The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Madhusuden Agrawal - One of the best experts on this subject based on the ideXlab platform.
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coupled transient cfd and diffraction modeling for installation of subsea equipment structures in Splash Zone
ASME 2013 32nd International Conference on Ocean Offshore and Arctic Engineering, 2013Co-Authors: Madhusuden AgrawalAbstract:In development of deep water oil and gas fields, successfully and economically installing subsea equipment and structure is critically important. This paper presents a state-of-the-art methodology for predicting the motions and loads of subsea equipment/structure during such operations basing on time domain simulations of the combined installation vessel and subsea equipment/structure. The time domain diffraction simulation of the moving lifting vessel is coupled with multiphase CFD simulation of subsea equipment/structure in Splash Zone. Transient CFD model with rigid body motion for the equipment/structure calculates added masses, forces and moments on the equipment/structure for diffraction analysis, while diffraction analysis calculates linear and angular velocities for CFD simulation. This paper has many potential applications, such as, installation of pile, manifold, subsea tree, PLET/PLEM, or other subsea equipment/structure. This coupled approach has been successfully implemented on a cylindrical structure. The results show that total load level, and dynamics of the subsea equipment/structure due to waves in Splash Zone are predicted. Current practice of installation analysis in accordance with the recommendations from DNV-RP-H103 [1] cannot determine in detail the wave loads either during the passage through Splash Zone, or added mass and damping when the equipment/structure is submerged. In order to determine wave loads in detail, model tests are needed. In the absence of tests, simplified equations or empirical formulations have to be used to calculate/estimate these hydrodynamics coefficients as recommended in DNV-RP-H103. Steady-state CFD simulations on a stationary equipment/structure are usually used to predict drag and added masses on submerged structures. However the steady-state assumption in CFD ignores the resonating motion of equipment/structure in calculating hydrodynamics coefficients, which can severely affect the accuracy of these predictions. The above methods often give overly conservative results for allowable sea state which results in uneconomical vessel time or inaccurate results for installation. The methodology of this paper gives more accurate results, and provides potentially economical vessel time during installation. The intent of this paper is to demonstrate the solution and methodology.Copyright © 2013 by ASME
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Coupled Transient CFD and Diffraction Modeling for Installation of Subsea Equipment/Structures in Splash Zone
Volume 7: CFD and VIV, 2013Co-Authors: Madhusuden AgrawalAbstract:In development of deep water oil and gas fields, successfully and economically installing subsea equipment and structure is critically important. This paper presents a state-of-the-art methodology for predicting the motions and loads of subsea equipment/structure during such operations basing on time domain simulations of the combined installation vessel and subsea equipment/structure. The time domain diffraction simulation of the moving lifting vessel is coupled with multiphase CFD simulation of subsea equipment/structure in Splash Zone. Transient CFD model with rigid body motion for the equipment/structure calculates added masses, forces and moments on the equipment/structure for diffraction analysis, while diffraction analysis calculates linear and angular velocities for CFD simulation. This paper has many potential applications, such as, installation of pile, manifold, subsea tree, PLET/PLEM, or other subsea equipment/structure. This coupled approach has been successfully implemented on a cylindrical structure. The results show that total load level, and dynamics of the subsea equipment/structure due to waves in Splash Zone are predicted. Current practice of installation analysis in accordance with the recommendations from DNV-RP-H103 [1] cannot determine in detail the wave loads either during the passage through Splash Zone, or added mass and damping when the equipment/structure is submerged. In order to determine wave loads in detail, model tests are needed. In the absence of tests, simplified equations or empirical formulations have to be used to calculate/estimate these hydrodynamics coefficients as recommended in DNV-RP-H103. Steady-state CFD simulations on a stationary equipment/structure are usually used to predict drag and added masses on submerged structures. However the steady-state assumption in CFD ignores the resonating motion of equipment/structure in calculating hydrodynamics coefficients, which can severely affect the accuracy of these predictions. The above methods often give overly conservative results for allowable sea state which results in uneconomical vessel time or inaccurate results for installation. The methodology of this paper gives more accurate results, and provides potentially economical vessel time during installation. The intent of this paper is to demonstrate the solution and methodology.Copyright © 2013 by ASME
Yongxue Wang - One of the best experts on this subject based on the ideXlab platform.
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experimental study of unidirectional irregular wave slamming on the three dimensional structure in the Splash Zone
Ocean Engineering, 2008Co-Authors: Zhaoqiang Ding, Yongxue WangAbstract:Abstract The experimental investigation of unidirectional random wave slamming on the three-dimensional structure in the Splash Zone is presented. The experiment is conducted in the marine environment channel in the State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology. The test wave is unidirectional irregular wave. The experiments are carried out with perpendicular random waves (β=0°) and oblique random waves (β=15°, 30°, 45°), the significant wave heights H1/3 ranging from 7.5 to 20 cm with 2.5 cm increment, the peak wave periods Tp ranging from 0.75 to 2.0 s with 0.25 s increment, and the clearance of the model with respect to the significant wave height s/H1/3 ranging from 0.0 to 0.5 with 0.1 increment. The statistical analysis results of different test cases are presented. The statistical distribution characteristics of the perpendicular irregular wave impact pressures are compared with that of the oblique irregular wave on the underside of the structure. The effect of the wave direction β on the wave impact forces on the underside of the structure is determined. The relation between the impact forces and the parameters such as the significant wave height, the relative structure width and the relative clearance of the structure is also discussed.
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experimental study of regular wave impact on the three dimensional structure in the Splash Zone
The Seventeenth International Offshore and Polar Engineering Conference, 2007Co-Authors: Zhaoqiang Ding, Yongxue WangAbstract:The experimental investigation of regular wave slamming on the three-dimensional structure in the Splash Zone is presented. The experiment is conducted in the marine environment channel in the State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology. The wave channel is 50m in length, 3.0m in width and 1 .Om in height. The test wave is unidirectional regular wave. The experiments are canied out with perpendicular waves (p=Oo) and oblique waves(D=l5O, 30°, 459, wave heiatsranging from 7.5 cm to 20 cm with 2.5 cm increment, wave periods ranging 6om 0.75 s to 2.0 s with 0.25 s increment, and the relative clearance of the model with respect to wave height ranging from 0.1 to 0.5 with 0.1 increment. The statistical analysis results of different test cases are presented. The statistical distribution characteristics of the perpendicular wave impact pressures are compared with that of the oblique wave on the underside of the structure. The influence of the wave direction p on the wave impact forces on the underside of the structure is investigated. Experimental results indicate that the impact forces depend on parameters such as wave height, wave period, the relative structure width and the relative clearance of the structure.
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numerical simulation of random wave slamming on structures in the Splash Zone
Ocean Engineering, 2004Co-Authors: Yongxue WangAbstract:Abstract The numerical investigation of random wave slamming on superstructures of marine structures in the Splash Zone is presented in this paper. The impact pressures on the underside of the structure are computed based on the improved volume of fluid method (VOF). The governing equations are Reynolds time-averaged equations and the two equation k – e model. The third order upwind difference scheme is applied to the convection term to reduce the effect of numerical viscosity. The numerical wave flume with random wave-maker suitable for VOF is established. Appropriate moving contact-line boundary conditions are introduced to the model wave in contact with and separated from the underside of structure. Parametric studies have been carried out for different incident waves, structure dimensions and structure clearance. The numerical results are verified by the experimental results.
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experimental study of irregular wave impact on structures in the Splash Zone
Ocean Engineering, 2003Co-Authors: Yongxue WangAbstract:Abstract The experimental investigation of irregular wave slamming on structure members with large dimension in the Splash Zone is presented. The time-domain and frequency-domain analyses results of the irregular wave impact pressure on the subface of the structure under various case studies are presented. The influence of different incident wave parameters and relative clearance s / H 1/3 on the impact pressure is discussed. The empirical formula of the characteristic impact pressure P c , P t and the spectral moment of the impact pressure m 0 on the structure are proposed. The empirical expression of the characteristic peak impact pressure P c and the spectral moment of the impact pressure m 0 on the structure is given.
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spectral analysis of irregular wave impact on the structure in Splash Zone
ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering, 2002Co-Authors: Yongxue WangAbstract:The spectral analysis from experimental data of irregular wave impact on the structures with large dimension in the Splash Zone is presented. The experiments were conducted in the large wave-current tank in the State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology. In the experiment, the target spectrum is JONSWAP spectrum, the significant wave height H1/3 is in the range from 0.1m to 0.3m, and the peak period of spectrum Tp in the range from 1.0s to 2.0s. The ratio of s/H1/3 , which refers to the clearance of the subface of the structure above still water level (s) to the incident wave height, is between −0.1 and 0.4. The spectral analysis results of the irregular wave impact pressure on the subface of the structure under various case studies are presented. The distribution of spectral moment of the impact pressure on the structure along the subface is given. And the influence of different incident wave parameters and relative clearance s/H1/3 on the average spectral moment of impact pressure are discussed.Copyright © 2002 by ASME
James R Welty - One of the best experts on this subject based on the ideXlab platform.
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heat transfer to a horizontal tube in the Splash Zone of a bubbling fluidized bed an experimental study of particle size effects
Experimental Thermal and Fluid Science, 1995Co-Authors: David Pidwerbecki, James R WeltyAbstract:Abstract The experimental results of an investigation involving particle size effects on the heat transfer for a horizontal tube located in the Splash Zone of a high-temperature bubbling fluidized bed are reported. This article is the second of a series [1] that investigates specific operating parameters of bubbling fluidized beds. The array of experimental conditions for this work involved three particle sizes, of nominal 1.1, 2, and 2.9 mm in diameter; four bed temperatures, 700, 810, 908, and 1003 K; and three tube locations, −127, 64 and 406 mm relative to the tube centerline to nonfluidized bed surface. The tube locations are representative of a tube totally immersed in the bed, located in the Splash Zone, and located in the freeboard, respectively. Convective and blackbody radiative heat transfer coefficient variations are presented as functions of the nondimensionalized velocity ratio and of the particle size for the 1003-K case. Maximum convective and blackbody radiative heat transfer coefficients are tabulated for the other temperatures and particle sizes. The tube outside diameter was 51 mm, and the superficial velocity was varied from near-minimum fluidization conditions ( U mf ) to over 2 U mf .
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Splash Zone heat transfer in bubbling fluidized beds an experimental study of temperature effects
Experimental Thermal and Fluid Science, 1994Co-Authors: David Pidwerbecki, James R WeltyAbstract:Abstract Experimental results are reported for the heat transfer between a high-temperature fluidized bed and a horizontal tube located within the Splash Zone. Of specific interest in this study is the effect of bed temperature. Four bed operating temperatures (700, 810, 908, and 1003 K) were investigated. At each temperature, five circumferential local time-averaged values of the total and blackbody radiative heat transfer coefficients were measured for three tube locations. The tube was located at 406, 64, and −127 mm relative to the packed bed-freeboard interface. These locations are representative of a tube in the freeboard, in the Splash Zone, and totally immersed in the bed, respectively. The tube outside diameter was 51 mm, the mean bed particle size was 2.9 mm, and the superficial fluidizing velocity varied from near minimum fluidization conditions ( U mf ) to over 1.5U mf . The work was performed in the Oregon State University high-temperature fluidized-bed test facility.
Hua Ai - One of the best experts on this subject based on the ideXlab platform.
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erosion corrosion of thermally sprayed coatings in simulated Splash Zone
Surface & Coatings Technology, 2010Co-Authors: Weimin Zhao, Yong Wang, Lixian Dong, Honghui Yu, Hua AiAbstract:Abstract The damage of marine steel structures in the Splash Zone is very severe. Applying thermally sprayed metal coatings is among the most important protective technologies, but the service life of current coatings is limited. In this paper, arc spray was used to prepare four types of metal coatings, that is, aluminum (Al), zinc bottom coating combined with aluminum topcoat (Zn + Al), aluminum–zinc pseudo alloy (Al/Zn) and aluminum–titanium pseudo alloy (Al/Ti) coatings. These metal coatings were sealed with epoxy priming and aliphatic polyurethane topcoat. Erosion–corrosion experiments were carried out on self-made device by simulating the Splash Zone working environment of steel structures and protective coatings. The results show that all the sealed coatings could improve the steel resistance to erosion–corrosion, and the aluminum–zinc pseudo alloy is the most excellent coating. In the coating failure process, mechanical erosion rather than corrosion is the key factor causing coating erosion–corrosion in Splash Zone. Improving the anti-cutting properties could help to prolong the coating life.
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Erosion–corrosion of thermally sprayed coatings in simulated Splash Zone
Surface & Coatings Technology, 2010Co-Authors: Weimin Zhao, Yong Wang, Lixian Dong, Honghui Yu, Hua AiAbstract:Abstract The damage of marine steel structures in the Splash Zone is very severe. Applying thermally sprayed metal coatings is among the most important protective technologies, but the service life of current coatings is limited. In this paper, arc spray was used to prepare four types of metal coatings, that is, aluminum (Al), zinc bottom coating combined with aluminum topcoat (Zn + Al), aluminum–zinc pseudo alloy (Al/Zn) and aluminum–titanium pseudo alloy (Al/Ti) coatings. These metal coatings were sealed with epoxy priming and aliphatic polyurethane topcoat. Erosion–corrosion experiments were carried out on self-made device by simulating the Splash Zone working environment of steel structures and protective coatings. The results show that all the sealed coatings could improve the steel resistance to erosion–corrosion, and the aluminum–zinc pseudo alloy is the most excellent coating. In the coating failure process, mechanical erosion rather than corrosion is the key factor causing coating erosion–corrosion in Splash Zone. Improving the anti-cutting properties could help to prolong the coating life.
Jun Hu - One of the best experts on this subject based on the ideXlab platform.
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corrosion behavior of low c medium mn steel in simulated marine immersion and Splash Zone environment
Journal of Materials Engineering and Performance, 2017Co-Authors: Dazheng Zhang, Guanqiao Su, Linxiu Du, Jun HuAbstract:The corrosion behavior of low-C medium-Mn steel in simulated marine immersion and Splash Zone environment was studied by static immersion corrosion experiment and wet-dry cyclic corrosion experiment, respectively. Corrosion rate, corrosion products, surface morphology, cross-sectional morphology, elemental distribution, potentiodynamic polarization curves and electrochemical impedance spectra were used to elucidate the corrosion behavior of low-C medium-Mn steel. The results show that corrosion rate in immersion Zone is much less than that in Splash Zone owing to its relatively mild environment. Manganese compounds are detected in the corrosion products and only appeared in Splash Zone environment, which can deteriorate the protective effect of rust layer. With the extension of exposure time, corrosion products are gradually transformed into dense and thick corrosion rust from the loose and porous one in these two environments. But in Splash Zone environment, alloying elements of Mn appear significant enrichment in the rust layer, which decrease the corrosion resistance of the steel.
