Design Challenges and Experience With Controlled Lateral Buckle Initiation Methods

2009 ◽  
Author(s):  
Forbes Sinclair ◽  
Malcolm Carr ◽  
David Bruton ◽  
Tim Farrant
Keyword(s):  
Control Method ◽  
Axial Stress ◽  
Local Buckling ◽  
Operating Conditions ◽  
Design Solution ◽  
Operational Experience ◽  
Complex Flow ◽  
Lateral Buckling ◽  
Weld Fatigue ◽  
Design Challenges

Subsea pipelines are increasingly being required to operate at higher temperatures and pressures. The natural tendency of such a pipeline is to relieve the resulting high axial stress in the pipe-wall by buckling. Uncontrolled buckling can have serious consequences for the integrity of a pipeline. An elegant and cost-effective design solution to this problem is to work with rather than against the pipeline by controlling the formation of lateral buckles along the pipeline. Controlled lateral buckling is a relatively new design option which has matured as more projects have adopted the approach. As with all new design techniques, knowledge and understanding has improved and evolved with design application, installation and operational experience. Methods used to control the formation of lateral buckles include snake lay, vertical upsets, localised weight reduction and local seabed imperfections. Selecting the right buckle initiation method for a flowline can be a complex issue which is influenced by the flowline type, operating conditions, environmental conditions and pipe-soil interaction. Detailed lateral buckling design is normally concerned with achieving reliable buckle formation, minimising the peak strains in the flowline (local buckling) and controlling through life girth weld fatigue. However, as lateral buckling design has progressed, other design challenges have become apparent, which must be considered during design. This paper discusses commonly used buckle initiation methods and focuses on the key design challenges associated with lateral buckling, in the light of feedback from operational experience of recently installed flowlines. Many of the design challenges are common to all initiation methods, such as pipe-soil interaction or girth weld fatigue. However, there are a number of issues which can be specific to a particular buckle control method or pipeline project, these can include sour service operating conditions or complex flow assurance implications. The paper highlights key information required for lateral buckling design and outlines typical test programmes performed to support the design process. Crucially, many of the flowline design issues identified in this paper have been identified as a result of lessons learnt from operational experience. This affirms the importance of rigorous visual inspection and survey to monitor the performance of flowlines during the first months and years after start-up.

On Pipeline Lateral Buckling: Lessons Learned and Current Design Challenges

2012 ◽  
Author(s):  
Emil A. Maschner ◽  
Basel Abdalla
Keyword(s):  
Cost Effective ◽  
Lessons Learned ◽  
Operating Conditions ◽  
Design Solution ◽  
Lateral Buckling ◽  
Diverse Range ◽  
Applied Loading ◽  
Direct Design ◽  
Safety Margins ◽  
Global Buckling

The subject of lateral buckling design in recent years has by necessity become increasingly more involved as pipeline projects have moved into more difficult environments where there is a need for optimized economic solutions with assured through-life reliability. The authors have had direct design responsibility and specialist involvement with a large number of projects covering a diverse range of environments, single or PIP systems, variable product characteristics and operating conditions, external applied loading type, and geographical installation limitations. These include shallow and deep water, large thin walled and small thick walled diameter pipes, flat to undulating hard to soft seabed, variable cohesive and non-cohesive surficial soil types and various other project considerations which have impacted on the chosen design solution. The purpose of this paper will be to highlight aspects of global buckling design associated with reliable in place systems and conversely those aspects associated with integrity risks to the as-laid operational pipelines. A review of past project challenges along with a commentary as to the state of the art at the time gives an opportunity to evaluate risks and challenges being faced on current projects. Particularly, as it seeks to develop ever more cost effective designs with proven robustness but optimized safety margins for the installation and operation of HT/HP pipelines in marginal fields.

scholarly journals Simple Design Solution for Harsh Operating Conditions: Redesign of Conveyor Transfer Station with Reverse Engineering and DEM Simulations

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4008
Author(s):  
Błażej Doroszuk ◽  
Robert Król ◽  
Jarosław Wajs
Keyword(s):  
Reverse Engineering ◽  
Laser Scanning ◽  
Design For Manufacturing ◽  
Operating Conditions ◽  
Design Solution ◽  
Dem Simulations ◽  
Transfer Station ◽  
Transfer Stations ◽  
Dem Model ◽  
Current Operating

This paper addresses the problem of conveyor transfer station design in harsh operating conditions, aiming to identify and eliminate a failure phenomenon which interrupts aggregate supply. The analyzed transfer station is located in a Polish granite quarry. The study employs laser scanning and reverse engineering methods to map the existing transfer station and its geometry. Next, a discrete element method (DEM) model of granite aggregate has been created and used for simulating current operating conditions. The arch formation has been identified as the main reason for breakdowns. Alternative design solutions for transfer stations were tested in DEM simulations. The most uncomplicated design for manufacturing incorporated an impact plate, and a straight chute has been selected as the best solution. The study also involved identifying areas of the new station most exposed to wear phenomena. A new transfer point was implemented in the quarry and resolved the problem of blockages.

Sootblowing Optimization Improves Heat Rate and Enhances Operational Flexibility at Hawthorn Unit 5

2014 ◽  
Author(s):  
Neel J. Parikh ◽  
Peter Rogge ◽  
Kenneth Luebbert
Keyword(s):  
Control System ◽  
Closed Loop ◽  
Heat Rate ◽  
Operating Conditions ◽  
Operational Experience ◽  
Unit Operation ◽  
Gas Temperature ◽  
Dynamic Adjustment ◽  
Operational Parameters ◽  
Unit Load

Coal-fired units are increasingly expected to operate at varying loads while simultaneously dealing with various operational influences as well as fuel variations. Maintaining unit load availability while managing adverse effects of various operational issues such as, flue gas temperature excursions at the SCR inlet, high steam temperatures and the like presents significant challenges. Dynamic adjustment of sootblowing activities and different operational parameters is required to effectively control slagging, fouling and achieve reliability in unit operation. Closed-loop optimizers aim to reduce ongoing manual adjustments by control operators and provide consistency in unit operation. Such optimizers are typically computer software-based and work by interfacing an algorithmic and/or artificial intelligence based decision making system to plant control system [1]. KCP&L is in the process of implementing Siemens SPPA-P3000 combustion and sootblowing optimizers at several Units. The Sootblowing Optimizer solution determines the need for sootblowing based on dynamic plant operating conditions, equipment availability and plant operational drivers. The system then generates sootblower activation signals for propagation in a closed-loop manner to the existing sootblower control system at ‘optimal’ times. SPPA-P3000 Sootblowing Optimizer has been successfully installed at Hawthorn Unit 5, a 594-MW, wall-fired boiler, firing 100 percent Powder River Basin coal. This paper discusses implementation approach as well as operational experience with the Sootblowing Optimizer and presents longer-term operational trends showing unit load sustainability and heat rate improvement.

scholarly journals Flow Field Investigation in the Exit Region of a Radial Inflow Turbine Using LDV

1994 ◽  
Author(s):  
D. Muthuvel Murugan ◽  
Widen Tabakoff ◽  
Awatef Hamed
Keyword(s):  
Flow Field ◽  
Field Investigation ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Complex Flow ◽  
Tip Clearance Flow ◽  
Exit Region ◽  
Flow Investigation ◽  
Clearance Flow ◽  
Radial Inflow Turbine

Detailed flow investigation in the downstream region of a radial inflow turbine has been performed using a three component Laser Doppler Velocimetry. The flow velocities are measured in the exit region of the turbine at off-design operating conditions. The results are presented as contour and vector plots of mean velocities, flow angles and turbulent stresses. The measured parameters are correlated to the rotor blade rotation to observe any periodic nature of the flow. The measurements reveal a complex flow pattern near the tip region at the rotor exit due to the interaction of the tip clearance flow. The degree of swirl of the flow near the tip region at the rotor exit is observed to be high due to the gross under turning of the flow near the tip region. The effect of the rotor on the exit flow field is observed in the proximity of the rotor exit.

Investigation of Brush Seal Flow Characteristics Using Bulk Porous Medium Approach

2005 ◽  
Vol 127 (1) ◽  
pp. 136-144 ◽  
Author(s):  
Yahya Dogu
Keyword(s):  
Porous Medium ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Operating Conditions ◽  
Force Balance ◽  
Complex Flow ◽  
Blow Down ◽  
Permeability Coefficients ◽  
Backing Plate ◽  
Brush Seal

The flow behavior through a brush seal has been investigated by developing a flow analysis procedure with a porous medium approach. In order to increase the brush seal performance and use at more severe operating conditions, the complex flow in the bristle pack has become the major concern affecting seal features such as blow-down, hang-up, hysteresis, and bristle flutter. In this study, an axisymmetric CFD model is employed to calibrate anisotropic permeability coefficients for the bristle pack based on available experimental data: leakage, axial pressure on the rotor surface, and radial pressure on the backing plate. A simplified form of the force balance equation is introduced for the flow in the porous bristle pack. Different sets of permeability coefficients are defined for the fence height region below the seal backing plate and the upper region of the seal to correlate the different physical structures and behavior of these regions during operation. The upper region is subject to more stiffening due to backing plate support while the fence height region is free to spread and bend in the axial direction. It is found that flow resistance for the upper region should be 20% higher than the fence height region in order to match the experimental pressure within the bristle pack. Analysis results prove that the brush seal is well represented as a porous medium with this approach. Based on the model developed, characteristic flow and pressure fields in the entire bristle pack have been explored.

scholarly journals Assessment of vehicle brake control functional stability

2021 ◽  
Vol 12 (2) ◽  
pp. 33-44
Author(s):  
Volodymyr Volkov ◽  
◽  
Igor Gritsuk ◽  
Tetiana Volkova ◽  
Volodymyr Kuzhel ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Control Method ◽  
Operating Conditions ◽  
National Standards ◽  
Passenger Vehicles ◽  
The Difference ◽  
Braking Control ◽  
The Stability ◽  
Friction Surfaces

The article is devoted to the study of the influence of the brake control elements of passenger vehicles on the stability of their braking properties. The analysis of the influence of uneven braking forces on the wheels of one axle of vehicles on the deviation of the distribution of braking forces between the axles from its calculated value is carried out. When assessing the error in regulating the distribution of braking forces between the axles of vehicles, three components were taken into account: the theoretical error due to the imperfection of the selected control method (the difference between the actual calculated control characteristic from the ideal), the error created due to the instability of the ratio of the braking forces on the front and rear wheels, an additional error caused by the unevenness of the braking forces on the wheels of individual axles, since the fulfillment of the most stringent requirements of international and national standards for the efficiency of braking of vehicles and is inextricably linked with the need to increase the energy consumption of brake mechanisms. The energy consumption of braking mechanisms is understood as the ability of the latter to dissipate the greatest amount of energy of the braking machine without reducing the braking efficiency indicators to the minimum permissible level. Excessive heating of the braking mechanisms leads to a decrease in the friction coefficient μ of the friction surfaces and increased wear of the friction linings, and the brakes are the most unstable element of the braking control, which ensures the absorption and dissipation of the vehicle's energy during braking. The instability of the braking torques on the front and rear wheels, caused by a change in the coefficients of friction of friction pairs, leads not only to a change in the distribution of braking forces between the axles and individual wheels, but also to a decrease in the braking efficiency of vehicles under operating conditions. A method is proposed that makes it possible to assess the quality of regulation of the distribution of braking forces between the axles of a car, taking into account the instability of the braking forces on the wheels.

scholarly journals On the prospects of improving the numerical analysis of symmetric airfoils at low Reynolds numbers and high angles of attack by a LES approach: the case of NACA0021 profile

2020 ◽  
Vol 197 ◽  
pp. 08015
Author(s):  
Simone Giaccherini ◽  
Filippo Mariotti ◽  
Lorenzo Pinelli ◽  
Michele Marconcini ◽  
Alessandro Bianchini
Keyword(s):  
Turbine Blades ◽  
Separated Flow ◽  
Reynolds Numbers ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
High Fidelity ◽  
Complex Flow ◽  
Energy Applications ◽  
Low Reynolds ◽  
High Angles Of Attack

The working conditions of airfoils along modern wind turbine blades are putting new focus on the importance of properly characterizing the aerodynamic performance of different airfoil families also at high angles of attack (AoAs) beyond stall and at Reynolds numbers much lower (from few thousands to one million) than those commonly analyzed before. Several test cases are showing that even higher-order computational methods (like RANS/URANS CFD) are unable to properly capture the complex flow physics taking place past the blades, when deep stall occurs or when the AoA changes so rapidly to provoke the onset of dynamic stall. To fill this gap, the use of high-fidelity methods, like the Large Eddy Simulation (LES) is proposed, even though it implies a massive increase of the calculation cost. In order to analyze the prospects of using LES in comparison to RANS for low Reynolds, high AoAs, this work presents an in-depth study of the NACA 0021 aerodynamics at the Reynolds number of 80,000, by means of both traditional RANS approaches and high-fidelity (LES) simulations using the OpenFOAM suite. The selected airfoil has been showing in fact several issues in the correct characterization of its performance in similar conditions in many recent wind energy applications. The LES approach showed the ability to overcome the limitations of traditional RANS simulations, improving the accuracy of the results and reducing their dispersion thanks to the fact that the flow structures in the separated-flow regions are properly captured. Overall, this work underlines that accurate investigations of the aerodynamic performance of the NACA 0021 at low Reynolds require multiple sensitivity studies when RANS approaches are used, and suggests the use of LES simulations in order to increase the accuracy of estimations, especially when studying the stalledflow operating conditions of the airfoil.

Application of Blow-off Wind Tunnel Control Based on Genetic Algorithm Optimized BP-Neural Network PID Neural Network

2013 ◽  
Vol 310 ◽  
pp. 557-559 ◽  
Author(s):  
Li Ji ◽  
Xiao Fei Lian
Keyword(s):  
Neural Network ◽  
Genetic Algorithm ◽  
Wind Tunnel ◽  
Bp Neural Network ◽  
Control Method ◽  
Network Control ◽  
Operating Conditions ◽  
Algorithm Optimization ◽  
Large Delay ◽  
Neural Network Pid

For a blow-off tunnel running, there is the large delay and lag issues. We build a mathematical model of the wind tunnel Mach number control by the test modeling method, then analyse the pros and cons of various control methods based on BP neural network control algorithm. Put forward genetic algorithm optimization neural network adaptive control method to solve the large inertia of the wind tunnel system, and large delay. A large number of simulation studies, run a variety of operating conditions for the wind tunnel simulation proved that the improved adaptive neural network PID control method is reasonable and effective.

scholarly journals Multibody dynamic modelling of a direct wind turbine drive train

2019 ◽  
Vol 44 (5) ◽  
pp. 519-547
Author(s):  
Saeed Asadi ◽  
Håkan Johansson
Keyword(s):  
Wind Turbine ◽  
Measurement Data ◽  
Dynamic Modelling ◽  
Simulation Software ◽  
Operating Conditions ◽  
Drive Train ◽  
Operational Experience ◽  
Main Bearing ◽  
Wide Range ◽  
Turbine Drive

Wind turbines normally have a long operational lifetime and experience a wide range of operating conditions. A representative set of these conditions is considered as part of a design process, as codified in standards. However, operational experience shows that failures occur more frequently than expected, the costlier of these including failures in the main bearings and gearbox. As modern turbines are equipped with sophisticated online systems, an important task is to evaluate the drive train dynamics from online measurement data. In particular, internal forces leading to fatigue can only be determined indirectly from other locations’ sensors. In this contribution, a direct wind turbine drive train is modelled using the floating frame of reference formulation for a flexible multibody dynamics system. The purpose is to evaluate drive train response based on blade root forces and bedplate motions. The dynamic response is evaluated in terms of main shaft deformation and main bearing forces under different wind conditions. The model was found to correspond well to a commercial wind turbine system simulation software (ViDyn).

The design of an optimized portable artificial kidney system using recirculation and regeneration of dialysate

1998 ◽  
Vol 212 (5) ◽  
pp. 373-381 ◽  
Author(s):  
R J A Bigsby ◽  
R J Rider ◽  
G N Blount
Keyword(s):  
Activated Carbon ◽  
Small Volume ◽  
Operating Conditions ◽  
Artificial Kidney ◽  
Design Solution ◽  
Peltier Effect ◽  
Prototype System ◽  
Dialysis Session ◽  
Dialysate Volume ◽  
Dialysate Temperature

This paper is intended as an overview of the research carried out at Coventry University in the design of a portable artificial kidney system. It was seen that the key to the problem was the reduction in dialysate volume, and so it was decided to develop a prototype that would utilize the regeneration and recirculation of a small volume of dialysate. A prototype system has been produced and used to simulate a dialysis session. Activated carbon was used as a sorbent for the regeneration of the dialysate, circulating in a closed loop. For the purpose of this work, the adsorption of urea was investigated as this is, volumetrically, the major solute to be removed. Peltier effect cooling was used to vary the dialysate temperature down to 2 °C, as activated carbon will adsorb greater amounts of urea at lower temperatures. A series of tests was then carried out to investigate the effect of dialysate temperature, flowrate and volume on the amount of urea that could be dialysed. From the experimental results, a model of the system was derived, which made it possible to determine the implications of different operating conditions on the overall mass and size of a portable dialysis system. The output of this model was then used to establish a design specification and produce an optimum design solution for the system.

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