Characteristics Of Hydraulic Jumps Research Articles

Hydraulic Jump Characteristics Downstream of a Compound Weir consisting of Two Rectangles with a below Semicircular Gate

Weirs are often used in laboratories, industries, and irrigation channels to measure discharge. The discharge capacity of a structure is vital for its safety and plays an important role in the combined gate-weir flow, which is a complicated phenomenon in hydropower. This study carried out experiments on a combined hydraulic structure, which included a compound sharp-crested weir made up of two rectangles along with an inverted semicircular sharp gate. Installed on a straight channel, this structure served as a control instrument. The study aimed to investigate the downstream hydraulic jump characteristics of this combined structure, specifically, the sequent depth ratio (y2/y1), the hydraulic jump height ratio (Hj/y1), the energy loss ratio through the jump (EL/Eu), and the jump length ratio (Lj/y1). The width of the upper rectangle on the weir was set at 20 cm. The width of the lower rectangle (W2) was set at 5, 7, and 9 cm, while its depths (z) were fixed at 6, 9, and 11 cm. The gate's diameters varied between 8, 12, and 15 cm. These measurements were alternated with varying initial Froude numbers (Fn1) ranging between 1.32 and 1.5. The results showed that the dimensions of both the weir and the gate influenced the hydraulic jump characteristics. Empirical formulas were developed to predict y2/y1, Hj/y1, EL/Eu, and Lj/y1 based on the differing dimensions of the combined structure. The findings and analysis of this study are limited to the range of data that were tested.

Effect of Surface Roughness and Channel Slope on Hydraulic Jump Characteristics: An Experimental Approach Towards Sustainable Environment

Effect of Surface Roughness and Channel Slope on Hydraulic Jump Characteristics: An Experimental Approach Towards Sustainable Environment

Analysis of the Hydraulic Jump Characteristics in a Stilling Basin to Avoid Dam Failure

Flooding may occur due to dam failure at downstream of the spillway. Stilling basin of the spillway plays an important role in reducing turbulence generated by hydraulic jumps. It can avoid flooding and local scouring as well. Therefore, this study aims to analyze hydraulic jump characteristics experimentally. Two series of structures namely initial (S0) and final (S1) were tested. The S0 model is the United States Bureau of Reclamation (USBR) III type, while S1 is set the adverse slope of 1:2 at the downstream and lowering the bottom elevation of the channel by 4 m. Measurements were taken on the length of hydraulic jumps, water level and high speed before-after hydraulic jumps at various return periods discharges (Q) of 2, 5, 10, 25, 50, 100 and 1000 years. It is found that at S1, the jump is submerged, causing the relative hydraulic jump height (y2-y1)/y1 to be 40-90% higher than S0. Furthermore, the compression of more than 50% of the hydraulic jump length ratio (Lj/y2) was indicated at S1. In addition, the energy dissipation efficiency (εt) obtained for each discharge at S1 ranged from 58-84% (good absorption). On the other hand, at S0, the εt produced was around 70-89% (Q2-Q50) and 45% (Q100 and Q1000). It can be concluded that the modification of USBR III can reduce the vulnerability of the bottom and downstream parts of the stilling basin. It is expected that the potential flood disaster due to the stilling basin failure of the dam can be eliminated. These results may be used as recommendation to the disaster management strategies, such as improving dam safety guidelines, informing emergency response plans, or guiding infrastructure design to withstand hydraulic forces.

Effect of Submerged Counter Flow Jet on Hydraulic Jump Characteristics in Stilling Basins

Effect of Submerged Counter Flow Jet on Hydraulic Jump Characteristics in Stilling Basins

Experimental Investigation of the Joint Effect of Flow Expansion and Submerged Vanes on Hydraulic Jump Characteristics

Experimental Investigation of the Joint Effect of Flow Expansion and Submerged Vanes on Hydraulic Jump Characteristics

A Novel Analytical Method for Evaluating the Characteristics of Hydraulic Jump at a Positive Step

We present a new method to evaluate the hydraulic jump characteristics in a horizontal rectangular channel with a positive step. We considered the flow curvature effect and the free surface’s small rise at the A-type hydraulic jump’s end. First, we present a novel method to give jump length estimation based on the similarity of the jump and the turbulent wall-jet, considering the pressure gradient. Then, considering the jump as a curvilinear flow and using a one-dimensional momentum equation, we present an accurate expression for the conjugate flow depth regarding the initial Froude number and step height. Finally, we compute the jump’s energy dissipation rate. Compared to the theoretical models for conjugate flow depth in a hydraulic jump, the proposed equation in this study fit the experimental data better, even for high steps and large initial Froude numbers. However, for low Froude numbers (F1 < 5), the equation was less accurate in estimating the jump length. Regarding the jump’s energy dissipation rate, the results agreed well with the experimental data from previous investigations. However, it is noted that the increased energy dissipation rate dwindled in larger Froude numbers.

Sloshing dynamics of shallow water tanks: Modal characteristics of hydraulic jumps

The dynamics of slosh induced wave systems in shallow water tanks is analyzed for various excitation conditions. Shake table experiments have been systematically performed to understand the complex interaction of multi-wave system under harmonic excitation. From the experiments, it was observed that, for relatively large excitation amplitudes, the hydraulic jumps emanated around the resonance region. The hydraulic jump phenomenon is further explored for different tank aspect ratios, i.e, 2.5 ≤L∕B≤ 4.038. To establish the frequency bounds for hydraulic jumps, excitation amplitude and frequency are demarcated over the range of 0.841 ≤β≤ 1.628 and liquid depth range of 0.034 ≤h∕L≤0.069. The experimental bounds are juxtaposed with the theoretical bounds to analyze the margins present in hydraulic jumps. Although, the theoretical bound is independent of liquid depth, experimental observations clearly indicate a strong dependency.

Effect of Porous Media on Hydraulic Jump Characteristics by Using Smooth Particle Hydrodynamics Method

In order to understand the effect of porous media on hydraulic jumps, a smoothed particle hydrodynamics (SPH) model is applied to investigate the characteristics of hydraulic jumps interacting with porous media. Various porosities including cases without an obstacle or with a solid obstacle or porous media are considered. The opening of a gate was altered to adjust the hydraulic jump. The conjugate depth ratio, bottom shear stress distribution, and energy dissipation are reported. In the present study, validations are in a good agreement with previous studies. Overall, the result showed that the average error between numerical and experimental data was less than 7.2%. Energy dissipation is compared among cases with three porosities, with and without a solid obstacle. The porosity of 0.68 is found to dissipate more energy than do other porosities. Thus, porous media can be used to enhance energy dissipation of hydraulic jumps in an open channel. In conclusion, the proposed SPH model can simulate the effect of porous media on hydraulic jump characteristics.

Prediction Characteristics of Free and Submerged Hydraulic Jumps on Horizontal and Sloping Beds using SVM Method

Doubtlessly hydraulic jump is a useful phenomenon in open channel flow such as rivers and spillways. As the most important characteristics of hydraulic jump, length, and sequent depth ratio play a key role in designing of hydraulic structures. The hydraulic jump length is one of the most important parameters, which cannot be calculated by mathematical analyses directly. In this context, several relations have been proposed to estimate the length and sequent depth ratio of the hydraulic jumps, but the results of the mentioned equations are not general and acceptable due to the uncertainty of the functions. Achievements of this study follows three aims; firstly to develop and examine support vector machine (SVM) for estimating characteristics of five types of free and submerged hydraulic jumps; secondly to compare the results of SVM models with analytical and semi-empirical equations; and finally to perform a sensitivity analysis to investigate the effect of each input parameter on the output in terms of root mean square error (RMSE), correlation coefficient (R) and Nash-Sutcliffe or determination coefficient (NS or DC). The meteorological data sets used herein to develop the models are obtained from previous credible researches. Performance of the models appoints dominant parameters for predicting the characteristics of the different types of hydraulic jumps As Also based on the comparisons among the SVM models, analytical and semi-empirical equations, it can be seen that, SVM models depict better results than those equations.

Effect of Channel Boundary Conditions in Predicting Hydraulic Jump Characteristics using an ANFIS-Based Approach

Effect of Channel Boundary Conditions in Predicting Hydraulic Jump Characteristics using an ANFIS-Based Approach

Experimental Investigations on Hydraulic Jump Characteristics for Different Hydraulic and Geometric Conditions

Experimental Investigations on Hydraulic Jump Characteristics for Different Hydraulic and Geometric Conditions

SPH numerical investigation of characteristics of hydraulic jumps

In the present work, oscillating characteristics and cyclic mechanisms in hydraulic jumps are investigated and reproduced using a weakly-compressible XSPH scheme which includes both an algebraic mixing-length model and a two-equation turbulence model to represent turbulent stresses. The numerical model is applied to analyze oscillations of different hydraulic jump types based on the laboratory experiments. The comparison between SPH and experimental results shows an influence of different turbulence models on the amplitude spectrum and peak amplitude of the time-dependent surface elevation upstream and downstream of the hydraulic jump. By analyzing a single cycle of the oscillating phenomena of a hydraulic jump it is possible to indicate their correlation with the vortex structures of the roller. Furthermore, analysis of the oscillating phenomena indicates a correlation among the surface profile elevations, velocity components and pressure fluctuations. This observation leads to conclude that oscillations phenomena are particularly important for analysis of the turbulence characteristics.

Variations of Hydraulic Jump Characteristics Due to Different Sill with Slot Layouts

Variations of Hydraulic Jump Characteristics Due to Different Sill with Slot Layouts

Estimation of hydraulic jump on corrugated bed using artificial neural networks and genetic programming

Artificial neural networks (ANNs) and genetic programming (GP) have recently been used for the estimation of hydraulic data. In this study, they were used as alternative tools to estimate the characteristics of hydraulic jumps, such as the free surface location and energy dissipation. The dimensionless hydraulic parameters, including jump depth, jump length, and energy dissipation, were determined as functions of the Froude number and the height and length of corrugations. The estimations of the ANN and GP models were found to be in good agreement with the measured data. The results of the ANN model were compared with those of the GP model, showing that the proposed ANN models are much more accurate than the GP models.

Interaction between free-surface, two-phase flow and total pressure in hydraulic jump

A hydraulic jump is characterised by intense turbulent flow patterns and substantial flow aeration. The flow turbulence, at both macroscopic and microscopic scales, interacts with the air entrainment process and the free-surface. A series of simultaneous measurements of the free-surface fluctuations, jump toe oscillations, void fraction and total pressure variations allowed for an investigation of the interactions between these characteristics. Experiments were conducted for a range of Froude numbers from 3.8 to 8.5. The total pressure measurements were justified for the air–water flow characterisation of the flow region with a positive time-averaged velocity. The interactions between roller surface deformation, air entrainment and diffusion, velocity variation, flow bulking, and the associated total pressure field modulation highlighted different flow regions, hence flow patterns, in the roller. The jump toe oscillation was found closely linked to the air entrapment at the toe and velocity variation in the shear flow. The instable total pressure distribution was primarily associated with the free-surface fluctuation for the bubbly roller region and with the velocity re-distribution for the lower shear region underneath. The present work provides new information on the physical characteristics of hydraulic jumps and a comprehensive insight into the nature of such complex turbulent two-phase flow.

Effect of Channel Slope on Hydraulic Jump Characteristics

Effect of Channel Slope on Hydraulic Jump Characteristics

Characteristics of hydraulic jumps over rough beds – an experimental study

The present knowledge on the behaviour of hydraulic jump is only for smooth, horizontal channel beds and very limited studies have been reported in literature on the performance of hydraulic jumps on rough beds. This research attempts to investigate the characteristics of hydraulic jumps formed on rough, horizontal channel beds under different flow conditions using laboratory investigations. A series of experiments were carried out in a rectangular flume which consists of artificially roughened beds formed by placing rectangular wooden strips in specific intervals. The hydraulic parameters such as, initial water depth, sequent water depth, and flow rate were measured for different bed roughnesses. The analysis of experimental data showed that the rough bed reduces the distance to the jump from the gate and the sequent depth ratio than those on smooth beds while creating a high energy loss. With the availability of a large number of experimental data on hydraulic jumps over rough channel beds, mathematical formulations were developed to express the hydraulic jump characteristics relating roughness parameters such as; roughness density and roughness height. DOI: http://dx.doi.org/10.4038/engineer.v46i3.6779 ENGINEER, Vol. 46, No.03, pp.1-7, 2013

Effect of Corrugated Bed on Hydraulic Jump Characteristic Using SPH Method

AbstractA hydraulic jump is a common phenomenon that can be observed in open channel flows such as rivers and spillways. It can cause damage of the downstream bed and bank of the channel due to the process of continuous erosion and degradation. In order to reduce the hydraulic jump destruction, the energy in the hydraulic jump must be dissipated as much as possible. One method to increase dissipation of energy is using a corrugated bed. In order to know the effect of a corrugated bed on the hydraulic jump, a smoothed particle hydrodynamics (SPH) model is applied to investigate the characteristics of hydraulic jumps in various corrugated beds. A variety of corrugated beds that are smooth, triangular, trapezoidal, and sinusoidal are considered. The opening of a gate is changed to adjust the hydraulic jump. The conjugate depth ratio, the jump length, the bottom shear stress distribution, and the energy dissipation are reported. The results of the present study are in a good agreement with previous studies. E...

EFFECT OF AERATED INFLOWS ON CHARASTERISTICS OF HYDRAULIC JUMPS IN SLOPING CHANNELS

Many researchers have investigated characteristics of the hydraulic jump in sloping channels, but the effect of aerated inflow on flow characteristics of the hydraulic jump has not been shown. This paper presents the effect of aerated inflow on flow characteristics of hydraulic jumps in steep sloping channels (i.e., 30 and 55 degrees). The experimental investigation reveals that the jump length is affected by the air-concentration of the aerated inflow. The length of the jump has been formulated. By considering the air-concentration in the jump, the sequent depth ratio of the jump in sloping channels has been obtained on the basis of the momentum equation.

EFFECT OF AERATED INFLOWS ON CHARACTERISTICS OF HYDRAULIC JUMPS IN STEEP SLOPING CHANNELS

Manyr esearchersin vestigatejdu mp characteristicisn slopingc hannels, b ut the effecto f an aeratedi nflowo n flowcharacteristicosf hydraulicju mps has not been shown at all. This paper presents the effect of aerated in flow on flow characteristics of hydraulic jumps in steeps lopingc hannels (i. e., 30 and 55 degrees). The experimental in vestigation reveals the relationship between velocity decay, jumps length, and air-concentration distribution in hydraulic jumps under different air-concentration of aerated inflows. Further, an air-concentration distribution in hydraulic jumps has been characterized, and the magnitude and distributionp atterno fair-concentratioin n jumps has been discussed betweena erateda nd non -aeratedi nflows.