Experimental study of energy loss through submerged trashracks

Abstract

Experimental results for several trashrack models placed in a pressurized rectangular conduit are presented. The tests were performed for both straight and oblique approach flows. Trashrack models of different bar cross-sectional shapes, bar thicknesses, bar depths and bar spacing were studied for a range of velocities. The results indicate that the head loss across the trashrack increases with increasing approach velocity, flow inclination, and blockage ratio. Lower head losses were observed for bars with cross-sectional shape other than rectangular. Results were found to differ only moderately from the previous trashrack energy loss literature based almost entirely on open channel flow experiments. An equation has been developed that well represents the current experimental findings.

Keywords:

• Energy loss
• experimental hydraulics
• fish mortality
• hydraulic efficiency
• trashrack

Acknowledgements

The authors wish to thank Dennis Lemke, Efrem Teklemariam and Kevin Sydor from Manitoba Hydro, Christos Katopodis and Haitham Ghamry from the Department of Fisheries and Oceans, as well as Mark Tachie from the University of Manitoba for their assistance throughout this project. Thanks also to Nicholas Kehler for constructing the test apparatus.