Experimental Comparison of Discharge Coefficient for Mesh Panel Bottom Intakes With and Without Sediment

Document Type : Research Paper


1 Assistant Professor, Civil Eng. Dept., Khavaran Institute of Higher Education

2 Professor, Civil Eng. Dept, Ferdowsi Univ. of Mashhad

3 Associate Professor, Civil Eng. Dept., Ferdowsi Univ. of Mashhad


Bottom rack is a
hydraulic structure which is placed on the bed of mountainous rivers through
which part of flow in the main channel is diverted. These structures have very
wide application in industry, irrigation, drainage and etc. The present study
was directed to estimate the discharge coefficient of a new kind of bottom
racks including both transverse and longitudinal bars which is named "mesh
panel racks" with and without considering solids in the fluid. This kind
of bottom intake has advantages from structural point of view and has less
deformation under static and dynamic loads. Laboratory setup with three mesh
panel intakes was built and the effects of various parameters such as racks
slope, porosity and geometry, sediment size and sediment grading were explored.
A dimensional analysis using Buckingham theory showed the effective hydraulic
and geometric factors that affect the discharge coefficient (Cd) of
bottom racks. Then, a statistical approach to determine the discharge
coefficient of a rack structure was developed with linear and nonlinear
regression using SPSS software. Finally, hydraulic performance of mesh panel
intakes was compared with and without sediment.