An Experimental Investigation of Hydrodynamic Impacts of Marine Growth on Mid-Water Arch System

2014 ◽  
Author(s):  
Michael Farmakis ◽  
Yuting Jin ◽  
Shuhong Chai ◽  
Henri Morand ◽  
Cecile Izarn
Keyword(s):  
Experimental Investigation ◽  
Oil And Gas ◽  
Physical Modelling ◽  
Operating Conditions ◽  
Hydrodynamic Drag ◽  
Marine Biofouling ◽  
Drag Forces ◽  
Arch System ◽  
3D Scans ◽  
Hydrodynamic Effects

The presence of marine growth modifies hydrodynamic effects to subsea structures and could lead to incorrect modelling if not properly accounted for. Widely-used design practice codes do not contain any specific guidelines or recommendations to account for the effects of marine fouling on complex subsea structures and due to the desired longevity of oil and gas constructs, considerable amounts of marine biofouling can accumulate. In the experimental investigation described in the paper, the impacts of different marine growth severities, current velocities and current directions on the hydrodynamic drag were carried out in the Flume Tank at the University of Tasmania. A 1:15 scale mid-water arch (MWA) was employed during this investigation. Several marine biofouling severities were tested as well as the structure without marine growth, representing scenarios based on realistic MWA operating conditions. Physical modelling was validated with numerical simulations using computational fluid dynamics. Experimental results gathered show a rise in drag forces when the artificial marine growth is attached. The highest force magnitudes were observed when the marine growth severity was at its maximum roughness. This has been complemented by numerical results, with input parameters coming from 3D scans of the artificial marine growth.

scholarly journals Fluid Parameter Identification for Underwater Snake Robots

2018 ◽  
Author(s):  
Eleni Kelasidi ◽  
Gard Elgenes ◽  
Henrik Kilvær
Keyword(s):  
Marine Biology ◽  
Oil And Gas ◽  
Fluid Dynamic ◽  
Autonomous Underwater Vehicles ◽  
Oil And Gas Industry ◽  
Underwater Vehicles ◽  
Analytical Models ◽  
Hydrodynamic Drag ◽  
Drag Forces ◽  
Snake Robots

Nowadays different types of unmanned underwater vehicles (UUVs), such as remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs), are widely used for sub-sea inspection, maintenance, and repair (IMR) operations in the oil and gas industry, archaeology, oceanography and marine biology. Also, lately, the development of underwater snake robots (USRs) shows promising results towards extending the capabilities of conventional UUVs. The slender and multi-articulated body of USRs allows for operation in tight spaces where other traditional UUVs are incapable of operating. However, the mathematical model of USRs is more challenging compared to models of ROVs and AUVs, because of its multi-articulated body. It is important to develop accurate models for control design and analysis, to ensure the desired behaviour and to precisely investigate the locomotion efficiency. Modelling the hydrodynamics poses the major challenge since it includes complex and non-linear hydrodynamic effects. The existing analytical models for USRs consider theoretical values for the fluid coefficients and thus they only provide a rough prediction of the effects of hydrodynamics on swimming robots. In order to obtain an accurate prediction of the hydrodynamic forces acting on the links of the USRs, it is necessary to obtain the fluid coefficients experimentally. This paper determines the drag and added mass co-efficients of a general planar model of USRs. In particular, this paper presents methods for identifying fluid parameters based on both computational fluid dynamic (CFD) simulations and several experimental approaches. Additionally, in this paper, we investigate variations of the drag force modelling, providing more accurate representations of the hydrodynamic drag forces. The obtained fluid coefficients are compared to the existing estimates of fluid coefficients for a general model of USRs.

Geology and age of the Precambrian basement in the Windsor, Chatham, and Sarnia area, southwestern Ontario

1982 ◽  
Vol 19 (8) ◽  
pp. 1627-1634 ◽  
Author(s):  
A. Turek ◽  
R. N. Robinson
Keyword(s):  
Oil And Gas ◽  
Precambrian Basement ◽  
Grenville Province ◽  
Metasedimentary Rocks ◽  
Gas Drilling ◽  
Arch System ◽  
Grenvillian Orogeny ◽  
Anomaly Map ◽  
Paleozoic Rocks ◽  
Basement Surface

Precambrian basement in the Windsor–Chatham–Sarnia area is covered by Paleozoic rocks that are up to 1300 m thick. The basement surface is characterized by a northeast–southwest arch system with a relief of about 350 m. Extensive oil and gas drilling has penetrated and sampled this basement, and an examination of core and chip samples from 133 holes and an assessment of the magnetic anomaly map of the area have been used to produce a lithologic map of the Precambrian basement. The predominant rocks are granite gneisses and syenite gneisses but also significant are gabbros, granodiorite gneisses, and metasedimentary rocks. The average foliation dips 50° and is inferred to have a northeasterly trend. The Precambrian basement has been regarded as part of the Grenville Province. An apparent Rb–Sr whole rock isochron, for predominantly meta-igneous rocks, yields an age of 1560 ± 140 Ma. This we interpret as pre-Grenvillian, surviving the later imprint of the Grenvillian Orogeny. Points excluded from the isochron register ages of 1830, 915, and 670 Ma, and can be interpreted as geologically meaningful.

A Transient 3D CFD Model of a Progressive Cavity Pump

2016 ◽  
Author(s):  
K. R. Mrinal ◽  
Md. Hamid Siddique ◽  
Abdus Samad
Keyword(s):  
Oil And Gas ◽  
Complex Geometry ◽  
Transient Behavior ◽  
Oil And Gas Industry ◽  
High Viscosity ◽  
Solid Content ◽  
Operating Conditions ◽  
Cfd Model ◽  
Ansys Fluent ◽  
Flow Variables

A progressive cavity pump (PCP) is a positive displacement pump and has been used as an artificial lift method in the oil and gas industry for pumping fluid with solid content and high viscosity. In a PCP, a single-lobe rotor rotates inside a double-lobe stator. Articles on computational works for flows through a PCP are limited because of transient behavior of flow, complex geometry and moving boundaries. In this paper, a 3D CFD model has been developed to predict the flow variables at different operating conditions. The flow is considered as incompressible, single phase, transient, and turbulent. The dynamic mesh model in Ansys-Fluent for the rotor mesh movement is used, and a user defined function (UDF) written in C language defines the rotor’s hypocycloid path. The mesh deformation is done with spring based smoothing and local remeshing technique. The computational results are compared with the experiment results available in the literature. Thepump gives maximum flowrate at zero differential pressure.

Designing CO2 Transmission Pipelines Without Crack Arrestors

2010 ◽  
Author(s):  
Graeme G. King ◽  
Satish Kumar
Keyword(s):  
Wall Thickness ◽  
Carbon Capture ◽  
Power Plants ◽  
Oil And Gas ◽  
Cost Optimization ◽  
Operating Conditions ◽  
Operating Pressure ◽  
Design Work ◽  
Industrial Facilities ◽  
Pipeline Network

Masdar is developing several carbon capture projects from power plants, smelters, steel works, industrial facilities and oil and gas processing plants in Abu Dhabi in a phased series of projects. Captured CO2 will be transported in a new national CO2 pipeline network with a nominal capacity of 20×106 T/y to oil reservoirs where it will be injected for reservoir management and sequestration. Design of the pipeline network considered three primary factors in the selection of wall thickness and toughness, (a) steady and transient operating conditions, (b) prevention of longitudinal ductile fractures and (c) optimization of total project owning and operating costs. The paper explains how the three factors affect wall thickness and toughness. It sets out code requirements that must be satisfied when choosing wall thickness and gives details of how to calculate toughness to prevent propagation of long ductile fracture in CO2 pipelines. It then uses cost optimization to resolve contention between the different requirements and arrive at a safe and economical pipeline design. The design work selected a design pressure of 24.5 MPa, well above the critical point for CO2 and much higher than is normally seen in conventional oil and gas pipelines. Despite its high operating pressure, the proposed network will be one of the safest pipeline systems in the world today.

Experimental investigation of isothermal and reacting flow characteristics downstream of axisymmetric bluff body stabilizers under stratified or fully premixed inlet mixture conditions

2020 ◽  
Author(s):  
Γεώργιος Πατεράκης
Keyword(s):  
Experimental Investigation ◽  
Turbulent Flow ◽  
Bluff Body ◽  
Operating Conditions ◽  
Reacting Flow ◽  
Wide Range ◽  
Flow Features ◽  
Air Mixing ◽  
The Impact ◽  
Stratified Flames

The current work describes an experimental investigation of isothermal and turbulent reacting flow field characteristics downstream of axisymmetric bluff body stabilizers under a variety of inlet mixture conditions. Fully premixed and stratified flames established downstream of this double cavity premixer/burner configuration were measured and assessed under lean and ultra-lean operating conditions. The aim of this thesis was to further comprehend the impact of stratifying the inlet fuelair mixture on the reacting wake characteristics for a range of practical stabilizers under a variety of inlet fuel-air settings. In the first part of this thesis, the isothermal mean and turbulent flow features downstream of a variety of axisymmetric baffles was initially examined. The effect of different shapes, (cone or disk), blockage ratios, (0.23 and 0.48), and rim thicknesses of these baffles was assessed. The variations of the recirculation zones, back flow velocity magnitude, annular jet ejection angles, wake development, entrainment efficiency, as well as several turbulent flow features were obtained, evaluated and appraised. Next, a comparative examination of the counterpart turbulent cold fuel-air mixing performance and characteristics of stratified against fully-premixed operation was performed for a wide range of baffle geometries and inlet mixture conditions. Scalar mixing and entrainment properties were investigated at the exit plane, at the bluff body annular shear layer, at the reattachment region and along the developing wake were investigated. These isothermal studies provided the necessary background information for clarifying the combustion properties and interpreting the trends in the counterpart turbulent reacting fields. Subsequently, for selected bluff bodies, flame structures and behavior for operation with a variety of reacting conditions were demonstrated. The effect of inlet fuel-air mixture settings, fuel type and bluff body geometry on wake development, flame shape, anchoring and structure, temperatures and combustion efficiencies, over lean and close to blow-off conditions, was presented and analyzed. For the obtained measurements infrared radiation, particle image velocimetry, laser doppler velocimetry, chemiluminescence imaging set-ups, together with Fouriertransform infrared spectroscopy, thermocouples and global emission analyzer instrumentation was employed. This helped to delineate a number of factors that affectcold flow fuel-air mixing, flame anchoring topologies, wake structure development and overall burner performance. The presented data will also significantly assist the validation of computational methodologies for combusting flows and the development of turbulence-chemistry interaction models.

Hydrodynamic drag in steller sea lions (Eumetopias jubatus)

2000 ◽  
Vol 203 (12) ◽  
pp. 1915-1923 ◽  
Author(s):  
L.L. Stelle ◽  
R.W. Blake ◽  
A.W. Trites
Keyword(s):  
Minimum Cost ◽  
The Body ◽  
Hydrodynamic Drag ◽  
Eumetopias Jubatus ◽  
Steller Sea Lions ◽  
California Sea Lions ◽  
Cost Of Transport ◽  
Sea Lions ◽  
Drag Forces ◽  
The Individual

Drag forces acting on Steller sea lions (Eumetopias jubatus) were investigated from ‘deceleration during glide’ measurements. A total of 66 glides from six juvenile sea lions yielded a mean drag coefficient (referenced to total wetted surface area) of 0.0056 at a mean Reynolds number of 5.5×10(6). The drag values indicate that the boundary layer is largely turbulent for Steller sea lions swimming at these Reynolds numbers, which are past the point of expected transition from laminar to turbulent flow. The position of maximum thickness (at 34 % of the body length measured from the tip of the nose) was more anterior than for a ‘laminar’ profile, supporting the idea that there is little laminar flow. The Steller sea lions in our study were characterized by a mean fineness ratio of 5.55. Their streamlined shape helps to delay flow separation, reducing total drag. In addition, turbulent boundary layers are more stable than laminar ones. Thus, separation should occur further back on the animal. Steller sea lions are the largest of the otariids and swam faster than the smaller California sea lions (Zalophus californianus). The mean glide velocity of the individual Steller sea lions ranged from 2.9 to 3.4 m s(−)(1) or 1.2-1.5 body lengths s(−)(1). These length-specific speeds are close to the optimum swim velocity of 1.4 body lengths s(−)(1) based on the minimum cost of transport for California sea lions.

Experimental investigation of friction in compliant contact: The effect of configuration, viscoelasticity and operating conditions

2021 ◽  
pp. 107340
Author(s):  
Cheney Quinn ◽  
David Nečas ◽  
Petr Šperka ◽  
Max Marian ◽  
Martin Vrbka ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Operating Conditions
Sign in / Sign up

Export Citation Format

Share Document