Experimental Investigation of Curved Trash Screens

Abstract

Conventional trash screens are widely used to prevent debris from being transported to downstream reaches of waterways and to allow safe passage along the same waterways. However, debris accumulation at the screens can significantly affect their hydraulic performance, resulting in negative economic and environmental consequences. Thus, this study aims to find applicable solutions for a range of screen arrangements and blockage ratios to reduce the negative hydraulic impacts caused by using the classical screen. This paper reports the results of a laboratory investigation of trash screen models in which four screen angles to the flow direction, four blockage ratios, and five flow discharges are studied. A novel curved screen shape (α<90°) and circular bars were developed, methodically investigated, and compared to classical screens with respect to their head losses and the downstream screen velocities. The results demonstrate that the curved screens are more advantageous than the classical screens used in open channels because of the appreciably reduced head loss coefficients and improved hydraulic performance. New head loss relationship prediction formulas are developed with the tested parameters, which are strongly interrelated, for optimum engineering solutions.