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Showing 5 results for Energy Loss
The Influence of Roughness in Adverse Bed Slopes on Conjugate Depth and Energy Losses of Hydraulic Jump
N. Pourabdollah, T. Honar, R. Fatahi,
Volume 18, Issue 67 (6-2014)
Abstract
Most of researches related to hydraulic jump have been done on horizontal and rough beds, and little attempt has been made on rough beds with adverse slopes. The aim of this study was to investigate the influence of rough beds with adverse slope on hydraulic jump characteristics. The variations of energy loss in stilling basins with three adverse slopes and three different roughnesses were studied. Results showed that increase of roughness caused that relative depth of jump in stilling basins with rough bed and adverse slope decreased as compared to horizontal smooth beds. The experiments were performed on rough beds in different conditions where Froude number ranging between 4.9 and 7.8. Result showed that reduction of relative depth was about 31.15%. Results also showed that in such cases the relative energy losses are more than that for classic conditions.
Assessing Effect of End Sill with Different Forms on Hydraulic Jump Characteristics
A. Ahmadi, T. Honar,
Volume 18, Issue 70 (3-2015)
Abstract

One of the most important problems in the design of a stilling basin is determination of the exact location of the hydraulic jump or stabilization of the hydraulic jump. In the present study, the effects of different forms of end sills on hydraulic jump characteristics were studied. The experiments were carried out for three different forms of end sills, rectangular, square and stepped, with three heights in two distances and for Froude numbers in the range of 4.7-8.23. The results showed that the end sill with larger cross section (square and stepped) will have a greater effect on reducing sequent depths of hydraulic jump and increasing energy loss than narrow end sills. However, in this type of end sills, water fall and the risk of erosion at downstream is greater.


Evaluation of ANFIS and ANFIS-PSO Models for Estimating Hydraulic Jump Characteristics
N. Pourabdollah, J. Abedi Koupai, M. Heidarpour, M. Akbari,
Volume 25, Issue 4 (3-2022)
Abstract
In this study accuracy of the ANFIS and ANFIS-PSO models to estimate hydraulic jump characteristics including sequence depth ratio, the jump length, the roller length ratio, and relative energy loss was evaluated in stilling basin versus laboratory results. The mentioned characteristics were measured in the stilling basin with a rectangular cross-section with four different adverse slopes, four diameters of bed roughness, four heights of positive step, three Froude numbers, and four discharges. The average statistical parameters of NRMSE, CRM, and R2 for estimating hydraulic jump characteristics with the ANFIS model were 0.059, -0.001, and 0.989, respectively. While, the mean values of these parameters for the ANFIS-PSO model were 0.185, 0.002, and 0.957, respectively. The results indicated that these models were capable of estimating hydraulic jump parameters with high accuracy. However, the ANFIS model was moderately more accurate than the ANFIS-PSO model to estimate the sequence depth ratio, the jump length, the roller length ratio, and relative energy loss.

The Effect of Submerged Vanes on Improving Hydraulic Jump Characteristics and Investigating the Role of Attack Angle
Kimia Akhavan, M. Heidarpour, N. Pourabdollah,
Volume 28, Issue 3 (10-2024)
Abstract
One of the ways to improve the characteristics of the hydraulic jump in the stilling basin is to use natural and artificial roughness. Recently, due to the advantages of immersed plates compared to other non-continuous artificial roughness, such as the smaller number of these and the vanes' ability to design their geometry and arrangement, it has been approached more. In this article, the effect of submerged vanes with three contact angles of 45°, 75°, and 90° has been investigated on the improvement of the characteristics of a hydraulic jump and its effect on parameters such as the depth ratio, relative length, energy loss rate, and bed shear force coefficient has been evaluated. The results of this research showed that the average effect of submerged vanes on reducing the depth ratio, jump length, and roller length compared to the classical mode is 9.4%, 24.6%, and 28.4%, respectively and the average relative energy loss is 5.5% compared to the classical state and maximum relative energy loss at the angle of 90 degrees of submerged vanes is 6.5%. Considering these results and other conditions such as ease of construction and use, stabilization, and ‌reduction of economic costs among the available choices of sunken vanes, the angle of incidence of 75° is a suitable option for the optimal design of the stilling basin.

Investigating the Energy Loss in the Dentated Flip Bucket and Dentated Triangular Sill Spillways in Laboratory and Numerical Conditions
M. Niroubakhsh, A.r. Masjedi, M. Heidarnejad, A. Bordbar,
Volume 28, Issue 4 (2-2025)
Abstract
The application of flip bucket and triangular launchers with different shapes has been given more attention due to safety and better energy consumption to protect the downstream bed of water structures, as well as economic benefits compared to other energy consumers. The objective of this research was to investigate the energy loss of the passing flow in the dentated flip bucket and dentated triangular sill spillways in laboratory and numerical conditions. Physical and numerical modeling was used in a rectangular flume with a length of 9 meters, a width of 0.5 meters, and a height of 0.5 meters, flip bucket, and triangular spillways with dentated with specific dimensions according to the USBR standard in different discharges intensities in laboratory and numerical conditions. The amount of energy loss in the dentated flip bucket spillway was 71.4% and the dentated triangular sill spillway was 74.8% in laboratory conditions, which showed that the dentated triangular sill spillway has a better performance in terms of energy loss than the flip bucket and triangular spillway. The results showed that the shape of the spillway geometry and the presence of the dentated at the end of the structure is an important and influential factor in the amount of energy loss of the currents passing through the dentated flip bucket and dentated triangular sill spillways, which causes more broken and compressed flow lines and, as a result, an increase in speed at the moment. The launch and finally the relative loss of energy is more downstream of the structure. After determining the better performance of the dentated triangular sill spillway in energy loss, the numerical simulation of the dentated triangular sill spillway was performed using the numerical calculation method in Flow-3D software. The results of the analyses indicated that the amount of energy loss in the dentated triangular sill spillway in the numerical calculations was 87.5%, which showed the alignment and correctness of the tests performed with the laboratory conditions.

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