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CN-116467902-B - Liquid carrier rocket transverse vibration analysis method considering shaking effect

CN116467902BCN 116467902 BCN116467902 BCN 116467902BCN-116467902-B

Abstract

The invention provides a liquid carrier rocket transverse vibration analysis method considering a shaking effect, which is characterized in that liquid in a storage tank has the shaking effect and comprises the steps of 1, establishing a finite element model for whole rocket transverse vibration analysis, 2, collecting the structural size of each storage tank of the carrier rocket and liquid parameters in the storage tank, 3, enabling first-order shaking liquid in the storage tank to be equivalent to a transverse spring vibrator model, 4, recalculating the liquid level, 5, establishing a mass unit of the shaking liquid in the storage tank, 6, establishing a spring connection node of the mass unit of the shaking liquid in the storage tank, 7, connecting a reference node with the spring connection node through the spring unit, 8, simulating the rest liquid in the storage tank by adopting a virtual mass method, 9, repeating, 10, submitting finite element analysis software to complete the calculation. The invention can effectively simulate the influence of the liquid shaking effect in the storage tank on the transverse vibration characteristic of the whole rocket, and is convenient for obtaining more accurate transverse vibration characteristic of the whole rocket.

Inventors

  • TAN JINQIANG
  • HONG GANG
  • ZHU LIANGCONG
  • MAO YUMING
  • SUN DAN
  • HU LIANGLIANG
  • WU TIAN

Assignees

  • 上海宇航系统工程研究所

Dates

Publication Date
20260508
Application Date
20230320

Claims (10)

  1. 1. The method for analyzing the transverse vibration of the liquid carrier rocket by considering the sloshing effect is characterized in that the liquid carrier rocket comprises a liquid propellant storage tank, and liquid in the storage tank has the sloshing effect, and the method comprises the following steps: Step 1, collecting a digital prototype model of a carrier rocket solid structure, and establishing a finite element model of full rocket transverse vibration analysis; Step 2, collecting the structural size of each storage tank of a carrier rocket and the liquid parameters in the storage tank, wherein the structural size of the storage tank refers to the radius R i of the inner edge of a storage tank barrel section, the liquid parameters in the storage tank refer to the liquid density rho i , the liquid level height H i , the first-order shaking mass M i , the coordinate X i of the first-order shaking mass center along the axial direction of an rocket body and the first-order shaking frequency f i , and i is the storage tank code number; Step 3, the first-order shaking liquid in the storage tank is equivalent to a transverse spring vibrator model, wherein the vibrator mass is equal to the first-order shaking mass M i , and the calculation formula of the spring stiffness K i is K i ＝M i ·(2·π·f i ) 2 ; Step 4, subtracting the shaking part in the step 3 from the liquid in the storage tank, and recalculating the liquid level height, wherein a new liquid level height h i has a calculation formula as follows: step 5, a mass unit of shaking liquid in the storage tank is built in a full arrow transverse vibration analysis model, and the position reference node coordinate of the mass unit is (X i , 0); Step 6, establishing a spring connection node of a shaking liquid mass unit in the storage tank in the full arrow transverse vibration analysis model, and fixedly connecting the spring connection node with an adjacent storage tank structure node; Step 7, connecting the reference node of the shaking liquid mass unit in the step 5 with the spring connecting node in the step 6 through a spring unit, and referring to the stiffness value of the spring unit in the step 3; Step 8, simulating the rest liquid in the storage tank by adopting a virtual mass method according to the new liquid level height h i obtained in the step 4; step 9, repeating the steps 3-8, and enabling all shaking liquid in the storage tanks to be equivalent to a transverse spring vibrator model; And 10, setting all-arrow modal solving parameters, including setting a modal extraction method and a modal frequency range, and submitting finite element analysis software to complete the solving.
  2. 2. A method of analyzing lateral vibrations of a liquid carrier rocket in consideration of sloshing effect as recited in claim 1, wherein the lateral vibrations are vibrations of the carrier rocket which are elastically deformed by bending after being disturbed in a direction perpendicular to a longitudinal direction of the rocket body.
  3. 3. A method of analyzing lateral vibration of a liquid carrier rocket in consideration of sloshing effect according to claim 1, wherein the digital sample machine model in step 1 can accurately describe the actual external dimensions of the solid structure and includes using mechanical characteristic parameters of the material, wherein the mechanical characteristic parameters are material density, elastic modulus, shear modulus and poisson ratio.
  4. 4. The method for analyzing the transverse vibration of the liquid carrier rocket by considering the shaking effect according to claim 1, wherein the finite element model for analyzing the transverse vibration of the whole rocket in the step 1 adopts a hybrid modeling form of a three-dimensional entity unit, a shell unit, a beam unit and a mass unit, and the storage tank structure is simulated by adopting the shell unit.
  5. 5. A method of analyzing the lateral vibrations of a liquid carrier rocket in view of the sloshing effect as recited in claim 1, wherein the liquid sloshing mass unit in the tank in step 5 acts only on two orthogonal degrees of freedom of lateral translation, the lateral direction being the direction perpendicular to the axis of the rocket body.
  6. 6. A method of analyzing lateral vibration of a liquid carrier rocket in view of sloshing effect as claimed in claim 1, wherein the spring connection nodes in step 6 are established near the sloshing centroid, and the structural nodes fixedly connected with the spring connection nodes are not too much, wherein the fixedly connected form is a rigid connection form in the finite element modeling method.
  7. 7. A method of analyzing the lateral vibrations of a liquid carrier rocket in view of the sloshing effect as recited in claim 1, wherein the stiffness properties of the spring units in step 7 are applied to only two orthogonal degrees of freedom of lateral translation, the lateral direction being the direction perpendicular to the axis of the rocket body.
  8. 8. The method of claim 1, wherein in step 8, a virtual mass method is used to simulate the rest of the liquid in the tank, and a wet unit set, a liquid density, a liquid level height and a liquid level reference coordinate system are required to be set.
  9. 9. A method of analyzing lateral vibration of a liquid carrier rocket in view of sloshing effects as recited in claim 1, wherein the liquid carrier rocket includes 4 liquid propellant reservoirs.
  10. 10. The method for analyzing the transverse vibration of the liquid carrier rocket considering the sloshing effect according to claim 1, wherein in the step 8, a local coordinate system parallel to a global coordinate system is established by taking the theoretical lowest point of the inner edge of the rear bottom of the storage tank as an origin, the local coordinate system is referred to for a new liquid level height, and then the shell units of the rear bottom of the storage tank and the barrel section are set as single-sided wet units with wetted inner walls.

Description

Liquid carrier rocket transverse vibration analysis method considering shaking effect Technical Field The invention belongs to the technical field of finite element modeling analysis of carrier rockets, relates to a carrier rocket transverse vibration analysis method, and particularly relates to a liquid carrier rocket transverse vibration analysis method considering a shaking effect. Background The liquid carrier rocket is widely applied in the field of aerospace transportation due to the advantages of high engine specific impulse, strong working adaptability and the like, and the liquid rocket accounts for half of the ratio in the active carrier rocket spectrum at home and abroad. The dynamic characteristics of the whole rocket, particularly the transverse vibration characteristics of the liquid carrier rocket, are important inputs of important design links such as the design of the whole rocket load, the design of environmental conditions, the design of a stabilizing system and the like, so that the acquisition of the dynamic characteristics of the whole rocket which are as accurate as possible is particularly important. The finite element method is a widely used and effective numerical calculation method for acquiring the dynamic characteristics of the whole rocket, and along with the improvement of the reliability requirement of the carrier rocket, the requirement of the finite element calculation precision is also improved. The traditional finite element model of the liquid carrier rocket mainly comprises beam units and concentrated mass units, liquid in a storage tank is simplified into the concentrated mass units, in recent years, a combined modeling method of three-dimensional modeling and a liquid virtual mass method is popular, and model precision is effectively improved. However, in the flying process of the carrier rocket, the liquid in the storage tank always generates a shaking effect due to the existence of external interference, the shaking effect often has an important influence on the frequency characteristic of the whole rocket, particularly the first-order bending mode frequency, and the influence of the shaking effect on the dynamic characteristic of the whole rocket cannot be considered in the two modeling modes, so that the finite element modeling analysis method of the liquid carrier rocket is developed by taking the shaking effect into consideration. Disclosure of Invention The invention aims to provide a liquid carrier rocket transverse vibration analysis method considering a shaking effect, which effectively simulates the influence of the shaking effect on the dynamic characteristics of a whole rocket, thereby improving the finite element analysis precision and obtaining more accurate transverse vibration characteristics of the whole rocket. In order to achieve the aim of the invention, the invention is realized by the following technical scheme: the method for analyzing the transverse vibration of the liquid carrier rocket by considering the sloshing effect is characterized in that the liquid carrier rocket comprises a liquid propellant storage tank, and liquid in the storage tank has the sloshing effect, and the method comprises the following steps: Step 1, collecting a digital prototype model of a carrier rocket solid structure, and establishing a finite element model of full rocket transverse vibration analysis; Step 2, collecting the structural size of each storage tank of a carrier rocket and the liquid parameters in the storage tank, wherein the structural size of the storage tank refers to the radius R i of the inner edge of a storage tank barrel section, the liquid parameters in the storage tank refer to the liquid density rho i, the liquid level height H i, the first-order shaking mass M i, the coordinate X i of the first-order shaking mass center along the axial direction of an rocket body and the first-order shaking frequency f i, and i is the storage tank code number; Step 3, the first-order shaking liquid in the storage tank is equivalent to a transverse spring vibrator model, wherein the vibrator mass is equal to the first-order shaking mass M i, and the calculation formula of the spring stiffness K i is K i＝Mi·(2·π·fi)2; Step 4, subtracting the shaking part in the step 3 from the liquid in the storage tank, and recalculating the liquid level height, wherein a new liquid level height h i has a calculation formula as follows: step 5, a mass unit of shaking liquid in the storage tank is built in a full arrow transverse vibration analysis model, and the position reference node coordinate of the mass unit is (X i, 0); Step 6, establishing a spring connection node of a shaking liquid mass unit in the storage tank in the full arrow transverse vibration analysis model, and fixedly connecting the spring connection node with an adjacent storage tank structure node; Step 7, connecting the reference node of the shaking liquid mass unit in the step 5 with the spring connecting