A method for evaluating the collision characteristics of large-diameter rocket stage-to-stage spin ejection

Abstract

A large-diameter rocket interstage rotational ejection separation collision characteristic evaluation method, comprising the following steps: step S1, taking the separation surface center of the rocket and the first and second sub-stages in the non-separation state as the coordinate origin, establishing a combined body dynamics evaluation model, and determining the initial parameters of the structure parameters, mass characteristics and envelope geometric dimensions; step S2, based on the initial parameters, calculating the relative speed and angular velocity of the first and second sub-stages at the initial separation time; step S3, checking the geometric non-collision criterion for each time period interval in the relative motion process of the first and second sub-stages from the start of separation to the completion of one rotation of each other. The evaluation method can realize the phased and refined evaluation of the collision risk.

Description

Technical Field

[0001] This invention relates to the field of spacecraft separation dynamics analysis, and specifically to a method for evaluating the collision characteristics of large-diameter rockets that use a spinning jet propulsion method for interstage separation. Background Technology

[0002] Stage separation of large launch vehicles is a crucial step in their flight, and its success or failure directly determines the success or failure of the mission. For large-diameter rockets, spin-jet separation is a cold separation technique. Its core principle is to utilize the centrifugal effect generated by the rocket body rotating around its longitudinal axis, causing the separated stages to disperse simultaneously laterally and axially. This method is simple in structure and highly reliable, but in the initial stage of separation, the close proximity and complex relative motion of the two stages pose a high risk of collision.

[0003] Currently, assessments of separation collisions largely rely on full-process numerical simulations. This method is computationally intensive and makes it difficult to quickly and intuitively pinpoint the highest-risk motion phases and dominant collision modes.

[0004] Therefore, there is an urgent need for a method that can quickly, efficiently, and specifically evaluate the rotational ejection and separation collision characteristics of large-diameter rockets in order to guide the optimized design of the separation system and improve separation reliability. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for evaluating the collision characteristics of interstage rotational jettisoning in large-diameter rockets. This method divides the complex, continuous separation process into critical intervals based on risk patterns and establishes targeted geometric non-collision criteria, achieving a phased and refined assessment of collision risks, significantly improving assessment efficiency and the targeted nature of optimization design.

[0006] The technical solution of the present invention is as follows:

[0007] A method for evaluating the interstage rotational ejection and collision characteristics of large-diameter rockets includes the following steps:

[0008] Step S1: Using the center of the separation surface of the first and second stages of the rocket in the unseparated state as the origin of the coordinate system, establish a dynamic evaluation model of the combined body and determine the initial parameters of the structural parameters, mass characteristics and envelope geometry.

[0009] Step S2: Based on the initial parameters, calculate the relative velocity and angular velocity of the first and second sub-stages at the initial moment of separation.

[0010] Step S3: Perform geometric non-collision criterion verification for each time interval during the relative motion process of the first and second sub-stages from the start of separation until they each complete one rotation.

[0011] The preceding steps, S3, include:

[0012] Based on the main collision risk patterns during relative motion, the time intervals from the start of separation to the completion of one rotation for each of the two sub-stages are divided into multiple consecutive time intervals; and

[0013] For each time interval, a geometric non-collision criterion is established between the first and second sub-levels based on their motion trajectories and envelope geometry after separation within that time interval.

[0014] Step S4: If the non-collision criterion is not met in any time interval, optimize and adjust the rocket structural parameters or attitude control parameters, and repeat steps S1-S3 until the non-collision criterion is met in any time interval.

[0015] Furthermore, in step S1, the mass characteristics include the positions of the first-level centroid, the second-level centroid, and the combined centroid relative to the origin of the coordinate system.

[0016] Further, in step S1, the envelope geometry includes the distance from the first stage's center of mass to the outer envelope lines in the four directions of the first stage's body (up, down, left, and right), and the distance from the second stage's center of mass to the outer envelope lines in the four directions of the second stage's body (up, down, left, and right).

[0017] Furthermore, in step S2, at the moment of separation, both the first and second stage rocket bodies rotate around their respective centers of mass at the same angular velocity.

[0018] Furthermore, in step S3, the time interval is divided into four parts, namely:

[0019] Interval 1: From the moment of unlocking and separation until the relative rotation angle between the first and second sub-stages around the axis reaches 90 degrees;

[0020] Interval 2: Starting from the end of Interval 1, until the relative rotation angle around the axis reaches 180 degrees;

[0021] Interval 3: Starting from the end of Interval 2, until the relative rotation angle around the axis reaches 270 degrees;

[0022] Interval 4: Starting from the end of Interval 3, until both the first and second sub-stages have completed at least one full rotation.

[0023] Furthermore, in step S3, the main collision risk modes include circumferential sweep collisions caused by the difference in initial rotational angular velocities between the first and second substages, and asymmetric oscillating collisions caused by the centroid shift between the first and second substages.

[0024] Furthermore, in step S1, the initial state of spin-projectile separation in the dynamic model is divided into different types based on whether the first-stage centroid, the second-stage centroid, and the combined centroid are coaxial, and evaluated accordingly.

[0025] Furthermore, the initial state is divided into three types:

[0026] Type 1: The first-stage and second-stage centers of mass are not coaxial, each deviating towards the precession direction;

[0027] Type 2: The first-stage and second-stage centers of mass are coaxial;

[0028] Type 3: The first-stage and second-stage centers of mass are not coaxial and are each far from the precession direction.

[0029] Furthermore, in step S4, if a geometric collision risk is determined, the objects of optimization and adjustment are prioritized to be the centroid position and structural shape of the first and / or second sub-levels.

[0030] The assessment method of this application establishes a dynamic assessment model, takes the influence of structural parameters, mass characteristics and envelope geometry as key parameters, and combines the quantitative criterion of minimum distance of geometric envelope to divide the continuous separation process into several key intervals according to the risk mode, thereby realizing the "segmented and focused" assessment of collision risk. This makes the assessment standard objective and uniform, significantly improves the analysis efficiency, and realizes the phased and refined assessment of collision risk.

[0031] It should be understood that the above general description and the following specific embodiments are merely exemplary and illustrative, and do not limit the scope of the invention. Attached Figure Description

[0032] The accompanying drawings, which are part of the specification of this invention, illustrate exemplary embodiments of the invention. The drawings, together with the description in the specification, serve to illustrate the principles of the invention.

[0033] Figure 1 The flowchart below shows the overall process for evaluating the rotational ejection and separation collision characteristics of large-diameter rocket stages, as provided in this embodiment of the invention.

[0034] Figure 2 This is a schematic diagram of the coordinate system and the geometric model of the arrow body envelope established in an embodiment of the present invention.

[0035] Figures 3 to 6 This is a schematic diagram of the critical states of collisions between two sub-stages in four time intervals after the separation of the first and second sub-stages in an embodiment of the present invention. Detailed Implementation

[0036] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and to exemplify the principles of the present invention, and are not configured to limit the present invention. In addition, the structural components in the drawings are not necessarily drawn to scale. For example, the dimensions of some structural components or regions in the drawings may be enlarged for other structural components or regions to aid in the understanding of the embodiments of the present invention.

[0037] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of the embodiments of the present invention. In the description of the present invention, it should be noted that, unless otherwise stated, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0038] Furthermore, the terms "comprising," "including," "having," or any other variations thereof are intended to cover non-exclusive inclusion, such that a structure or component that includes a list of elements includes not only those elements but also other structural elements that are not expressly listed or inherent to the structure or component. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the article or apparatus that includes the element.

[0039] Spatial relation terms such as "below," "under," "under," "low," "above," "on," and "high" are used for descriptive convenience to explain the positioning of one element relative to a second element, indicating that these terms are intended to cover different orientations of the device, in addition to those different from those shown in the figure. Furthermore, phrases such as "one element on / below another element" can indicate that two elements are in direct contact, or that there are other elements between the two elements. In addition, terms such as "first" and "second" are also used to describe individual elements, areas, parts, etc., and should not be considered limiting. Similar terms are used throughout the description to refer to similar elements.

[0040] It will be apparent to those skilled in the art that the present invention can be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention.

[0041] Figure 1The flowchart below shows the overall process for evaluating the rotational ejection and separation collision characteristics of large-diameter rocket stages, as provided in this embodiment of the invention. Figure 2 This is a schematic diagram of the coordinate system and the geometric model of the arrow body envelope established in an embodiment of the present invention. Figures 3 to 6 This is a schematic diagram of the critical states of collisions between two sub-stages in four time intervals after the separation of the first and second sub-stages in an embodiment of the present invention.

[0042] like Figure 1 As shown in the figure, this embodiment provides a method for evaluating the rotational jettison and separation collision characteristics of large-diameter rocket stages. The specific implementation steps are as follows:

[0043] Step S1: Using the center of the separation surface of the first and second stages of the rocket in the unseparated state as the origin of the coordinate system, establish a dynamic evaluation model of the combined body and determine the initial parameters of the structural parameters, mass characteristics and envelope geometry.

[0044] like Figure 2 As shown, a Cartesian coordinate system xOy is established with the center O of the separation surface between the first and second stages of the rocket as the origin. The x-axis points in the direction of rocket body rotation, and the y-axis points along the rocket axis towards the rocket nose. A simplified multibody dynamics model including the first and second stages is established.

[0045] Determine the initial parameters of the model:

[0046] Structural parameters: The main structural dimensions of the first-stage and second-stage rocket bodies. In this embodiment, the first-stage and second-stage rocket bodies can adopt rectangular envelopes. In order to improve the evaluation accuracy, polygonal or elliptical envelopes that fit the shape of the rocket body can also be used.

[0047] Mass characteristics: First-stage mass m1, second-stage mass m2, first-stage center of mass G1, second-stage center of mass G2, combined center of mass G0, distances from first-stage center of mass G1 and second-stage center of mass G2 to combined center of mass G0. , The combined body rotates around its center of mass G0 at an angular velocity .

[0048] Envelope geometry: To simplify collision detection, the complex shapes of the first and second stages are simplified into geometric envelopes based on their respective centers of mass. For example, the distances from the first stage's center of mass G1 to its outer envelope surfaces in the four directions of +Y (up), -Y (down), -X (left), and +X (right) are recorded. , , , The distance from the second stage's center of mass G2 to the outer envelope of its second stage body in the four directions of +Y (up), -Y (down), -X (left), and +X (right). , , , .

[0049] Calculate the geometric proportionality coefficient , range [0,1].

[0050] Based on the positional relationship between the centroids of the first and second stages relative to the centroid of the combined body before separation, the initial state of spin-projectile separation in the dynamic model is divided into three types (e.g., Figure 2 (as shown)

[0051] Type 1: First-order mass center and the center of mass of the second stage They are not collinear along the y-axis, and each deviates towards the direction of precession;

[0052] Type 2: First-order mass center and the center of mass of the second stage Collinear along the y-axis;

[0053] Type 3: First-order mass center and the center of mass of the second stage They are not collinear along the y-axis and are each far from the direction of precession.

[0054] By classifying the initial separation states according to the relative positions of the centroids, separation schemes under different configurations or deviations can be evaluated more effectively, thus expanding the applicability and depth of the method.

[0055] Step S2: Based on the initial parameters, calculate the relative velocity and angular velocity of the first and second sub-stages at the initial moment after unlocking.

[0056] Based on the model and initial parameters from step 1, the initial motion states of the first and second sub-stages are calculated by applying the momentum and angular momentum theorems or directly solving the multibody dynamics equations, at the instant of separation and unlocking (t=0). In the simplified model of this embodiment, it is assumed that after unlocking, the first and second sub-stages rotate around their respective centers of mass with equal initial angular velocities ω in the same direction under the separation action.

[0057] First-stage rocket body: translational velocity of the center of mass angular velocity of rotation about the center of mass G1 .

[0058] Second-stage rocket body: translational velocity of the center of mass angular velocity of rotation about the center of mass G2 .

[0059] Step S3: Perform geometric non-collision criterion verification for each time interval during the relative motion process of the first and second sub-stages from the start of separation until they each complete one rotation.

[0060] The steps preceding S3 include: dividing the time interval from the start of separation to the completion of one rotation of each of the two sub-classes into multiple continuous time intervals based on the main collision risk patterns during relative motion; and for each time interval, establishing a geometric non-collision criterion between the first and second sub-classes based on the motion trajectory and envelope geometry of the two sub-classes after separation within that time interval.

[0061] The motion process of the first and second stages from separation to each completing one rotation is divided into four key continuous time intervals based on their relative rotation angle around the axis.

[0062] 1. Interval 1 [0, Collision characteristics of rotation angle: In the initial stage of separation, both stages begin to rotate.

[0063] like Figure 3 As shown, the rocket separation rotation angle is in the interval [0, ... [Diagram showing the motion relationship between the two sub-stages. For Type 1 and Type 2, after unlocking, the distance between the centers of mass of the two sub-stages increases monotonically, allowing them to move away rapidly; there is no risk of collision in this range.]

[0064] For type three, due to the initial stage ( The distance between the centroids of the two sub-stages will decrease, posing a risk of continuous contact or collision. The analysis of type 3 will not be considered in subsequent intervals.

[0065] 2. Interval Two [ , Collision characteristics of rotation angle: Circumferential sweep core stage one. The overlapping area of ​​the two-stage envelope projections in the plane perpendicular to the rocket axis is the largest, which is the stage with the highest risk of collision during circumferential sweep.

[0066] like Figure 4 As shown, the rocket separation rotation angle is within the range [ , This diagram illustrates the critical state at which two sub-stages collide. In this interval, the primary collision mode is a collision between the upper right corner of the first sub-stage and the lower left corner of the second sub-stage. To ensure no collision occurs, the geometric non-collision criterion requires at least one of the following two geometric criteria to be met:

[0067] 1) , The straight-line distance is always greater than + ;

[0068] 2) , The straight-line distance is equal to + hour, , The straight-line distance is greater than + .

[0069] The centers of mass of the first and second stages are respectively , ;

[0070] , The equation of the line is:

[0071]

[0072]

[0073] , Linear spacing:

[0074]

[0075] , The equation of the line is:

[0076]

[0077]

[0078] , Linear spacing:

[0079]

[0080] Substituting criteria 1) and 2) into simplified mathematical expressions, the results are as follows:

[0081]

[0082] hour,

[0083] 3. Interval Three [ , Collision characteristics based on rotation angle: Circumferential sweeping core stage two. Similar to interval two, this is another high-risk sweeping stage.

[0084] like Figure 5 As shown, the rocket separation rotation angle is within the range [ , This diagram illustrates the critical state at which two stages collide. In this interval, the primary collision mode is the collision between the lower right corner of the first stage and the upper left corner of the second stage. To ensure no collision occurs, the geometric non-collision criterion requires at least one of the following two geometric criteria to be met:

[0085] 3) , The distance between the lines is always greater than + ;

[0086] 4) , The distance between the lines is equal to + hour, , The distance between the lines is greater than + .

[0087] The calculation process is the same as in interval two. After simplification, the mathematical expressions for criteria 3) and 4) are as follows:

[0088]

[0089] hour,

[0090] 4. Interval Four [ , Collision characteristics of rotation angle: Rotational stabilization phase. The two stages have basically completed the establishment of separation attitude, and the main assessment is whether they have entered a stable, collision-free relative motion trajectory.

[0091] like Figure 6 As shown, the rocket separation rotation angle is within the range [ , This diagram illustrates the critical state at which two stages collide. In this interval, the primary collision mode is the collision between the lower left corner of the first stage and the upper right corner of the second stage. To ensure no collision occurs, the geometric non-collision criterion requires at least one of the following two geometric criteria to be met:

[0092] 5) , The distance between the lines is always greater than + ;

[0093] 6) , The distance between the lines is equal to + hour, , The distance between the lines is greater than + .

[0094] The calculation process is the same as in interval two. After simplification, the mathematical expressions for criteria 5) and 6) are as follows:

[0095]

[0096] hour,

[0097] Based on analytical and geometric methods, this invention provides a clear and concise evaluation process and criteria, revealing the direct mathematical relationship between key design parameters such as centroid distance and structural envelope dimensions and collision risk. This helps designers to deeply understand the impact of each parameter on separation safety and provides intuitive and clear guidance for design optimization.

[0098] Step S4: If the non-collision criterion is not met in any time interval, optimize and adjust the rocket structural parameters or attitude control parameters, and repeat steps S1-S3 until the non-collision criterion is met in any time interval.

[0099] For the four intervals divided in step S3, their corresponding geometric non-collision criteria are applied sequentially for verification. If all evaluation intervals meet the non-collision criteria, the spin-projectile separation scheme is determined to be safe and without collision risk. If any interval does not meet the collision criteria, the scheme is determined to have a collision risk, and the initial design parameters need to be adjusted. The optimization should prioritize the centroid position and structural shape of the first and / or second stages, and a re-evaluation should be conducted. Specifically, the optimization direction can prioritize design parameters that affect the mode, such as: adjusting the centroid position of the first or second stage (changing the oscillation characteristics), and optimizing the local structural shape of the rocket body (increasing the envelope gap). This targeted optimization, compared to blindly adjusting all parameters, can greatly improve the efficiency of design iteration.

[0100] This invention simplifies complex space dynamics problems into two-dimensional planar analytical geometry problems, avoiding complex three-dimensional modeling, mesh generation, and lengthy numerical solutions. Evaluation requires only simple algebraic and trigonometric function operations and can be completed within seconds, greatly improving evaluation efficiency. It is particularly suitable for early-stage rocket design, including scheme demonstration, parameter sensitivity analysis, and rapid selection of multiple schemes.

[0101] This invention uses the rectangular outer envelope of the arrow body as the collision criterion, which is essentially a conservative evaluation strategy. As long as the envelope does not collide, the actual circular or irregular cross-section arrow body will certainly not collide. This conservatism provides a more reliable safety margin for engineering design. When the criterion for a certain interval is not met, it can be directly linked to the typical risk mode and initial state type of that interval, thereby providing targeted optimization suggestions such as adjusting the centroid position, local shape, or separation parameters, forming an efficient "evaluation-diagnosis-optimization" design closed loop.

[0102] This method does not rely on expensive commercial simulation software and high-performance computing clusters; it can be implemented using only general-purpose computing software or even spreadsheets, significantly reducing R&D costs and technical barriers, and facilitating widespread application.

[0103] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for evaluating the interstage rotational jettison and separation collision characteristics of large-diameter rockets, characterized in that, Includes the following steps: Step S1: Using the center of the separation surface of the first and second stages of the rocket in the unseparated state as the origin of the coordinate system, establish a dynamic evaluation model of the combined body and determine the initial parameters of the structural parameters, mass characteristics and envelope geometry. Step S2: Based on the initial parameters, calculate the relative velocity and angular velocity of the first stage and the second stage at the initial moment of separation; Step S3: Perform geometric non-collision criterion verification for each time interval during the relative motion process of the first and second sub-stages from the start of separation until they each complete one rotation; The preceding steps, S3, include: Based on the main collision risk patterns during relative motion, the time interval from the start of separation to the completion of one rotation for each of the two sub-stages is divided into multiple consecutive time intervals; as well as For each time interval, a geometric non-collision criterion is established between the first and second sub-levels based on their motion trajectories and envelope geometry after separation within that time interval.

2. The method for evaluating the interstage rotational jettison and separation collision characteristics of large-diameter rockets according to claim 1, characterized in that, Following step S3, the following is also included: Step S4: If the non-collision criterion is not met in any time interval, optimize and adjust the rocket structural parameters or attitude control parameters, and repeat steps S1-S3 until the non-collision criterion is met in any time interval.

3. The method for evaluating the interstage rotational ejection and separation collision characteristics of large-diameter rockets according to claim 1, characterized in that, In step S1, the mass characteristics include the positions of the first-level centroid, the second-level centroid, and the composite centroid relative to the origin of the coordinate system.

4. The method for evaluating the interstage rotational jettison and separation collision characteristics of large-diameter rockets according to claim 3, characterized in that, In step S1, the envelope geometry includes the distance from the first stage's center of mass to the outer envelope lines in the four directions of up, down, left, and right of the first stage rocket body, and the distance from the second stage's center of mass to the outer envelope lines in the four directions of up, down, left, and right of the second stage rocket body.

5. The method for evaluating the interstage rotational jettison and separation collision characteristics of large-diameter rockets according to claim 1, characterized in that, In step S2, at the moment of separation, both the first and second stage rocket bodies rotate around their respective centers of mass at the same angular velocity.

6. The method for evaluating the interstage rotational jettison and separation collision characteristics of large-diameter rockets according to claim 1, characterized in that, The time period is divided into four intervals, namely: Interval 1: From the moment of unlocking and separation until the relative rotation angle between the first and second sub-stages around the axis reaches 90 degrees; Interval 2: Starting from the end of Interval 1, until the relative rotation angle between the first and second sub-stages around the axis reaches 180 degrees; Interval 3: Starting from the end of Interval 2, until the relative rotation angle around the axis between the first and second sub-stages reaches 270 degrees; Interval 4: Starting from the end of Interval 3, until both the first and second sub-stages have completed at least one full rotation.

7. The method for evaluating the interstage rotational jettison and separation collision characteristics of large-diameter rockets according to claim 6, characterized in that, In step S3, the main collision risk modes include, but are not limited to: circumferential sweep collisions caused by the difference in the initial rotational angular velocities of the first and second sub-stages, and asymmetric oscillating collisions caused by the centroid shift of the first and second sub-stages.

8. The method for evaluating the interstage rotational jettison and separation collision characteristics of large-diameter rockets according to claim 4, characterized in that, In step S1, the initial state of spin-projectile separation in the dynamic model is divided into different types based on whether the first-stage centroid, the second-stage centroid, and the combined centroid are coaxial.

9. The method for evaluating the interstage rotational jettison and separation collision characteristics of a large-diameter rocket according to claim 8, characterized in that, The initial state of spin-projectile separation can be divided into three types: Type 1: The first-stage and second-stage centers of mass are not coaxial and are each biased toward the precession direction; Type 2: The first-stage and second-stage mass centers are coaxial; Type 3: The first-stage and second-stage centers of mass are not coaxial and are each far from the precession direction.

10. The method for evaluating the interstage rotational ejection and separation collision characteristics of a large-diameter rocket according to claim 2, characterized in that, If a geometric collision risk is determined, the optimization and adjustment should prioritize the position of the centroid and the structural shape of the first and / or second sub-classes.

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