Pressure distribution of bottom rollers below the aerator device

2019 ◽  
Vol 79 (4) ◽  
pp. 668-675 ◽  
Author(s):  
Yu Wang ◽  
Jianhua Wu ◽  
Fei Ma ◽  
Shangtuo Qian
Keyword(s):  
Pressure Distribution ◽  
High Water ◽  
Geometrical Parameters ◽  
Cavitation Damage ◽  
Novel Approach ◽  
Water Head ◽  
Jet Impact ◽  
Hydraulic Conditions ◽  
Relative Errors ◽  
Large Flow

Abstract With regard to high water head and large flow velocity in the spillway tunnels of hydraulic projects in China, the aerator device has been introduced and is widely used to prevent cavitation damage. The bottom rollers in the nappe cavity below the aerator device are a serious concern in designing suitable cavity regimes; however, observation of roller size may be inaccurate due to high flow turbulence and de-aeration in the jet impact region. In this study, a novel approach is proposed to predict roller sizes using pressure distribution of the bottom rollers. Pressure distribution characteristics are experimentally investigated under different geometrical parameters of aerator device and hydraulic conditions. The results specify the influence of the relative step height and working gate opening on pressure distribution. The simplified estimating formula of pressure distribution is derived within relative errors of 15%. The evaluation of the applicability of the proposed equation shows test data are in good agreement with the calculated value. Research results provide a reference for estimating bottom rollers of similar engineering.

scholarly journals Impact pressure distribution of inverted arch plunge pool for large discharge

2019 ◽  
Vol 20 (1) ◽  
pp. 209-218
Author(s):  
Yu Wang ◽  
Yaan Hu ◽  
Jinde Gu ◽  
Yu Peng ◽  
Yang Xue
Keyword(s):  
Pressure Distribution ◽  
High Water ◽  
Impact Pressure ◽  
Engineering Practice ◽  
Plunge Pool ◽  
Novel Approach ◽  
Water Head ◽  
Relative Errors ◽  
The Impact ◽  
Large Discharge

Abstract In view of high water head and large discharge in the release structures of hydraulic projects, the inverted arch plunge pool has been put forward due to higher overload capability and stability. Impact pressure on the bottom is a serious concern in design safety precautions, however, the quantitative impact pressure distribution in the inverted arch plunge pool is not yet elucidated. In this study, a novel approach is presented to estimate the impact pressure of an inverted arch plunge pool. Impact pressure characteristics are experimentally investigated under different hydraulic conditions. The results detailed the effect of relative discharge coefficient and the deflection angle relative to the vertical central axis of the plunge pool bottom. The predicting formulas of impact pressure distribution are derived within small relative errors, and the proposed approaches have good applicability in three case studies. The achievements of this investigation are used to define issuance parameters relevant for engineering practice.

scholarly journals Hydrodynamic Model of the New Waterway Through the Vistula Spit

2020 ◽  
Vol 27 (3) ◽  
pp. 159-167
Author(s):  
Michał Szydłowski ◽  
Tomasz Kolerski
Keyword(s):  
Water Exchange ◽  
Storm Surges ◽  
High Water ◽  
Vistula Lagoon ◽  
Flow Rates ◽  
Water Head ◽  
Hydraulic Conditions ◽  
Flow Through ◽  
Made In ◽  
The Vistula Lagoon

AbstractThe decision to build a new waterway (strait) in the Polish part of the Vistula Spit was made in 2017. The new connection between the Gulf of Gdańsk and the Vistula Lagoon is planned as an artificial navigable channel with a lock and a small port. During storm surges and wind tides in the gulf or in the lagoon, sluicing will be required for vessels to tackle the Vistula Spit. This procedure does not require significant water flow through the channel in normal conditions. However, in the case of a lock failure or in the case of controlled opening of the gate to increase water exchange in the lagoon or to reduce flood risk in the Vistula Lagoon, high flow rates may occur in the navigable channel and in the neighboring port basin. In order to inves-tigate the hydraulic conditions in such extraordinary situations, numerical modeling of the hydrodynamics during water damming in the gulf or in the lagoon is performed. To analyze the hydrodynamics of the artificial connection between the sea and the lagoon during periods of high water stages, mathematical modeling is required. This paper presents the shallow water equations (SWE) model adapted to simulate the flow through the port basin and the navigable channel. The calcula-tions allowed the relation between the water head and the capacity of the navigable channel to be found, as well as to analyze circulations which may occur in the port basin.

New approach of suppressing cavitation in water hydraulic components

2016 ◽  
Vol 231 (21) ◽  
pp. 4022-4034 ◽  
Author(s):  
Zhang Zuti ◽  
Cao Shuping ◽  
Luo Xiaohui ◽  
Shi Weijie ◽  
Zhu Yuquan
Keyword(s):  
Pressure Distribution ◽  
Bubble Dynamics ◽  
Cloud Model ◽  
The Novel ◽  
Outlet Pressure ◽  
Cavitation Phenomenon ◽  
Throttle Valve ◽  
Novel Approach ◽  
Cavitation Intensity ◽  
Water Hydraulic

Cavitation frequently appears in high pressure water hydraulic components and leads to serious hydraulic erosions and horrible hydrodynamic noises. In this paper, a novel approach of suppressing cavitation was proposed, inducing the outlet pressure back to the orifice to improve the pressure distribution of throttle valves. In order to realize this approach, an optimized throttle valve chamber structure was designed. After that, the anticavitation performance of the valve was investigated. A theoretical cavitation cloud model was built based on bubble dynamics. In order to solve the mathematic cavitation model, the velocity field and pressure distribution of the novel throttle valve were simulated through Computational Fluid Dynamics(CFD). Combining the simulation results, the mathematic cavitation cloud model was solved through numerical calculations. Moreover, new indexes estimating cavitation intensity were proposed scientifically to investigate cavitation phenomenon. Then, the comparison of the novel throttle valve (with an innovative valve chamber) and traditional throttle valve in anticavitation performance was conducted under different conditions. Finally, the experiment about anticavitation performance was completed on the test rig. The calculation and experiment results indicated that the approach, inducing the outlet pressure back to the orifice, was effective in suppressing cavitation.

scholarly journals Numerical Modelling Approaches for Assessing Improvements to the Flow Circulation in a Small Lake

2011 ◽  
Vol 2011 ◽  
pp. 1-21
Author(s):  
Cheng He ◽  
Quintin Rochfort
Keyword(s):  
Water Quality ◽  
Three Dimensional ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Strong Wind ◽  
Small Lake ◽  
Hydraulic Conditions ◽  
Flow Circulation ◽  
Central Island ◽  
Large Flow

Kamaniskeg Lake is a long, narrow, and deep small lake located in the northern part of Ontario, Canada. The goals of this paper were to examine various options to improve the water quality in the northern part of the lake by altering the local hydraulic flow conditions. Towards this end, a preliminary screening suggested that the flow circulation could be increased around a central island (Mask Island) in the northern part of the lake by opening up an existing causeway connecting the mainland and central island. Three-dimensional (3D) hydraulic and transport models were adopted in this paper to investigate the hydraulic conditions under various wind forces and causeway structures. The modelling results show that opening the causeway in a few places is unlikely to generate a large flow circulation around the central island. Full circulation only appears to be possible if the causeway is fully removed and a strong wind blows in a favourable direction. The possible reasons for existing water quality variations at the intake of a local WTP (water treatment plant) are also explored in the paper.

scholarly journals Surface to sewer flow exchange through circular inlets during urban flood conditions

2018 ◽  
Vol 20 (3) ◽  
pp. 564-576 ◽  
Author(s):  
Matteo Rubinato ◽  
Seungsoo Lee ◽  
Ricardo Martins ◽  
James D. Shucksmith
Keyword(s):  
Steady State ◽  
Surface Flow ◽  
Scale Model ◽  
Geometrical Parameters ◽  
Flow Conditions ◽  
Urban Flood ◽  
Flood Modelling ◽  
Physical Scale ◽  
Hydraulic Conditions ◽  
Flow Through

Abstract Accurately quantifying the capacity of sewer inlets (such as manhole lids and gullies) to transfer water is important for many hydraulic flood modelling tools. The large range of inlet types and grate designs used in practice makes the representation of flow through and around such inlets challenging. This study uses a physical scale model to quantify flow conditions through a circular inlet during shallow steady state surface flow conditions. Ten different inlet grate designs have been tested over a range of surface flow depths. The resulting datasets have been used (i) to quantify weir and orifice discharge coefficients for commonly used flood modelling surface–sewer linking equations and (ii) to validate a 2D finite difference model in terms of simulated water depths around the inlet. Calibrated weir and orifice coefficients were observed to be in the range 0.115–0.372 and 0.349–2.038, respectively, and a relationship with grate geometrical parameters was observed. The results show an agreement between experimentally observed and numerically modelled flow depths but with larger discrepancies at higher flow exchange rates. Despite some discrepancies, the results provide improved confidence regarding the reliability of the numerical method to model surface to sewer flow under steady state hydraulic conditions.

NUMERICAL ANALYSES OF THE HOLISTIC HYDRAULIC LOADS CHARACTERISTICS OF HIGH WATER-HEAD PLANE GATE

2019 ◽  
Author(s):  
JINXIONG ZHANG ◽  
ZHIGANG WANG ◽  
WENYUAN ZHANG ◽  
HONGWEI ZHANG ◽  
YUCHEN DENG
Keyword(s):  
High Water ◽  
Numerical Analyses ◽  
Water Head

scholarly journals An analytical solution for steady seepage into a defective pipe

2017 ◽  
Vol 18 (3) ◽  
pp. 926-935 ◽  
Author(s):  
Yao Tang ◽  
Dave H. Chan ◽  
David Z. Zhu ◽  
Shuai Guo
Keyword(s):  
Analytical Solution ◽  
Groundwater Flow ◽  
Pressure Distribution ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Water Flow Rate ◽  
Infiltration Rate ◽  
Defect Position ◽  
Water Head ◽  
Parametric Studies

Abstract An analytical solution was proposed for the groundwater flow through a defective pipe, which can be used to estimate the water flow rate into the pipe and predict the pore water pressure distribution in surrounding soils. This analytical solution was verified by comparing with experimental results, and the predicted pressure distribution around the defective pipe is proved to be consistent with numerical simulations using the finite element method. From the parametric analysis, the infiltration rate increases as the defect position changes from top to bottom on the pipe, and the effect of defect position is not significant if the water head above the defect is 10 times greater than pipe radius. An approximated solution for estimating the groundwater flow infiltration rate through a circular orifice on the pipe is proposed as well. From the verification and parametric studies, this proposed analytical solution is proved to be an efficient approach for the estimation of groundwater infiltration through a defective pipe.

scholarly journals The spillway design for the dam’s height over 300 meters

2018 ◽  
Vol 40 ◽  
pp. 05009
Author(s):  
Weiwei Yao ◽  
Yuansheng Chen ◽  
Xiaoyi Ma ◽  
Xiaobin Li
Keyword(s):  
Power Plants ◽  
Air Entrainment ◽  
High Water ◽  
Western Region ◽  
Hydraulic Power ◽  
River Bank ◽  
Common Structure ◽  
Water Head ◽  
Novel Method ◽  
The Western Region

According the current hydropower development plan in China, numbers of hydraulic power plants with height over 300 meters will be built in the western region of China. These hydraulic power plants would be in crucial situation with the problems of high water head, huge discharge and narrow riverbed. Spillway is the most common structure in power plant which is used to drainage and flood release. According to the previous research, the velocity would be reaching to 55 m/s and the discharge can reach to 300 m3/s.m during spillway operation in the dam height over 300 m. The high velocity and discharge in the spillway may have the problems such as atomization nearby, slides on the side slope and river bank, Vibration on the pier, hydraulic jump, cavitation and the negative pressure on the spill way surface. All these problems may cause great disasters for both project and society. This paper proposes a novel method for flood release on high water head spillway which is named Rumei hydropower spillway located in the western region of China. This paper has following components: Determining the type and the layout of the spillway through the perspectives of air entrainment, flow jet angle and water energy dissipation in flushing pond structure. The physical hydraulic model has been used to evaluate spillway design effects.

The Establishment of Ninety Degree Gas Elbow Pipes Internal Pressure Distribution Model

2014 ◽  
Vol 670-671 ◽  
pp. 696-699 ◽  
Author(s):  
Xiao Yang Lu ◽  
Yong Zhou ◽  
Shi Ying Chen ◽  
Xin Guang Li ◽  
Hong Liang Zhu
Keyword(s):  
Numerical Simulation ◽  
High Pressure ◽  
Internal Pressure ◽  
Pressure Distribution ◽  
High Velocity ◽  
Three Dimensional ◽  
Distribution Model ◽  
Geometrical Parameters ◽  
Maximum Relative Error ◽  
Nonlinear Fitting

According to the principle of harmonious dimensions, the qualitative distribution model of the internal pressure on elbow pipes were determined; Through FLUENT numerical simulation, the internal pressure were given under 96 kinds of gas fluid conditions; By analyzing the variation of the internal pressure with flow and geometrical parameters, the variation of the internal pressure distribution within the elbow pipes has been studied; By means of 1stOpt nonlinear fitting package, the formula of three-dimensional internal pressure distribution was determined; Compared with the numerical results, the maximum relative error is 0.012%. The formula provides theoretical bases for strength check, the transport pipeline and wall thickness design of the high pressure, high velocity elbow.

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