Experimental Study of the Type VI Stilling Basin Performance

Understanding the estuarine turbulent flow from dams, channels, and pipes, as well as the river flow are very important due to the potential to cause damage to the bed of the river or channel and cause scouring of structures such as the saddles of bridges, because of the huge amount of the kinetic energy carried by the flow. One of the most efficient yet simple ways to dissipate this energy is to install a stilling basin at the discharge point to calm the flow. Turbulence data were recorded using acoustic Doppler velocimetry (ADV) for type VI2 of stilling basins for pipe outlets. During the study, various splitters and a cellular baffle were placed in the stilling basin, and the baffle locations were changed to assess the effect on the energy dissipation. Velocity at several locations in the basin was measured for different Froude numbers to investigate the effect of flow rate. Based on the findings of the experiments, several suggestions regarding the efficiency and geometry of stilling basins were made.

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Experimental study of open-channel flow with partial double-layered vegetation

E3S Web of Conferences ◽

10.1051/e3sconf/20198101010 ◽

2019 ◽

Vol 81 ◽

pp. 01010 ◽

Cited By ~ 5

Author(s):

Xiaonan Tang ◽

Hamidrez Rahimi ◽

Prateek Singh ◽

Zishun Wei ◽

Yuxuan Wang ◽

...

Keyword(s):

Experimental Study ◽

Riparian Vegetation ◽

Open Channel ◽

Open Channel Flow ◽

Doppler Velocimetry ◽

Flume Experiments ◽

Flow Process ◽

River Flood ◽

Acoustic Doppler Velocimetry ◽

Natural Rivers

Many rivers and wetlands have vegetation. The effect of riparian vegetation on ecological and flow process in channels has become increasingly important in river flood risk and aquatic environmental management. Most previous studies have been done on the flow structure of vegetation of the same height which is not realistic in natural rivers. There are only a few studies on flows with a mixing array of short and tall vegetation under either submerged or emergent flow condition. This paper is to undertake a novel experimental study on a flow with double-layered vegetation under submerged and emergent conditions, which often occur in most rivers. Two different heights of dowels, 10 cm and 20 cm, were used in the water flume to represent the short and tall vegetation respectively, and they were allocated on one side of the flume. Experiments in two flow depths were undertaken to represent different submergence ratios of vegetation, and velocities at various locations were measured by Acoustic Doppler Velocimetry (ADV) and propeller velocimetry. Experimental results show that the velocity profile is almost uniform within the depth of short vegetation in different configurations. The velocity starts to increase in the region near the edge of short vegetation, and then followed by a rapid increase through the height of tall vegetation to the free surface. Meanwhile, a strange shear layer exists laterally between vegetation and non-vegetation, showing that the vegetation significantly reduces the velocity of flow.

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Calibration of turbidity meter and acoustic doppler velocimetry (Triton-ADV) for sediment types present in drained peatland headwaters: Focus on particulate organic peat

River Research and Applications ◽

10.1002/rra.1304 ◽

2009 ◽

Vol 26 (8) ◽

pp. 1019-1035 ◽

Cited By ~ 6

Author(s):

Hannu Marttila ◽

Heini Postila ◽

Bjørn Kløve

Keyword(s):

Doppler Velocimetry ◽

Sediment Types ◽

Acoustic Doppler Velocimetry

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The Effect of Longitudinal Core Flow on Trailing Vortex Stability

Volume 7: Fluids Engineering Systems and Technologies ◽

10.1115/imece2014-38522 ◽

2014 ◽

Author(s):

Amir Allaf-Akbari ◽

A. Gordon L. Holloway ◽

Joseph Hall

Keyword(s):

Experimental Study ◽

Velocity Field ◽

Kinetic Energy ◽

Vortex Core ◽

Vortex Generator ◽

Core Flow ◽

Vortex Stability ◽

Vorticity Distribution ◽

Air Jet ◽

Jet Velocities

The current experimental study investigates the effect of longitudinal core flow on the formation and structure of a trailing vortex. The vortex is generated using four airfoils connected to a central hub through which a jet flow is added to the vortex core. Time averaged vorticity, circumferential velocity, and turbulent kinetic energy are studied. The statistics of vortex wandering are identified and corrections applied to the vorticity distribution. The vortex generator used in this study was built on the basis of the design described by Beninati et al. [1]. It uses four NACA0012 airfoils connected to a central hub. The wings orientation can be adjusted such that each contributes to a strong trailing vortex on the center of the test section. The vortex generator also had the capability to deliver an air jet directed longitudinally through a hole in the hub at the joint of the airfoils. Tests were done without the jet and with the air jet at jet velocities of 10 and 20 m/s. Planar PIV was used to measure the velocity field in the vicinity of the vortex core. The measurements were taken at 3 chords behind the vortex generator.

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Exploring probability distribution functions best-fitting the kinetic energy of coarse particles at above threshold flow conditions

10.5194/egusphere-egu21-1820 ◽

2021 ◽

Author(s):

Hamed Farhadi ◽

Manousos Valyrakis

Keyword(s):

Probability Distribution ◽

Kinetic Energy ◽

Test Section ◽

Particle Transport ◽

River Flow ◽

Distribution Functions ◽

Transport Processes ◽

Flow Conditions ◽

Probability Distribution Functions ◽

Transport Regime

Applying an instrumented particle [1-3], the probability density functions of kinetic energy of a coarse particle (at different solid densities) mobilised over a range of above threshold flow conditions&#160;conditions corresponding to the intermittent transport regime, were explored. The experiments were conducted in the Water Engineering Lab at the University of Glasgow on a tilting recirculating flume with 800 (length) &#215; 90 (width) cm dimension. Twelve different flow conditions corresponding to intermittent transport regime for the range of particle densities examined herein, have been implemented in this research. Ensuring fully developed flow conditions, the start of the test section was located at 3.2 meters upstream of the flume outlet. The bed surface of the flume is flat and made up of well-packed glass beads of 16.2 mm diameter, offering a uniform roughness over which the instrumented particle is transported. MEMS sensors are embedded within the instrumented particle with 3-axis gyroscope and 3-axis accelerometer. At the beginning of each experimental run, instrumented particle is placed at the upstream of the test section, fully exposed to the free stream flow. Its motion is recorded with top and side cameras to enable a deeper understanding of particle transport processes. Using results from sets of instrumented particle transport experiments with varying flow rates and particle densities, the probability distribution functions (PDFs) of the instrumented particles kinetic energy, were generated. The best-fitted PDFs were selected by applying the Kolmogorov-Smirnov test and the results were discussed considering the light of the recent literature of the particle velocity distributions.[1] Valyrakis, M.; Alexakis, A. Development of a &#8220;smart-pebble&#8221; for tracking sediment transport. In Proceedings of the International Conference on Fluvial Hydraulics (River Flow 2016), St. Louis, MO, USA, 12&#8211;15 July 2016.[2] Al-Obaidi, K., Xu, Y. & Valyrakis, M. 2020, The Design and Calibration of Instrumented Particles for Assessing Water Infrastructure Hazards, Journal of Sensors and Actuator Networks, vol. 9, no. 3, 36.[3] Al-Obaidi, K. & Valyrakis, M. 2020, Asensory instrumented particle for environmental monitoring applications: development and calibration, IEEE sensors journal (accepted).

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Noise Propagation Through Helicopter Gearbox Support Struts—An Experimental Study

Journal of Vibration and Acoustics ◽

10.1115/1.2893886 ◽

1998 ◽

Vol 120 (3) ◽

pp. 695-704 ◽

Cited By ~ 7

Author(s):

M. J. Brennan ◽

S. J. Elliott ◽

K. H. Heron

Keyword(s):

Experimental Study ◽

Kinetic Energy ◽

Flexural Vibration ◽

Dominant Mode ◽

Analytical Models ◽

Longitudinal Motion ◽

Transmission Path ◽

Modes Of Vibration ◽

The Subject ◽

Lateral Behavior

A dominant source of noise in a helicopter cabin is the meshing of the gears in the main rotor gearbox. The main structural noise transmission path from this gearbox to the cabin is through the gearbox support struts, and this is the transmission path which is the subject of this paper. An experimental study is described which quantifies the way in which vibration propagates through one of these struts and the experimental results are interpreted with the aid of some simple analytical models. The contribution of the various modes of vibration to the transmission of the structure-borne noise is quantified by calculating the kinetic energy of the receiving structure from measured data. The results show that although the dominant mode of vibration is longitudinal, flexural resonances occur at some frequencies, and the contribution of the flexural vibration to the kinetic energy of the receiving structure at these frequencies can be comparable with that due to the longitudinal motion. It is demonstrated that the lateral behavior of the strut is dependent upon the static loading but the longitudinal behavior is relatively insensitive to this loading.

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Discussion of “Hydraulic Design of Stilling Basins: Stilling Basin and Wave Suppressors for Canal Structures, Outlet Works, and Diversion Dams (Basin IV)”

Journal of the Hydraulics Division ◽

10.1061/jyceaj.0000196 ◽

1958 ◽

Vol 84 (2) ◽

pp. 47-58

Author(s):

W. H. R. Nimmo ◽

Walter Rand

Keyword(s):

Stilling Basin ◽

Hydraulic Design ◽

Stilling Basins

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Experimental Characterization of the Hydraulic Jump Profile and Velocity Distribution in a Stilling Basin Physical Model

Water ◽

10.3390/w12061758 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1758

Author(s):

Juan Macián-Pérez ◽

Francisco Vallés-Morán ◽

Santiago Sánchez-Gómez ◽

Marco De-Rossi-Estrada ◽

Rafael García-Bartual

Keyword(s):

Free Surface ◽

Energy Dissipation ◽

Velocity Distribution ◽

Physical Model ◽

Hydraulic Jump ◽

Surface Profile ◽

Air Entrainment ◽

Stilling Basin ◽

Free Surface Profile ◽

Stilling Basins

The study of the hydraulic jump developed in stilling basins is complex to a high degree due to the intense velocity and pressure fluctuations and the significant air entrainment. It is this complexity, bound to the practical interest in stilling basins for energy dissipation purposes, which brings the importance of physical modeling into the spotlight. However, despite the importance of stilling basins in engineering, bibliographic studies have traditionally focused on the classical hydraulic jump. Therefore, the objective of this research was to study the characteristics of the hydraulic jump in a typified USBR II stilling basin, through a physical model. The free surface profile and the velocity distribution of the hydraulic jump developed within this structure were analyzed in the model. To this end, an experimental campaign was carried out, assessing the performance of both, innovative techniques such as the time-of-flight camera and traditional instrumentation like the Pitot tube. The results showed a satisfactory representation of the free surface profile and the velocity distribution, despite some discussed limitations. Furthermore, the instrumentation employed revealed the important influence of the energy dissipation devices on the flow properties. In particular, relevant differences were found for the hydraulic jump shape and the maximum velocity positions within the measured vertical profiles, when compared to classical hydraulic jumps.

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A neural network model for short term river flow prediction

Natural Hazards and Earth System Science ◽

10.5194/nhess-6-629-2006 ◽

2006 ◽

Vol 6 (4) ◽

pp. 629-635 ◽

Cited By ~ 17

Author(s):

R. Teschl ◽

W. L. Randeu

Keyword(s):

Neural Network ◽

Artificial Neural Network ◽

River Flow ◽

Radar Data ◽

Rain Gauge ◽

Huge Amount ◽

Short Term ◽

Flow Prediction ◽

Spatial Coverage ◽

Radar Measurements

Abstract. This paper presents a model using rain gauge and weather radar data to predict the runoff of a small alpine catchment in Austria. The gapless spatial coverage of the radar is important to detect small convective shower cells, but managing such a huge amount of data is a demanding task for an artificial neural network. The method described here uses statistical analysis to reduce the amount of data and find an appropriate input vector. Based on this analysis, radar measurements (pixels) representing areas requiring approximately the same time to dewater are grouped.

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