Laboratory Investigation on the Effect of Screen's Location on the Flow Energy Dissipation

The energy dissipation through hydraulic structure is an important issue in hydraulic engineering. The performance of hydraulic structure with regard to energy dissipation can provide stability of structure and river bed. In this study the laboratory investigation on screen performance as the energy dissipator of supercritical flow is evaluated. The investigated parameters include: Froude number; screen porosity and location of screens. The Froude number of supercritical flow could vary within the range of 2.5 to 8.5, and the screen openings were 40 and 50%. Also the location of screens was considered as 62.5, 125 and 250 cm after supercritical flow generator gate. The results indicate that screen openings, location of screens from supercritical flow generator gate and also Froude number of supercritical flow have a significant effect on screen performance. The energy dissipation of system through screens was more than free hydraulic jump in the entire evaluated cases. The results also showed that the increasing Froude number results in screen performance (relative energy dissipation) increase, but screen efficiency (difference between the relative energy dissipation of system from free hydraulic jump) decrease. Also the screen with 50 openings which was been located at 125 cm from gate had the best performance.