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

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 hydraulicand 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.