A Method of the Dynamic Analysis of Pipeline Systems Considering the Effects of Casing

2004 ◽  
Author(s):  
Lin Li ◽  
Jun Sheng
Keyword(s):  
Structural Design ◽  
Complex Structure ◽  
Pipeline System ◽  
Rigid Surface ◽  
Free Interface ◽  
Modal Synthesis ◽  
Aero Engine ◽  
Pipeline Systems ◽  
Fixed Interface ◽  
Whole Systems

The paper deals with a new method called ‘mixed interface direct component modal synthesis’ to determine the modal parameters of a large and complex structure, such as outer casing-pipeline systems of aero-engine. In this method, the whole structure is divided into several parts. The interface of the main substructure (large and complex component) is considered as a free-interface, and that of the other branch substructures are considered as fixed-interfaces. The computation of each substructure is entirely independent. Especially this method simplifies the optimization of structural design. For case-pipeline systems for example, the changes of the location of the pipe’s support will have no influence on the casing model. Hence reduplicate computation is no longer needed. The analysis of pipeline systems using fixed-interface is just the same as the usual analysis, which clamps all of the interface DOFs on a rigid surface. Two examples, a cantilever beam and a simulative case-pipeline system, are considered. Both of them also are analyzed as whole systems in ANSYS, a widely used FEM software. The numerical results obtained by this method and by ANSYS are compared, and they are identical.

Research on Dynamic Characteristics of Bladed Disk System by Fixed Interface Prestressed-Free Interface CMS Super-Element Method

2015 ◽  
Vol 724 ◽  
pp. 218-221
Author(s):  
Liang Zhang ◽  
Xin Li ◽  
Tie Jian Liu
Keyword(s):  
Dynamic Characteristics ◽  
Complex Structure ◽  
Maximum Relative Error ◽  
Disk System ◽  
Free Interface ◽  
Bladed Disk ◽  
Substructure Analysis ◽  
Characteristics Analysis ◽  
Fixed Interface ◽  
Element Method

For the prestressed substructure analysis, the existing CMS super-element methods are only suitable for the model that relatively simple structure, less meshing and small number of nodes. Since the complex structure and more mesh division of an arbitrary large model such as a mistuned bladed disk system, it is more time-consuming for the dynamic characteristics analysis. Because of above shortcoming, an approximate analysis method is presented, it is called fixed interface prestressed-free interface CMS super-element method. The accuracy of this method is predicted by the example. The results showed that the dimensionless dynamic frequency maximum relative error of system is 3.072215%, which can be to meet the requirement of accuracy.

scholarly journals A Multiple and Multi-Level Substructure Method for the Dynamics of Complex Structures

2021 ◽  
Vol 11 (12) ◽  
pp. 5570
Author(s):  
Binbin Wang ◽  
Jingze Liu ◽  
Zhifu Cao ◽  
Dahai Zhang ◽  
Dong Jiang
Keyword(s):  
Structural Characteristics ◽  
Complex Structure ◽  
Complex Structures ◽  
System Matrix ◽  
Substructure Method ◽  
Residual Structure ◽  
The Matrix ◽  
Multi Level ◽  
Fixed Interface ◽  
Selection Of

Based on the fixed interface component mode synthesis, a multiple and multi-level substructure method for the modeling of complex structures is proposed in this paper. Firstly, the residual structure is selected according to the structural characteristics of the assembled complex structure. Secondly, according to the assembly relationship, the parts assembled with the residual structure are divided into a group of substructures, which are named the first-level substructure, the parts assembled with the first-level substructure are divided into a second-level substructure, and consequently the multi-level substructure model is established. Next, the substructures are dynamically condensed and assembled on the boundary of the residual structure. Finally, the substructure system matrix, which is replicated from the matrix of repeated physical geometry, is obtained by preserving the main modes and the constrained modes and the system matrix of the last level of the substructure is assembled to the upper level of the substructure, one level up, until it is assembled in the residual structure. In this paper, an assembly structure with three panels and a gear box is adopted to verify the method by simulation and a rotor is used to experimentally verify the method. The results show that the proposed multiple and multi-level substructure modeling method is not unique to the selection of residual structures, and different classification methods do not affect the calculation accuracy. The selection of 50% external nodes can further improve the analysis efficiency while ensuring the calculation accuracy.

Research on the Parameter Optimization of Certain Complex Structure

2011 ◽  
Vol 268-270 ◽  
pp. 200-204
Author(s):  
Bao Cheng Zhang ◽  
Peng Fei Zhao ◽  
Peng Li
Keyword(s):  
Structural Design ◽  
Cylinder Head ◽  
Maximum Stress ◽  
Combustion Engine ◽  
Mechanical Load ◽  
Structural Parameters ◽  
Complex Structure ◽  
Parameter Study ◽  
Side Plate ◽  
Von Mises

Using the method of the parameter study, some important dimensions of the cylinder head of an internal-combustion engine are analyzed. Under the mechanical load, the variational rules of the Von Mises maximum stress on cylinder head are obtained, which are influenced by the thickness of the floor plate, head plate, jobbing sheet, standing partition board, and side plate of inlet port and exhaust port. A hypothesis is verified that there is an ideal matching point among those above-mentioned main parameters. The quantificational proportion relations, between these key structural parameters and Von-Mises maximum stress of cylinder head, can provide a good help for the cylinder head’s structural design.

scholarly journals Experimental and Numerical Vibration Analysis of Hydraulic Pipeline System under Multiexcitations

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Peixin Gao ◽  
Hongquan Qu ◽  
Yuanlin Zhang ◽  
Tao Yu ◽  
Jingyu Zhai
Keyword(s):  
Pressure Fluctuations ◽  
Fluid Motion ◽  
Fluid Pressure ◽  
Point Of View ◽  
Pipeline System ◽  
Base Excitation ◽  
Fem Method ◽  
Pipeline Systems ◽  
Pump Pressure ◽  
Improved Model

Pipeline systems in aircraft are subjected to both hydraulic pump pressure fluctuations and base excitation from the engine. This can cause fatigue failures due to excessive vibrations. Therefore, it is essential to investigate the vibration behavior of the pipeline system under multiexcitations. In this paper, experiments have been conducted to describe the hydraulic pipeline systems, in which fluid pressure excitation in pipeline is driven by the throttle valve, and the base excitation is produced by the shaker driven by a vibration controller. An improved model which includes fluid motion and base excitation is proposed. A numerical MOC-FEM approach which combined the coupling method of characteristics (MOC) and finite element method (FEM) is proposed to solve the equations. The results show that the current MOC-FEM method could predict the vibration characteristics of the pipeline with sufficient accuracy. Moreover, the pipeline under multiexcitations could produce an interesting beat phenomenon, and this dangerous phenomenon is investigated for its consequences from engineering point of view.

Influence of Reference Conditions in the Analysis of the Impact of Flexible Bodies

2001 ◽  
Author(s):  
José L. Escalona ◽  
Juana Mayo ◽  
Jaime Domínguez
Keyword(s):  
Rigid Body ◽  
Reference Conditions ◽  
Normal Modes ◽  
Frame Of Reference ◽  
The Body ◽  
Natural Boundary Condition ◽  
Flexible Bodies ◽  
Free Interface ◽  
Fixed Interface ◽  
The Impact

Abstract In this paper, the floating frame of reference approach is applied to the dynamics of the impact of flexible bodies, while component mode synthesis is used to describe deformation. The influence of the reference conditions, that indicate the type of attachment between the body fixed frame of reference and the flexible bodies, is investigated. Rigid and free attachments allow the use of fixed interface and free interface normal modes, respectively. A finite number of fixed interface modes does not fulfil the natural boundary condition at the attachment point. Free interface normal modes cannot describe the compressive forces at the contact surface. However, it is shown that both set of modes are able to describe the impact-induced elastic waves. In the evaluation of the kinematic coefficient of restitution, these two approaches differ significantly. When free attachment is considered, the derivatives of the reference co-ordinates coincide with the equivalent rigid body velocities of the flexible bodies, remaining constant after the impact. However, if the body frame of reference is rigidly attached, the equivalent rigid body velocities of the flexible body have to be evaluated as a linear combination of the derivative of reference and elastic co-ordinates. The axial impact of a rigid body on a flexible rod and the transverse impact of a flexible pendulum with a fixed stop are simulated to illustrate these facts. Hertzian contact forces are assumed to occur during impact.

Development Direction of Pipeline Corrosion Research on Oil Refining and Chemical Enterprises

2020 ◽  
Vol 993 ◽  
pp. 1230-1234
Author(s):  
Xiao Jia Zhang ◽  
Rui Wang ◽  
Shang Yu Yang
Keyword(s):  
Corrosion Behavior ◽  
Low Risk ◽  
Oil Refining ◽  
Pipeline System ◽  
Corrosive Environment ◽  
Development Direction ◽  
A Site ◽  
Whole Systems ◽  
Corrosion Research ◽  
Pipeline Corrosion

The corrosion behavior of refinery due to severe corrosive environment was investigated in the present study, and the analysis was focused on the guiding of the corrosion into a site where is near the ground, easy to change, have low risk and so on. The corrosion parts were analyzed to study the influences of the corrosion pipe in the whole systems. Some suggestions were proposed to choose the corrosion site that can happened. By using the developed method in this study the low risk position of pipeline as a sacrificial location can be found, and then taking it as the priority corrosion place under the control of switchable subline. It is therefore to shut down for maintenance of whole pipeline, and to easily replace the corrosion parts without stop all. The serious corrosion of refining pipeline system can consequently be reduced and removed, thereby to make the long-cycle operation of refining factory be realized.

scholarly journals Hydraulic Engineering at 100 BC-AD 300 Nabataean Petra (Jordan)

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3498
Author(s):  
Charles R. Ortloff
Keyword(s):  
Water Supply ◽  
Flow Rate ◽  
Distribution Systems ◽  
Maximum Flow ◽  
Hydraulic Engineering ◽  
World Heritage Site ◽  
Maximum Flow Rate ◽  
Pipeline System ◽  
Supply And Distribution ◽  
Pipeline Systems

The principal water supply and distribution systems of the World Heritage site of Petra in Jordan were analyzed to bring forward water engineering details not previously known in the archaeological literature. The three main water supply pipeline systems sourced by springs and reservoirs (the Siq, Ain Braq, and Wadi Mataha pipeline systems) were analyzed for their different pipeline design philosophies that reflect different geophysical landscape challenges to provide water supplies to different parts of urban Petra. The Siq pipeline system’s unique technical design reflects use of partial flow in consecutives sections of the main pipeline to support partial critical flow in each section that reduce pipeline leakage and produce the maximum flow rate the Siq pipeline can transport. An Ain Braq pipeline branch demonstrated a new hydraulic engineering discovery not previously reported in the literature in the form of an offshoot pipeline segment leading to a water collection basin adjacent to and connected to the main water supply line. This design eliminates upstream water surges arising from downstream flow instabilities in the two steep pipelines leading to a residential sector of Petra. The Wadi Mataha pipeline system is constructed at the critical angle to support the maximum flow rate from a reservoir. The analyses presented for these water supply and distribution systems brought forward aspects of the Petra urban water supply system not previously known, revising our understanding of Nabataean water engineers’ engineering knowledge.

Designing Offshore Pipeline Safety Systems Utilising Flow and Pressure in Multi Design Pressure Pipeline Systems

2008 ◽  
Author(s):  
Gjertrud Elisabeth Hausken ◽  
Jo̸rn-Yngve Stokke ◽  
Steinar Berland
Keyword(s):  
Pressure Drop ◽  
Flow Measurement ◽  
Large Diameter ◽  
Pressure Sensors ◽  
Safety System ◽  
Pipeline System ◽  
Outlet Pressure ◽  
Pipeline Systems ◽  
Pipeline Safety ◽  
Design Pressure

The Norwegian Continental Shelf (NCS) has been a main arena for development of subsea pipeline technology over the last 25 years. The pipeline infrastructure in the North Sea is well developed and new field developments are often tied in to existing pipeline systems, /3/. Codes traditionally require a pipeline system to be designed with a uniform design pressure. However, due to the pressure drop when transporting gas in a very long pipeline, it is possible to operate multi design pressure systems. The pipeline integrity is ensured by limiting the inventory and local maximum allowable pressure in the pipeline using inlet and outlet pressure measurements in a Safety Instrumented System (SIS). Any blockage in the pipeline could represent a demand on the safety system. This concept was planned to be used in the new Gjo̸a development when connecting the 130 km long rich gas pipeline to the existing 450 km long FLAGS pipeline system. However, a risk assessment detected a new risk parameter; the formation of a hydrate and subsequent blockage of the pipeline. In theory, the hydrate could form in any part of the pipeline. Therefore, the pipeline outlet pressure could not be used in a Safety Instrumented System to control pipeline inventory. The export pressure at Gjo̸a would therefore be limited to FLAGS pipeline code. Available pressure drop over the Gjo̸a pipeline was hence limited and a large diameter was necessary. Various alternatives were investigated; using signals from neighbour installations, subsea remote operated valves, subsea pressure sensors and even a riser platform. These solutions gave high risk, reduced availability, high operating and/or capital expenses. A new idea of introducing flow measurement in the SIS was proposed. Hydraulic simulations showed that when the parameters of flow, temperature and pressure, all located at the offshore installation, were used; a downstream blockage could be detected early. This enabled the topside export pressure to be increased, and thereby reduced the pipeline diameter required. Flow measurement in Safety Instrumented Systems has not been used previously on the NCS. This paper describes the principles of designing a pipeline safety system including flow measurement with focus on the hydraulic simulations and designing the safety system. Emphasis will be put on improvements in transportation efficiency, cost reductions and operational issues.

Seismic Vulnerability Assessment and Retrofit of a Major Natural Gas Pipeline System: A Case History

2005 ◽  
Vol 21 (2) ◽  
pp. 539-567 ◽  
Author(s):  
Dharma Wijewickreme ◽  
Douglas Honegger ◽  
Allen Mitchell ◽  
Trevor Fitzell
Keyword(s):  
Natural Gas ◽  
Vulnerability Assessment ◽  
Seismic Vulnerability ◽  
Ground Improvement ◽  
Lateral Spreading ◽  
Gas Pipeline ◽  
Pipeline System ◽  
Seismic Vulnerability Assessment ◽  
Natural Gas Pipeline ◽  
Pipeline Systems

The performance of pipeline systems during earthquakes is a critical consideration in seismically active areas. Unique approaches to quantitative estimation of regional seismic vulnerability were developed for a seismic vulnerability assessment and upgrading program of a 500-km-long natural gas pipeline system in British Columbia, Canada. Liquefaction-induced lateral spreading was characterized in a probabilistic manner and generic pipeline configurations were modeled using finite elements. These approaches, developed during the early part of this 10-year program, are more robust than typical approaches currently used to assess energy pipeline systems. The methodology deployed within a GIS environment provided rational means of distinguishing between seismically vulnerable sites, and facilitated the prioritization of remedial works. While ground improvement or pipeline retrofit measures were appropriate for upgrading most of the vulnerable sites, replacement of pipeline segments using horizontal directional drilling to avoid liquefiable zones were required for others.

Overpressure Protections in Liquid Pipeline Hydraulic Design

2016 ◽  
Author(s):  
Alan X. L. Zhou ◽  
David Yu ◽  
Victor Cabrejo
Keyword(s):  
New Technologies ◽  
Pressure Control ◽  
Petroleum Products ◽  
Integrated System ◽  
Operating Conditions ◽  
Design Stage ◽  
Pipeline System ◽  
Protection Measures ◽  
Pipeline Systems ◽  
Pipeline Design

Continuous economic development demands safe and efficient means of transporting large quantities of crude oil and other hydrocarbon products over vast extensions of land. Such transportation provides critical links between organizations and companies, permitting goods to flow between their facilities. Operation safety is paramount in transporting petroleum products in the pipeline industry. Safety can affect the performance and economics of pipeline system. Pipeline design codes also evolve as new technologies become available and management principles and practices improve. While effective operation safety requires well-trained operators, adequate operational procedures and compliance with regulatory requirements, the best way to ensure process safety is to implement safety systems during the design stage of pipeline system. Pressure controls and overpressure protection measures are important components of a modern pipeline system. This system is intended to provide reliable control and prevent catastrophic failure of the transport system due to overpressure conditions that can occur under abnormal operating conditions. This paper discusses common pressure surge events, options of overpressure protection strategies in pipeline design and ideas on transient hydraulic analyses for pipeline systems. Different overpressure protection techniques considered herein are based on pressure relief, pressure control systems, equipment operation characteristics, and integrated system wide approach outlining complete pressure control and overpressure protection architecture for pipeline systems. Although the analyses presented in this paper are applicable across a broad range of operating conditions and different pipeline system designs, it is not possible to cover all situations and different pipeline systems have their own unique solutions. As such, sound engineering judgment and engineering principles should always be applied in any engineering design.

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