CN-121997574-A - Cantilever type deep sea mining pipeline vibration response numerical forecasting method under outflow excitation

CN121997574ACN 121997574 ACN121997574 ACN 121997574ACN-121997574-A

Abstract

A cantilever type deep sea mining pipeline vibration response numerical forecasting method under outflow excitation belongs to the technical field of pipeline lifting type mining. The invention aims to solve the problem that the two-end hinged marine riser model is difficult to effectively simulate the complex dynamic response of a cantilever pipeline under the real deep sea mining working condition. The method comprises the steps of establishing vibration control equations of a cantilever pipeline in the transverse direction and the flow direction respectively aiming at a vortex-induced vibration coupling model of the cantilever pipeline with a concentrated mass block at the tail end, integrating an external flow field excitation model of the transverse direction and the flow direction into the vibration control equations, coupling a cantilever pipeline structure with the external flow field based on a vector analysis theory, establishing a cantilever pipeline vibration numerical value forecasting model under the action of outflow excitation, and solving the coupling model based on a central difference method and a backward difference method with second-order precision aiming at the cantilever pipeline vibration numerical value forecasting model under the action of outflow excitation so as to realize cantilever deep sea mining pipeline vibration response numerical value forecasting.

Inventors

GAO YUN
Qi zhengyang
CHENG ZHIKANG
FANG QINGHE

Assignees

哈尔滨工业大学（威海）

Dates

Publication Date: 20260508
Application Date: 20260112

Claims (10)

1. A cantilever type deep sea mining pipeline vibration response numerical forecasting method under outflow excitation is characterized by comprising the following steps: Step 1, regarding a cantilever pipeline with a concentrated mass block at the tail end and a flow direction vortex-induced vibration coupling model, regarding a cantilever vertical lifting pipeline as an Euler-Bernoulli beam, and respectively establishing vibration control equations of the cantilever pipeline in the transverse direction and the flow direction; Step 2, establishing a transverse and flow-direction external flow field excitation model based on a wake vibrator model, respectively integrating the transverse and flow-direction external flow field excitation model into a vibration control equation of the cantilever pipeline established in the transverse and flow directions, and coupling the cantilever pipeline structure with the external flow field based on a vector analysis theory, so as to establish a cantilever pipeline vibration numerical prediction model under the action of outflow excitation; And 3, aiming at the cantilever pipeline vibration numerical forecasting model under the action of outflow excitation, carrying out numerical solution on the coupling model based on a central difference method and a backward difference method with second-order precision so as to realize the cantilever deep sea mining pipeline vibration response numerical forecasting.
2. The method for predicting vibration response values of the cantilever type deep sea mining pipeline under outflow excitation according to claim 1, wherein the vibration control equation of the cantilever type pipeline established in the transverse direction and the flow direction respectively is as follows: (1) (2) Wherein m is the mass of the cantilever pipeline vibration system in unit length, and R s and R f respectively represent the structural damping coefficient and the fluid damping coefficient; in order to calculate the partial Stohar vortex shedding frequency according to the Stohar relation, X, Y, Z represents the displacement of the pipeline along the X, Y, Z axial direction, T is time, O-XYZ is the world coordinate system, and Z is perpendicular to the XOY plane; 、 the cantilever pipeline is stressed in the X, Y axial direction, namely fluid force, wherein EI is bending rigidity; Representing a deviation derivative; Is the axial tension at any coordinate Z.
3. The method for predicting vibration response value of cantilever type deep sea mining pipeline under outflow excitation according to claim 2, wherein the mass m of the cantilever type pipeline vibration system in unit length is as follows: (3) in the formula, 、 And The pipeline material density, the pipeline internal fluid density and the pipeline external fluid density are respectively, and C M is an additional mass coefficient; And Is the inner and outer diameter of the pipe.
4. A method for predicting vibration response of a cantilever type deep sea mining pipeline under outflow excitation according to claim 3, wherein the axial tension at any coordinate Z M b represents the end concentration mass attached at the lower free boundary position, g is the gravitational acceleration, L is the cantilever pipe length, and W r represents the wet weight of the structure per unit length.
5. The method for predicting vibration response of a cantilever type deep sea mining pipeline under outflow excitation according to claim 4, wherein the wet weight of the structure per unit length is as follows 。
6. The method for predicting vibration response values of the cantilever type deep sea mining pipeline under outflow excitation according to any one of claims 1 to 5, wherein an external flow field excitation model of transverse and flow directions established based on a wake vibrator model is as follows: (17) (18) Wherein, the Is the density of the fluid outside the pipeline; The device is the outer diameter of a pipeline, C D0 and C L0 respectively represent oscillation drag force coefficients and lift force coefficients on a static pipeline, p (Z, T) and q (Z, T) respectively represent wake vibrator variables of the pipeline in the motion states of wake vibrators in X and Y directions, namely the oscillation states of fluid acting force generated by vortex shedding, and U (Z) represents incoming flow speed along the axial direction of the pipeline, namely the Z direction; 、、 is a dimensionless parameter related to speed, T is time; Is the average drag coefficient.
7. The method for predicting vibration response values of the cantilever type deep sea mining pipeline under the outflow excitation according to claim 6, wherein the model for predicting vibration values of the cantilever type deep sea mining pipeline under the outflow excitation is as follows: (23) (24) (25) (26) Wherein, the For conversion to an intermediate variable in dimensionless form, The frequency is calculated according to the reference flow velocity U ref ; Is based on The result obtained by dimensionless treatment is that, 、 Is based on 、 A dimensionless result; 、 Is based on 、 Omega f (z) represents different flow profiles; 、 A x and a y are empirical parameters, Is a viscous force coefficient; The mass ratio is as follows; 、、、、 is a non-dimensional parameter, and is a non-dimensional parameter, C D (Z, T) and C L (Z, T) represent average drag coefficient, oscillating drag coefficient, and lift coefficient, respectively, C D0 and C L0 represent oscillating drag coefficient and lift coefficient on stationary pipes, For the Stohal number, EI is the bending stiffness, m is the overall mass of the pipe, Is axial tension.
8. The method for predicting vibration response of a cantilever type deep sea mining pipeline under outflow excitation according to claim 7, wherein the flow profile ω f (z)=U(z)/U ref ,U ref is a reference flow velocity, and U (Z) is an incoming flow velocity U (Z) along the axial direction of the pipeline Results after transformation.
9. The method for predicting vibration response of a cantilever type deep sea mining pipeline under outflow excitation according to claim 8, wherein the reference flow rate U ref is the maximum flow rate in the flow profile.
10. The method for predicting vibration response values of a cantilever type deep sea mining pipeline under outflow excitation according to claim 7, wherein the step of solving the spread values of the coupling model based on a center difference method and a backward difference method with second-order accuracy comprises the steps of: Assuming that the total length of the cantilever pipe body in a dimensionless manner is divided into M sections, and the M+1 discrete space points are expressed as z=z i , i=0, 1,2, & gt, M; the calculated dimensionless total time t total is divided into N segments, the discrete n+1 time points are expressed as t=t j , j=0, 1,2,..n, and the corresponding dimensionless parameters x, y, p and q at the z m position at the time of t n are assumed to be expressed as 、、 And Further according to 、、 And Performing second-order center differential representation on each partial derivative term in (23) - (26), and simultaneously performing second-order center differential representation on each partial derivative term And The middle partial derivative term is expressed in a second-order backward differential format, then is substituted into a formula (23) -a formula (26) and is arranged, and x, y, p, q at the initial moment is brought into a value at a moment x, y, p, q of t=t 1 ; after the time t=t 2 , the final x, y, p and q are obtained by repeated iterative solution in combination with the solution of the boundary conditions to y and q.

Description

Cantilever type deep sea mining pipeline vibration response numerical forecasting method under outflow excitation Technical Field The invention belongs to the technical field of pipeline lifting type mining, and particularly relates to a deep sea mining pipeline vibration response numerical forecasting method. Background The ocean is not only an important component of the global ecological system, but also contains huge resources on which human future development depends. The exploration results in recent years further show that the submarine mineral resources in China are rich in reserves and huge in development potential, and the submarine mineral resources are high-efficient in development and utilization, have long-term strategic values for guaranteeing national resource safety and promoting economic and social sustainable development, and are extremely wide in future development space. However, these resources are often located on the seafloor, which is several kilometers deep, and the harsh environmental conditions make the mining process challenging. Therefore, development of deep sea mining technology has become an important research direction in the field of ocean engineering in the world today, and pipeline lifting type mining systems are widely regarded as the most promising development mode in the world due to the structural integrity and high technical maturity. A pipeline-lifting mining system is shown in fig. 1, wherein a vertical lifting pipeline with a large slenderness ratio is the pulse of the whole mining system and is the weak link with the highest technical difficulty and the most breakthrough. How to ensure that the vertical lifting pipeline does not generate instability or large vibration under the outflow effect is one of the key problems to be solved in the research of deep sea mining systems. When the actual deep sea mining operation is carried out, the vertical lifting pipeline is exposed to the action of external ocean currents for a long time, vortex shedding can be generated behind the pipeline when the ocean currents bypass the pipeline, periodic vortex shedding can generate periodic hydrodynamic load on the structure, vortex-induced vibration of the structure is induced, and further fatigue damage is caused to the structure. If fatigue fracture occurs in the vertical lifting pipeline, the fatigue fracture can not only directly lead to failure of a key conveying channel of a deep sea mining system, cause operation interruption and equipment damage, but also possibly cause ore pulp leakage, and cause potential pollution to marine ecology. In the research of vortex-induced vibration response characteristics of a pipeline under the action of outflow excitation at present, most of the existing research objects are marine risers with hinged two ends, which are conventionally used for oil and gas transportation, and the vibration response of a cantilever pipeline with one end fixedly supported and the other end free for ore transportation in a real marine environment is concerned with insufficient attention. In addition, in the prior research on the coupling response characteristics of the cross flow and the vortex-induced vibration of the ocean riser in the forward flow direction, for convenience of research, the fluid force applied to the ocean riser is mostly simplified based on the assumption that the vibration speed of the ocean riser is small compared with the flow speed. In actual deep sea mining operation, the simplified treatment is difficult to comprehensively reflect the coupling stress characteristics of the marine riser in the cross flow and forward flow directions and the vibration response mechanism thereof. Therefore, in order to accurately evaluate the dynamic characteristics and the vibration response rules of the vertical lifting pipeline under the action of ocean currents, it is very necessary to establish a numerical forecasting model which fully considers the stress and the complete vibration mutual coupling action of the cantilever type marine riser in the transverse direction and the flow direction, and to research the vibration response characteristics under the action of the external flow excitation based on the method. The research can provide important technical support for the early engineering design of the cantilever type deep sea vertical lifting pipeline and the safe operation of the service stage of the cantilever type deep sea vertical lifting pipeline. Currently, there is a technical gap in cantilever type lifting pipeline vibration response numerical prediction for ore transportation in deep sea mining. The existing method is mostly dependent on a two-end hinged marine riser model which is conventionally used for oil and gas transportation, and the model is difficult to effectively simulate the complex dynamic response of a cantilever pipeline under the actual deep sea mining working condition. In addition, in the prior art, complete coupling an