scholarly journals Effect of Energy Dissipation on Scour Hole Development Downstream of the Chute

2021 ◽  
Vol 906 (1) ◽  
pp. 012117
Author(s):  
Martin Hladík ◽  
Martin Králík ◽  
Jan Ouhel ◽  
Vojtěch Sýs ◽  
Milan Zukal
Keyword(s):  
Energy Dissipation ◽  
Critical Infrastructure ◽  
Water Levels ◽  
Hydraulic Structures ◽  
Full Width ◽  
Stilling Basin ◽  
Construction Design ◽  
Scour Hole ◽  
Elementary Form ◽  
Energy Dissipated

Abstract An energy dissipation on hydraulic structures is a scientifically highly examined field of study. Gained knowledge can be used to ensure the safety of the hydraulic structures and the channels which is crucial during floods. Above that, those structures are also part of the critical infrastructure therefore their function is necessary. It is assumed that in the Czech Republic the precipitation distribution is changing due to climate change thus episodes of extreme floods may be observed more often. The paper brings brand new knowledge on the kinetic energy dissipation on the chute and in the stilling basin and its impact on the riverbed scour hole development. The presented research was conducted in the Water Management Experimental Centre of Czech Technical University in Prague, Faculty of Civil Engineering. The research aimed to examine the energy dissipation mechanism on different geometric modifications of the construction of spillway chute and stilling basin and its impact on the process of scour hole development. These various types of dams’ flood safety equipment were examined in the hydraulic laboratory: an elementary form of the spillway without any stilling basin; the elementary form of the spillway and the stilling basin (crest and spillway channel had the same width); the chute width was reduced, and the stilling basin had the full width; steps were added on the narrowed chute and the and stilling basin had the full width; only the spillway crest was reduced to a half-width; only the stilling basin width was smoothly reduced; the chute’s width was smoothly reduced along the chute and the stilling basin had full width; the chute’s width was smoothly reduced along the chute and the stilling basin had the width reduced to a half. The flow, water levels, scour hole and deposit dimensions were measured. Then the amount of energy dissipated was computed. The correlation and connection between energy dissipation and scour hole development was investigated. These outcomes can be used as a recommendation of an appropriate construction design to provide better flood safety of the hydraulic structure.

scholarly journals Experimental Analysis of the Influence of Aeration in the Energy Dissipation of Supercritical Channel Flows

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 576 ◽  
Author(s):  
Juan Rebollo ◽  
David López ◽  
Luis Garrote ◽  
Tamara Ramos ◽  
Rubén Díaz ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Turbulent Flows ◽  
Air Entrainment ◽  
Flood Risk Management ◽  
Hydraulic Structures ◽  
Air Concentration ◽  
Velocity Increase ◽  
Stilling Basin ◽  
Dissipation Mechanism ◽  
Manning’S Coefficient

Energy dissipation structures play an important role in flood risk management. Many variables need to be considered for the design of these structures. Aeration has been one of the more studied phenomena over the last years, due to its influence in the performance of hydraulic structures. The purpose of the work presented in this article is to experimentally characterize the effects of aeration on boundary friction in supercritical and fully turbulent flows. The physical model used to analyze the aeration effects consists of a spillway chute 6.5 m high and a stilling basin of 10 m length and 2 m high. A pump and compressor supply the water-air mixture and are controlled at the entrance by valves and flowmeters. The ensuing channel is monitored to determine the velocity profile and air concentration of the flow into the stilling basin. The average values of both variables and Manning’s coefficient along the channel are used to determine the relation between air concentration and energy dissipation by friction. A velocity increase with greater air entrainment has been found in all scenarios since friction is the main energy dissipation mechanism in open channels flow. Finally, an equation is proposed to characterize this evolution based on the results obtained.

The Effect of Netting Dissipaters on Increasing the Efficiency of Energy Dissipation in Vertical Drops

2011 ◽  
Vol 90-93 ◽  
pp. 2427-2430
Author(s):  
Elham Bakhshian ◽  
Abdorreza Kabiri-Samani
Keyword(s):  
Energy Dissipation ◽  
Hydraulic Jump ◽  
Flow Direction ◽  
Hydraulic Structures ◽  
Hydraulic Systems ◽  
Stilling Basin ◽  
Bed Elevation ◽  
Abrupt Changes ◽  
New Type ◽  
Flow Kinematic

Abrupt changes of the channel bed elevation in hydraulic systems, e.g. in chutes, drops and steeped spillways, results to create a sever flow kinematic energy. This excess energy, can tend to different phenomena, such as tremendous forces, scouring and degrading the channel bed, resulting to destruction of the downstream hydraulic structures. The most important source to cause this phenomena is the the existence of sequent vertical drops along the the channel. In this study, the energy dissipation efficiency was increased by installing a new type of dissipaters namely netting dissipater on the crest of the vertical drops based on model experimtation. Also, the features of hydraulic jump, created in the stilling basin, were compared to those of a simple vertical drop. By assembling the above mentioned structure to the top of the stilling basin, the jet flow direction is changed, the degree of turbulence is increased and as the results, the kinematic energy loss increases and the length of the hydraulic jump decreses. The enhanced efficiency of the proposed structure was quantified based on the achieved experimental data.

In-Plane Vibration Damping of a U-Tube With Wet and Dry Flat-Bar Supports

2014 ◽  
Author(s):  
Paul A. Feenstra ◽  
Victor P. Janzen ◽  
Bruce A. W. Smith
Keyword(s):  
Energy Dissipation ◽  
Plane Motion ◽  
Test Facility ◽  
Vibration Energy ◽  
Test Rig ◽  
Two Phase ◽  
Support Conditions ◽  
Vibration Tests ◽  
Energy Dissipated ◽  
Steam Generator Tubes

Tests are being planned which will use AECL’s MR-3 Freon test facility and a Multi-Span U-Bend (MSUB) test rig to investigate the dynamics of tube vibration in two-phase flow, in particular those mechanisms that can cause excessive damage to steam-generator tubes. In preparation for the tests, free- and forced-vibration tests were conducted to measure the vibration energy dissipation (damping) of a single U-bend tube in air, with dry and wet anti-vibration bars, under a variety of tube-support conditions. This paper presents the relevant damping mechanisms and documents methods used to conduct the tests and to analyze the energy dissipated at the supports. Results indicate that for in-plane motion without tube-to-support contact, viscous damping related to wet AV B supports is much smaller than guidelines based on other types of supports suggest. To begin to examine the effects of the tube coming into contact with its supports, such as friction-related energy dissipation, the results of tests with light tube-to-support preloads are also presented.

Energy Dissipation Pool for a SAF Stilling Basin

1987 ◽  
Vol 3 (1) ◽  
pp. 52-56 ◽  
Author(s):  
C. E. Rice ◽  
F. W. Blaisdell
Keyword(s):  
Energy Dissipation ◽  
Stilling Basin

scholarly journals Energy Dissipation in Solid Roller Bucket and Controlled Stilling Basin for Ogee Stepped Spillway

2019 ◽  
Vol 8 (4) ◽  
pp. 2109-2112
Keyword(s):  
Energy Dissipation ◽  
Laboratory Experiments ◽  
Ideal Condition ◽  
Stepped Spillway ◽  
Type Ii ◽  
Dimensional Parameter ◽  
Stilling Basin ◽  
Sequent Depth ◽  
Tail Water ◽  
The Ideal

Hydraulic jump type II stilling basin is generally preferred as an energy dissipator for ogee spillway but it is uneconomical due to longer structure. On the other hand, roller bucket uses relatively shorter structure over a sloping apron or horizontal stilling basin. In this study, an attempt has been made to evaluate the performance of an ogee profile stepped spillway in combination with solid roller bucket and stilling basin type II for energy dissipation. Laboratory experiments are performed on a physical working model of ogee profile stepped spillway at discharge ranging from 0.0032 to 0.0069 m3 /s for a head of 1.5m, 4m & 7m and the results compared for energy dissipation (non-dimensional parameter (y c / h) = 0.69). The model results show that stepped spillway model without v-notch achieves 92.40 % energy dissipation. Thus this model is found to be more suitable to acquire the ideal condition of sequent depth and tail water depth in stilling basin for all the discharges.

scholarly journals Study of Mechanical Energy Dissipation by Normal and Decalcified Animals Bones

2019 ◽  
Vol 16 (1) ◽  
pp. 113-119
Author(s):  
Abdul Rauf ◽  
Syed Ismail Ahmad
Keyword(s):  
Energy Dissipation ◽  
Viscoelastic Properties ◽  
Applied Load ◽  
Mechanical Energy ◽  
Maximum Energy ◽  
Hysteresis Curve ◽  
Normal Bone ◽  
Dissipation Of Energy ◽  
Mechanical Energy Dissipation ◽  
Energy Dissipated

The energy dissipated properties of normal and decalcified femur, rib and scapula bones of animals ox and camel have been studied by uniform bending technique. A hysteresis curve has been observed between the elevation in bone and load applied. It is observed that the energy dissipated as calculated from the hysteresis loop for rib is more than that of femur and scapula of ox and camel. It has been observed that the dissipation of energy in normal bone is less than that of decalcified bone under the same condition of applied load. The highest energy dissipation was observed in case of rib bone of camel compared to that of any other bone, rib of camel and scapula of ox dissipates maximum energy than femur bones. The study suggests that this technique is simple, elegant and inexpensive besides accurate in determining viscoelastic properties of bone.

scholarly journals Energy Evolution Law of Marble Failure Process Under Different Confining Pressures Based on Particle Discrete Element Method

2021 ◽  
Vol 8 ◽  
Author(s):  
Yan-Shuang Yang ◽  
Wei Cheng ◽  
Zhan-Rong Zhang ◽  
Hao-Yuan Tian ◽  
Kai-Yue Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Energy Dissipation ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Failure Process ◽  
Rock Failure ◽  
Biaxial Compression ◽  
Energy Evolution ◽  
Confining Pressures ◽  
Energy Dissipated

The energy dissipation usually occurs during rock failure, which can demonstrate the meso failure process of rock in a relatively accurate way. Based on the results of conventional triaxial compression experiments on the Jinping marble, a numerical biaxial compression model was established by PFC2D to observe the development of the micro-cracks and energy evolution during the test, and then the laws of crack propagation, energy dissipation and damage evolution were analyzed. The numerical simulation results indicate that both the crack number and the total energy dissipated during the loading process increase with confining pressures, which is basically consistent with the experiment results. Two damage variables were presented in terms of the density from other researchers’ results and energy dissipation from numerical simulation, respectively. The energy-based damage variable varies with axial strain in the shape of “S,” and approaches one more closely than that based on density at the final failure period. The research in the rock failure from the perspective of energy may further understand the mechanical behavior of rocks.

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

Water ◽  
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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