Hydraulic jump is one of the most important methods of energy depreciation, which is used to control a structure called relaxation pool. It costs a lot to build this structure. So, to reduce costs, many methods such as floor roughness, elemental, middle and end blocks, etc. are presented. In recent studies, submerged jet has been used for the relaxation pond. The purpose of this study was to investigate the effect of number of submerged jet jets on hydraulic jump characteristics such as jump length, relative loss of energy and sustainability. All experiments were carried out in a flume with a length of 10 meters, a width of 25 cm and a height of 50 cm. A supercritical overflow USBR was used to create the supercritical flow of the test. Also, a horizontal jet model with a length of 2.40 m and a width of 24 cm and a height of 5 cm was installed on the floor of the flume and an ogy was installed on it. To change the number of jets used from metal sheets and adhesives. This study was performed with 60 experiments in 3 slopes of 0%, 0.5% and 1% flume. The results of this study showed that as the number of submerged jets increased, energy depreciation decreased. This is due to the increased jet resistance to the jet outflow, which reduces energy depletion and increases the depth of the jump and hydraulic jump. The highest energy depreciation belonged to the jet mode and at the zero fluctuation slope, which increased by about 6.97% of energy depreciation compared to the control. In the constant number of submerged jets, energy depreciation for the high rates was lower in most cases. With the increase in the number of submerged jets, in most cases the secondary depth and the length of the hydraulic jump also decreased to a lesser extent. The maximum decrease in the secondary depth was 20 liters / s on the slope of the zero flume and the number of jets was reduced to 13 percent. The greatest reduction in the length of the hydraulic jump was 20 liters per day, with a number of jets and a zero gradient and a hydraulic jump of 22.83 percent

 Hydraulic jump is one of the most important methods of energy depletion
Which controls a structure called a stilling basin. It costs a lot to build this structure Therefore, in order to reduce costs, many methods such as floor roughness, elemental, middle and end blocks and ... are presented. In recent studies, submerged jet has been used for the stilling basin. The purpose of this study was to investigate the effect of submerged jet on hydraulic jump characteristics such as jump length, relative loss of energy and probability depth. Experiments were carried out in a flume of 25 cm width, 50 cm depth and 10 m length. In order to create the supercritical flow an ogee spillway with the design discharge of 30 lit/s was designed.Also, a horizontal jet model with a length of 3 meters and a width of 24 cm and a height of 5 cm was installed on the floor of the flume and an ogyum was installed on it. A droop valve was used to adjust the discharge of the submerged jet. In this study, a total of 90 trials on 3 slopes The flume was zero percent, half percent, and percent. The results of this study showed that, with increasing submerged jet, the energy depreciation rate increased, due to the interaction between the jet and submerged junctions. Increased energy depreciation by increasing the discharge submerged jet And because of their opposition to the current jet stream is the main stream Which increased with the increase in discharge-jet strength and drag force against the stream. Which has led to an increase in energy depreciation and a lower Sequent Depth jump and hydraulic jump. The maximum amount of energy depreciation related to the total discharge of 40 lit/s was observed on the slope of zero flume and with the ratio of submerged jet total to 20.45 percent to 12 percent of energy depreciation. discharge jet submerged in a constant flow of high energy dissipation for higher. With the increase in discharge submerged jet, Sequent Depth of jump and the length of the hydraulic jump also decreased more. The maximum decrease Sequent Depth in the of jump was 40 liters / s on the flume slope of zero percent, and the ratio of discharge jet to total discharge to 20.45 percent decreased by 23 percent. The maximum reduction of the length of the hydraulic jump is related to discharge 40 l/s ratio and discharge jet to total discharge 20.45 precent that is decrease the length of the hydraulic jump 28 precent.

 

For controlling hydraulic jumps, Stilling basin is one of the commonest structures. They are widely utilized in order to reduce the devastating effects of conversion of supercritical flow to subcritical flow. To determine the economic design of hydraulic structures, various approaches are considered such as designing desirable dimensions of bed roughness, chute blocks, baffle blocks and end sill. Recent studies using stepped sill in the stilling basin have shown a beneficial effect on the characteristics of hydraulic jumps. The main objective of the peresent research is to study the effect of Perforated stepped sill on the characteristics of hydraulic jump such as length of jump, relative energy dissipation and required tail water depth. Experiments were carried out in a flume of 25 cm width, 50 cm depth and 10 m length. In order to create the supercritical flow an ogee spillway with the design discharge of 30 L/S was designed. To access the appropriate height three different sills were used with relative height equal to 1.33, 1 and 0.67 at two relative distances. In addition, to investigate the effect of the sill shape on the characteristics of hydraulic jump, experiments were carried out for stepped sill with constant relative height equal to 1.33 at three forms of positive, negative and conjugated at two relative distance equal to 18.75 and 14.6. after obtaining the proper height and the most effective sill shape, experiment were carried for negative stepped sill with costant relative height equal to 1.33 for four ratious of opening of holes equal to 12, 25, 50 and 70% at three relative distance equal to 18.75, 14.6 and 10.4. The number of 125 tests were performed totaly. The results have shown that the negative stepped sill with costant relative height equal to 1.33, has a more effect on reducing the length of hydraulic jump and increase relative energy dissipation compared to other options. a Perforated stepped sill compared to continuous sill (rigid) has shown desirable performance in controlling and stabilizing the hydraulic jump in the Stilling basin. this type of the sill reduced the length of jump and required tail water depth and also increase relative energy dissipation. results also showed that the sill ratio of opening of the holes equal to %25 has a maximum effect on reduction of the length of hydraulic jump than other sills and also it is reduction length of hydraulic jump of 40.8% on an average than classical hydraulic jump. The best position for the sill ratio of opening of holes equal to %12 is the relative distance more than 14.6 or in other words L_s>3.8〖(y_2-y_1)〗_design. also the curvature of stream lines passing through sill will more severe when the relative distance is reduced. So that a series of vortexes is created in downstream of sill that they increase the confution and turbulence in the stilling basin. This situation is very sensible for the sill ratio of opening of holes equal to %12 at the relative distance equal to 10.4. finally the results of the present study were compared with relationships of USBR and other researchers.

 In order to prevent the losses caused by flow energy in supercritical velocities and also in order to reduce the extra kinematic energy in such flows, energy dissipation structures could be used. Stilling basin is a kind of such hydraulic structures with solid bed and specified length which are constructed at the downstream of control structures. In energy dissipators, obstacles would be placed in front of flow to create the hydraulic jump inside the basin. Parameters including basin length, thickness of bed beam and the downstream water depth are among important factors affecting the economical design of the basin. Energy dissipation structures are used in order to change the flow status from super critical to sub critical. Horizontal jets are among new energy dissipation facilities which increase the efficiency of energy dissipation by creating shear stress areas. Comprehensive studies on the effect of angle of the bottom of jet on their energy dissipation have not yet been conducted. Generally it is concluded that increasing the angle of jet bottom will increase the energy dissipation and the length of basin could be decreased in order to have a more economical structure.Energy dissipation structures are designed and implemented in order to convert flow condition from super critical to sub critical. Horizontal submerged jets are among novel structures in this regard which increase the efficiency of energy dissipation by creating high shear stress areas. The effect of the bottom angle of submerged jets on the characteristics of hydraulic jump is investigated experimentally in this study.Experiments were performed in a laboratory flume of 80 cm width, 12 meters length and 0.65 m height with 5 different discharges with Froude number changing from 2 to 4 and the horizontal submerged jet’s bottom angles of 0 , ¬5 and 8 degrees. Results indicated that changing the angle of jet’s bottom increases the ratio of energy dissipation. This is specifically significant in changing the angle of jets sub-layer and it dissipates the energy of free jump in average ratio of 59 percent. In this condition, the jump length and rolling length had least change and they are decreased equal to 15% and 5% respectively.

Control of energy in high-velocity flows is one of the important items in the design of hydraulic structures. The excessive energy of the flow can cause serious damages to the structures and downstream end scouring. The energy dissipation is made by hydraulic jump and using blocks in structures outlet for dam spillways. Using the large dimensional blocks, causes detachment of the water jets on the structure surface and thus decreases the flow energy. It since, for the structures with large dimensional blocks the water flows between and on the blocks which are located on the structure outlet, and thus the kinematic energy is decreased. According to this feature, the main purpose of this study is the investigation of energy dissipation in Piano Key Weirs. In this study research, the discharge coefficient and the energy dissipation, for investigation of the effect of block design, height design & distance of the first block row from the beginning of outlet key for piano key weir, on the structure’s discharge coefficient and also energy dissipation, after knowing the effective parameters, by mading physical models with 2 different heights (12 , 8 cm), 2 different designs ((3-2) , (2-2)) and 2 different distances (1/4 , 1/3 of the length of outlet key) and 9 different discharges (5, 20, 35, 50, 65, 80, 95, 120, 135 lit/s), and in total a number of 81 tests was carried out. The tests were carried out in hydraulic models laboratory of water research institute of Tehran. The results showed that the discharge coefficient is constant in all models with and without blocks. The emount of energy dissipation for baffled models is more than the model with no baffles. And also, increasing blocks height and increasing block distance increases energy dissipation. The block heights is most effective parameter in comparison to other parameters, and it was abserved no significant difference between block distance and block design. Also among all baffled laboratory models, model S8 (the model with baffles design (2-2), baffles height 8 cm and distance of the first baffle row of 1/3) makes most amount of energy dissipation (75 percents). In addition to, in comparison to model with no baffle, Nearly 12.94 percent of the energy is dissipated in this model. Also, in comparison to model with design (3-2), nearly 1.17 percent and in comparison to model with no baffle, nearly 0.28 percent of the energy is dissipated on model with design (2-2). In comparison to model with 8 cm height, nearly 1.45 percent and in comparison to model with no baffle, nearly 1.45 percent of the energy is dissipated on model with 12 cm height. In comparison to model with distance 1/4, nearly 1.17 percent and in comparison to model with no baffle, nearly 0.28 percent of the energy is dissipated on model with distance 1/3.

One of the most important challenges of hydraulic engineering science is to dissipating excess energy of supercritical flows. This kind of high-speed flow usually occur, at the spillway structures of dams, drainage systems of urban areas and in the steep mountain rivers. The excessive energy of these flows can cause serious damage to the surface of the structure itself and the downstream end by scouring. Some of energy dissipaters include conventional stilling basin, stepped spillways and flip buckets. The main disadvantages of flip buckets is high rate of water spray in the air, strong atomization and high close-to-bed velocity. A new type of energy dissipater has been proposed by researchers named stilling basin with Multi-horizontal Submerged Jets (MHSJ) which is a new method in eliminating excessive energy. The energy dissipation in this type of stilling basin occurs after the submerged jets entering horizontally to the tail water and forming a submerged hydraulic jump. MHSJ has been designed by the mechanism of energy dissipation in sky jump stilling basins which takes place at the shear layer of it but in MHSJ increasing the number of jets to more than one jet and also entering them horizontally to tail water, develops the shear layer and subsequently the rate of energy dissipation. Moreover the mentioned characteristics of MHSJ results in decreasing the amount of close to bed velocity and removes the effects of negative bed pressure. The fluctuation of water surface is low and the flow is easy to control at the downstream section. In this study the effects of jet number and type of hydraulic jump forming after MHSJ on the characteristics of hydraulic jump and energy dissipation rate has been investigated. Experiments carried out for 3 physical models with 5, 7 and 9 jets with Froude numbers ranging from 2 to 5. Also in order to investigate the effects of jets submergence, two types of free hydraulic jump and submerged hydraulic jump were examined and eventually with 60 runs for flow discharges ranging from 70 to 250 lit/s, experimental equations for hydraulic jump characteristics have been presented. The results indicated that increasing number of jets does not has a remarkable effect on the energy dissipation rate but causes to decrease length of the jump and length of the roller. The study of jet submergence for a particular jet model showed that length of the jump for free hydraulic jump is more than that of submerged hydraulic jump but length of the roller has higher amounts for submerged hydraulic jump. The energy dissipation rate in free hydraulic jump is much more than that of submerged hydraulic jump at lower Froude numbers, but as the Froude number increases, the difference correspondingly gets ignorable.