Laboratory Investigation Hydraulic Performance of Grate Inlets in Urban Storm Water Networks

In the past decades many of Iran northem cities due to located in the temperate climate have been always exposed intense rainfalls ,The adverse effects are of the flooding streets, pedestrian and vehicle traffic problem and damage to the public and private property. one of the causes of this situation is the hydraulic performance of grate inlets in storm water networks and clogging them. in this article, hydraulic performance of grate inlets common in urban storm water networks and impact strap angle in discharge coefficient and hydraulic efficiency is studied. built in both the longitudinal and transverse arrangement of straps and in grate inlets is used from 5 straps different angles and two conduit main cross slop. Also to evaluate the effect of flow rate in flow interception were used from 6 different discharge. The results of 120 series of experiments showed that the straps longitudinal arrangement than traverse arrangement are grater from discharge coefficient and hydraulic efficiency and increase rate discharge coefficient in straps longitudinal arrangement than traverse arrangement in the state without transvers slops and terrain slops 2 percent is respectively 52-70 percent. In condition without travers slope 45 strap angle in to length and traverse strap grate inlets from more discharge coefficient in comparision with remnat are fruition Although straps angle has a negligible impact on the discharge coefficient .Also increasing discharge will reduce grate inlets hydraulic performance.