Experimental Investigation of Flow Pattern at a 90 Degree Sharp Rectangular Bend

In this study a series of tests in a 90 degree sharp bend with R/B=2 and constant flow depth 17cm at three different flow discharges of 15، 25 and 35 lit/sec having Froude numbers of 0. 17، 0. 28 and 0. 4 respectively are conducted. By applying a mesh with the nodes no. of 4*12*60 (in depth، width and longitude) within the bend، the three components of flow velocity were measured at each node. The obtained data were plotted by Tecplot and were analyzed by Excel software. The results show that by increasing the Froude number، the initiation separation region from the inner wallbends at bend middle has been shifted to the upstream. Bed shear stress distribution show that it reaches to a maximum value at two locations: the first location is within 10-70 degree in inner wall and the second location is within 80 degree till the end of bend in outer wall. Computation of secondary flow strength show that its maximum magnitude happens at 50 degree (in inner bank) and 80 degree (in outer wall) locations.