Evaluation of Spar In-Field Performances for Topsides Payload Increase and Operational Changes

2015 ◽  
Author(s):  
Aldric Baquet ◽  
Joe Zhou ◽  
Lixin Xu ◽  
Yong Chen
Keyword(s):  
Hurricane Katrina ◽  
Weight Change ◽  
Operating Conditions ◽  
Design Stage ◽  
Design Criteria ◽  
Accurate Information ◽  
Original Design ◽  
Operational Conditions ◽  
Overall Design ◽  
Operating Limits

In the initial design stage of an offshore platform, some conservative assumptions might be used for the platform hull and Topsides weights, wind area and Metocean criteria of environments. After the platform is installed, actual results from weight surveys and real-time snapshots of the as-built operating platform typically provide more accurate information for the purpose of assessing real operational conditions and future changes of these conditions. For example, in field operations, it is particularly useful to quantify how much weight can be added to the as-built operating facility, while assuring that the platform still meets the overall design criteria and regulatory requirements. This paper presents an effective method for evaluation of an in-field operating Spar platform, to determine the maximum allowable envelops for topsides weight change verse the topsides VCG, based on the Spar global performances and riser operating limits. The case study is performed for a Spar in the Gulf of Mexico (GOM), based on the Spar as-built data and actual in-field configurations of hull/mooring and risers, and using the updated Metocean criteria (after the Hurricane Katrina in the GOM). The analysis results of the allowable topsides weight change and topsides VCG limits, accounting for the Spar in operating, extreme and survival conditions, are based on three governing factors: (1) the Spar motions meet the original design criteria for global performances, and are within the safety range of riser operations; (2) the maximum loads at critical connections between the Spar hard tank and the topsides structures are within the design loads; and (3) the reserve variable ballast is sufficient to balance the Spar at an even keel position at the design draft for all required operating conditions.

Analytical and Experimental Flow-Induced Vibration Analysis of a Shell and Tube Cooling Water Heat Exchanger

2002 ◽  
Author(s):  
Alberto F. Marti´n Ghiselli ◽  
Rau´l M. Kulichevsky ◽  
Mauricio A. Sacchi ◽  
Alberto J. Pastorini ◽  
Ce´sar G. Belinco
Keyword(s):  
Heat Exchanger ◽  
Cooling Water ◽  
Fretting Wear ◽  
Design Stage ◽  
Dynamical Response ◽  
Original Design ◽  
Flow Induced Vibration ◽  
Design Modification ◽  
Operational Conditions ◽  
Shell And Tube

A flow-induced vibration problem evaluation of a shell and tube cooling water heat exchanger equipment installed in a power plant is presented in this paper. The problem produced loss of thickness in many tubes of the bundle, by impact or fretting wear, and the need to plug these tubes to avoid leakage. These vibrations could had been produced by changes in the equipment operational conditions or by a wrong evaluation during the design stage. An analytical and experimental evaluation was made to predict tubes dynamical response and to identify the excitation mechanisms. The original design modification adopted to solve the problem is presented and evaluated.

scholarly journals Managing energy performance in buildings from design to operation using modelling and calibration

2021 ◽  
pp. 014362442110083
Author(s):  
Nishesh Jain ◽  
Esfand Burman ◽  
Dejan Mumovic ◽  
Mike Davies
Keyword(s):  
Best Practice ◽  
Good Practice ◽  
Energy Performance ◽  
Operating Conditions ◽  
Design Stage ◽  
Performance Gap ◽  
Actual Performance ◽  
Simulation Tools ◽  
Calibration Protocol ◽  
Covering Design

To manage the concerns regarding the energy performance gap in buildings, a structured and longitudinal performance assessment of buildings, covering design through to operation, is necessary. Modelling can form an integral part of this process by ensuring that a good practice design stage modelling is followed by an ongoing evaluation of operational stage performance using a robust calibration protocol. In this paper, we demonstrate, via a case study of an office building, how a good practice design stage model can be fine-tuned for operational stage using a new framework that helps validate the causes for deviations of actual performance from design intents. This paper maps the modelling based process of tracking building performance from design to operation, identifying the various types of performance gaps. Further, during the operational stage, the framework provides a systematic way to separate the effect of (i) operating conditions that are driven by the building’s actual function and occupancy as compared with the design assumptions, and (ii) the effect of potential technical issues that cause underperformance. As the identification of issues is based on energy modelling, the process requires use of advanced and well-documented simulation tools. The paper concludes with providing an outline of the software platform requirements needed to generate robust design models and their calibration for operational performance assessments. Practical application The paper’s findings are a useful guide for building industry professionals to manage the performance gap with appropriate accuracy through a robust methodology in an easy to use workflow. The methodological framework to analyse building energy performance in-use links best practice design stage modelling guidance with a robust operational stage investigation. It helps designers, contractors, building managers and other stakeholders with an understanding of procedures to follow to undertake an effective measurement and verification exercise.

Reliability Analysis of Jack-Up Platforms Based on Fatigue Degradation

2002 ◽  
Author(s):  
Naser Shabakhty ◽  
Pieter van Gelder ◽  
Hotze Boonstra
Keyword(s):  
Service Time ◽  
Great Part ◽  
Fatigue Reliability ◽  
Original Design ◽  
Operational Conditions ◽  
Stress Fluctuation ◽  
The Difference ◽  
Offshore Industry ◽  
Jack Up ◽  
Load Conditions

Generally, jack-up structures are used for production drilling and exploration of hydrocarbons. The combination of mobility and the behavior as a fixed structure in operational conditions has made it an important structure in the offshore industry over the last 40 years. When a jack-up structure has been in operation for a great part of its original design-life and intention is there to extend the usage of this structure at a specific location, an investigation on fatigue degradation of the structure is an essential factor that has to be carried out before taking any decision. Fatigue is the process of damage accumulation in material due to stress fluctuation caused by variation of loads in service time. The fatigue failure occurs when accumulated damage has exceeded a critical level. In this paper, the remaining fatigue capacity of the jack-up structure is considered as an indicator for adequate use of the structure. It can be specified based on the difference between design-fatigue and fatigue experienced by the structure. The design-fatigue can be determined based on fluctuation of loads during the lifetime of the structure and experienced fatigue is specified by the load conditions, which the structure has experienced during its service time. When the information on the load conditions which the structure has experienced in its service time is available or known precisely, determination of the remaining fatigue capacity could be carried out by using the Palmgren–Miner’s rule. In practice, uncertainties are present in loads and characteristics of material. Hence it will be reasonable to determine the remaining fatigue reliability of the structure by the reliability methods. In this paper, based on a crack propagation approach and achieved information from inspection, it is shown that the remaining fatigue reliability of jack-up structures could be determined and updated by using a Bayesian procedure in the duration of the service time.

CFD Investigation of Downhole Natural Gas Separation Efficiency in the Churn Flow Regime

2021 ◽  
Author(s):  
Charles Okafor ◽  
Patrick Verdin ◽  
Phill Hart
Keyword(s):  
Natural Gas ◽  
Flow Regime ◽  
Gas Separation ◽  
Separation Efficiency ◽  
Operating Conditions ◽  
Analytical Models ◽  
Design Stage ◽  
Average Error ◽  
Multiphase Model ◽  
Churn Flow

Abstract Downhole Natural Gas Separation Efficiency (NGSE) is flow regime dependent, and current analytical models in certain conditions lack accuracy. Downhole NGSE was investigated through 3D Computational Fluid Dynamics (CFD) transient simulations for pumping wells in the Churn flow regime. The Volume of Fluid (VOF) multiphase model was considered along with the k – ε turbulence model for most simulations. A mesh independence study was performed, and the final model results validated against experimental data, showing an average error of less than 6 %. Numerical simulation results showed that the steady state assumption used by current mathematical models for churn flow can be inaccurate. Several key parameters affecting the NGSE were identified, and suggestions for key improvements to the widely used mathematical formulations for viscous flow provided. Sensitivity studies were conducted on fluid/geometric parameters and operating conditions, to gain a better understanding of the influence of each parameter on NGSE. These are important results as they equip the ESP engineer with additional knowledge to maximise the NGSE from design stage to pumping operations.

Avoiding Sedimentation and Air Entrainment in Pump Sump for Wet Pit Pumping Stations

2015 ◽  
Author(s):  
Raja Abou Ackl ◽  
Andreas Swienty ◽  
Flemming Lykholt-Ustrup ◽  
Paul Uwe Thamsen
Keyword(s):  
Physical Model ◽  
Air Entrainment ◽  
Flow Patterns ◽  
Operating Conditions ◽  
Design Criteria ◽  
Flow Conditions ◽  
Pumping Station ◽  
Pumping Stations ◽  
Pump Sump ◽  
Pump Stations

In many places lifting systems represent central components of wastewater systems. Pumping stations with a circular wet-pit design are characterized by their relatively small footprint for a given sump volume as well as their relatively simple construction technique [1]. This kind of pumping stations is equipped with submersible pumps. These are located in this case directly in the wastewater collection pit. The waste water passes through the pump station untreated and loaded with all kind of solids. Thus, the role of the pump sump is to provide an optimal operating environment for the pumps in addition to the transportation of sewage solids. Understanding the effects of design criteria on pumping station performance is important to fulfil the wastewater transportation as maintenance-free and energy efficient as possible. The design of the pit may affect the overall performance of the station in terms of poor flow conditions inside the pit, non-uniform und disturbed inflow at the pump inlet, as well as air entrainment to the pump. The scope of this paper is to evaluate the impact of various design criteria and the operating conditions on the performance of pump stations concerning the air entrainment to the pump as well as the sedimentation inside the pit. This is done to provide documentation and recommendations of the design and operating of the station. The investigated criteria are: the inflow direction, and the operating submergence. In this context experiments were conducted on a physical model of duplex circular wet pit wastewater pumping station. Furthermore the same experiments were reproduced by numerical simulations. The physical model made of acrylic allowed to visualize the flow patterns inside the sump at various operating conditions. This model is equipped with five different inflow directions, two of them are tangential to the pit and the remaining three are radial in various positions relative to the pumps centerline. Particles were used to enable the investigation of the flow patterns inside the pit to determine the zones of high sedimentation risk. The air entrainment was evaluated on the model test rig by measuring the depth, the width and the length of the aerated region caused by the plunging water jet and by observing the air bubbles entering the pumps. The starting sump geometry called baseline geometry is simply a flat floor. The tests were done at all the possible combinations of inflow directions, submergence, working pump and operating flow. The ability of the numerical simulation to give a reliable prediction of air entrainment was assessed to be used in the future as a tool in scale series to define the scale effect as well as to analyze the flow conditions inside the sump and to understand the air entrainment phenomenon. These simulations were conducted using the geometries of the test setup after generating the mesh with tetrahedral elements. The VOF multiphase model was applied to simulate the interaction of the liquid water phase and the gaseous air phase. On the basis of the results constructive suggestions are derived for the design of the pit, as well as the operating conditions of the pumping station. At the end recommendations for the design and operating conditions are provided.

CAD in the CIM Environment: Where Do We Go From Here?

1986 ◽  
Vol 39 (9) ◽  
pp. 1345-1349 ◽  
Author(s):  
Dell K. Allen ◽  
W. Van Twelves
Keyword(s):  
Computer Aided Design ◽  
Material Selection ◽  
Operating Conditions ◽  
Computer Integrated Manufacturing ◽  
Accurate Information ◽  
Functional Requirements ◽  
Essential Information ◽  
Design Systems ◽  
Aided Design ◽  
Product Definition

The importance of computer-aided design (CAD) has not been fully appreciated as it relates to computer integrated manufacturing (CIM). The CAD product definition model can provide essential information for many down-stream production, estimating, tooling, and quality assurance functions in the CIM environment. However, the product definition model may be inaccurate or incomplete, thus causing incomplete communication with possible scrap, re-work, and missed production deadlines. Other problems are related to the fact that many of our expert designers are retiring and taking their expertise with them. Merely being able to make 2D or 3D drawings on a CAD workstation does not make its operator a designer. A knowledge of production processes, tolerances, surface finish, and material selection is needed to supplement a designers knowledge of user needs, product functional requirements, operating conditions, cost, quality, and reliability targets. One of the most promising methods for providing timely and accurate information to the designer on an “as-needed” basis is through the use of expert design systems. Such systems promise to bridge the knowledge gap between CAD and CAM and help to incorporate these functions into the overall CIM environment.

scholarly journals Material Origins of Accelerated Operational Wear of RD-33 Engine Blades

2020 ◽  
Author(s):  
Adam Kozakiewicz ◽  
Stanislaw Jóźwiak ◽  
Przemysław Jóźwiak ◽  
Stanisław Kachel
Keyword(s):  
Chemical Composition ◽  
Construction Material ◽  
Operating Conditions ◽  
Design Stage ◽  
Strength Analysis ◽  
Jet Engine ◽  
Emergency Situations ◽  
Low Pressure Turbine ◽  
Propulsion Unit ◽  
Selection Of

The structural and strength analysis of the material used to construct such an important engine element as the turbine is of great significance, both at the design stage as well as during tests and expertises related to emergency situations. Bearing in mind the conditions above mentioned, the paper presents the results of research on the chemical composition, morphology and phased structure of the metallic construction material used to produce the blades of the high and low pressure turbine of the RD-33 jet engine, which is the propulsion unit of the MiG-29 aircraft. The data obtained as a result of the material tests of the blades allowed, on the basis of the analysis of chemical composition and phased structure, to determine the grade of the alloy used to construct the tested elements of the jet engine turbine. The structural stability of the material was found to be lower in comparison with engine operating conditions, which manifested itself as a clear decrease in the resistance properties of the blade material. The results obtained can be used as a basis for analyzing the life span of an object or a selection of material replacements, which enable to produce the analyzed engine element.

scholarly journals Hydrodynamic and hydrostatic forces as factors affecting tailing dump stability

2021 ◽  
Vol 44 (1) ◽  
pp. 63-72
Author(s):  
D. Sh. Sharipov
Keyword(s):  
Research Methods ◽  
Operating Conditions ◽  
Design Stage ◽  
Tailing Dump ◽  
Initial Development ◽  
Technical Problems ◽  
Factors Affecting ◽  
Deformation Processes ◽  
Tailing Dams ◽  
The Impact

The study of the processes occurring deep in the earth's crust has always been a relevant research topic. The results of these studies allowed development and safe mining of mineral deposits in various conditions. The growth in the consumption of extracted resource and the increase in the scale of mining are forcing enterprises to search for the solutions to complex engineering and technical problems, one of which is the problem of displacement of rock masses and the earth's surface in industrial production-affected areas including tailings dams. The purpose of this study is to improve the operation safety of tailing dams. The object of the study is embankment dams of dressing plant tailing dumps. The subject of the study is deformation processes occurring in dam bodies and slope surfaces. The main research methods used in the work are: the study of safe operation methods for tailing dams based on the operating conditions of Uchalinskoye tailing dump using the modern methods of stability assessment, analysis and generalization of domestic and foreign experience, as well as the study of current methods of geomechanical monitoring of deformation processes – engineering and geological, geophysical, mine surveying and hydrogeological ones. The article describes geographic, hydrographic, climatic, geological and mining operation conditions of the tailing dump of Uchalinsky GOK (Ore Mining and Processing Plant) JSC. The influence of hydrodynamic and hydrostatic forces on embankment tailing dam stability is substantiated. Based on the data obtained and the research methods used, it is concluded that hydrodynamic and hydrostatic forces are fundamental destructive factors affecting dams. The results of these studies can be applied at the design stage of hydraulic structures, since they will supplement theoretical knowledge about the impact of liquid waste on the safety of tailing dams and earth-filled dams, as well as allow detecting deformation processes at their initial development stage and making decisions on their elimination.

scholarly journals Performance analysis of the working surface of the rails from test batches on the Test Loop of JSC “VNIIZhT”

2018 ◽  
Vol 77 (3) ◽  
pp. 141-148
Author(s):  
M. Yu. Khvostik ◽  
I. V. Khromov ◽  
O. A. Bykova ◽  
G. A. Beresten’
Keyword(s):  
Wear Resistance ◽  
Operating Time ◽  
Operating Conditions ◽  
Continuous Change ◽  
Wear Area ◽  
Railway Network ◽  
Operational Conditions ◽  
Rolling Surface ◽  
Test Loop ◽  
The Impact

The monitoring of railway rails damage on the railway network of the JSC “Russian Railways” as well as operational and polygon tests are conducted with the purpose of assessing the impact of operating conditions on the intensity of rails damage, obtaining initial data for forecasting rails failures. The increased intensity of rails wear on sites with a complex plan and profile leads to the fact that with a continuous change from the track, rails which have an underutilized service life of more than 20 % are retrieved. Polygon tests on the Test Loop of the JSC “VNIIZhT” near the Scherbinka station can provide the repeatability and reliability of the results, comparative tests are carried out under identical conditions and their duration is several times less than when tested at experimental sites under operational conditions. The results of the polygon tests of new differentially heat-strengthened rails did not reveal any advantages in the wear resistance of special purposed rails (laid in the recommended radius of the curve for its application) when comparing the rails of domestic manufacturers. Metal shelling out on the rolling surface of rails is the main reason for the removal of rails from test batches. The origin and development of defects of this kind is due to both violations of the technology of manufacturing rails, and because of violations of the current maintenance of the track. The metal stock in the area of the rail head of R65 type due to the increase in its dimensions positively affects the extension of the lifetime of the rails, reducing the cost of the life cycle and the rail itself, and the design of the track as a whole. When carrying out a separate study in order to obtain results characterizing the stability of high-quality rails to contact fatigue damage, it is advisable to optimize the conditions of the polygon tests, bringing them closer to operational ones. When forming the test results, it is necessary to expand the list of criteria for assessing the wear resistance of rails, supplementing it with the size of the wear area at the time of a certain operating time of the tonnage, with the introduction of this criterion into the appropriate methods for the polygon (operational) tests.

scholarly journals Modeling in marine ice engineering

2021 ◽  
Vol 11 (4) ◽  
pp. 557-567
Author(s):  
A.A. Dobrodeev ◽  
◽  
K.E. Sazonov ◽  
Keyword(s):  
Modeling And Simulation ◽  
Operating Conditions ◽  
Design Stage ◽  
Modern World ◽  
Marine Structures ◽  
Modeling Methods ◽  
Wide Range ◽  
Comparative Advantages ◽  
Quantitative Results

In the modern world, it is already difficult to imagine the creation of a significant engineering structure without modeling its external and internal appearance, the operation modeling of the main mechanisms, operating conditions and many other design features and emerging phenomena at the design stage. The paper interprets modeling and simulation as one of the computational methods that allow us to obtain quantitative results when studying ice impact on marine structures, for e.g. icebreakers and transport vessels, platform substructures, hydro-technical installations. In connection with the above, from the existing classification of modeling methods, the authors consider the physical and mathematical ones in the work. They present comparative advantages of both methods in their application in the problems of marine ice engineering, as well as the prospects for their development for solving a wide range of scientific problems aimed at the development of Arctic shipbuilding.

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