Numerical modeling of concrete block shapes and their placement angles on energy dissipation, pressure and velocity in the stilling basin (USBR III)

One of the common methods for dissipating kinetic energy of the stream downstream is the aqueous structures of concrete blocks in the pond. Parameters such as shape, jump length, ratio of secondary depth to primary depth and energy loss rate are among the important parameters that have a great impact on the cost of relaxation stilling basin structure. In a numerical study, the middle blocks in divergent and convergent positions relative to the central axis of the channel It is rectangular in shape and in each position ۵ positioning angles (α = ۱۰-۵۰) degrees are considered for the blocks to achieve the best simulation and turbulence model to describe the turbulence terms of the two-phase flow of water and Mixture model and four turbulence models were used. In this study, modeling the effect of concrete block angles along the hydraulic jump and conjugate depths in the stilling basin (USBR III) was performed using ANSYS CFX software. Show that, in calm basins, the landing number upstream is greater than one and the current is supercritical, while after the hydraulic jump, the landing number is less than one and the flow is subcritical. The flow energy in the stilling basin with convergent block, At all angles of convergence of the block, more than the stilling basin with divergent block is consumed. What is more relaxation with divergent block than stilling basin of relaxation with convergent block. The amount of negative pressure indicates the possibility of cavitation. In this study, it was concluded that in the stilling basin with convergent blocks, the amount of pressure on the structure has always been positive, while the amount of pressure on the stilling basin with divergent blocks is negative and cavitation is likely to occur. It was important to conclude that an angle of ۳۰ degrees in the blocks can be considered as the most optimal in all cases.۱

کلیدواژه ها:

Hydraulic jump ، stilling basin (USBR III) ، Block placement angle ، Cavitation ، Turbulence model