Fish damage due to tubular turbine: Experiments and CFD simulations

Abstract

Fishes passing through a tubular turbine could eventually be damaged by mechanisms such as impact (s), pressure change (A), pressure gradient (B), and shear stress (C). In the study, the damage of the test fish under different pressure conditions is investigated by pressure tests, and the damage thresholds derived from the tests are combined with CFD simulations to further quantify the fish damage mechanisms caused by the tubular turbine under plausible flow rate and head conditions. Pressure tests show the anatomy of the fish (>94%) remains normal if the induced pressure is between −0.015 and 0.68 MPa. However, the induction of larger negative pressures significantly hampered fish health, with 90% of fish dying at −0.075 MPa 1.5 days after the test and 100% 6 days after the test. Additionally, CFD simulation results show that fish are more vulnerable to blade impact than other mechanisms, with the highest injury probability of 11.02%, and this trend decreases with the increase of turbine head, flow rate and guide vane opening. Negative pressure and pressure gradient are the secondary factors, with the highest probability of 6.45% and 4.61%, respectively. Shear stress is the most insignificant factor, with the highest damage probability of only 0.00699%.