Wyniki wyszukiwania - BazTech

1

CFD Analysis of the Effects of Compound Downstream Slope on Flow Over the Spillway

Jahad Udai A., Chabuk Ali, Alabas Mohammed A., Mahmoud Ammar S., Al-Ansari Nadhir, Laue Jan

Journal of Ecological Engineering

|

2023

|

Vol. 24, nr 11

274--286

EN

The volume of the stilling basin can be reduced, energy can be dissipated, and floods can be contained with the help of spillways. The aim of this Computational Fluid Dynamics (CFD) study is to investigate how compound slopes change water flows through spillways. To measure turbulence, the Realizable k-ε model was used, and the multiphase volume of fluid (VOF) method was utilized to determine where air and water meet. Five models of spillways with different slopes (normal slope (MS1) = 30°, compound slope(MS2 and MS3) = 20°/39°, and compound slope (MS4 and MS5) = 39°/20°) were modelled and simulated using the ANSYS Fluent software to determine their flow characteristics. Numerical simulation results were compared to experimental results, and it was found that the CFD model captured the key flow aspects accurately. The numerical model carefully observes the several flow patterns (nappe, transition, and skimming) that emerged owing to variations in slope and geometry. When it comes to dissipating energy, models with a compound slope (39°/20°) do the best. When compared to the normal slope model (30°) with a step size of 10, the increase in energy dissipation is 14%. According to the findings, the TKE (turbulent kinetic energy) was elevated by the compound slope. The results of this research show that the spillway can be operated effectively and reliably under a wide range of flow conditions, fulfilling an important goal of the project.

2

Experimental study of the hydraulic jump length in a smooth trapezoidal channel

Ngoc Nguyen Minh, Cuong Pham Hong, Son Tran Thanh, Nam Nguyen Van, Phong Nguyen Thanh

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

|

2022

|

Vol. 31, No. 1

63--76

EN

The article showed the result of investigation of the length of hydraulic jump in trapezoidal channel. In this study, the basic factors that affect the length (Lj) and roller length (Lr) of hydraulic jump were investigated by physical trapezoidal channel’s model. The experiment carried out in purpose to establish a new empirical equation for calculating the roller length (Lr) of the jump in the horizontal trapezoidal channel with the upstream flow Froude number 4.0 to 9.0 (the steady jump). The hydraulic characteristics of forced jump were measured and statistically calculated by excel software. The results of data analysis showed that the MAPE was relatively small (< 5%), and R2 > 0.9 (strong correlation between predicted and observed values) and other statistical indicators are less than 0.1 (MSE = 0.004, RMSE = 0.062 và MEA = 0.047). Therefore, the equation found could be appropriated and applied to calculate characteristics of hydraulic jump trapezoidal channel.

3

Experimental and numerical investigation of scour downstream contracted spillways

Nasralla Tarek H.

Journal of Water and Land Development

|

2022

|

no. 52

53--59

EN

A study of scour downstream of free hydraulic jump in stilling basin of stepped spillways was carried out. This paper employed an experimental study to investigate the stepped spillway with the movable bed material of D50= 3.1 mm. The effect of the contraction ratio of the stepped spillway was highlighted. Different downstream divergent angle was studied to minimise the scour depth, the results showed that the relative scour depth was reduced by 23% for divergent angle is equal to 170°, different shapes of buffer in stilling basin were also studied to reduce the scour depth where the considered buffer decrease the relative scour depth up to 84%. This study was simulated by Flow 3D program to analyse the scour hole formed using velocity vectors at the bed. The simulated results well agreed with the measured data.

4

Laboratory study of stilling basin using trapezoidal bed elements

Al-Fatlawi Thair J.M., Al-Mansori Nassrin J.H., Othman Nariman Y.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

|

2020

|

Vol. 29, No. 4

409--420

EN

When designing dam spillway structures, the most significant consideration is the energy dissipation arrangements. Different varieties of baffle blocks and stilling basins have been used in this context. However, the hydraulic jump form of stilling basin is considered to be the most suitable. The main objective of this research was to introduce four different baffle block shapes (models arranged from A to D, installed at slopes 0.00, 0.04, 0.06 and 0.08 in the stilling basins). To illustrate the consequences for the qualities of pressure-driven bounce, each model was attempted in the bowl. The trials applied Froude numbers between 6.5 and 9.2. The puzzle square model D provided the best outcomes compared to the models A, B, C and smooth. Model D with different models at inclines 0.00, 0.04, 0.06 and 0.08 was used to consider the impacts of perplex hinders on water driven-bounce when bed slants were changed. When the model D baffle used instead of a smooth bed at 0.08 slope, the reduction in y2 / y1 reached 12.8%, and Lj / y1 was 18.9%. Among the different bed slopes, a normal decrease in y2 / y1 ranged from approximately 10.3%, whereas the normal decrease in Lj / y1 was about 13.8% when the model D baffle was used instead of the model A baffle with a horizontal slope bed of 0.00. The results show that the new shapes led to a decrease in sequent profundity proportion and length of jump proportion; however, the energy dissipation proportion increased.

5

Analysis of the flow characteristics of energy dissipating structures in dam spillways by CFD method

Büyüktaş K., Tezcan A., Sajid İ., Büyükkök S.

Infrastruktura i Ekologia Terenów Wiejskich

|

2017

|

nr II/1

439--448

EN

During flow of water from upstream to downstream in a controlled manner, the flow of water at high velocity and pressure, which occurs as a result of hydraulic jump is broken by energy dissipation structures in relief or accumulation structures. Otherwise, the flow of water with high velocity and pressure in the downstream section, where the stream passes from a flood regime to a river regime, will damage its own structure and surrounding environment. For this reason, it is necessary to design energy-dissipating structures at appropriate locations with appropriate sections so that large pressure and friction forces do not cause abrasion and erosion in flow chamber. In this study, flow characteristics such as pressure distribution, outlet flow, velocity distribution etc. of the water flowing from a dam infill located in Adrasan town of Antalya province was determined. Then, dam spillway was modelled in the computer environment with the actual measurements and analyzed according to Computational Fluid Dynamics method (CFD) using ANSYS-Fluent software. Finally, the actual measurements were compared with the simulation results. Additionally, measured data were compared with the downstream flow characteristic by defining to dam and spillway projecting software of General Directorate of State Hydraulic Works (pro-SHW). As a result, the current dam spillway values are similar to the simulation values. It is clear that the CFD method provides the convenience of users and institutions in sizing and calculating the flow characteristic before projecting large fixed constructions which has high cost.

6

Modelling spillway flow conditions at Złotniki storage reservoir on the Kwisa river

Machajski J., Olearczyk D.

Studia Geotechnica et Mechanica

|

2012

|

Vol. 34, nr 1

35-49

EN

An important part of the work connected with planning modernization of outlet devices of Złotniki storage reservoir on the Kwisa river was numerical modelling of flow conditions in the flume of the side-channel spillway. The modelling was preceded by the analysis of operating principles of such a device and performing analytical calculations that defined the spillway capacity ability as a function of the required water levels in the reservoir and the conditions of water flow through the flume that are significant to spillway operation. The results of the numerical modelling performed pointed to the evident need to reconstruct this device, guaranteeing exploitation safety of the reservoir, mainly in view of the computational discharges, exceeding considerably the nominal capacity ability of the reservoir's outlet installation in the existing constructional state.