Benchmarking of VIV Suppression Systems

2008 ◽  
Author(s):  
Kenneth J. Schaudt ◽  
Christopher Wajnikonis ◽  
Don Spencer ◽  
Jie Xu ◽  
Steve Leverette ◽  
...  
Keyword(s):  
Reynolds Number ◽  
The Body ◽  
Test Results ◽  
In Situ Tests ◽  
Image Velocimetry ◽  
High Reynolds ◽  
Viv Suppression ◽  
Almost All ◽  
Flow Splitter

A new form of Vortex-Induced Vibration (VIV) suppression device, the AIMS Dual-fin Flow Splitter (ADFS), has been developed, tested and benchmarked against bare-pipe, 5d and 15d pitch strakes and conventional teardrop fairings. Testing included high-mode number in-situ tests as well as low Reynolds number (<300,000) and high Reynolds number (<1.9 million) forced and free tank tests. Finally, wind tunnel tests and in-water Particle Image Velocimetry (PIV) were used to test the hypothesis that the dual-fin flow splitter replaces the oscillating wake of a blunt body with a stable, attached circulation behind the body and between the fins. Such a replacement was hypothesized to result in reduced drag, and the elimination of almost all VIV. The paper will describe the testing program and results, and present the incorporation of the test results into riser models.

scholarly journals Movement of a finite body in channel flow

2016 ◽  
Vol 472 (2191) ◽  
pp. 20160164 ◽  
Author(s):  
Frank T. Smith ◽  
Edward R. Johnson
Keyword(s):  
Reynolds Number ◽  
Channel Flow ◽  
Flow Instability ◽  
Flow Direction ◽  
Finite Size ◽  
The Body ◽  
Thin Body ◽  
Shear Stresses ◽  
Unsteady Interaction ◽  
High Reynolds

A body of finite size is moving freely inside, and interacting with, a channel flow. The description of this unsteady interaction for a comparatively dense thin body moving slowly relative to flow at medium-to-high Reynolds number shows that an inviscid core problem with vorticity determines much, but not all, of the dominant response. It is found that the lift induced on a body of length comparable to the channel width leads to differences in flow direction upstream and downstream on the body scale which are smoothed out axially over a longer viscous length scale; the latter directly affects the change in flow directions. The change is such that in any symmetric incident flow the ratio of slopes is found to be cos ⁡ ( π / 7 ) , i.e. approximately 0.900969, independently of Reynolds number, wall shear stresses and velocity profile. The two axial scales determine the evolution of the body and the flow, always yielding instability. This unusual evolution and linear or nonlinear instability mechanism arise outside the conventional range of flow instability and are influenced substantially by the lateral positioning, length and axial velocity of the body.

scholarly journals The Effect of Surface Roughness of a Body in the High Reynolds-Number Flow

1995 ◽  
Vol 2 (1) ◽  
pp. 23-32
Author(s):  
Tsutomu adachi
Keyword(s):  
Surface Roughness ◽  
Reynolds Number ◽  
High Reynolds Number ◽  
The Body ◽  
Reynolds Number Flow ◽  
Flow Phenomena ◽  
Number Flow ◽  
High Reynolds ◽  
Cryogenic Wind Tunnel ◽  
Effect Of Surface

In this paper, first, the principle, structures, operations, and performances of the cryogenic wind tunnel are described. By changing the pressure, temperature and velocity of gas a high Reynolds-number flow(5×104<Re<107)can be obtained. From the research results, a high Reynolds-number flow with comparatively low power, LN consumptions was attained. It was with Mach-number independent of each other, o show some examples of high Reynolds-number flow, the effects of surface roughness and grooves on the surface of a cylinder on the flow are measured using models with various values of roughness and size. A model test of an airship was also conducted. With the high Reynolds-number flow, the thickness of the boundary layer becomes thinner. Then the surface conditions of a body have great effect on the flow phenomena and on the drag of the body. Some attempts to reduce the drag of the body were shown.

Flow Around a Simplified Car, Part 1: Large Eddy Simulation

2005 ◽  
Vol 127 (5) ◽  
pp. 907-918 ◽  
Author(s):  
Siniša Krajnović ◽  
Lars Davidson
Keyword(s):  
Reynolds Number ◽  
The Body ◽  
Ground Vehicle ◽  
Surface Separation ◽  
Recirculating Flow ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Reynolds Number Effects ◽  
Sharp Edges ◽  
High Reynolds

Large eddy simulations (LES) were made of flows around a generic ground vehicle with sharp edges at the rear end (an Ahmed body with a 25° angle of the rear slanted surface). Separation of the flow at the rear results in large regions with recirculating flow. As the separation is determined by the geometry, the Reynolds number effects are minimized. Resolution requirements of this recirculating flow are smaller than those in LES of wall attached flows. These two consequences of the geometry of the body are used to predict the experimental flow at relatively high Reynolds number. Recommendations are presented for the preparation and realization of LES for vehicle flows. Comparison of the LES results with the experimental data shows good agreement.

scholarly journals Local velocity scaling in an impeller discharge flow in T400 vessel agitated by tooth impeller in a fully turbulent region

2018 ◽  
Vol 180 ◽  
pp. 02102 ◽  
Author(s):  
Radek Šulc ◽  
Pavel Ditl ◽  
Ivan Fořt ◽  
Darina Jašíkova ◽  
Michal Kotek ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Reynolds Number ◽  
Test Results ◽  
Flat Bottom ◽  
Time Resolved ◽  
Discharge Flow ◽  
Image Velocimetry ◽  
Fully Developed Turbulent Flow ◽  
Inner Diameter ◽  
High Level

Hydrodynamics and flow field were measured in an agitated vessel using 2-D Time Resolved Particle Image Velocimetry (2-D TR PIV). The experiments were carried out in a fully baffled cylindrical flat bottom vessel 400 mm in inner diameter agitated by a tooth impeller 133 mm in diameter. The velocity fields were measured in the impeller discharge flow for impeller rotation speeds from 300 rpm to 700 rpm and three liquids of different viscosities (i.e. (i) distilled water, ii) a 28% vol. aqueous solution of glycol, and iii) a 43% vol. aqueous solution of glycol), corresponding to the impeller Reynolds number in the range 68 000 < Re < 221 000. This Re range secures the fully-developed turbulent flow of agitated liquid. In accordance with the theory of mixing, the dimensionless mean and fluctuation velocities in the measured directions were found to be constant and independent of the impeller Reynolds number. On the basis of the test results the spatial distributions of dimensionless velocities were calculated. The radial turbulence intensity was found to be in the majority in the range from 0.3 to 0.9, which corresponds to the high level of this quantity.

Initial DPSH Soil Test Results with Accelerometer Installed in the Probe Cone

2016 ◽  
Author(s):  
Kęstutis Kelevišius ◽  
Gintaras Žaržojus
Keyword(s):  
Soil Analysis ◽  
Cohesive Soil ◽  
Test Results ◽  
Cone Penetration ◽  
In Situ Tests ◽  
Soil Response ◽  
Dynamic Penetration ◽  
Dynamic Cone Penetration ◽  
Cpt Test

Dynamic penetration test (DPSH) is one of the large amount of soil in-situ tests are known. In world practice, this method usually used for granular soil investigations although it could be applied in cohesive soils. Correlation of received DPSH test results with soil properties is complex and often not reliable. Especially it becomes obvious after application in cohesive soil analysis. In most cases, correlation depends on soil response to dynamic cone penetration and deformation of dynamic sounding equipment. Measurement of cone accelerations allows precisely evaluate loss of hammer energy, displacement of the cone during strike and other parameters. Correlation of DPSH (measured acceleration of the cone) and CPT test results are presented in this article. In this article also presented studies of possibilities to determine dynamic soil characteristics.

Friction Losses in Turbulent Pipe-flow

1951 ◽  
Vol 165 (1) ◽  
pp. 88-111 ◽  
Author(s):  
L. E. Prosser ◽  
R. C. Worster ◽  
S. T. Bonnington
Keyword(s):  
Reynolds Number ◽  
Friction Coefficient ◽  
Water Flow ◽  
Reynolds Numbers ◽  
Transition Function ◽  
Turbulent Pipe Flow ◽  
Rational Form ◽  
Iron And Steel ◽  
High Reynolds ◽  
Almost All

Significant developments in the theory of turbulent flow in smooth and rough pipes are reviewed to establish a rational basis for the commonly accepted logarithmic laws for pipe friction. The Prandtl (1932)‡ smooth-pipe law, , where f is the friction coefficient in the formula , agrees with measured results on smooth pipes up to Reynolds numbers of at least 3 × 106. With rough pipe walls and sufficiently high Reynolds numbers, viscosity (and hence Reynolds number) ceases to have any direct effect and the friction coefficient depends on wall roughness and pipe size only. Almost all practical cases of water flow in commercial pipes lie between these two extremes of completely smooth and fully rough conditions, where the friction coefficient varies with both Reynolds number and roughness. Exponential flow formulae of the Manning type— V = *** Am1xiy—can be rearranged into a more rational form f = B( Re) p( k/d) q*** relating f to Reynolds number and relative roughness for a given class of pipe carrying a fluid of given viscosity. A detailed study is made of published test data on wrought-iron and steel pipes which generally operate in the transition zone, and an exponential formula is derived which agrees with these results. This is found to be similar to that given by Blair for this class of pipe. The relative merits of these exponential formulae, and of the Colebrook-White transition function, are discussed and it is concluded that, for most practical cases of water flow in pipes, the simple formulae are no less reliable.

scholarly journals The comparative analysis of the seismic test results performed using the cross-hole and down-hole methods in terms of test reliability and efficiency

2018 ◽  
Vol 66 ◽  
pp. 01021
Author(s):  
Wojciech Tschuschke ◽  
Sławomir Gogolik ◽  
Maciej Kroll ◽  
Krzysztof Janicki
Keyword(s):  
Comparative Analysis ◽  
Small Strain ◽  
Test Reliability ◽  
Engineering Practice ◽  
Test Results ◽  
In Situ Tests ◽  
The Cross ◽  
Seismic Tests

Seismic tests are becoming more and more meaningful in modern geoengineering since they allow precise assessment of changes in the analyzed profile of soil deformation parameters at very small strain. The engineering practice generally uses two methods for such kinds of tests: reference cross-hole test and commercial down-hole method. The costs of implementation of this kind of research and the reliability of the results obtained along with any additional benefits from the type of the selected testing technique are not without significance. Seismic measurements for which comparative analysis was performed were carried out in a strongly anisotropic materials base of a tailings. The results of tests conducted with a standard cross-hole method were compared with those conducted using the down-hole method, in which the seismic piezocone (SCPTU) and seismic dilatometer (SDMT) were used. Test results have shown that in terms of assessment of their credibility, there were no fundamental differences in the quality of the recorded signals. It has been pointed out, however, that there are many advantages to penetration in situ tests, which complement identification of subsoil structure with many crucial elements that cannot be achieved using the cross-hole method.

Root reinforcement of soil: review of analytical models, test results, and applications to design

2013 ◽  
Vol 50 (3) ◽  
pp. 259-274 ◽  
Author(s):  
Tien H. Wu
Keyword(s):  
Analytical Models ◽  
Test Results ◽  
In Situ Tests ◽  
Design Problems ◽  
Root Reinforcement ◽  
And Performance

This paper reviews analytical models that are used to evaluate results of laboratory and in situ tests on soil reinforced by vegetation roots and performance of slopes with vegetation. Predicted and observed performances are compared to illustrate the accuracy and refinement of the models and their relationships to the quality of the available data. General guidelines for application to design problems are provided.

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