Zero position measuring and adjusting method for multi-machine parallel liquid rocket engine

Abstract

The invention relates to a multi-machine parallel liquid rocket engine zero position measuring and adjusting method. The method comprises the following specific steps: (1) measuring and acquiring point cloud data of an engine nozzle and a throat part under a zero position coordinate system under a plurality of stations; (2) performing fitting calculation according to the obtained point cloud data to obtain center point coordinates of a nozzle and a throat, and connecting the two center points to obtain a thrust line space equation before zero adjustment of the engine; and (3) whether the zero position of the engine is out of tolerance or not is judged, if the zero position is out of tolerance, adjustment is needed, based on the thrust line space equation in the step (2), the coordinates of the nozzle and the throat center point are obtained in real time in the thrust line adjustment process, the adjusted thrust line can be obtained in real time, and therefore zero position adjustment is completed. According to the adjusting method, the adjusted engine thrust line can be obtained in real time, the situation that the measurement time is prolonged due to the fact that the thrust line is repeatedly measured through multiple times of station transferring is avoided, and the zero position measurement and adjusting efficiency is greatly improved.

Description

Technical Field

[0001] The invention relates to a zero position measurement and adjustment method for multi-machine parallel liquid rocket engines, belonging to the field of metrological science and technology. Background Art

[0002] The power of rocket flight comes from the reverse force formed by the high-pressure gas generated by the combustion of propellant and the engine nozzle. The zero position of the rocket engine directly determines the flight direction of the rocket, but due to the influence of factors such as the technical level of production and assembly, the accuracy of measuring tools, etc., the thrust line of the rocket engine often deviates from the design value, resulting in a certain lateral shift and deflection, which leads to a deviation in the zero position of the engine. The zero position deviation will cause the engine to generate a deflection torque during operation, affecting the rocket's hit accuracy. Therefore, it is of great significance to measure and adjust the zero position of the rocket engine before assembly and launch.

[0003] The parallel liquid rocket engine includes a plurality of single engines, each of which is connected to a frame (such as Figure 1 As shown in the figure, hereinafter referred to as the engine), currently when the engine is measured at zero position, due to the large spatial size of the engine, the laser tracker needs to be used for multiple tracker station transfer operations to complete the engine measurement. If the engine exceeds the technical requirements after zero position measurement, its zero position needs to be adjusted. By adjusting the length of the process pull rod, the swing of the single engine can be completed and the movement of the engine thrust line can be realized, so that the thrust line moves to the appropriate position to complete the zero position adjustment process. After the adjustment is completed, the engine zero position needs to be re-measured, and during the re-measurement, the engine needs to be measured multiple times to construct a new thrust line. This process usually takes a long time to measure and is inefficient. Summary of the invention

[0004] The technical problem solved by the present application is: to overcome the deficiencies of the prior art and to provide a method for zero-position measurement and adjustment of multi-machine parallel liquid rocket engines, with the aim of solving the problem of long measurement time and low efficiency of the existing zero-position adjustment method.

[0005] The technical solutions provided by this application are as follows:

[0006] A method for measuring and adjusting the zero position of a multi-machine parallel liquid rocket engine, wherein the parallel liquid rocket engine comprises a plurality of single engines, each of which is connected to a frame through a process tie rod, comprising:

[0007] S1: Establish zero coordinate system;

[0008] S2: Measure and obtain the point cloud data of each engine nozzle and throat in the zero-position coordinate system at multiple stations;

[0009] S3: Based on the point cloud data of the nozzle and throat of a single engine, the central point coordinates of the nozzle and throat are obtained through fitting calculation, and the spatial equation of the thrust line of the single engine is obtained by connecting the two central points;

[0010] S4: Calculate the thrust line of each single engine to obtain the spatial equation of the thrust line of each single engine;

[0011] S5: For each single engine, calculate the angular deviation between the thrust line of the single engine and the coordinate axes of the zero position coordinate system, and judge whether the engine zero position is out of tolerance according to the angular deviation. If it is not out of tolerance, end. If it is out of tolerance, go to step S6;

[0012] S6: According to the angular deviation and the distance between the swing center point of the single engine and the plane where the engine nozzle is located, calculate and obtain the adjustment amount Δ of the nozzle;

[0013] S7: Paste feature points on the nozzle and throat respectively, and adjust the position of the single engine through the process pull rod according to the adjustment amount Δ of the nozzle;

[0014] S8: Calculate the thrust line after adjusting the position of the single engine;

[0015] S9: Repeat steps S5 - S8 until the zero position is not out of tolerance.

[0016] In the above S1, establishing the zero position coordinate system includes: the upper end face of the frame is used as the XOY reference plane, the origin is the center of the circumscribed circle of the frame, the vertical upward direction is the Z direction, and the direction pointing to a single engine is the Y direction.

[0017] In the above S2, measuring and obtaining the point cloud data of the nozzle and throat of each single engine in the zero position coordinate system at multiple stations includes: using a laser tracker to measure the point cloud data of the nozzle and throat of each single engine, and measuring at multiple stations.

[0018] The position of the laser tracker at each station forms a corresponding machine coordinate system. At least 4 common points are arranged in the measurement space, and through the positions of the common points, the point cloud data in the machine coordinate system is unified into the zero position coordinate system.

[0019] In the above S3, according to the point cloud data of the nozzle and throat of each single engine, the least square method is used to fit and calculate the central point coordinates of the nozzle and throat.

[0020] In the above S3, the spatial equation of the thrust line of the single engine is:

[0021] where, (x p , y p , z p) is the center point coordinate of the nozzle, (x q , y q , z q ) is the center point coordinate of the nozzle.

[0022] In the above S6, according to the angle deviation and the distance between the swing center point of the single engine and the plane where the engine nozzle is located, the adjustment amount Δ of the nozzle is calculated, including:

[0023] Δ = H * sinα

[0024] where H is the distance between the swing center point of the single engine and the plane where the engine nozzle is located; α is the angle deviation between the thrust line and the X-axis or Y-axis of the zero-position coordinate system;

[0025] When α takes the angle deviation between the thrust line and the X-axis of the zero-position coordinate system, the adjustment amount Δ of the nozzle along the X-axis direction of the zero-position coordinate system is obtained 1 ; when α takes the angle deviation between the thrust line and the Y-axis of the zero-position coordinate system, the adjustment amount Δ of the nozzle along the Y-axis direction of the zero-position coordinate system is obtained 2 .

[0026] In the above S8, calculating the thrust line after adjusting the position of the single engine includes: the characteristic point coordinates pasted on the nozzle and the throat before position adjustment are A and B respectively, and the coordinates of the characteristic points after the i-th adjustment are A i and B i , the movement amounts of the nozzle center p i and the throat center q i are respectively:

[0027] PP i = AA i = (Δx, Δy, Δz)

[0028] QQ i = BB i = (Δx', Δy', Δz')

[0029] The adjusted thrust line l i is:

[0030]

[0031] In summary, the present application at least includes the following beneficial technical effects:

[0032] When using a laser tracker to measure the thrust chamber of a parallel engine, due to the complex structure and numerous pipelines of the parallel engine, and at the same time, the jacks will hinder the laser tracker from measuring the positions of the engine throat and nozzle, so 4 to 5 times of station transfer measurements are required during this process, the measurement time is long, and the measurement efficiency of the engine is low.

[0033] Since the nozzle and throat of the engine are composed of a large amount of point cloud data during measurement, during the movement of a single engine, the point cloud data is also offset, and the data offset of each point is the same. Therefore, the offset of the engine thrust line can be replaced by the movement of the characteristic points of the engine throat and nozzle. By substituting the movement of the characteristic points into the space equation of the thrust line, the adjusted engine thrust line can be obtained in real time, and then the adjusted engine zero position can be obtained, avoiding the increase in measurement time caused by multiple instrument setups and greatly improving the measurement efficiency. Description of the Drawings

[0034] Figure 1 is a model diagram of a multi-engine parallel engine;

[0035] Figure 2 is a schematic diagram of the measurement principle of a laser tracker;

[0036] Figure 3 is a unified schematic diagram of the conversion between different coordinate systems at multiple instrument setups;

[0037] Figure 4 is a schematic diagram of the point cloud data and fitting results of the engine nozzle and throat, and the offset relationship between the center coordinates of the engine nozzle and throat and the thrust line;

[0038] Figure 5 is a schematic diagram of the positions of the characteristic points of the engine nozzle and throat. Detailed Implementation Manner

[0039] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will further describe in detail the disclosed implementation manners of the present invention with reference to the accompanying drawings.

[0040] To solve the above problems, the present invention provides a new zero position adjustment method for adjusting the zero position of a parallel liquid rocket engine. The parallel liquid rocket engine includes multiple single engines, and each single engine is independently connected to the frame through a process pull rod. The main steps are as follows:

[0041] (1) Establish a zero position coordinate system. The upper end face of the frame is used as the XOY reference plane, the origin is the center of the circumscribed circle of the frame, the vertical upward direction is the Z direction, and the direction pointing to a single engine is the Y direction;

[0042] Use a laser tracker to measure the outer cross-sectional circle of the nozzle and the cylindrical section of the throat of each single engine at multiple instrument setups to obtain the point cloud data of the nozzle and throat in the zero position coordinate system;

[0043] (2) Based on the point cloud data obtained in step (1), taking a single engine as an example, calculate the coordinates p(x p , y p , z p) and the coordinates q(x q , y q , z q ) of the center point of the throat. Connecting point p and q can obtain the engine thrust line l. At this time, the spatial equation l of the thrust line can be expressed as:

[0044]

[0045] Repeat step (2) to calculate the spatial equation of the thrust line of each single engine.

[0046] (3) Calculate the angular deviation between the thrust line of the single engine and the X-axis or Y-axis of the zero coordinate system to determine whether the zero position of the engine is out of tolerance. If the zero position is out of tolerance, the position of each individual single engine needs to be adjusted through the process pull rod to achieve the purpose of thrust line adjustment. Based on the spatial equation of the thrust line in step (2), the coordinates of the nozzle center point p i and the coordinates q i of the center point of the throat can be obtained in real time during the thrust line adjustment process, and then the adjusted thrust line l i can be obtained in real time. The solution method of the thrust line after adjustment is as follows:

[0047] During the adjustment of the thrust line of the single engine, the single engine can be regarded as a whole when it moves. Assume that the overall movement amounts of the nozzle and the throat of the single engine during the movement are respectively:

[0048] AA i =(Δx, Δy, Δz)

[0049] BB i =(Δx', Δy', Δz')

[0050] Then the movement amounts of the nozzle center p i and the throat center q i can be obtained, that is

[0051] PP i = AA i =(Δx, Δy, Δz)

[0052] QQ i = BB i =(Δx', Δy', Δz')

[0053] Therefore, the coordinate values of the center points of the throat and the nozzle of the single engine during the movement can be expressed in real time as:

[0054]

[0055] During the adjustment process, the adjusted thrust line l i can be obtained in real time, and its spatial equation can be expressed as:

[0056]

[0057] Based on the above steps, the thrust line of the single engine after adjustment can be obtained.

[0058] Embodiment 1

[0059] The zero-position measurement and adjustment method for multi-engine parallel liquid rocket engines provided by the present invention comprises the following specific steps:

[0060] The present invention uses a laser tracker to obtain the point cloud data of the nozzle and the throat. Its basic principle is as Figure 2 shown. By measuring the horizontal azimuth angle α and the vertical azimuth angle β of the laser beam through the angle encoder of the laser tracker, and using the absolute laser rangefinder of the laser tracker to measure the distance L from the center of the reflector sphere of the laser tracker to the rotation center of the laser tracker, the spatial point coordinates P(x, y, z) of the target position can be obtained, that is:

[0061]

[0062] As Figure 3 shown, when using a laser tracker to measure the zero position of the engine, the main coordinate systems involved are the machine coordinate system 3-1 and the zero-position coordinate system 3-2. The point cloud data obtained by the laser tracker at a single station (such as Figure 3 the middle station A) is in the coordinates of the machine coordinate system 3-1. However, in the actual measurement process, to ensure the integrity and accuracy of the point cloud data, measurements need to be carried out at multiple stations (such as Figure 3 the middle stations B, C, D). At this time, it is necessary to unify the point cloud data obtained at multiple stations into the zero-position coordinate system 3-2. The unification of the point cloud data can be achieved by arranging no less than 4 common points 3-3 in the measurement space. The 4 common points 3-3 are all set on the ground.

[0063] In addition, when calculating the center point coordinates of the engine nozzle and the throat, it is necessary to use the zero-position coordinate system 3-2 to guide the measurement and adjustment of the engine zero position. Therefore, it is first necessary to determine and construct the zero-position coordinate system 3-2 of the engine, and convert the point cloud data in the machine coordinate system 3-1 to the zero-position coordinate system 3-2 to ensure that the center coordinates of the nozzle and the throat and the thrust line equation in the subsequent steps are all in the zero-position coordinate system 3-2.

[0064] After that, use a laser tracker to obtain the point cloud data P and Q of the engine nozzle and the throat. During the measurement, it is necessary to ensure that the point cloud data of the measured characteristic parts is complete and evenly distributed. The point cloud data is fitted and calculated by the least squares method, and the center point coordinates p(x p , y p , z p) and the coordinates q(x q , y q , z q ) of the center point of the throat. Figure 4 The figure shows the point cloud data and the fitting results of the engine nozzle and the throat obtained by using a laser tracker. Connecting point p and q can obtain the engine thrust line l. At this time, the spatial equation l of the thrust line can be expressed as:

[0065]

[0066] After obtaining the engine thrust line l, calculate the angular deviation α between the thrust line and the axes of the zero position coordinate system to determine whether the engine zero position is out of tolerance. If the zero position is out of tolerance, adjustment is required. According to the spatial equation of the thrust line, it can be known that if the coordinates p of the center point of the nozzle i and the coordinates q of the center point of the throat i can be obtained in real time during the adjustment process of the thrust line, i .

[0067] When adjusting the engine thrust line, the position of the engine thrust chamber needs to be adjusted through the process pull rod to achieve the adjustment purpose. During the adjustment of the thrust line, the thrust chamber can be regarded as a whole when it moves. Since the engine nozzle and the throat are composed of a large amount of point cloud data during measurement, during the movement of the thrust chamber, the point cloud data also shifts accordingly and the data shift amount of each point cloud is the same. Therefore, the shift amount of the engine thrust line can be replaced by the movement amount of the characteristic points of the engine throat and the nozzle. Substituting the movement amount of the characteristic points into the spatial equation of the thrust line, the adjusted engine thrust line can be obtained in real time, which specifically includes the following steps:

[0068] Before zero position adjustment, first calculate the adjustment amount Δ of the nozzle according to the position of the thrust line at this time:

[0069] Δ = H * sinα

[0070] where H is the distance between the engine swing center and the engine nozzle, as Figure 1 shown; α is the angular deviation between the thrust line and the X-axis or Y-axis of the zero position coordinate system.

[0071] After that, paste the characteristic points A and B on the nozzle and the throat respectively, as shown in 5-1 and 5-2 in Figure 5 . Use the laser tracker to obtain the coordinates A and B of the characteristic points before adjustment respectively. Adjust the position of the nozzle according to the adjustment amount Δ of the nozzle and use the laser tracker to monitor the coordinate value of the characteristic point A in real time. After adjusting to the appropriate position, measure the characteristic points A and B again to obtain the coordinates A i and B iDuring the adjustment of the engine thrust line, the thrust chamber can be regarded as a whole when it moves. Therefore, according to the coordinate relationship between A and A i and B and B i , the displacement of the nozzle and throat during the adjustment can be obtained:

[0072] Δ 喷口 = AA i = (Δx, Δy, Δz)

[0073] Δ 喉部 = BB i = (Δx', Δy', Δz')

[0074] Since the data offset of each point cloud is also the same, as Figure 4 shown, the movement of the nozzle center p i and the throat center q i can be obtained simultaneously at this time, that is

[0075] PP i = AA i = (Δx, Δy, Δz)

[0076] QQ i = BB i = (Δx', Δy', Δz')

[0077] Therefore, after the zero position adjustment is completed, the center point coordinate values of the throat and nozzle can be expressed as:

[0078]

[0079] Connecting the adjusted nozzle and throat centers can obtain the adjusted thrust line l i , and its space equation can be expressed as:

[0080]

[0081] Calculate the angle deviation α i between the thrust line l i and the coordinate axes of the zero position coordinate system again, where i is the i-th adjustment until the angle deviation meets the requirements.

[0082] According to the above steps, the measurement and adjustment of the engine zero position can be completed.

[0083] The content not described in detail in this application specification belongs to the well-known technology of those skilled in the art.

[0084] The present application has been described in detail above in conjunction with specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present application. Those skilled in the art understand that without departing from the spirit and scope of the present application, various equivalent substitutions, modifications or improvements can be made to the technical solutions and their implementation manners of the present application, and all of these fall within the scope of the present application. The protection scope of the present application shall be subject to the appended claims.

Claims

1. A method for zero position measurement and adjustment of multiple parallel liquid rocket engines, wherein the parallel liquid rocket engine comprises a plurality of single engines, each of which is connected to a frame via a process tie rod, characterized in that: include: S1: Establish zero coordinate system; S2: Measure and obtain the point cloud data of each engine nozzle and throat in the zero-position coordinate system at multiple stations; S3: Based on the point cloud data of a single engine nozzle and throat, the coordinates of the center points of the nozzle and throat are obtained by fitting calculation, and the spatial equation of the thrust line of the single engine is obtained by connecting the two center points; S4: Calculate the thrust line of each single engine and obtain the thrust line space equation of each single engine; S5: for each single engine, calculate the angle deviation between the thrust line of the single engine and the coordinate axis of the zero position coordinate system, and determine whether the engine zero position is out of tolerance according to the angle deviation. If not, end; if so, proceed to step S6; S6: Calculate the nozzle adjustment amount Δ according to the angle deviation and the distance between the swing center point of the single engine and the plane where the engine nozzle is located; S7: sticking feature points on the nozzle and throat respectively, and adjusting the position of the single engine through the process tie rod according to the nozzle adjustment amount Δ; S8: Calculate the thrust line after adjusting the position of the single engine; S9: Repeat steps S5-S8 until the zero position is within tolerance.

2. A method for zero position measurement and adjustment of multiple parallel liquid rocket engines according to claim 1, characterized in that: In S1, a zero-position coordinate system is established, including: the upper end surface of the frame is used as the XOY reference plane, the origin is the center of the circumscribed circle of the frame, the vertical upward direction is the Z direction, and the direction pointing to a single engine is the Y direction.

3. A method for zero position measurement and adjustment of multiple parallel liquid rocket engines according to claim 1, characterized in that: In S2, point cloud data of the nozzle and throat of each single engine in the zero-position coordinate system are measured and obtained at multiple stations, including: using a laser tracker to measure the point cloud data of the nozzle and throat of each single engine, and the measurement is performed at multiple stations.

4. A method for zero position measurement and adjustment of multiple parallel liquid rocket engines according to claim 3, characterized in that: The position of the laser tracker at each station forms a corresponding machine coordinate system, and no less than 4 common points are arranged in the measurement space. Through the positions of the common points, the point cloud data in the machine coordinate system are unified into the zero-position coordinate system.

5. The method for zero position measurement and adjustment of multiple parallel liquid rocket engines according to claim 1, characterized in that: In S3, based on the point cloud data of the nozzle and throat of each single engine, the least square method is used to fit the point cloud data to obtain the center point coordinates of the nozzle and throat.

6. A method for zero position measurement and adjustment of multiple parallel liquid rocket engines according to claim 1, characterized in that: In S3, the spatial equation of the thrust line of the single engine is: Among them, (x p ,y p , z p ) is the coordinate of the center point of the nozzle, (x q ,y q , z q ) is the coordinate of the center point of the nozzle.

7. A method for zero position measurement and adjustment of multiple parallel liquid rocket engines according to claim 1, characterized in that: In S6, the nozzle adjustment amount Δ is calculated based on the angle deviation and the distance between the swing center point of the single engine and the plane where the engine nozzle is located, including: Δ=H*sinα Wherein, H is the distance between the swing center of the single engine and the plane where the engine nozzle is located; α is the angular deviation between the thrust line and the X-axis or Y-axis of the zero-position coordinate system; The value of α is the angular deviation between the thrust line and the X-axis of the zero-position coordinate system, and the adjustment amount Δ1 of the nozzle along the X-axis direction of the zero-position coordinate system is obtained; the value of α is the angular deviation between the thrust line and the Y-axis of the zero-position coordinate system, and the adjustment amount Δ2 of the nozzle along the Y-axis direction of the zero-position coordinate system is obtained.

8. A method for zero position measurement and adjustment of multiple parallel liquid rocket engines according to claim 6, characterized in that: In the step S8, the thrust line after adjusting the position of the single engine is calculated, including: the coordinates of the feature points attached to the nozzle and the throat before the position adjustment are A and B, and the coordinates of the feature points after the i-th adjustment are A i and B i , nozzle center p i and laryngeal center q i The movement amounts are: PP i =AA i =(Δx,Δy,Δz) QQ i =BB i =(Δx',Δy',Δz') Adjusted thrust line l i for:

Images