shaft 4 as L2. Let the correction coefficient According to the mechanical relationship, there is:

[0022] (G - F)·L1 = N·L2

[0023] Therefore,

[0024] Record the correction coefficient Then F = G - k·N

[0025] When F = 0, G = k·N

[0026] Considering that there will be errors when adjusting the level of the force measuring device, and the values of L1 and L2 are not easy to measure directly, a calibration experiment should be carried out before the experiment to measure the correction coefficient k and determine the ratio of L2 to L1. When conducting the calibration experiment, use a tensiometer to simulate the engine thrust, select n calibration points according to the actual situation. When conducting experiments at different calibration points, record the current tensiometer reading and the reading N of the pressure sensor 8. After completing the calibration experiment, fit a straight line regarding the reading N of the pressure sensor 8. The absolute value of the slope of this fitted straight line is the correction coefficient k. Then repeat the experiment m times and take the average of the k values obtained from different experiments i (i = 1, 2, 3,..., m), which is the accurate correction coefficient of this device Thus, when F = 0, read the reading N of the pressure sensor 8, and then G can be accurately obtained through simple conversion. Then conduct the vertical thrust measurement experiment of the engine. The vertical thrust of the engine can be calculated by the formula F = G - k·N

[0027] Measure the horizontal thrust generated by the vector nozzle:

[0028] The horizontal thrust generated by the engine vector nozzle is efficiently transmitted to the tension-compression sensor 16 through the slide rail 12 and the slider 15. The tension-compression sensor 16 exerts a reaction force F' on the engine through the fixed seat 13, 水平 which is equal in magnitude and opposite in direction to the horizontal thrust 水平 The reading of the tension-compression sensor 16 is the horizontal thrust F 水平 The measured value, and the force relationship is as 水平 shown. When the reading of the tension-compression sensor 16 is negative, it indicates that the acting force is a pressure, and the absolute value of this reading is the magnitude of the horizontal thrust F Figure 7 The direction of the horizontal thrust F is towards the direction of the tension-compression sensor 16; when the reading of the tension-compression sensor 16 is positive, it indicates that the acting force is a tension, and the absolute value of this reading is the magnitude of the horizontal thrust. The direction of the horizontal thrust is away from the direction of the tension-compression sensor 16 水平 of the horizontal thrust F 水平

[0029] Measure the vertical thrust of the engine with a vector nozzle installed:

[0030] As Figure 8 shown, compared with the measurement of the vertical thrust of the engine without a vector nozzle installed, the measurement of the vertical thrust of the engine with a vector nozzle installed will be affected by the horizontal thrust F generated by the vector nozzle 水平 ​and the reaction force F' generated by the tension and compression sensor 16 水平 Due to the influence of the couple force generated by the combined action, it is necessary to correct the data measured for the vertical thrust of the engine with the vector nozzle installed. In the vertical thrust measurement experiment of the engine without the vector nozzle installed, the correction coefficient k and the total gravity G of the moving frame (including the micro turbojet engine) are obtained. On this basis, the data measured for the vertical thrust of the engine with the vector nozzle installed is corrected.

[0031] Let the horizontal thrust couple generated by the vector nozzle be M, and the distance between the axis of rotation of the vector nozzle and the horizontal axis of the tension and compression sensor 16 be L3. According to the mechanical relationship, we have:

[0032] M = F 水平 ·L3

[0033] When the vector nozzle faces one end of the pressure sensor 8, the direction of the couple is opposite to the direction of the moment of the engine vertical thrust about the axis of rotation, and we get:

[0034] (G - F)·L1 + M = N·L2

[0035] So,

[0036] When the vector nozzle faces one end of the tension and compression sensor 16, the direction of the couple is the same as the direction of the moment of the engine vertical thrust about the axis of rotation, and we get:

[0037] (G - F)·L1 - M = N·L2

[0038] So,

Claims

1. A thrust measurement device for a vertical-position micro turbojet engine, characterized in that It consists of a static frame and a moving frame, and can measure the vertical thrust and horizontal thrust of a micro turbojet engine with a vector nozzle when it is in the vertical position.

2. The thrust measurement device for a vertical micro turbojet engine according to claim 1, characterized in that The static frame part includes feet 1, a bracket 2, a static frame mounting flat plate 3, a bearing seat 6, a pressure sensor fixing sleeve 9, and a pressure sensor 8. The feet 1 can be used to adjust the horizontal level of the static frame to make the static frame mounting flat plate 3 parallel to the horizontal plane, so that the engine axis is perpendicular to the horizontal plane; the bracket 2 is the support of the entire thrust measuring device and keeps the engine at a certain height from the ground to prevent the high-temperature exhaust gas generated by the engine from burning the ground; the static frame mounting flat plate 3 serves to fix the bearing seat 6 and the pressure sensor fixing sleeve 9. The pressure sensor fixing sleeve 9 is installed on the static frame mounting flat plate 3 at a position opposite to the rotating shaft 4 for fixing the pressure sensor 8; the pressure sensor 8 is installed on the top of the pressure sensor fixing sleeve 9 for measuring the vertical thrust generated by the micro turbojet engine 10.

3. The thrust measuring device for a vertical-position micro turbojet engine according to claim 1, characterized in that The moving frame part includes a moving frame mounting flat plate 5, a rotating shaft 4, a shaft support seat 7, a tension and compression sensor mounting seat 17, a tension and compression sensor 16, a tension and compression sensor connecting piece 14, a fixing seat 13, a slider 15, a slide rail 12, and a force transmission rod 11. The rotating shaft 4 is fixed to the bearing seat 6; the shaft support seat 7 is installed below the moving frame mounting flat plate 5 and is fixedly connected to the rotating shaft 4, enabling the moving frame mounting plate to rotate around the rotating shaft 4; the tension and compression sensor mounting seat 17 is located above the moving frame mounting flat plate 5 for positioning the tension and compression sensor 17; the tension and compression sensor connecting plate 14 is located between the tension and compression sensor 16 and the micro turbojet engine 10 and serves to transmit the horizontal force; the micro turbojet engine 10 is installed on two fixing seats 13 and is further fixedly connected to the slider 15 through the fixing seats 13 and can slide horizontally on the slide rail 12: the tension and compression sensor 16 is used to measure the horizontal thrust generated by the vector nozzle; the tension and compression sensor connecting piece 14 is connected to the two fixing seats 13, and the horizontal thrust generated by the micro turbojet engine 10 is sequentially transmitted to the tension and compression sensor 16 through the fixing seats 13 and the tension and compression sensor connecting piece 14; the force transmission rod 11 is on one side of the moving frame mounting flat plate 5 opposite to the rotating shaft 4 and above the pressure sensor 8, supports the moving frame to keep it in a balanced state, and transmits the pressure generated by the moving frame and the micro turbojet engine 10 to the pressure sensor 8.

4. A thrust measurement device for a vertical micro turbojet engine according to claim 1, characterized in that The measuring principle is as follows: the weight of the moving frame of the thrust measuring device is greater than the maximum thrust of the engine, so as to ensure that the moving frame does not tilt during the engine test. During the operation of the engine, the magnitude of the vertical thrust of the engine is calculated based on the reading of the pressure sensor 8 and the relationship of the balance moment of the moving frame. And the magnitude of the horizontal force generated by the vector nozzle of the engine can be directly measured by using the tension and compression sensor 16.

5. A vertical position micro turbojet engine thrust measuring device according to claim 1, and its usage method includes the following steps: 1) Measure the vertical thrust of the engine without installing the vector nozzle: First, conduct a calibration experiment to determine the ratio of the horizontal distance from the axis of the pressure sensor 8 to the axis of the rotating shaft 4 to the horizontal distance from the axis of the engine to the axis of the rotating shaft 4. When conducting the calibration experiment, use a tensiometer to simulate the engine thrust. Select multiple calibration points according to the actual situation. When conducting experiments at different calibration points, record the current readings of the tensiometer and the pressure sensor 8. After completing the calibration experiment, fit a straight line of the tensiometer reading with respect to the reading of the pressure sensor 8. The absolute value of the slope of this fitted straight line is the correction coefficient. Repeat the experiment multiple times and calculate the average value of the correction coefficients measured in these experiments for subsequent thrust measurement. When the vertical thrust of the micro turbojet engine 10 is 0, read the reading of the pressure sensor 8, and then multiply the reading of the pressure sensor 8 by the correction coefficient. The result is the total gravity of the moving frame (including the micro turbojet engine). Then, conduct the measurement of the engine vertical thrust. Subtract the product of the correction coefficient and the reading of the pressure sensor 8 from the total gravity of the moving frame (including the micro turbojet engine). The obtained difference is the vertical thrust of the engine. 2) Measure the horizontal thrust generated by the vector nozzle: Efficiently transmit the horizontal thrust generated by the engine vector nozzle to the tension-compression sensor 16 through the slide rail 12 and the slider 15. The reading of the tension-compression sensor 16 is the measured value of the horizontal thrust. When the reading of the tension-compression sensor 16 is negative, it indicates that the acting force is pressure, and the absolute value of this reading is the magnitude of the horizontal thrust. The direction of the horizontal thrust is towards the tension-compression sensor 16; when the reading of the tension-compression sensor 16 is positive, it indicates that the acting force is tension, and the absolute value of this reading is the magnitude of the horizontal thrust. The direction of the horizontal thrust is away from the tension-compression sensor 16. 3) Measure the vertical thrust of the engine equipped with the vector nozzle: Compared with the measurement of the vertical thrust of the engine without the vector nozzle, the measurement of the vertical thrust of the engine equipped with the vector nozzle will be affected by the couple force generated by the combined action of the horizontal thrust generated by the vector nozzle and the reaction force generated by the tension-compression sensor 16. Therefore, it is necessary to correct the data measured for the vertical thrust of the engine equipped with the vector nozzle. Obtain the correction coefficient and the total gravity of the moving frame (including the micro turbojet engine) in the experiment of measuring the vertical thrust of the engine without the vector nozzle. On this basis, correct the data measured for the vertical thrust of the engine equipped with the vector nozzle. The magnitude of the couple force generated by the horizontal thrust and its reaction force is the product of the horizontal thrust and the distance between the axis of the vector nozzle rotating shaft and the horizontal axis of the tension-compression sensor 16. When the vector nozzle faces the end of the pressure sensor 8, subtract the product of the correction coefficient and the reading of the pressure sensor 8 from the total gravity of the moving frame (including the micro turbojet engine), and then add the ratio of the couple force to the horizontal distance from the axis of the engine to the axis of the rotating shaft 4. The obtained value is the corrected vertical thrust. When the vector nozzle faces the end of the tension-compression sensor 16, subtract the product of the correction coefficient and the reading of the pressure sensor 8 from the total gravity of the moving frame (including the micro turbojet engine), and then subtract the ratio of the couple force to the horizontal distance from the axis of the engine to the axis of the rotating shaft 4. The obtained value is the corrected vertical thrust.

6. The thrust measurement device for a vertical-position micro turbojet engine according to claim 1, characterized in that The thrust calculation method is as follows: The vertical thrust of the engine without a vector nozzle is equal to the total gravity of the moving frame (including the micro turbojet engine) minus the product of the correction coefficient and the reading of the pressure sensor 8; the magnitude of the horizontal thrust of the engine with a vector nozzle is the absolute value of the reading of the tension-compression sensor 16. When the reading is positive, the direction of the horizontal thrust is away from the tension-compression sensor 16, and when the reading is negative, the direction of the horizontal thrust is towards the tension-compression sensor 16. For the measurement of the vertical thrust of the engine with a vector nozzle, when the vector nozzle faces the end of the pressure sensor 8, the vertical thrust is the total gravity of the moving frame (including the micro turbojet engine) minus the product of the correction coefficient and the reading of the pressure sensor 8 plus the ratio of the couple to the horizontal distance between the engine axis and the axis of the rotating shaft 4. When the vector nozzle faces the end of the tension-compression sensor 16, the vertical thrust is the total gravity of the moving frame (including the micro turbojet engine) minus the product of the correction coefficient and the reading of the pressure sensor 8 minus the ratio of the couple to the horizontal distance between the engine axis and the axis of the rotating shaft 4.

Images