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Journal ArticleDOI

Performance evaluation of tapered vane

01 Jul 2007-Journal of Hydraulic Research (Taylor & Francis Group)-Vol. 45, Iss: 4, pp 472-477
TL;DR: In this paper, the effect of taper angle variation within a range 33.7° to 45° on moment of momentum (MOM) has been investigated and it is observed that for a given optimal angle of attack as 40°, MOM can be further increased by keeping the taper angles as 33. 7°
Abstract: Tapered submerged vanes are installed inWapsipinicon river bend in the USA and outside a new water intake in Nepal. Taper angle is the angle made by leading edge of vane with horizontal in vertical plane. A tapered vane also induces something called the vortex lift (at high angles of attack) which is a secondary lift caused by a reattachment of the flow due to a spanwise leading edge vortex. The aptitude of the vane/foil to form this leading edge vortex is highly dependent on the shape of the leading edge, generally a sharp leading edge will form a strong vortex whilst a rounded leading edge will form a weaker vortex (with the vortex centre further downstream). In this paper, the effect of taper angle variation within a range 33.7° to 45° on moment of momentum (MOM) has been investigated and it is observed that for a given optimal angle of attack as 40°, MOM can be further increased by keeping the taper angle as 33.7°
Citations
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Journal ArticleDOI
TL;DR: In this article, the results of an experimental study characterizing thorough variation of turbulent hydrodynamics and flow distribution in emergent and sparsely vegetated open channel flow were reported.
Abstract: This present study reports the results of an experimental study characterizing thorough variation of turbulent hydrodynamics and flow distribution in emergent and sparsely vegetated open channel flow. An emergent and rigid sparse vegetation patch with regular spacing between stems along the flow and transverse directions was fixed in the central region of the cross-section of open channel. Experiments were conducted in subcritical flow conditions and velocity measurements were obtained with an acoustic Doppler Velocimetry system. Large variations of the turbulence intensities, Reynolds shear stress, turbulent kinetic energy and vortical motions are found in and around the vegetation patch. At any cross-section through the interior of the vegetation patch, streamwise velocity decreases with increase in streamwise length and the velocity profiles converge from the log-law to a linear profile with increasing slope. Time-averaged lateral and vertical velocities inside the vegetation patch increase with increasing streamwise distance and converge from negative values to positive values. Turbulence intensities interior of the sparse vegetation patch are more than those of without the vegetation patch. Similar to the trend of streamwise velocity profiles inside the vegetation, turbulence intensities and longitudinal-normal Reynolds shear stress profile decreases with streamwise direction. In the interior of the vegetation patch and downstream of the trailing edge, turbulent kinetic energy profiles are exhibiting irregular fluctuations and the maximum values are occurring in the outer layer. Analysis of flow distribution confirms sparse vegetation patch is inducing a serpentine flow pattern in its vicinity. At the leading edge, flow is rushing towards the right hand sidewall, and at the trailing edge, flow is turning to the left hand sidewall. In between the leading and trailing edges, the streamlines are following a zig-zag fashion at varied degree along the streamwise and lateral directions. Immediate upstream of the leading edge and in the interior of the vegetation patch, vortex motion is clearly visible and the vortices are stretched along the width of the channel with streamwise direction.

17 citations


Additional excerpts

  • ...14 where the MOM at a point P for unit weight of water is computed as follows [24]....

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Journal ArticleDOI
TL;DR: In this paper, the effect of the introduction of vanes in form of rows on parameters like turbulence intensities, Reynolds stresses, turbulent kinetic energy, anisotropy index, and the velocity profile of the flow was studied.

9 citations

Journal ArticleDOI

8 citations


Cites background from "Performance evaluation of tapered v..."

  • ...To improve the efficiency of submerged vanes in sediment control, the shape of the vanes such as curved vanes (Gupta et al., 2007), sheet piles (Boniforti et al., 2015), a set of upper and bottom vanes (Barkdoll et al., 1999), tapered vane (Gupta et al., 2007; Azizi et al., 2012) and trapezoidal,…...

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  • ...To improve the efficiency of submerged vanes in sediment control, the shape of the vanes such as curved vanes (Gupta et al., 2007), sheet piles (Boniforti et al....

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  • ..., 1999), tapered vane (Gupta et al., 2007; Azizi et al., 2012) and trapezoidal, forward-swept and backward-swept vanes (Ouyang, 2009) was investigated....

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  • ...…shape of the vanes such as curved vanes (Gupta et al., 2007), sheet piles (Boniforti et al., 2015), a set of upper and bottom vanes (Barkdoll et al., 1999), tapered vane (Gupta et al., 2007; Azizi et al., 2012) and trapezoidal, forward-swept and backward-swept vanes (Ouyang, 2009) was investigated....

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Journal ArticleDOI
TL;DR: In this paper, experiments were conducted to control sediment entry into an intake channel using submerged vanes in a physical model with a rectangular mobile-bed main channel and a trapezoidal rigid-bed intake channel diverting at an angle of 45°.
Abstract: Intake canals are used to withdraw water from rivers for various purposes. Sedimentation in the intake canal reduces the quality and quantity of water being delivered. In this study, experiments were conducted to control sediment entry into an intake channel using submerged vanes in a physical model with a rectangular mobile-bed main channel and a trapezoidal rigid-bed intake channel diverting at an angle of 45°. The variables in the study included vane angle, number of vane rows, and vane spacing in terms of mean flow depth in the main channel. In addition to the commonly used vane array with uniform vane heights, three other vane-height configurations were also tested. The least local scour around vanes and highest sediment reduction (~70%) were observed for vanes oriented at a 15° vane angle with an increasing vane-height configuration placed in two rows. It was also observed that control of sediment entry into the intake canal increased with an increase of both vane spacing and number of vane rows.

7 citations

Dissertation
14 Dec 2015
TL;DR: In this article, an experimental study was conducted to analyze the physical flow turbulence and sediment distribution with submerged vanes, where the vanes were made of 14 mm-thick PVC sheet, they were rectangular in shape, with height H = 7 cm = 0.4337d, and length L = 25 cm = 3.571H.
Abstract: Experimental study was conducted to analyze the physical flow turbulence and sediment distribution with submerged vane. The objectives behind the investigation were verified and compare results with the Odgaard theory, also; achieved to measure vertical pressures acting on both sides of submerged vane, calculate lift and drag forces, lift and drag coefficients experimentally, that the theory of Odgaard was fails to predict satisfactorily. Other motivation of the study was investigates experimentally the hydrodynamic characterization of submerged vanes as; velocities fields, circulation, vorticity, bed topography, pressures, drag and lift forces with its coefficients, study physical fluid turbulence of submerged vanes as; Reynolds normal and shear stresses, turbulent kinetic energy and rate of dissipation, turbulence intensities, Kolmogorov scales, kinetic energy spectrum, turbulent velocities fields, fluctuating velocities and finally Reynolds stresses histograms. Tests were conducted with clear water was transported throughout the re-circulated rectangular channel with cross-section 7.5 m long, 2.52 m wide channel with a bed consisting of 50 cm thick layer of sand with a median diameter of 1.6-mm and a geometric standard deviation of 1.36. Velocities were measured with a 7 Acoustic Doppler Velocimeter ADV, which were calibrated and checked periodically, depths and water surface elevations were measured with a gauge that could be read with an error of less than 0.3 mm. The current meter, gauges were mounted on a movable instrument sliding carriage, which rode on rails a top of the channel walls, on a traversing mechanism, which enabled them to be positioned at any desired location in the channel. Positioning and data sampling were controlled from a computer program. The water surface elevations were used to determine water surface slope S and Darcy-Weisbach friction factor f=8gRS/u_o^2, where uo = undisturbed (pre-vane) cross-sectional-averaged velocity. In all tests, uo=0.2867 m/s, and the discharge Q=116,62 l/s =0.11662 m^3/s. The vanes were made of 14 mm-thick PVC sheet, they were rectangular in shape, with height H = 7 cm = 0.4337d, and length L = 25 cm = 3.571H. In all tests, the vanes were placed at an angle of attack of 20 degrees with the channel centerline. Water depth was 0.1614 m, pre-vane water surface slope, friction factor and geometric standard deviation, sg, were 1.6×10^(-3), 0.045 and 1.36 respectively. The Vectrinos were been calibrated to work at 25Hz and for each position taken data for 4 minutes, a sample volume that is located approximately 4.3 mm of the device. For each position there are seven Vectrinos 10 cm distance from one to other taking data, so data recorded 7 points at the same time. Data recorded were taking on about 24.080 points on whole the sectional cross channel, with the aim to measure the velocities once the channel-bed has reached to the permanent regime or steady state (equilibrium), during the measurements of velocities, we has taken the bed topography (bathymetry) of the channel-bed by using ADV. In the current dissertation, we installed 30 piezometers in each side of Vane. Once obtained the experimental pressures measured at the laboratory on both sides of vane, the pressure difference between vane sides (?P), and the perpendicular resultant force (FR?) acting on the vane, first calculated the resultant force between drag and lift components (FR), then we used this force to calculate drag force FD and lift force FL, also calculated Drag coefficient CD, and finally we calculated the Lift coefficient CL. Results, includes submerged vanes turbulence statistics as; Probability distribution of the velocity field, Reynolds stresses, Turbulence intensity, Kinetic and Dissipation energy, and finally, Kolmogorov turbulence scales. Other results contain energy spectrum, turbulent velocities fields, fluctuating velocities and Reynolds stresses histograms.

7 citations

References
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01 Dec 1966
TL;DR: In this article, a concept for the calculation of the vortex lift of sharp-edge delta wings is presented and compared with experimental data, based on an analogy between vortex lift and the leading-edge suction associated with the potential flow about the leading edge.
Abstract: Polhamus Langley Research Center SUMMARY A concept for the calculation of the vortex lift of sharp-edge delta wings is pre­sented and compared with experimental data. The concept is based on an analogy between the vortex lift and the leading-edge suction associated with the potential flow about the leading edge. This concept, when combined with potential-flow theory modified to include the nonlinearities associated with the exact boundary condition and the loss of the

401 citations


"Performance evaluation of tapered v..." refers background in this paper

  • ...Polhamus (1966) developed his leading edge suction analogy, resulting in a concept called vortex lift, to explain the non-linear lift behaviour of delta wings at high angles of attack....

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  • ...Polhamus (1966) assumed that total lift coefficient can be concluded as a sum of a potential flow lift (CLp) together with the existence of the separated leading edge spiral vortices (CLv) and presented them in the form of Eqs (1) and (2)....

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Book
01 Jan 1979
TL;DR: In this article, the non-tidal alluvial river is considered and the principles of river engineering are discussed, including the nontidal river engineering principles, and the importance of water flow in river engineering.
Abstract: Principles of river engineering: the non-tidal alluvial river , Principles of river engineering: the non-tidal alluvial river , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

207 citations


"Performance evaluation of tapered v..." refers background in this paper

  • ...Submerged vanes are frequently used as vortex generating devices that have several applications, such as protection of erosion (Jansen et al., 1979; Odgaard and Kennedy, 1983; Odgaard and Mosconi, 1987; Odgaard and Wang, 1991a,b); maintaining depth in navigation channel (Odgaard and Spoljaric,…...

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Journal ArticleDOI
TL;DR: Submerged vanes as mentioned in this paper are small flow-training structures (foils), designed to modify the near-bed flow pattern and redistribute flow and sediment transport within the channel cross section.
Abstract: Recent research results with the submerged‐vane technique for sediment control in rivers are described. Submerged vanes are small flow‐training structures (foils), designed to modify the near‐bed flow pattern and redistribute flow and sediment transport within the channel cross section. The structures are installed at an angle of attack of 15–25° with the flow, and their initial height is 0.2–0.4 times local water depth at design stage. The vanes function by generating secondary circulation in the flow. The circulation alters magnitude and direction of the bed shear stresses and causes a change in the distributions of velocity, depth, and sediment transport in the area affected by the vanes. As a result, the river bed aggrades in one portion of the channel cross section and degrades in another. The vanes can be laid out to develop and maintain any desired bed topography. Vanes have been used successfully for protection of stream banks against erosion and for amelioration of shoaling problems at water inta...

139 citations


"Performance evaluation of tapered v..." refers background in this paper

  • ...…devices that have several applications, such as protection of erosion (Jansen et al., 1979; Odgaard and Kennedy, 1983; Odgaard and Mosconi, 1987; Odgaard and Wang, 1991a,b); maintaining depth in navigation channel (Odgaard and Spoljaric, 1986); maintaining the pump-intake bays sediment-free…...

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Journal ArticleDOI
TL;DR: In this article, it was shown that short, vertical, submerged vanes installed at incidence to the channel axis in the outer half of a river-bend channel significantly reduce the secondary currents and the attendant undermining and high-velocity attack of the outer bank.
Abstract: It is shown, theoretically and by a physical model, that short, vertical, submerged vanes installed at incidence to the channel axis in the outer half of a river-bend channel significantly reduce the secondary currents and the attendant undermining and high-velocity attack of the outer bank. The effect of the vanes on the secondary flow is estimated by a simple torque calculation using the Kutta-Joukowski theorem. A design relation for the vane spacing is derived by equating the torque, about the channel centroid, produced by the flow curvature to that resulting from the lateral force exerted on the vanes. The relation is verified in an idealized, physical model of a bend of the Sacramento River, California.

133 citations


"Performance evaluation of tapered v..." refers background in this paper

  • ...Submerged vanes are frequently used as vortex generating devices that have several applications, such as protection of erosion (Jansen et al., 1979; Odgaard and Kennedy, 1983; Odgaard and Mosconi, 1987; Odgaard and Wang, 1991a,b); maintaining depth in navigation channel (Odgaard and Spoljaric,…...

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Journal ArticleDOI
TL;DR: In this paper, the authors describe the design, installation and performance of a system of submerged vanes for erosion protection in a bend of the East Nishnabotna River, Iowa.
Abstract: A summary is given of the design, installation and performance of a system of submerged vanes (“Iowa Vanes”) for erosion protection in a bend of East Nishnabotna River, Iowa. The system functions by eliminating, or reducing, the centrifugally induced helical motion of the flow (the root cause of bank undermining). The system was installed during the summer of 1985. Its performance was evaluated with data obtained in surveys in the spring of 1986. The system was found to effectively reduce velocity and scour along the bank without changing the energy slope of the channel. Areas of design improvements were identified. The summary includes a brief description of the theoretical and experimental background for the design.

109 citations


"Performance evaluation of tapered v..." refers background in this paper

  • ...(9), i indicates the direction of MOM along the direction of flow of fluid (here water)....

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  • ...(9), (m y Vz) is MOM due to vertical velocity and {−m (z − 0....

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  • ...…used as vortex generating devices that have several applications, such as protection of erosion (Jansen et al., 1979; Odgaard and Kennedy, 1983; Odgaard and Mosconi, 1987; Odgaard and Wang, 1991a,b); maintaining depth in navigation channel (Odgaard and Spoljaric, 1986); maintaining the…...

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