scholarly journals Scaling of Scour Depth at Bridge Pier Based on Characteristic Dimension of Large-Scale Vortex

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2458 ◽  
Author(s):  
Nian-Sheng Cheng ◽  
Maoxing Wei
Keyword(s):  
Large Scale ◽  
Horseshoe Vortex ◽  
Bridge Pier ◽  
Theoretical Formula ◽  
Scour Depth ◽  
Flow Depth ◽  
Flow Conditions ◽  
Hydraulic Radius ◽  
Vortex System ◽  
Large Scale Vortex

By examining the variations in the dimensions of a horseshoe vortex system in front of a pier, the present study proposes a new length scale, called pier hydraulic radius, for the scaling of the maximum scour depth at a bridge pier. It is shown that, in comparison with other length scales, the pier hydraulic radius is more effective for quantifying combined effects of pier width and flow depth on the local scour for both low and high flow conditions. A theoretical formula is finally derived, which agrees well with experimental data reported in the literature.

scholarly journals Length Parameter for Scaling Abutment Scour Depth

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3508
Author(s):  
Puer Xu ◽  
Niansheng Cheng ◽  
Maoxing Wei
Keyword(s):  
Large Scale ◽  
Scour Depth ◽  
Length Scale ◽  
Bed Shear Stress ◽  
Combined Effects ◽  
Flow Depth ◽  
Vortex System ◽  
Bridge Abutment ◽  
Abutment Scour ◽  
Scale Turbulence

Flow constriction caused by bridge abutment increases bed shear stress and thus enhances local scour. For scaling the maximum scour depth at the abutment, either abutment length or flow depth has been empirically used in previous studies. By performing a step-by-step analysis, this study proposes a new length scale, which is able to represent combined effects of abutment length, approach flow depth and channel width. Physically, the new length scale describes the maximum possible dimension of the associated vortex system (or large-scale turbulence). Six series of data compiled from the published literature were used in the analysis. The results indicate that the new length scale helps improve the agreement of predictions with the experimental data.

scholarly journals A Study on Interaction between Overfall Types and Scour at Bridge Piers with a Moving-Bed Experiment

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 152
Author(s):  
Wei-Lin Lee ◽  
Chih-Wei Lu ◽  
Chin-Kun Huang
Keyword(s):  
Large Scale ◽  
River Flow ◽  
Extreme Event ◽  
Bridge Pier ◽  
Bridge Piers ◽  
Flow Conditions ◽  
Moving Bed ◽  
Directional Flow ◽  
Scour Hole ◽  
Additional Protection

River slopes can be changed due to an extreme event, e.g., a large-scale earthquake. This can uplift a riverbed greatly and thereby change the behavior of the river flow into a free or submerged overfall. Corresponding damage, including extreme erosion, on bridge piers located in the river can take place due to the aforementioned flow conditions. A reconstructed bridge pier in the same location would also experience a similar impact if the flow condition is not changed. It is important to identify these phenomena and research the mechanism in the interaction between overfall types and scour at bridge piers. Therefore, this paper is aimed at studying a mechanism of free and submerged overfall flow impacts on bridge piers with different distances by a series of moving-bed experiments. The experiment results showed clearly that bridge pier protection requires attention particularly when the pier is located in the maximum scour hole induced by the submerged overfall due to the z directional flow eddies. In many other cases, such as when the location of the bridge pier was at the upstream slope of a scour hole induced by a flow drop, a deposition mound could be observed at the back of the pier. This indicates that, while a pier is at this location, an additional protection takes place on the bridge pier.

scholarly journals Impact of armour layer on the depth of scour hole around side-by-side bridge piers under ice-covered flow condition

2019 ◽  
Vol 67 (3) ◽  
pp. 240-251
Author(s):  
Mohammad Reza Namaee ◽  
Jueyi Sui
Keyword(s):  
Grain Size ◽  
Froude Number ◽  
Large Scale ◽  
Bridge Piers ◽  
Scour Depth ◽  
Flow Conditions ◽  
Densimetric Froude Number ◽  
Open Flow ◽  
Scour Holes ◽  
The Impact

Abstract In the present study, experiments were conducted in a large-scale flume to investigate the issue of local scour around side-by-side bridge piers under both ice-covered and open flow conditions. Three non-uniform sediments were used in this experimental study. Analysis of armour layer in the scour holes around bridge piers was performed to inspect the grain size distribution curves and to study the impact of armour layer on scour depth. Assessments of grain size of deposition ridges at the downstream side of bridge piers have been conducted. Based on data collected in 108 experiments, the independent variables associated with maximum scour depth were assessed. Results indicate that the densi-metric Froude number was the most influential parameter on the maximum scour depth. With the increase in grain size of the armour layer, ice cover roughness and the densimetric Froude number, the maximum scour depth around bridge piers increases correspondingly. Equations have been developed to determine the maximum scour depth around bridge piers under both open flow and ice covered conditions.

scholarly journals Streakline Flow Visualization Study of a Horseshoe Vortex in a Large-Scale, Two-Dimensional Turbine Stator Cascade

1980 ◽  
Author(s):  
R. E. Gaugler ◽  
L. M. Russell
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Leading Edge ◽  
Horseshoe Vortex ◽  
Main Stream ◽  
Two Dimensional ◽  
Vortex System ◽  
Turbine Stator ◽  
Neutrally Buoyant ◽  
Limiting Streamlines

Neutrally buoyant helium-filled bubbles were observed as they followed the streamlines in a horseshoe vortex system around the vane leading edge in a large-scale, two-dimensional, turbine stator cascade. Inlet Reynolds number, based on true chord, ranged between 1.0 × 10 ⅝ to 3.0 × 10 ⅝. Bubbles were introduced into the endwall boundary layer through a slot upstream of the vane leading edge. The paths of the bubbles were recorded photographically as streaklines on 16-mm movie film. Individual frames from the film have been selected, and overlayed to show the details of the horseshoe vortex around the leading edge, the transport of the vortex across the passage near the leading edge is clearly seen when compared to the streaks formed by bubbles carried in the main stream. Limiting streamlines on the endwall surface were traced by the flow of oil drops.

An Experimental Study Heat Transfer in a Large-Scale Turbine Rotor Passage

1994 ◽  
Vol 116 (1) ◽  
pp. 1-13 ◽  
Author(s):  
M. F. Blair
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Large Scale ◽  
Leading Edge ◽  
Horseshoe Vortex ◽  
Turbine Rotor ◽  
Secondary Flows ◽  
Vortex System ◽  
Tip Leakage ◽  
High Heat Transfer

An experimental study of the heat transfer distribution in a turbine rotor passage was conducted in a large-scale, ambient temperature, rotating turbine model. Heat transfer was measured for both the full-span suction and pressure surfaces of the airfoil and for the hub endwall surface. The objective of this program was to document the effects of flow three dimensionality on the heat transfer in a rotating blade row (versus a stationary cascade). Of particular interest were the effects of the hub and tip secondary flows, tip leakage, and the leading-edge horseshoe vortex system. The effect of surface roughness on the passage heat transfer was also investigated. Midspan results are compared with both smooth-wall and rough-wall finite-difference two-dimensional heat transfer predictions. Contour maps of Stanton number for both the rotor airfoil and endwall surfaces revealed numerous regions of high heat transfer produced by the three-dimensional flows within the rotor passage. Of particular importance are regions of local enhancement (as much as 100 percent over midspan values) produced on the airfoil suction surface by the secondary flows and tip-leakage vortices and on the hub endwall by the leading edge horseshoe vortex system.

scholarly journals Local scour around a bridge pier under ice-jammed flow condition – an experimental study

2021 ◽  
Vol 69 (3) ◽  
pp. 275-287
Author(s):  
Jun Wang ◽  
Zhixing Hou ◽  
Hongjian Sun ◽  
Bihe Fang ◽  
Jueyi Sui ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Local Scour ◽  
Bridge Pier ◽  
Scour Depth ◽  
Flow Conditions ◽  
Hole Depth ◽  
Open Flow ◽  
Ice Jam ◽  
Scour Hole ◽  
Ice Jam Thickness

Abstract The appearance of an ice jam in a river crucially distorts local hydrodynamic conditions including water level, flow velocity, riverbed form and local scour processes. Laboratory experiments are used for the first time here to study ice-induced scour processes near a bridge pier. Results show that with an ice sheet cover the scour hole depth around a bridge is increased by about 10% compared to under equivalent open flow conditions. More dramatically, ice-jammed flows induce both greater scour depths and scour variability, with the maximum scour depth under an ice-jammed flow as much as 200% greater than under equivalent open flow conditions. Under an ice-jammed condition, both the maximum depth and length of scour holes around a bridge pier increase with the flow velocity while the maximum scour hole depth increases with ice-jam thickness. Also, quite naturally, the height of the resulting deposition dune downstream of a scour hole responds to flow velocity and ice jam thickness. Using the laboratory data under ice-jammed conditions, predictive relationships are derived between the flow’s Froude number and both the dimensionless maximum scour depth and the dimensionless maximum scour length.

scholarly journals Effects on Scour for Different Foundation Geometry of Compound Circular Bridge Piers

2019 ◽  
Vol 8 (2) ◽  
pp. 2439-2446
Keyword(s):  
Experimental Study ◽  
Rate Of Change ◽  
Bridge Pier ◽  
Bridge Piers ◽  
Scour Depth ◽  
Flowing Water ◽  
Sound Design ◽  
Flow Conditions ◽  
The Past ◽  
Bridge Failure

This experimental study examines the variation of scour depth with time of Clearwater scour condition around compound circular bridge piers for steady flow conditions. Most of the circular bridge piers are resting on the bigger diameter caissons known as the compound circular bridge piers and are widely used in India for construction of road and railways bridge across the rivers. In past studies, it has been observed that most bridge failure occurs because of scouring due to flowing water around a bridge pier across a river. Most of the past studies were done on the uniform bridge pier and a very few studies have been done so far on scouring around non-uniform bridge piers. Estimation of scour depth is required for the economical and a sound design of bridge pier foundation. In present study, an experimental investigation has been done in a tilting flume for computation of rate of change of depth of scour with time at two different models of compound circular bridge piers by varying the foundation top position with respect to level of bed, i.e., 1. The foundation top at the level of bed, and 2. The foundation top below the level of bed (viz. 10mm, 20mm, 30mm and 40mm) for uniform sediments.

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