Probability Evaluation of Hydrodynamic Shear Damage for Fish Passing through Jet Fish Pumps

Abstract

Jet fish pump is an efficient tool to transport fish. Due to the operation principle, shear flow cannot be avoided in jet fish pumps. Shear flow is a potential risk for fish damage in the fluid machinery. Therefore, it is valuable to evaluate the probability of hydrodynamic shear damage for fish passing through jet fish pumps. In the present study, the numerical investigation was performed on the distribution of dangerous region, where exposure strain rate was above 500 s-1, and probability of hydrodynamic shear damage for fish. Experiments were conducted to check the damage probability calculated by numerical simulation and the injury of fish was analyzed. The results showed that the dangerous region is usually distributed in the near wall region. As the rise of flow ratio, the range of dangerous region gradually became wider and the dangerous region extended into the throat. In the same inlet boundary conditions, the damage probability is lower for a jet fish pump with a bigger area ratio. With the increase of flow ratio, both probability of hydrodynamic shear damage and effect of area ratio grow. Compared with the results of experiments, the probability of hydrodynamic shear damage can be overestimated. The main reasons lie in the extremely short transit time for fish, independent movement of fish and the velocity difference between fish and flow.