Introduction: Each Dam consists of a large number of side structures, one of the most important of which is flood discharge structures. Among these structures, we can mention lower drains and overflows, which are mostly used for flood discharge in large Dams. Spillways and lower dischargers must be able to discharge the volume of water equal to the largest possible flood in the Dam catchment area in a short period of time. If this work is not done with enough confidence, the flood will pass over the crown of the dam and cause a lot of damage to the dam and its ancillary facilities, and in many cases this will cause the Dam to fail. Until now, various types of launchers have been used to consume flow energy, which can be mentioned as simple launchers, compound and toothed launchers. Launchers are usually used at the end of shot weirs, tunnel weirs and horizontal channels if the topographical and geological conditions are suitable. From the point of view of geometry, simple launchers are also divided into two types: cup-shaped and triangular-shaped, of which the cup-shaped type is more common. A cup-shaped launcher has an axial curvature along the longitudinal axis in the flow direction.

Methodology: In general, until now, the investigation of the flow on the launchers leading to the shot overflows and dynamic pressure has been done through laboratory models. As far as the criterion for the design of launchers has been presented experimentally and the selection of the optimal shape of the launcher has been through the construction of hydraulic models. So far, the calculation of dynamic pressures on the bed of Cup Launchers has been of piezometric type (Dynamic pressures are taken with a piezometer). In this research, it has been tried to determine the fluctuations of pressure and force in the bed of cup-shaped launchers leading to inclined shot overflows, within the scope of the available capabilities and options by using the experiments conducted by others, as well as the values calculated in the numerical method for the speed and pressure to be investigated and studied. In this research, by using Heger's pressure distribution equation, the power distribution was obtained in experimental tests on the hydraulic model of Jarah dam.

Results and Discussion: Due to the fact that it has been tested in Jare overflow in different landing numbers, so the dimensionless diagram of relative force, relative pressure and force distribution on the bottom of the bucket will be as follows. Of course, it should be considered that since the length of the bucket in the overflow of the jar is Lt=19.08 and also the maximum pressure value is at xmax=9.8098, so the last value for the relative location X=x/xmax=95/ is 1. The maximum pressure occurs inside the cup and in a range of xpm={(0.45),(0.6)Lt}2, but the minimum pressure in two places of the cup xpin=(0.1),(0.9)Lt is more likely to occur. that force fluctuations are in the range of positive and negative values, which is in very good agreement with analytical and laboratory studies and its difference in the range of (0.7-0) L is less than 28% error, which Paying attention to the fact that it has been investigated with experimental studies is acceptable. It should be noted that in the laboratory model, the flow is developed, but in the numerical model, the flow is uniform, for this reason, a large difference is observed at the beginning. Another reason for its difference is that, in reality, the nature of the laboratory is different from the nature of the numerical model, which is in the form of average Navirastox equations, which itself causes errors. Another reason for the error difference in the range of (0.7, 0.9) L is that the minimum and maximum power coefficients increase with the increase in flow rate and decrease in the Froude number, so the smallest difference occurs at the edge of the cup launcher.

Conclusion: The presence of the launcher at the end of the shot overflow creates a dynamic pressure on the bed of the end of the shot, but the effect of this pressure is less compared to channels without slope, due to the presence of the shot slope. Inside the cup, the maximum pressure head is created almost at the bottom of the launcher. The maximum pressure occurs inside the cup and in a range of xpm={(0.45),(0.6)Lt}, but the minimum pressure in two places of the cup xpin=(0.1),(0.9)Lt has a high probability of its occurrence. The size of the force in the analytical and numerical calculations is also in good agreement with the force values whose fluctuations are shown in Figure 4, and the overall error percentage in the desired overflow is about 35% during the interval L(0.8-0). is, that this difference is due to the constant input number in the integral. In the discussion about the location of the minimum force in buckets, XPmin ≈ 0.1 and XPmin ≈ 0.6 where the force will be at its lowest value and the thickness of the slab required in that range is the minimum value and one of the reasons is that in this range It reaches its minimum when the value of angle α decreases in this range and reduces the centrifugal force, and in that range it becomes similar to an open flow on a horizontal surface, and the difference It is about 5% by numerical calculations.