Print ISSN: 1813-0526

Online ISSN: 2220-1270

Main Subjects : Hydraulic


The Effect of the Spur Dikes at the Entrance to the Curved Channel on the Morphology of the Bed

Ahmed Shareef Hayder; Mwafaq Younes Mohammed

Al-Rafidain Engineering Journal (AREJ), 2022, Volume 27, Issue 1, Pages 153-161
DOI: 10.33899/rengj.2021.131080.1127

The meander rivers are notice condition in nature more the existing river in nature. In which the river continues process in scour and deposition sediment transport normally the scour in the outer side of a river bank and the deposition will be in the lift bank. Due to centrifugal and secondary currents for the flow. To control the movement of the sediment to overcome of the scour and deposition the spur dikes used as a one way to protect the river bank and to control of the sediment movement. In this research we locate spur dike in the straight portion of laboratory channel before entering the bend or meander to see what is the effects of this spur dike. The spur was fixed in different location in this straight portion at left, right and both side in different angle (30°, 90°,135°, 150°) with different discharge (24.096, 27.477, 31.016, 34.71) l/sec. The results shown that the spur dikes at the left side are  Reduces erosion and deposition Compared without spur dike at the section (1.9, 2.9, 3.9, 6.1)m, and the large erosion and deposition was when we put spur dikes at both side of channel with angle 90°.  

Numerical and Physical Modelling to Dissipate the Flow Energy of Spillway Using Multiple Rows of Chute Blocks

Mohamed Saad Alhmdany; Mena Ahmed Alsawaf; Zeyad Ayoob Sulaiman

Al-Rafidain Engineering Journal (AREJ), 2022, Volume 27, Issue 1, Pages 172-180
DOI: 10.33899/rengj.2021.130576.1112

Physical and Numerical models have been used to maximize the dissipation of flow energy of a sipllway, and to guarantee the occurring of hydraulic jump in the stilling basin in shorter length, and to find the right model to simulate turbulent flow properties using the techniques of Computational Fluid Dynamics (CFD). 5 models have been tested which they had different rows of chute blocks. For each, 6 slopes of chute were examined, 1:0.8, 1:1.0, 1:1.2, 1:1.4, 1:1.6, 1:1.8, with 10 cm of tail water. Physical models were emplemnted to represent a sucssecfully models that compared with the theoretical model in a slope 1:1.2 for chute. Using the RNG & K-є as a turbulent theoretical model and a non uniform distribution of the mesh led to sucssesfully simulating the stream lines, velosities and shape of hydraulic jumps and Froude numbers. Using four rows of choute blocks at the end of the chute near the edge is the best design to dissipate the energy, which was 61.9%, and for spillway slope of 1:0.8, while the percentage of energy dissipation that depending reducing the distance of the roller jump and reducing the distance of the supercritical flow was laid between (17.8, 94.8)%, respectively, when the spillway slope is 1:1.0.

The Effect of the Permeable and Impermeable Spur Dikes on the Morphology of the Bed

Ahmed Shareef Hayder; Mwafaq Younes Mhammad

Al-Rafidain Engineering Journal (AREJ), 2022, Volume 27, Issue 1, Pages 162-171
DOI: 10.33899/rengj.2021.131198.1128

Flow becomes more complicated in meandering and natural channel which leads the researchers to focus on the observations of natural and laboratory channels to study the characteristics and hydraulics flow in meandering channel. Three cases for installing impermeable and permeable spur dike with 30o in the entrance of meandering channel (left side, right side and both sides of channel) are used in this study using four levels of discharge (24.096, 27.477, 31.016, 34.71) l/sec for each case. The study concluded that the permeable spur dike reduced the amount of erosion and deposition in the meandering channel and maximum deposition (18.2cm) occurred in the case of impermeable spur dike on both side of channel at 2.5m from the beginning of the curvature of meandering channel and at biggest discharge (34.71) l/sec. The results of experiments showed that the minimum erosion (9cm) occurred in the case of permeable spur dike on right side of channel at 0.3m from the beginning of the curvature of meandering channel and at biggest discharge (34.71) l/sec where the impermeable spur dike has reduced the maximum depth of engraving by (10)%.

The Effect of Entrance Edges Shape of the Diversion Channel on the Dividing Streamlines Behavior at the Junction Region

Ahmed Yahya Abdalhafedh; Nashwan K. Alomari

Al-Rafidain Engineering Journal (AREJ), 2021, Volume 26, Issue 2, Pages 218-226
DOI: 10.33899/rengj.2021.130181.1096

                  Diversion channels are used in irrigation networks and many of water resource projects. Due to the diversion of a portion of the water, a ratio of the main flow streamlines is deflected to the diversion channel (on the diversion side). The ratio of dividing streamlines increases from the surface to the bottom due to the high momentum of the flow upper layers,which resists its diversion. This negatively affects the quality of diversion water, as the largest proportion of it comes from the high sediment concentration of the lower layers. In this study, the effect of changing the sharp edge of the diversion channel entrance to a circular edge (at upstream, downstream or both sides) on the behavior of dividing streamlines. The study considered five different percentages of the diversion discharge ratio (between 7.5% and 30% of the total discharge) with five different diameters of the circular edge. The results indicated that there is a noticeable improvement of the dividing streamlines uniformity along the flow depth when using the upstream and downstream circular edge, as well as when using large diameter of the upstream circular edge only.  In addition, increasing the discharge ratio reduces the regularity of the flow lines.

The Effect of Dual Water Jet on Discharge Coefficient of Vertical Spillway

Firas I. Khaleel; Ahmed Mohammed

Al-Rafidain Engineering Journal (AREJ), 2021, Volume 26, Issue 2, Pages 291-299
DOI: 10.33899/rengj.2021.130443.1104

The water intakes is one of the important hydraulic installations that is built with the dam and is used to control the water level in the dam's lake. The vertical spillway is a type of intakes used in dams to control floods and as on intakes to change the river stream in mountainous areas. One of the most important problems that occur at vertical intakes is the vortex of water which occurs when the depth of submerge is less than the critical depth, dual water jet applied to the vertical spillway was used with different vertical and horizontal distances, the effect of dual water spillway was tested on six discharges entering the vertical spillway and the three diameters. The results shown that the dual water jet has a clear effect in dissipating the energy of the vortices formed at the vertical spillway, especially in the case of orifice flow, and it is effective in the large diameters of the vertical spillway.

Using the Submerged vanes to control the sediment entering branch channel with 30° angle with the direction of the main channel

Ehsan Elewy Salman; Mwafaq Younes Mhammad

Al-Rafidain Engineering Journal (AREJ), 2021, Volume 26, Issue 1, Pages 90-95
DOI: 10.33899/rengj.2020.128056.1058

A common problems faced by the side intake channels are sedimentation and sediment entry. These cause problems as limiting the flow ability in irrigation channels, and threatening to waterway block when the water level is low. This laboratory study was conducted to find out the effect of using one-row immersed vans in the main channel to control the sediments amount of entering the intake channel at an angle  with two sand concentrations at granular diameter rate (  = 0.5mm). The first concentration flow rate was (1.8 ) And the second (2.22 ). The results showed that the use of a single row of submerged vans reduces the sediment amount that entered the intake channel by (35-65)% of the total sediments that were fed by the feeder channel for both concentrations. This indicates that use of submerged vans has a positive role in entry process and sediment transfer to branched channels.

Hydraulic Properties Downstream Multi-Opened Sluice Gate

mohammad yasin Al-Qattan; Ahmed Y Mohammed

Al-Rafidain Engineering Journal (AREJ), 2021, Volume 26, Issue 1, Pages 63-68
DOI: 10.33899/rengj.2020.127108.1037

In this paper four gate openings and fifteen operating scenarios in terms of the difference in the arrangement of working gates were studied. The Expansion Ratio (e) which is (the ratio of total width of the channel to the total width of the working gates) was calculated for each scenario. It can be seen that when the value of (e) was the largest possible, which is (5.34), the value of the discharge coefficient (Cd) was also as high as possible, reached to (0.845). Also, the value of the contraction coefficient (Cc) was the highest value, (0.693). The increasing in the value of (e) means that the number of openings that work is less. Both (Cd) and (Cc) are decreases when Froude Number increased for all scenarios of gate worked operations.

Study of Scour Around Cylindrical Bridge Piers with Circular Openings

Mays Ibrahim Alsaidi; Ghania Abd Al-Majeed Hayawi; Mena Ahmed Alsawaf

Al-Rafidain Engineering Journal (AREJ), 2020, Volume 25, Issue 2, Pages 66-74
DOI: 10.33899/rengj.2020.126863.1029

            To reduce the local scour around bridge piers and ensure their safety, an experimental study was conducted to examine the effect of a single tubular hole that faces the flow direction through three successive cylindrical bridge piers. In order to reduce the local scour, occurred because of the collision of the flux. Two groups of successive piers were used, both had diameters of 5, 11, 16 cm. First group of piers with internal tubular opening which had 20% diameter of the pier and located at half the water depth. The second group just solid pier for comparison. The spacing between them was varied to be 30, 40 or 50 cm for each group. As well as the discharge was varied. The used moveable bed material classified as non-uniform coarse sand, which had 0.5 mm mean diameter. The results showed that the presence of the openings helps effectively to reduce the depth of scour and its effect increases as the diameter of the opening increases, as the highest reduction reaches 55.56%, 53.33% and 10% for diameters 16, 11 and 5 cm, respectively. The scour depth increases when the diameter of the pier the increase of and the short distance between the successive piers.

Studying The Effect of Intake Channel Angle on the Sediment Transport Branching Channels

Ehsan Elewy Salman; Mwafaq Younis Mohammed

Al-Rafidain Engineering Journal (AREJ), 2020, Volume 25, Issue 2, Pages 60-65
DOI: 10.33899/rengj.2020.126731.1018

An experimental investigation was conducted to observe the connection angle effect of the branched channel front with the main channel on the entering sediments amounts into the branched channel. Three angles were taken to the branched channel inlet (60°,45°,30°), that connected with the main channel from the left side with two concentrations of sand at a granular diameter rate (D50=0.5mm). The concentration flow rates were 1.8 and 2.22(g/s), respectively. The sand was fed and organized by a speed regulator to main channel to obtain the concentrations. The results showed that the 60° was better than the rest in the sediment numbers. Compared to the 30° and 45° angles, the reduction at the 60° was at (32-40)% of 40% of the discharge rate. Besides, at the 30% discharge rate, the reduction was (16-19)%. Within the study limits, it has indicated that the greater angle is the better and it reduces sediments.