An experimental study on fish-friendly trashracks – Part 1. Inclined trashracks

Experimental results are presented for trashracks placed in an open water channel with different bar shapes, spaces between bars and screen inclination angles. The numerous configurations provided results on head losses and on changes in velocity along the rack for a large range of situations, including fish-friendly trashracks. A new head-loss equation is proposed that takes into account the effect of the different tested parameters and demonstrates the need to separate the effect of the trashrack bars, which is directly related to the inclination of the trashrack, from the effect of the transversal elements such as spacer rows whose effect on the flow is not altered by rack inclination. Velocity measurements also adduce rules for efficient water intakes complying with fish-friendly criteria.