A method for measuring and adjusting zero of multi-parallel liquid rocket engine

Abstract

The method relates to a zero position measurement and adjustment method of multiple parallel liquid rocket engines, and the specific steps of the method are as follows: (1) measuring and obtaining point cloud data of engine nozzles and throat portions under a zero position coordinate system at multiple stations; (2) fitting and calculating center point coordinates of the nozzles and the throat portions according to the obtained point cloud data, connecting the two center points to obtain a thrust line space equation before zero position adjustment of the engine; (3) judging whether the zero position of the engine is out of tolerance, if the zero position is out of tolerance, adjustment is needed, and based on the thrust line space equation in step (2), the center point coordinates of the nozzles and the throat portions are obtained in real time during thrust line adjustment, so that the adjusted thrust line can be obtained in real time, and the adjustment of the zero position is completed. The adjustment method can obtain the adjusted engine thrust line in real time, avoids the increase of measurement time caused by repeated measurement of the thrust line at multiple stations, and greatly improves the measurement and adjustment efficiency of the zero position.

Description

Technical Field

[0001] This invention relates to a method for zero-position measurement and adjustment of a multi-engine parallel liquid rocket engine, belonging to the field of metrology science and technology. Background Technology

[0002] The propulsion for rocket flight comes from the reaction force between the high-pressure gas generated by propellant combustion and the engine nozzle. The zero position of the rocket engine directly determines the rocket's flight direction. However, due to factors such as the level of production and assembly technology and the accuracy of measuring tools, the thrust line of the rocket engine often deviates from the design value, resulting in a certain degree of lateral displacement and skewness. This causes a deviation in the engine's zero position, which in turn generates a bias torque during operation, affecting the rocket's accuracy. Therefore, measuring and adjusting the zero position of the rocket engine before assembly and launch is of great significance.

[0003] The parallel liquid rocket engine consists of multiple individual engines, each of which is connected to the frame via process tie rod 1-1 (e.g., Figure 1 As shown (hereinafter referred to as the engine), currently, when measuring the engine at zero position, due to the large size of the engine space, multiple tracker relocation operations are required to complete the measurement using a laser tracker. If the engine's zero-position measurement exceeds the technical requirements, its zero position needs to be adjusted. By adjusting the length of the process tie rod, the swing of the individual engine can be achieved, thereby moving the engine's thrust line to a suitable position to complete the zero-position adjustment process. After adjustment, the engine's zero position needs to be re-measured. During the re-measurement, multiple relocation measurements are required to construct a new thrust line. This process is usually time-consuming and inefficient. Summary of the Invention

[0004] The technical problem solved by this application is to overcome the shortcomings of the prior art and provide a method for zero-position measurement and adjustment of multi-engine parallel liquid rocket engines. The purpose is to solve the problems of excessive measurement time and low efficiency of the existing zero-position adjustment methods.

[0005] The technical solution provided in this application is as follows:

[0006] A method for zero-position measurement and adjustment of a multi-engine parallel liquid rocket engine, wherein the parallel liquid rocket engine includes multiple individual engines, each individual engine being connected to a frame via a process tie rod, comprising:

[0007] S1: Establish the zero-position coordinate system;

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

[0009] S3: According to the point cloud data of the nozzle and the throat of one single engine, the center point coordinates of the nozzle and the throat are calculated by fitting, and the spatial equation of the thrust line of the single engine is obtained by connecting the two center points;

[0010] S4: The thrust line of each single engine is calculated to obtain the spatial equation of the thrust line of each single engine.

[0011] S5: For each single engine, the angle deviation between the thrust line of the single engine and the coordinate axis of the zero position coordinate system is calculated, and whether the engine zero position is out of tolerance is judged according to the angle deviation. If not, end, if out of tolerance, proceed to step S6.

[0012] 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.

[0013] S7: Paste feature points on the nozzle and the throat respectively, adjust the position of the single engine by 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 S1, the zero position coordinate system is established, including: the upper end surface of the rack as the XOY reference surface, the origin as the center of the circumscribed circle of the rack, the vertical upward as the Z direction, and the direction pointing to one single engine as the Y direction.

[0017] In S2, the point cloud data of the nozzle and the throat of each single engine in the zero position coordinate system is measured and obtained at multiple stations, including: measuring the point cloud data of the nozzle and the throat of each single engine by laser tracker, and measuring at multiple stations.

[0018] The position of the laser tracker at each station forms a corresponding machine coordinate system, and not less than 4 common points are arranged in the measurement space. The point cloud data in the machine coordinate system is unified to the zero position coordinate system through the position of the common points.

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

[0020] In 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. q , y q , z q ) is the center point coordinate of the nozzle.

[0022] In the 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 and obtained, including:

[0023] Δ=H*sinα

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

[0025] The value of α is the angle deviation between the thrust line and the X axis of the zero coordinate system, so as to obtain the adjustment amount Δ1 of the nozzle along the direction of the X axis of the zero coordinate system; and the value of α is the angle deviation between the thrust line and the Y axis of the zero coordinate system, so as to obtain the adjustment amount Δ2 of the nozzle along the direction of the Y axis of the zero coordinate system.

[0026] In the S8, the thrust line after adjusting the position of the single engine is calculated, including: the feature point coordinates respectively pasted on the nozzle and the throat before the position adjustment are A and B, the coordinates of the feature point after the i-th adjustment are A i and B i , and 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 the laser tracker is used to measure the parallel engine thrust chamber, due to the complex structure of the parallel engine, there are more pipelines, and the jack will hinder the measurement of the engine throat and nozzle position by the laser tracker, so 4 to 5 times of station measurement are required in this process, the measurement time is long, and the measurement efficiency of the engine is low.

[0033] Because the nozzle and the throat of the engine are composed of a large amount of point cloud data during the measurement, the point cloud data is offset during the movement of the single engine, and the data of each point is offset by the same amount. Therefore, the offset amount of the engine thrust line can be replaced by the movement amount of the feature points of the engine throat and nozzle. The movement amount of the feature points is brought into the thrust line space equation, so that the adjusted engine thrust line can be obtained in real time, and the adjusted engine zero position is obtained, thereby avoiding the increase of the measurement time caused by multiple station switching, and greatly improving the measurement efficiency. BRIEF DESCRIPTION OF DRAWINGS

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

[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 under multiple stations;

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

[0038] Figure 5 is a schematic diagram of the feature point positions of the engine nozzle and throat. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the present application clearer, the following will combine the drawings to further describe the disclosed embodiments of the present application in detail.

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

[0041] (1) Establish a zero position coordinate system, the upper end surface of the rack as the XOY reference surface, the origin as the center of the circumscribed circle of the rack, the vertical upward as the Z direction, and the direction pointing to a single engine as the Y direction;

[0042] Use a laser tracker to measure the nozzle outer section circle and the throat cylindrical segment of each single engine under multiple stations to obtain the point cloud data of the nozzle and the throat under the zero position coordinate system;

[0043] (2) Based on the point cloud data obtained in step (1), taking one single engine as an example, the center point coordinates p(x p ,y p ,z p) and throat center point coordinate q(x q ,y q ,z q ), connecting point p and q, the engine thrust line l can be obtained, and the space equation of the thrust line l can be expressed as:

[0044]

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

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

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

[0048] AA i =(Δx,Δy,Δz)

[0049] BB i =(Δx',Δy',Δz')

[0050] Then the movement 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 single engine throat and nozzle center point coordinates during the movement process 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 space equation can be expressed as:

[0056]

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

[0058] Example 1

[0059] The multi-engine parallel liquid rocket engine zero measurement and adjustment method provided by the application has the following specific steps:

[0060] The laser tracker is used to obtain the point cloud data of the nozzle and the throat, and the basic principle is as shown in Figure 2 The horizontal azimuth angle α and the vertical azimuth angle β of the laser beam are measured by the angle encoder of the laser tracker, and the distance L from the mirror sphere center of the laser tracker to the rotation center of the laser tracker is measured by the laser absolute range finder of the laser tracker, so that the spatial point coordinates P(x, y, z) of the target position are obtained, that is:

[0061]

[0062] As shown in Figure 3 , when measuring the engine zero using the laser tracker, the coordinate systems mainly involved are the machine coordinate system 3-1 and the zero coordinate system 3-2. The point cloud data obtained by the laser tracker at a single station (such as Figure 3 station A) is in the machine coordinate system 3-1, but in the actual measurement process, in order to ensure the integrity and accuracy of the point cloud data, measurement needs to be performed at multiple stations (such as Figure 3 stations B, C, and D), at which time the point cloud data obtained at the multiple stations needs to be unified under the zero coordinate system 3-2, and the unification of the point cloud data can be realized by arranging not less than 4 common points 3-3 in the measurement space. The 4 common points 3-3 are all arranged on the ground.

[0063] In addition, when calculating the center point coordinates of the engine nozzle and the throat, the zero coordinate system 3-2 is needed to guide the measurement and adjustment of the engine zero. Therefore, the zero coordinate system 3-2 of the engine needs to be determined and constructed first, and the point cloud data in the machine coordinate system 3-1 needs to be converted to the zero coordinate system 3-2, so as to ensure that the center coordinates of the nozzle and the throat and the thrust line equation in the subsequent steps are all under the zero coordinate system 3-2.

[0064] Then, the point cloud data P and Q of the engine nozzle and the throat are obtained using the laser tracker, and the point cloud data of the measured feature parts needs to be complete and uniformly distributed during measurement. The point cloud data is calculated by the least square method, and the nozzle center point coordinates p(x p ,y p ,z p) and the coordinates of the center point of the throat q(x) q ,y q ,z q ), Figure 4 The diagram shows the point cloud data and fitting results of the engine nozzle and throat obtained using a laser tracker. Connecting points p and q yields the engine thrust line l, and the spatial equation l of the thrust line can then be expressed as:

[0065]

[0066] After obtaining the engine thrust line l, the angular deviation α between the thrust line and the coordinate axes of the zero-position coordinate system is calculated 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, if the nozzle center point coordinate p can be obtained in real time during the thrust line adjustment process... i and the coordinates of the center point of the throat q i The adjusted thrust line can be obtained in real time. i .

[0067] Adjusting the engine thrust curve requires using process tie rods to adjust the position of the engine thrust chamber. During the adjustment process, the thrust chamber can be considered as a whole as it moves. Since the engine nozzle and throat are composed of a large amount of point cloud data during measurement, this point cloud data shifts along with the thrust chamber, with each point cloud shifting by the same amount. Therefore, the shift in the engine thrust curve can be replaced by the movement of characteristic points in the engine throat and nozzle. Substituting the movement of these characteristic points into the thrust curve spatial equation allows for real-time acquisition of the adjusted engine thrust curve. The specific steps include the following:

[0068] Before zero-position adjustment, the adjustment amount Δ of the nozzle needs to be calculated based on the current position of the thrust line.

[0069] Δ=H*sinα

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

[0071] Next, feature points A and B are pasted onto the nozzle and throat respectively, as shown below. Figure 5 As shown in Figures 5-1 and 5-2, the coordinates of feature points A and B before adjustment are obtained using a laser tracker. The nozzle position is adjusted according to the adjustment amount Δ, and the coordinates of feature point A are monitored in real time using the laser tracker. After adjustment to a suitable position, feature points A and B are measured again to obtain the coordinates of feature point A at this point. i and B iThe engine thrust line is considered as a whole during the adjustment process, so the displacement of the nozzle and the throat during the adjustment process can be obtained according to the coordinate relationship between A and A i , B and B i :

[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 shown in Figure 4 , the displacement of the nozzle center p i and the throat center q i can be obtained at the same time, i.e.

[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 the nozzle can be represented as:

[0078]

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

[0080]

[0081] The angle deviation α i between the thrust line l i and the zero coordinate system coordinate axis is calculated again, 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 contents not described in detail in the specification of the present application are the known technology of those skilled in the art.

[0084] The application has been described in detail with specific reference to particular embodiments and exemplified examples, but it will be understood that these are only examples and are not intended to limit the application, as the application can be modified in various equivalent and / or functional ways and can be implemented in various examples. It will be appreciated that those skilled in the art will be able to devise numerous alternative arrangements and procedures for carrying out the application without departing from the spirit and scope of the application. The scope of the application is not to be limited by the specific examples given.

Claims

1. A method for nulling and adjusting a plurality of liquid rocket engines in parallel, the plurality of liquid rocket engines comprising a plurality of individual engines, each individual engine connected to a frame by a process tie rod, the method comprising: nulling the plurality of individual engines by adjusting the process tie rods to a predetermined position; and adjusting the plurality of individual engines to a predetermined thrust level by adjusting the process tie rods. The method comprises the following steps: S1: establishing a zero position coordinate system, comprising: taking the upper end surface of the rack as the XOY reference surface, taking the center of the circumscribed circle of the rack as the origin, taking the vertical upward direction as the Z direction, and taking the direction pointing to a single engine as the Y direction; S2: measuring and obtaining point cloud data of the nozzle and the throat of each single engine in the zero position coordinate system at multiple stations; S3: fitting and calculating the center point coordinates of the nozzle and the throat according to the point cloud data of the nozzle and the throat of a single engine, and connecting the center points of the nozzle and the throat to obtain the spatial equation of the thrust line of the single engine; S4: calculating the thrust line of each single engine to obtain the spatial equation of the thrust line of each single engine; S5: for each single engine, calculating the angle deviation between the thrust line of the single engine and the coordinate axis of the zero position coordinate system, judging whether the engine zero position is out of tolerance according to the angle deviation, if not, ending, if yes, proceeding to step S6; S6: calculating and obtaining the adjustment amount Δ of the nozzle according to the angle deviation and the distance between the swing center point of the single engine and the plane where the nozzle is located; S7: pasting feature points on the nozzle and the throat respectively, and adjusting the position of the single engine by the process pull rod according to the adjustment amount Δ of the nozzle; S8: Calculate the thrust line after adjusting the position of the single engine, including: the coordinates of the feature points pasted on the nozzle and the throat before position adjustment are A and B, respectively, the coordinates of the feature 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: PP i = AA i = (Δx, Δy, Δz) QQ i = BB i = (Δx', Δy', Δz') Adjusted thrust line l i is: wherein (x p , y p , z p ) is the coordinate of the center point of the nozzle, and (x q , y q , z q ) is the coordinate of the center point of the throat. S9: repeating steps S5-S8 until the zero position is not out of tolerance.

2. The method of claim 1, wherein, In the S2, the point cloud data of the nozzle and the throat of each single engine in the zero position coordinate system is measured and obtained at multiple stations, comprising: measuring the point cloud data of the nozzle and the throat of each single engine by using a laser tracker, and measuring at multiple stations.

3. The method of claim 2, wherein: The position of the laser tracker at each station forms a corresponding machine coordinate system, and not less than 4 common points are arranged in the measurement space, and the point cloud data in the machine coordinate system is unified to the zero position coordinate system through the positions of the common points.

4. The method of claim 1, wherein: In the S3, the least square method is used to fit and calculate the center point coordinates of the nozzle and the throat according to the point cloud data of each single engine nozzle and throat.

5. The method of claim 1, wherein, In the S3, the spatial equation of the thrust line of the monoblock engine is:

6. The method of claim 1, wherein, In the S6, the adjustment amount Δ of the nozzle is calculated and obtained according to the angle deviation and the distance between the swing center point of the single engine and the plane where the nozzle is located, comprising: Δ = H * sin α Wherein, H is the distance between the swing center point of the single engine and the plane where the 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; α takes the angle deviation between the thrust line and the X axis of the zero position coordinate system, to obtain the adjustment amount Δ1 of the nozzle along the X axis direction of the zero position coordinate system; α takes the angle deviation between the thrust line and the Y axis of the zero position coordinate system, to obtain the adjustment amount Δ2 of the nozzle along the Y axis direction of the zero position coordinate system.

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