The entrainment envelope of dye-core vortices at submerged hydraulic intakes

2002 ◽  
Vol 29 (3) ◽  
pp. 400-408 ◽  
Author(s):  
E C Carriveau ◽  
R E Baddour ◽  
G A Kopp
Keyword(s):  
Water Surface ◽  
Laboratory Experiments ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Swirling Flows ◽  
Surface Phenomenon ◽  
Acoustic Doppler Velocimeter ◽  
Velocity Measurements ◽  
Frazil Ice ◽  
Hydraulic Intake

Each winter in Canada, operational difficulties are encountered at various water works resulting from intake blockages caused by frazil ice entrainment. In a lake setting, frazil is a surface phenomenon, the strong downward current produced by a swirling flow, with an intake vortex present, provides a mechanism by which frazil is transported from the water surface to the submerged intake below. Laboratory experiments were conducted to study the entrainment envelope associated with swirling and non-swirling flows into submerged water intakes. Three-dimensional velocity measurements were made with an acoustic Doppler velocimeter. The results clearly show that the entrainment envelope for swirling flow is several times larger than that for non-swirling flow. This paper details, for a given set of conditions, the differences in the non-swirling and swirling flow entrainment envelopes and emphasizes the potential difficulties with frazil ice that vortices can cause at intakes.Key words: vortex, dye-core vortex, submerged hydraulic intake, entrainment envelope, three-dimensional velocity measurements, acoustic Doppler velocimeter.

Flow Measurements in a Model Burner—Part 2

1993 ◽  
Vol 115 (2) ◽  
pp. 309-316
Author(s):  
D. F. G. Dura˜o ◽  
M. V. Heitor ◽  
A. L. N. Moreira
Keyword(s):  
Laser Doppler Velocimetry ◽  
Swirling Flow ◽  
Laser Sheet ◽  
Three Dimensional ◽  
Swirling Flows ◽  
Dimensional Structure ◽  
Mixing Efficiency ◽  
Flow Measurements ◽  
Circular Jets ◽  
Turbulence Production

The isothermal swirling flow in the vicinity of a model oxy-fuel industrial burner is analyzed with laser-Doppler velocimetry together with laser-sheet visualization. The burner consists of a central axisymmetric swirling jet surrounded by sixteen circular jets, simulating the injection of oxygen in practical burners. The results extend those obtained for non-swirling flows, and presented in Part 1 of this paper, to the analysis of the dependence of the mixing efficiency of the burner assembly upon the swirl motion of the central jet and have the necessary detail to allow to assess the accuracy of calculation procedures of the flow in industrial burners. It is shown that swirl attenuates the three-dimensional structure typical of multijet flows in such a way that turbulence production and transport in the near burner zone are dominated by swirl-induced processes.

On the Use of the Squire-Long Equation to Estimate Radial Velocities in Swirling Flows

2006 ◽  
Vol 129 (2) ◽  
pp. 209-217 ◽  
Author(s):  
Michel J. Cervantes ◽  
L. Håkan Gustavsson
Keyword(s):  
Boundary Conditions ◽  
Radial Velocity ◽  
Swirling Flow ◽  
Draft Tube ◽  
Three Dimensional ◽  
Swirling Flows ◽  
Laser Doppler Velocimeter ◽  
Test Case ◽  
Swirl Number ◽  
Experimental Values

A method to estimate the radial velocity in swirling flows from experimental values of the axial and tangential velocities is presented. The study is motivated by the experimental difficulties to obtain this component in a draft tube model as evidenced in the Turbine-99 IAHR∕ERCOFTAC Workshop. The method uses a two-dimensional nonviscous description of the flow. Such a flow is described by the Squire-Long equation for the stream function, which depends on the boundary conditions. Experimental values of the axial velocities at the inlet and outlet of the domain are used to obtain the boundary conditions on the bounded domain. The method consists of obtaining the equation related to the domain with an iterative process. The radial velocity profile is then obtained. The method may be applied to flows with a swirl number up to about Sw=0.25. The critical value of the swirl number depends on the velocity profiles and the geometry of the domain. The applicability of the methodology is first performed on a swirling flow in a diffuser with a half angle of 3deg at various swirl numbers, where three-dimensional (3D) laser Doppler velocimeter (LDV) velocity measurements are available. The method is then applied to the Turbine-99 test case, which consists in a model draft tube flow where the radial inlet velocity was undetermined. The swirl number is equal to Sw=0.21. The stability and the convergence of the approach is investigated in this case. The results of the pressure recovery are then compared to the experiments for validation.

Vorticity Modeling of Blade Wakes behind Isolated Annular Blade-Rows: Induced Disturbances in Swirling Flows

1981 ◽  
Vol 103 (2) ◽  
pp. 279-287 ◽  
Author(s):  
C. S. Tan
Keyword(s):  
Swirling Flow ◽  
Three Dimensional ◽  
Stagnation Pressure ◽  
Swirling Flows ◽  
Axial Distance ◽  
Free Vortex ◽  
Blade Row ◽  
Type 3 ◽  
Theoretical Considerations ◽  
Type Potential

A general analysis is proposed for studying the fluid-mechanical behavior of blade wakes from an annular blade-row in highly swirling flow. The coupling between the centrifugal force and the vorticity, which is inherent to highly swirling flows, can significantly modify the wake behavior from that in a two-dimensional situation. In steady flow, theoretical considerations show that a blade wake consists primarily of two distinct types of vorticity: (1) trailing vorticity shed from the blade due to a spanwise variation in blade circulation; and (2) vorticity associated with defects in stagnation pressure (or rotary stagnation in relative coordinate system). Three types of disturbances can be identified in the resulting three-dimensional disturbance field: (1) the exponentially decaying type (potential, irrotational), (2) the purely convected type (rotational), and (3) the nonconvected type (both rotational and irrotational parts). Type (3) arises because of the interaction of centrifugal and Coriolis forces with (1) and (2). It is found that near the blade row the nonconvected disturbances grow linearly in magnitude with the axial distance. However, although those nonconvected disturbances associated with the trailing vorticity (also called Beltrami vorticity) persist for moderate distances downstream, they eventually decay inversely with the axial distance, irrespective of the types of swirl distribution. In contrast, those parts of nonconvected disturbances which are induced by the vorticity caused by (rotary) stagnation pressure defects persist indefinitely downstream for any type of swirl other than free-vortex. In the limit of free-vortex swirl, all disturbances decay at least inversely with the axial distance downstream.

Large-scale laboratory experiments on tsunamis generated by submarine volcanic eruptions in a wave basin

2020 ◽  
Author(s):  
Yibin Liu ◽  
Hermann M. Fritz
Keyword(s):  
Volcanic Eruption ◽  
Water Surface ◽  
Laboratory Experiments ◽  
Three Dimensional ◽  
Volcanic Eruptions ◽  
Explosive Eruptions ◽  
Wave Basin ◽  
Eruptive Column ◽  
Volcanic Tsunami ◽  
Underwater Camera

<p>Among the wide spectrum of volcanic tsunamis, the most devastating events have been caused by extremely explosive eruptions, pyroclastic flows and debris avalanches of underwater or near surface volcanos. The 2015 “orange” alert at the Kick ‘em Jenny submarine volcano in the Caribbean Sea highlighted the challenges in characterizing the tsunami waves for a potential submarine volcanic eruption. The 2018 Anak Krakatau eruption and flank collapse generated tsunami resulted in a near water surface setting of the volcanic vents similar to these laboratory experiments and relevant for the remaining and future tsunami hazards.</p><p>Source and runup scenarios are physically modeled using generalized Froude similarity in the three dimensional NHERI tsunami wave basin at Oregon State University. A novel volcanic tsunami generator (VTG) was deployed to study submarine volcanic eruptions with varying initial submergence and kinematics. The VTG consists of a telescopic eruptive column with an outer diameter of 1.2 m. The top cap of the pressurized eruptive column is accelerated vertically by eight synchronized 80 mm diameter pneumatic pistons with a stroke of 0.3 m. More than 300 experimental runs have been performed which include around 120 combinations of velocities and water depths. The variable eruption velocities of the VTG can mimic a wide range of processes ranging from relatively slow mud volcanoes and rapid explosive eruptions. The gravitational collapse of the eruptive column represents the potential engulfment and caldera formation. Water surface elevations and onshore runup are recorded by an array of resistance wave gauges and runup gauges. The VTG displacement is measured with an internal linear potentiometer and above and underwater camera recordings. Water surface reconstruction and kinematics are determined with a stereo particle image velocimetry (PIV) system. The water surface spike from the concentric collision of wave crest is observed under a limited range of Froude numbers. The energy conversion rates from the volcanic eruption to the wave train are quantified for various scenarios. Predictive equations of wave and spike characteristics are obtained and compared with existing linear and non-linear theories. The measured volcanic eruption and tsunami data serve to validate and advance three-dimensional numerical volcanic tsunami prediction models.</p>

scholarly journals Vorticity Modelling of Blade Wakes Behind Isolated Annular Blade-Rows: Induced Disturbances in Swirling Flows

1980 ◽  
Author(s):  
C. S. Tan
Keyword(s):  
Coordinate System ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Stagnation Pressure ◽  
Swirling Flows ◽  
Two Dimensional ◽  
Blade Row ◽  
Theoretical Considerations ◽  
Type Potential ◽  
Disturbance Field

A general analysis is proposed for studying the fluid-mechanical behavior of blade wakes from an annular blade-row in highly swirling flow. The coupling between the centrifugal force and the vorticity, which is inherent to highly swirling flows, can significantly modify the wake behavior from that in a two-dimensional situation. In steady flow, theoretical considerations show that a blade wake consists primarily of two distinct types of vorticity: a) trailing vorticity shed from the blade due to a span wise variation in blade circulation, and b) vorticity associated with defects in stagnation pressure (or rotary stagnation in relative coordinate system). Three types of disturbances can be identified in the resulting three-dimensional disturbance field: a) the exponentially decaying type (potential, irrotational), b) the purely convected type (rotational), and c) the non-convected type (both rotational and irrotational parts).

Asymmetric Swirling Flows in Turbomachine Annuli

1978 ◽  
Vol 100 (4) ◽  
pp. 618-629 ◽  
Author(s):  
E. M. Greitzer ◽  
T. Strand
Keyword(s):  
Experimental Investigation ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Swirling Flows ◽  
Experimental Measurements ◽  
Strongly Coupled ◽  
Flow Disturbances ◽  
Different Types ◽  
Theoretical Predictions ◽  
Good Agreement

An analytical and experimental investigation of asymmetric annular swirling flows is presented. It is shown that, in contrast to the situation in nonswirling flow, the different types of flow disturbances (pressure and vorticity) are not separable in a swirling flow but are strongly coupled. The flows that occur due to this coupling are inherently three-dimensional and exhibit new features not seen in the nonswirling case. The theoretical predictions are in good agreement with experimental measurements carried out in an annular swirl rig.

Analytical Investigations of Incompressible Turbulent Swirling Flow in Stationary Ducts

1969 ◽  
Vol 36 (2) ◽  
pp. 151-158 ◽  
Author(s):  
A. Rochino ◽  
Z. Lavan
Keyword(s):  
Flow Field ◽  
Transport Theory ◽  
Swirling Flow ◽  
Pipe Wall ◽  
Three Dimensional ◽  
Eddy Diffusivity ◽  
Small Region ◽  
Swirling Flows ◽  
Entire Flow ◽  
Vorticity Transport

Turbulent swirling flows in stationary cylindrical ducts were investigated analytically using Taylor’s modified vorticity transport theory and von Karman’s similarity hypothesis extended to consider a three-dimensional fluctuating velocity field. The resulting similarity conditions were used to formulate the expression for eddy diffusivity in the entire flow field except in a small region near the pipe wall where a mixing-length expression analogous to that assumed by Prandtl for parallel flow in channels was used. The swirl equation was solved numerically using a constant that was obtained indirectly from an experiment by Taylor, and the analytical results were compared with two different sets of experimental measurements. In both cases, the agreement between experiment and analysis was satisfactory. Some discrepancies appeared when the flow field was predominantly irrotational or in solid-body rotation: This might have been expected since, for these situations, some of the similarity conditions were indeterminate or infinite.

THREE-DIMENSIONAL LAMINAR SWIRLING FLOW IN A PIPE

2019 ◽  
Author(s):  
Rodrigo Vidal Cabral ◽  
Andre Damiani Rocha
Keyword(s):  
Swirling Flow ◽  
Three Dimensional

Operational Model and its Validation with Drift Tests in Water Areas Around the Baltic Sea

1994 ◽  
Vol 29 (2-3) ◽  
pp. 293-308
Author(s):  
J. Koponen ◽  
M. Virtanen ◽  
H. Vepsä ◽  
E. Alasaarela
Keyword(s):  
Three Dimensional ◽  
Fast Response ◽  
Velocity Measurements ◽  
Short Term ◽  
Large Lakes ◽  
Operational Model ◽  
Water Currents ◽  
Emergency Situations ◽  
Sensitivity Tests ◽  
The Baltic

Abstract Three-dimensional (3-D) mathematical models of water currents, transport, mixing, reaction kinetic, and interactions with bottom and air have been used in Finland regularly since 1982 and applied to about 40 cases in large lakes, inland seas and their coastal waters. In each case, model validity has been carefully tested with available flow velocity measurements, tracer studies and water quality observations. For operational use, i.e., for spill combatting and sea rescue, the models need fast response, proven validity and illustrative visualization. In 1987-90, validated models were implemented for operational use at five sea areas along the Finnish coast. Further validation was obtained in model applications from nine documented or arranged cases and from seven emergency situations. Sensitivity tests supplement short-term validation. In the Bothnian Sea, it was nescessary to start the calculation of water currents three days prior to the start of the experiment to reduce initial inaccuracies and to make the coastal transport estimates meaningful.

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