A method for determining the separation time between stages containing a reverse thrust spring

Abstract

This invention discloses a method for determining the separation time between stages containing thrust reversers and springs. This method can accurately determine the separation time between the booster and the main stage, providing support for separation safety and a reference for the main stage engine ignition time. The method mainly includes three parts: spring reverser time calculation, initial separation time calculation, and complete separation time calculation. First, aerodynamic simulation is used to calculate the aerodynamic forces in the initial state of the spring reverser and the fully extended state of the spring, thereby obtaining the spring reverser time through variable acceleration motion calculation. Then, using the fully extended spring state as the initial time point, the time it takes for the main stage and booster to reach a 5mm gap is calculated as the initial separation time. Subsequently, through coupled computational fluid dynamics and rigid body dynamics simulation, the separation trajectory of the booster under aerodynamic forces is obtained, thus obtaining the time for complete booster separation. Finally, the total separation time including thrust reversers and springs is obtained by summing the three time components.

Description

Technical Field

[0001] This invention relates to the field of aerodynamic simulation and analysis technology for aircraft, specifically to a method for determining the separation time between stages containing thrust reversers. Background Technology

[0002] To achieve greater range and speed, modern spacecraft often employ a main stage plus booster configuration, necessitating careful consideration of interstage separation reliability and safety. Targeted scissor lift, due to its speed and reliability, is widely used for spacecraft structural separation. To ensure safe separation, a significant acceleration difference between the main stage and booster is generally required. In practical engineering, thrust reversers are typically installed at the interstage separation point to increase the booster's reverse acceleration during initial separation. Existing separation time assessment methods generally only consider ideal separation scenarios, judging separation safety through the booster separation trajectory, without considering the influence of thrust reversers. In reality, the separation process involving thrust reversers differs significantly from the ideal separation scenario.

[0003] This invention discloses a method for determining the separation time between stages containing thrust reversers. This method can accurately determine the separation time between stages containing thrust reversers, providing support for separation safety and a reference for the ignition time of the main stage engine. This method simplifies the complex aerodynamic separation process into three time processes, making it easier for engineers to quickly determine the separation time and providing a reference for structural design. Summary of the Invention

[0004] The purpose of this invention is to provide a method for determining the separation time between stages containing thrust reversers, which overcomes the shortcomings of existing methods for determining the separation time between stages containing thrust reversers, facilitates engineers to quickly determine the separation time, provides support for separation safety, and provides a reference for the ignition time of the main stage engine.

[0005] To achieve the above objectives, the present invention provides a method for determining the separation time between stages containing a reverse thrust spring, comprising the following steps:

[0006] Step 1: Establish an aerodynamic simulation model of the aircraft and determine the separation angle of attack α, flight Mach number Ma, separation height H, spring force magnitude and compression amount L;

[0007] Step 2: Determine the booster mass m and the center of mass X c Principal moments of inertia in three directions I 11 I 22 I 33 The calculation neglects the change of aerodynamic force on the motion state of the main stage;

[0008] Step 3: Calculate the initial state boost aerodynamic drag F of the spring reverse thrust using steady-state analysis. L And the aerodynamic drag F0 when the spring is fully extended;

[0009] Step 4: Based on the calculation results in Step 3, calculate the spring push-back time t1 using variable acceleration motion;

[0010] Step 5: Using the spring fully extended as the initial time point, and employing uniform motion, calculate the time it takes for the main stage and booster to reach a gap of 5mm as the initial separation time t2.

[0011] Step 6: Establish a computational fluid dynamics and rigid body dynamics coupled analysis model with a 5mm gap between the main stage and the booster;

[0012] Step 7: Use transient analysis to calculate the trajectory of the booster under the combined action of gravity and aerodynamic forces, and determine the time t3 from the initial separation to the complete separation of the booster and the main stage;

[0013] Step 8: Verify the mesh independence of the coupling analysis model in Step 6 to ensure the accuracy of the calculation results in Step 6;

[0014] Step 9: Calculate the total time T for the separation between the stages including the reverse spring.

[0015] In the aforementioned method for determining the separation time between stages containing a reverse thrust spring, in step one, the spring force magnitude includes: the initial spring force T in the reverse thrust state. L The spring force T0 is the same as when the spring is fully extended.

[0016] The above-mentioned method for determining the separation time between stages containing a reverse-thrust spring, wherein in step four, the variable acceleration motion is an acceleration motion with acceleration changing linearly with time, and the calculation expression for the spring reverse-thrust time t1 is as follows:

[0017]

[0018] Where m is the boost mass.

[0019] In the above method for determining the separation time between stages containing a reverse thrust spring, the calculation expression for the initial separation time t2 in step five is as follows:

[0020]

[0021] Among them, δ is the gap between the main stage and the booster, which is generally taken as 5mm.

[0022] In the aforementioned method for determining the separation time between stages containing a thrust spring, in step six, the relative velocity v between the booster and the main stage is determined using a computational fluid dynamics and rigid body dynamics coupled analysis model. 12 The calculation expression:

[0023]

[0024] In the above-mentioned method for determining the separation time between stages containing a thrust spring, in step seven, the criterion for determining that the main stage and the booster are completely separated is that the minimum distance between the main stage and the booster reaches the absolute value of the distance difference between the booster's center of mass and the front and rear end faces of the booster.

[0025] The above-mentioned method for determining the separation time between stages containing thrust springs, wherein in step eight, the method for verifying the mesh independence of the coupling analysis model is to increase the mesh density of the booster surface by 1.5 times, and the change in the axial force and normal force of the booster does not exceed 5%.

[0026] In the above method for determining the separation time between stages containing the thrust spring, the expression for calculating the total time T for the separation between stages containing the thrust spring in step S9 is as follows:

[0027] T = t1 + t2 + t3.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] (1) The method of the present invention simplifies the complex aerodynamic interstage separation process into three parts: spring back push time, initial separation time, and complete separation time, thereby simplifying the complex aerodynamic coupling analysis and simulation problem and greatly improving the solution efficiency.

[0030] (2) The method of the present invention takes into account the velocity difference between the main stage and the booster caused by the initial back thrust, which improves the accuracy of separation time assessment;

[0031] (3) The method of the present invention can be implemented in general commercial fluid analysis and calculation software, which reduces the threshold for engineers to perform simulation calculations;

[0032] (4) The simulation results obtained by the method of the present invention can provide a reference for the design of the reverse spring structure device and provide support for determining the reverse spring force. Attached Figure Description

[0033] The present invention provides a method for determining the separation time between stages containing a thrust spring, as illustrated in the following embodiments and figures.

[0034] Figure 1 This is a diagram of the fluid calculation model of the present invention;

[0035] Figure 2 This is a diagram showing the initial pressure distribution derived from the reverse process of this invention.

[0036] Figure 3 This is a pressure distribution diagram of the spring in its fully extended state according to the present invention;

[0037] Figure 4 This is a pressure distribution diagram of the main stage and booster in the state of complete separation of the present invention. Detailed Implementation

[0038] The following is a further detailed description of a method for determining the separation time between stages containing a reverse thrust spring according to the present invention.

[0039] A method for determining the separation time between stages containing a thrust spring includes the following steps:

[0040] S1: Establish an aerodynamic simulation model of the aircraft, such as Figure 1 As shown, the separation angle of attack α = 0.1°, the flight Mach number Ma = 1.6, the altitude H = 3km, and the initial spring force T of the spring thrust are... L =4000N, spring force T0=0 in fully extended state, compression L=60mm.

[0041] S2: Boosting mass m = 200 kg, center of mass X c =7m, principal moments of inertia I in three directions 11 =10kg·m 2 I 22 =30kg·m 2 I 33 =30kg·m 2 The calculation neglects the change of aerodynamic force on the motion state of the main stage;

[0042] S3: The initial state booster aerodynamic drag F of the spring thrust is calculated using steady-state analysis. L =10200N and the booster aerodynamic drag F0 in the fully extended spring state =11200N, the reverse initial pressure is as follows Figure 2 As shown, the pressure of the spring in its fully extended state is as follows: Figure 3 As shown;

[0043] S4: Based on the calculation results of S3, the spring counter-thrust time is obtained through variable acceleration motion calculation.

[0044]

[0045] S5: Using the spring at full extension as the initial time point and employing uniform motion, calculate the time it takes for the main stage and booster to reach a 5mm gap as the initial separation time.

[0046]

[0047] S6: Establish a computational fluid dynamics and rigid body dynamics coupled analysis model with a 5mm gap between the main stage and the booster; where the relative velocity between the booster and the main stage is...

[0048]

[0049] S7: The transient analysis method is used to calculate the trajectory of the booster under the combined effects of gravity and aerodynamic forces, such as... Figure 4As shown, the minimum distance between the main stage and the booster reaches the absolute value of the distance difference between the booster's center of mass and the front and rear end faces of the booster, and the main stage and the booster completely separate. The time from the initial separation to the complete separation of the booster and the main stage is t3 = 50.0 ms.

[0050] S8: The mesh independence of the coupled analysis model in S6 was verified by increasing the mesh density of the booster surface by 1.5 times. The calculation showed that the change in the axial force and normal force of the booster did not exceed 5%, and the calculation model met the calculation accuracy requirements.

[0051] S9: Calculate the total time for the separation of the stages including the reverse thrust spring, T = t1 + t2 + t3 = 94.81 ms.

[0052] This invention simplifies the complex aerodynamic stage separation process into three parts: spring pushback time, initial separation time, and complete separation time, thereby simplifying the complex aerodynamic coupling analysis and simulation problem and greatly improving the solution efficiency. At the same time, this invention can be implemented in general commercial fluid analysis software, lowering the simulation calculation threshold for engineers.

[0053] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for determining the separation time between stages containing a reverse thrust spring, characterized in that, The steps include the following: Step 1: Establish an aerodynamic simulation model of the aircraft and determine the separation angle of attack. Mach number of flight Separation height Spring force and compression The magnitude of the spring force includes: the spring force in the initial reverse state. Spring force in the fully extended state ; Step 2: Determine the boost mass Center of mass Principal moments of inertia in three directions , , The calculation neglects the change of aerodynamic force on the motion state of the main stage; Step 3: Calculate the initial state boost aerodynamic drag of the spring thrust using steady-state analysis. And the boost aerodynamic drag when the spring is fully extended ; Step 4: Based on the calculation results in Step 3, calculate the spring push-back time using variable acceleration motion. ; Step 5: Using the spring at full extension as the initial time point, and employing uniform motion, calculate the time it takes for the main stage and booster to reach a 5mm gap as the initial separation time. ; Step 6: Establish a computational fluid dynamics and rigid body dynamics coupled analysis model with a 5mm gap between the main stage and the booster; Step 7: Calculate the trajectory of the booster under the combined effects of gravity and aerodynamic forces using transient analysis methods, and determine the time from initial separation to complete separation between the booster and the main stage. ; Step 8: Verify the mesh independence of the coupling analysis model in Step 6 to ensure the accuracy of the calculation results in Step 6; Step 9: Calculate the total time for separation between stages including the thrust spring. ; In step four, the variable acceleration motion is transformed into an acceleration motion where the acceleration changes linearly with time, and the spring counteracts the time. The calculation expression: ,in, To boost quality; In step five, the initial separation time The calculation expression: ,in, The gap between the main stage and the booster.

2. The method for determining the separation time between stages containing a reverse thrust spring as described in claim 1, characterized in that, In step six, the computational fluid dynamics and rigid body dynamics coupled analysis model is used to determine the relative velocity between the booster and the main stage. The calculation expression: 。 3. The method for determining the separation time between stages containing a reverse thrust spring as described in claim 2, characterized in that, In step seven, the criterion for determining that the main stage and the booster are completely separated is that the minimum distance between the main stage and the booster reaches the absolute value of the distance difference between the booster's center of mass and the front and rear end faces of the booster.

4. The method for determining the separation time between stages containing a reverse thrust spring as described in claim 3, characterized in that, In step eight, the method for verifying the mesh independence of the coupled analysis model is to increase the mesh density of the booster surface by 1.5 times, and the change in the booster axial force and normal force does not exceed 5%.

5. The method for determining the separation time between stages containing a reverse thrust spring as described in claim 4, characterized in that, In step nine, step S9 includes the total time for the separation between the reverse spring stages. Calculate the expression: 。

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