Fatigue Capacity of Wellhead Housings

2017 ◽  
Author(s):  
Sergey Kuzmichev ◽  
Javier Rodriguez Garcia ◽  
Kristoffer H. Aronsen ◽  
Guttorm Grytøyr ◽  
Finn Kirkemo ◽  
...  
Keyword(s):  
High Pressure ◽  
Boundary Conditions ◽  
Base Material ◽  
Low Pressure ◽  
Cross Sectional ◽  
Applied Loading ◽  
Load Paths ◽  
Calculated Load ◽  
Stress Curve ◽  
Sensitivity Studies

The issue of wellhead fatigue has been given significant attention during recent years. The complexity of the wellhead system in terms of interactions betwe[en conductor (low pressure) and wellhead (high pressure) housings leads to various analysis methods being proposed to evaluate fatigue damage in the system. Most of the critical base material hotspots are located in the wellhead housing region where the loads start to distribute between the high- and low pressure housing and the load paths are highly complex varying for different input parameters. Due to this, detailed fatigue analyses are typically performed on a project to project basis for the same wellhead geometry. This paper proposes an approach that simplifies the analysis of the base material hotspots in the housings and makes it independent of where the specific type of the wellhead system is used. It is suggested to consider the housings of the wellhead system as one component with a single characteristic M-N curve, or a few M-N curves if complexity requires so. The M-N curve is a specialization of the standard S-N curves provided in rules and standards. They are generated by combining the calculated load-to-stress curve at a given hotspot with the applicable S-N curve. The load used as a reference is typically a cross-sectional moment at the top of high pressure housing. For these purposes 3D FE models have been developed for two principal wellhead types, rigid lock and non-rigid lock. The models are used to investigate the effect of different boundary conditions and applied loading on M-N curves for each hotspot analysed. Sensitivity studies have been performed for several parameters that are considered important in wellhead fatigue analysis. Based on the sensitivity studies, the effect of each parameter on typical base material hotspots is presented. This paper provides estimates for the spread in the M-N curves for each individual base material hotspot in the wellhead housings. Results indicate that a single characteristic M-N curve per wellhead system type can be selected to represent the wellhead housings. In addition, based on results from the analyses carried out, recommendations regarding generalized boundary conditions to obtain a characteristic M-N curve for a specific wellhead type have been given.

Aerodynamic Interactions Between a High Pressure Turbine and the First Low Pressure Stator

2013 ◽  
Author(s):  
Pierre Gougeon ◽  
Ghislaine Ngo Boum ◽  
Francis Lebœuf
Keyword(s):  
Boundary Condition ◽  
High Pressure ◽  
Boundary Conditions ◽  
Numerical Study ◽  
Low Pressure ◽  
Single Stage ◽  
High Pressure Turbine ◽  
Low Pressure Turbine ◽  
Unsteady Rans ◽  
Rotating Boundary

This paper presents a numerical study on the interaction between a single-stage high-pressure turbine and the first vane row of a low-pressure turbine at aerodesign conditions. It focuses on the simulation of the flow within the inter-turbine duct and the loss generated in the downstream low-pressure vane. Former experiments provided steady and unsteady measurements in the duct between the high and the low-pressure turbines and after the low-pressure nozzle. A 3D unsteady RANS approach with phase-lagged boundary conditions is used to characterize the unsteady periodic effects developing in the inter-turbine channel and downstream in the low-pressure vane. For the numerical study, two different configurations were considered: a single stage high-pressure turbine configuration and a high-pressure rotor coupled with a low-pressure vane. For the second one, two inlet boundary conditions are considered upstream of the rotor: a circumferentially uniform boundary condition and a circumferentially non uniform rotating boundary condition. The resulting flow fields are compared within the intermediate duct. A harmonic Fourier analysis is carried out to underline the effects of upstream and downstream stator and the interaction with the high-pressure rotor. An unsteady Adamczyk decomposition within a plane located in the duct showed the influence of the different components and the levels of unsteadiness. Comparisons with experimental data show a reasonable good agreement.

Aerodynamic Interactions Between a High-Pressure Turbine and the First Low-Pressure Stator

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Pierre Gougeon ◽  
Ghislaine Ngo Boum
Keyword(s):  
Boundary Condition ◽  
High Pressure ◽  
Boundary Conditions ◽  
Numerical Study ◽  
Low Pressure ◽  
Flow Fields ◽  
Single Stage ◽  
Navier Stokes ◽  
High Pressure Turbine ◽  
Rotating Boundary

The accurate prediction of turbines performance and flow fields requires the assessment of unsteady numerical simulations. This paper presents a numerical study on the interaction between a single-stage high-pressure turbine and the first vane row of a low-pressure turbine. It focuses on the simulation of the flow within the interturbine duct and the loss generated in the downstream low-pressure vane. Former experiments provided steady and unsteady measurements in the interturbine duct and after the low-pressure vane. A 3D unsteady Reynolds-averaged Navier–Stokes (URANS) approach with phase-lagged boundary conditions is used to characterize the unsteady periodic effects in the interturbine channel and downstream in the low-pressure vane. For the numerical study, two different configurations are considered: a single-stage high-pressure turbine configuration and a high-pressure rotor coupled with a low-pressure vane. For the second one, two inlet boundary conditions are implemented upstream of the rotor: a circumferentially uniform boundary condition and a circumferentially nonuniform rotating boundary condition. The resulting flow fields are compared within the intermediate duct. A harmonic Fourier analysis is carried out to underline the effects of the high-pressure rotor. An unsteady Adamczyk decomposition of the flow field within the duct gives the influence of the different components and the levels of unsteadiness. Comparisons with experimental data show a reasonable good agreement.

Fouling Is the Beginning: Upcycling Biopolymer-Fouled Substrates for Fabricating High-Permeance Thin-Film Composite Polyamide Membranes

2020 ◽  
Author(s):  
Ruobin Dai ◽  
Hongyi Han ◽  
Tianlin Wang ◽  
Jiayi Li ◽  
Chuyang Y. Tang ◽  
...  
Keyword(s):  
Thin Film ◽  
High Pressure ◽  
End Of Life ◽  
Water Purification ◽  
Low Pressure ◽  
Polymeric Membranes ◽  
Membrane Recycling ◽  
Film Composite ◽  
Thin Film Composite ◽  
First Time

Commercial polymeric membranes are generally recognized to have low sustainability as membranes need to be replaced and abandoned after reaching the end of their life. At present, only techniques for downcycling end-of-life high-pressure membranes are available. For the first time, this study paves the way for upcycling fouled/end-of-life low-pressure membranes to fabricate new high-pressure membranes for water purification, forming a closed eco-loop of membrane recycling with significantly improved sustainability.

scholarly journals High-Pressure Spectroscopy Study of Zn(IO3)2 Using Far-Infrared Synchrotron Radiation

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 34
Author(s):  
Akun Liang ◽  
Robin Turnbull ◽  
Enrico Bandiello ◽  
Ibraheem Yousef ◽  
Catalin Popescu ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Synchrotron Radiation ◽  
Infrared Radiation ◽  
Room Temperature ◽  
Far Infrared ◽  
Low Pressure ◽  
Pressure Response ◽  
Spectroscopy Study ◽  
Far Infrared Radiation

We report the first high-pressure spectroscopy study on Zn(IO3)2 using synchrotron far-infrared radiation. Spectroscopy was conducted up to pressures of 17 GPa at room temperature. Twenty-five phonons were identified below 600 cm−1 for the initial monoclinic low-pressure polymorph of Zn(IO3)2. The pressure response of the modes with wavenumbers above 150 cm−1 has been characterized, with modes exhibiting non-linear responses and frequency discontinuities that have been proposed to be related to the existence of phase transitions. Analysis of the high-pressure spectra acquired on compression indicates that Zn(IO3)2 undergoes subtle phase transitions around 3 and 8 GPa, followed by a more drastic transition around 13 GPa.

scholarly journals Crystal and electronic structure engineering of tin monoxide by external pressure

2021 ◽  
Author(s):  
Kun Li ◽  
Junjie Wang ◽  
Vladislav A. Blatov ◽  
Yutong Gong ◽  
Naoto Umezawa ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Band Gap ◽  
High Pressures ◽  
Low Pressure ◽  
Widespread Application ◽  
Space Group ◽  
Tin Monoxide ◽  
High Possibility ◽  
Pressure Phase

AbstractAlthough tin monoxide (SnO) is an interesting compound due to its p-type conductivity, a widespread application of SnO has been limited by its narrow band gap of 0.7 eV. In this work, we theoretically investigate the structural and electronic properties of several SnO phases under high pressures through employing van der Waals (vdW) functionals. Our calculations reveal that a metastable SnO (β-SnO), which possesses space group P21/c and a wide band gap of 1.9 eV, is more stable than α-SnO at pressures higher than 80 GPa. Moreover, a stable (space group P2/c) and a metastable (space group Pnma) phases of SnO appear at pressures higher than 120 GPa. Energy and topological analyses show that P2/c-SnO has a high possibility to directly transform to β-SnO at around 120 GPa. Our work also reveals that β-SnO is a necessary intermediate state between high-pressure phase Pnma-SnO and low-pressure phase α-SnO for the phase transition path Pnma-SnO →β-SnO → α-SnO. Two phase transition analyses indicate that there is a high possibility to synthesize β-SnO under high-pressure conditions and have it remain stable under normal pressure. Finally, our study reveals that the conductive property of β-SnO can be engineered in a low-pressure range (0–9 GPa) through a semiconductor-to-metal transition, while maintaining transparency in the visible light range.

scholarly journals Investigation of Vorticity during Prevalent Winter Precipitation in Iran

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Iman Rousta ◽  
Farshad Javadizadeh ◽  
Fatemeh Dargahian ◽  
Haraldur Ólafsson ◽  
Amin Shiri-Karimvandi ◽  
...  
Keyword(s):  
Cluster Analysis ◽  
High Pressure ◽  
Persian Gulf ◽  
Low Pressure ◽  
Winter Precipitation ◽  
Central Iran ◽  
Precipitation Data ◽  
East Europe ◽  
Precipitation Threshold ◽  
Dual Core

In this study, precipitation data for 483 synoptic stations, and the U&V component of wind and HGT data for 4 atmospheric levels were respectively obtained from IRIMO and NCEP/NCAR databases (1961–2013). The precipitation threshold of 1 mm and a minimum prevalence of 50% were the criteria based on which the prevalent precipitation of Iran was identified. Then, vorticity of days corresponding to prevalent winter precipitation was calculated and, by performing cluster analysis, the representative days of vorticity were specified. The results showed that prevalent winter precipitation vorticity in Iran is related to the vorticity patterns of low pressure of Mediterranean-low pressure of Persian Gulf dual-core, low pressure closed of central Iran-high pressure of East Europe, Ural low pressure-Middle East High pressure, Saudi Arabia low pressure-Europe high pressure, and high-pressure belt of Siberia-low pressure of central Iran. At the same time, the most intense vorticity occurred when the climate of Iran was influenced by a massive belt pattern of Siberian high pressure-low pressure of central Iran. However, at the time of prevalent winter precipitation in Iran, an intense vorticity is drawn with the direction of Northeast and Northwest from the center of Iraq to the south of Iran.

Study on the Deposition Profile Characteristics in the Micron-Scale Trench Using Direct Simulation Monte Carlo Method

1998 ◽  
Vol 120 (2) ◽  
pp. 296-302 ◽  
Author(s):  
Masato Ikegawa ◽  
Jun’ichi Kobayashi ◽  
Morihisa Maruko
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Boundary Conditions ◽  
Gas Flow ◽  
Direct Simulation Monte Carlo ◽  
Low Pressure ◽  
Sputter Deposition ◽  
Direct Simulation ◽  
Simulation Monte Carlo ◽  
Profile Characteristics

As integrated circuits are advancing toward smaller device features, step-coverage in submicron trenches and holes in thin film deposition are becoming of concern. Deposition consists of gas flow in the vapor phase and film growth in the solid phase. A deposition profile simulator using the direct simulation Monte Carlo method has been developed to investigate deposition profile characteristics on small trenches which have nearly the same dimension as the mean free path of molecules. This simulator can be applied to several deposition processes such as sputter deposition, and atmospheric- or low-pressure chemical vapor deposition. In the case of low-pressure processes such as sputter deposition, upstream boundary conditions of the trenches can be calculated by means of rarefied gas flow analysis in the reactor. The effects of upstream boundary conditions, molecular collisions, sticking coefficients, and surface migration on deposition profiles in the trenches were clarified.

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