Research on Influence of Horizontal Offsets of Underwater Equipment Based on Pendulous Installation Method

2018 ◽  
Author(s):  
Jingqian Wang ◽  
Liping Sun ◽  
Zhongchao Deng ◽  
Gang Ma ◽  
Xiaomeng Zhu ◽  
...  
Keyword(s):  
Deep Water ◽  
Water Environment ◽  
Three Dimensional ◽  
Mooring Line ◽  
Analysis Model ◽  
Lumped Mass ◽  
Lumped Mass Method ◽  
Traction Fluid ◽  
Simulation Problem ◽  
Domain Coupling

Large underwater equipment used in deep-sea engineering, which needs mooring line in order to hang down while using pendulous installation method in 1500m deep-water installation. During the procession, the mooring line will suffer the vessel’s pull, large equipment’s traction, fluid force leading to elongation, bending and other deformation, so need to analyze its motion. Aiming at the numerical simulation problem of underwater equipment installed by pendulous installation method in deep-water environment, this paper combines lumped mass method, three-dimensional potential theory and Morison equation to establish the analysis model of the whole installation system. Under the different horizontal dropping offsets of the equipment, this paper computes not only tension of mooring line, but motion performance of underwater equipment and working vessel during the pendulous lowering phase. The Pendulous Installation Method (PIM) puts a working vessel, a mooring line and a underwater equipment installed in succession, and there is a coupling interaction among them, so it is essential to do time-domain coupling analysis. So the Orcaflex Software is used to simulate the entire deep-water installation system. Using different horizontal dropping position as a variable, we can get the contrast about the different movement states of the mooring line and underwater equipment, and finally we will get the conclusion.

Numerical Modelling of the Mooring Line Failure Induced Performance Changes of a Marine Fish Cage in Irregular Waves and Currents

2019 ◽  
Author(s):  
Hung-Jie Tang ◽  
Ray-Yeng Yang ◽  
Chai-Cheng Huang
Keyword(s):  
Marine Fish ◽  
Low Frequency ◽  
Frequency Region ◽  
Irregular Waves ◽  
Mooring Line ◽  
Lumped Mass ◽  
Lumped Mass Method ◽  
Waves And Currents ◽  
Failure Scenario ◽  
The Time Domain

Abstract This study aims to investigate the performance changes resulted from a mooring line failure of a marine fish cage exposed to irregular waves and current. A numerical model based on the lumped mass method and Morison equation was extended to simulate the mooring line failure scenario. In this study, the failed resulting changes were compared with its normal counterpart in both the time domain and the frequency domain. After one upstream anchor loss, the maximum tension on the remaining anchor has increased significantly, as well as the drift distance of the rearing part (net chamber, floating collar, and tube-sinker) of the fish cage. The resulting changes can also be seen in both the wave-frequency and the low-frequency region in the spectra, including mooring tensions and body motions.

Addition of dynamic mooring line force based on lumped-mass method in SPH

2019 ◽  
Vol 182 ◽  
pp. 90-101 ◽  
Author(s):  
Jie Cui ◽  
Qian Li ◽  
Yong Cheng ◽  
Chun-Yan Ji ◽  
Xiao-Kang Deng
Keyword(s):  
Mooring Line ◽  
Lumped Mass ◽  
Lumped Mass Method ◽  
Line Force

Three-Dimensional Dynamic Analysis Method of Multi-Component Mooring Lines

2019 ◽  
Author(s):  
Yuda Apri Hermawan ◽  
Yoshitaka Furukawa
Keyword(s):  
Dynamic Analysis ◽  
Numerical Method ◽  
Three Dimensional ◽  
Experimental Results ◽  
Mooring Line ◽  
Lumped Mass ◽  
Mooring Lines ◽  
Dynamic Behaviors ◽  
Component Object ◽  
Deep Depth

Abstract Complicated mooring system well-known as a multi-component mooring line is highly required owing to the deep depth of water and severe sea conditions. Since the dynamic behaviors of such mooring line are quite complex, proper numerical method is indispensable to predict the dynamic behaviors of a multi-component mooring line efficiently and precisely. In this paper, a numerical method improving the lumped mass method is proposed to introduce the three-dimensional dynamic analysis of multi-component mooring line with the motion of an anchor and clump weights. The mooring line is regarded as a multi-component object which has nonuniform segment line characteristics. In this method, lumped mass technique is developed to represent the three-dimensional dynamic behavior of each segment individually, allowing the motion of bottom-end segment as well as the anchor. Then, the motion of the end-segment is regarded as the motion of the upper-end of lower segment. Meanwhile, calculation method of initial condition for dynamic calculation is developed by adopting the basic principle of multi-component mooring line catenary equations. The results of time histories representing the three-dimensional dynamic analysis of mooring line are obtained and compared with other numerical and experimental results presented in published papers. The results show good agreement with both numerical and experimental results.

A novel parallel algorithm for computing the mooring line based on lumped-mass method

2017 ◽  
Vol 08 (01) ◽  
pp. 1750004 ◽  
Author(s):  
Zhong-Xian Zhu ◽  
Yong Yin ◽  
Muhammad Mobeen Movania
Keyword(s):  
Parallel Algorithm ◽  
Real Time ◽  
Mooring Line ◽  
Dynamics Model ◽  
Graphic Processing Units ◽  
Lumped Mass ◽  
The Real ◽  
Runge Kutta Method ◽  
Lumped Mass Method ◽  
Speed Up

Dynamic modeling and simulation of the mooring system are the key technologies in anchor handling simulator (AHS). Built up the mooring line’s dynamics model based on lumped-mass method (LMM), and fourth-order Runge–Kutta method was used to solve the model; because of the huge amounts of calculation in the model’s solving, the very time-consuming process brings great impact on the real-time, fidelity and immersed feeling in the anchor handling scene simulation, seriously hindered its application in AHS. A novel parallel algorithm was proposed to speed-up the model’s solving process by taking the advantages of graphic processing units (GPU’s) massive parallel computing and float point computing capability. The model’s solving process was implemented on vertex shader based on the transform feedback (TF) mechanism in modern GPU. Experimental results show that, the new algorithm reduced the calculating time largely without losing accuracy, and can finally realize the real-time solving and simulation.

Modeling and Solving of Non-Linear Vibration Model of the Multi-Clearance and Bend and Torsion Coupled Gear-Driven System

2014 ◽  
Vol 1006-1007 ◽  
pp. 280-284
Author(s):  
Xing Han ◽  
Chang Li
Keyword(s):  
Fast Fourier Transformation ◽  
Analysis Model ◽  
Lumped Mass ◽  
Runge Kutta Method ◽  
Lumped Mass Method ◽  
Driven System ◽  
Non Linear ◽  
Phase Map ◽  
Tooth Flank ◽  
Fifth Order

Comprehensively taking the effects of variable rigidities, tooth flank clearances, bearing clearances, contact rigidities, and other multiple non-linear factors into account, it built a bend and torsion coupled gear-driven system’s dynamics analysis model in use of lumped mass method. After dimensionless dealing, it solved this dynamic model by the method of fifth order adaptive variable step (Runge-Kutta) method, and then it obtained system vibratory responses’ time domain diagrams, frequency domain diagrams, phase map, Poincare diagram, fast Fourier transformation (FFT) diagrams, and system branch diagrams under different parameters. All of them analyzed the effects of parameter variations on gearing system’s dynamic characteristics, and it provided a foundation for gearing system dynamic optimum designs.

Modeling and experimental verification on directivity of an electret cell array loudspeaker

2012 ◽  
Vol 24 (3) ◽  
pp. 326-333 ◽  
Author(s):  
Yu-Chi Chen ◽  
Wen-Ching Ko ◽  
Han-Lung Chen ◽  
Hsu-Ching Liao ◽  
Wen-Jong Wu ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Digital Control System ◽  
Analysis Model ◽  
Cell Array ◽  
Element Analysis ◽  
Finite Element Analysis Model ◽  
The Finite Element Analysis ◽  
Directivity Characteristics

We propose a model to give us a method to investigate the characteristic three-dimensional directivity in an arbitrarily configured flexible electret-based loudspeaker. In recent years, novel electret loudspeakers have attracted much interest due to their being lightweight, paper thin, and possessing excellent mid- to high-frequency responses. Increasing or decreasing the directivity of an electret loudspeaker makes it excellent for adoption to many applications, especially for directing sound to a particular area or specific audio location. Herein, we detail a novel electret loudspeaker that possesses various directivities and is based on various structures of spacers instead of having to use multichannel amplifiers and a complicated digital control system. In order to study the directivity of an electret loudspeaker based on an array structure which can be adopted for various applications, the horizontal and vertical polar directivity characteristics as a function of frequency were simulated by a finite-element analysis model. To validate the finite-element analysis model, the beam pattern of the electret loudspeaker was measured in an anechoic room. Both the simulated and experimental results are detailed in this article to validate the various assertions related to the directivity of electret cell-based smart speakers.

Study of dynamic pressure on the packer for deep-water perforation

Open Physics ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 215-223
Author(s):  
Hao Huang ◽  
Qiao Deng ◽  
Hui Zhang
Keyword(s):  
Deep Water ◽  
Peak Pressure ◽  
Orthogonal Design ◽  
Dynamic Pressure ◽  
Three Dimensional ◽  
Calculation Model ◽  
Well Testing ◽  
Technical Problems ◽  
Wellbore Pressure ◽  
Three Dimensional Finite Element

Abstract The packer is one of the most important tools in deep-water perforation combined well testing, and its safety directly determines the success of perforation test operations. The study of dynamic perforating pressure on the packer is one of the key technical problems in the production of deep-water wells. However, there are few studies on the safety of packers with shock loads. In this article, the three-dimensional finite element models of downhole perforation have been established, and a series of numerical simulations are carried out by using orthogonal design. The relationship between the perforating peak pressure on the packer with the factors such as perforating charge quantity, wellbore pressure, perforating explosion volume, formation pressure, and elastic modulus is established. Meanwhile, the database is established based on the results of numerical simulation, and the calculation model of peak pressure on the packer during perforating is obtained by considering the reflection and transmission of shock waves on the packer. The results of this study have been applied in the field case of deep-water well, and the safety optimization program for deep-water downhole perforation safety has been put forward. This study provides important theoretical guidance for the safety of the packer during deep-water perforating.

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