The Role of chute Blocks Geometry in Current Erosion Power Loss

مهندسی عمران فردوسی

Article 3, Volume 33, Issue 3 - Serial Number 31, October 2020, Pages 31-47   

Document Type: پژوهشی

DOI: 10.22067/civil.v33i3.86241

Authors

sobhan moradi¹; hamed shahsavari¹; kazem esmaili^{* 2}

¹Department of Water Engineering, Ferdowsi University of Mashhad, Iran.

²Associate Professor at Department of Water Engineering, Ferdowsi university of Mashhad. Iran.

Abstract

The high energy impinging on the outflow through the overflows is controlled by the design of the energy absorber structures in the downstream or downstream relaxation pool. However, the occurrence of downstream local scour is one of the major threats to the stability of the overflows. In the present laboratory research, first, by conducting control experiments (unimpeded shot) at different landing numbers, the geometry of the scour pit was investigated, then by providing a basic block-height protection method in three geometric shapes (Rectangular, Semicircular, Triangle), four mounting positions proportional to the total L_b/L_f shot length (0.2, 0.4, 0.6, 0.8) and also, to concave the installation of blocks, the dimensions of the scour pit are measured and Dimensional analysis was performed using Pie-Buckingham method. The results showed; The use of block base on the slope of the shot in all the models tested has an effect on the dimensionality of the scour and has always reduced the dimensions of the scour pit. In summary: 1. The depth and final length of the scour increases with the increase in the number of upstream landing overflows. 2. In the series of upward concave tests, blocks always have lower values ​​of scour dimension than low facing concave. 3. By decreasing the installation distance of the blocks from the overflow claw, the scour depth and length decrease. So that at position (Lb/Lf = 0.8) the highest energy damping occurred at other positions. And under different conditions the flow decreases between 15 to 61.2% of the depth of the scour pit. 4. In position (Lb/Lf = 0.6), semicircular and rectangular blocks with low upward concavity and also in position (Lb/Lf = 0.8) triangular block with high upward concavity, with average yield 38/1 to 73/4% had the highest decrease during scour compared to other states. 5. By increasing the number of downstream currents, the relative damping energy of the current in the shoot paw decreases.

Keywords

Block Geometry; Scour hole; Barrier Pattern; Energy; Depreciation

Supplementary Files

3-moradi-Revised.pdf

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