A Study of the Location of the Entrance of a Fishway in a Regulated River with CFD and ADCP

Abstract

Simulation-driven design with computational fluid dynamics has been used to evaluate the flow downstream of a hydropower plant with regards to upstream migrating fish. Field measurements with an Acoustic Doppler Current Profiler were performed, and the measurements were used to validate the simulations. The measurements indicate a more unstable flow than the simulations, and the tailrace jet from the turbines is stronger in the simulations. A fishway entrance was included in the simulations, and the subsequent attraction water was evaluated for two positions and two angles of the entrance at different turbine discharges. Results show that both positions are viable and that a position where the flow from the fishway does not have to compete with the flow from the power plant will generate superior attraction water. Simulations were also performed for further downstream where the flow from the turbines meets the old river bed which is the current fish passage for upstream migrating fish. A modification of the old river bed was made in the model as one scenario to generate better attraction water. This considerably increases the attraction water although it cannot compete with the flow from the tailrace tunnel.

Vertical and horizontal distribution of ascending Atlantic salmon in power plant tailrace channels

“…As Andersson et al. () also proposed, the nearer the shoreline the salmon swim, the easier it is for them to locate fishway entrances. Some salmon specimens tracked in the middle part of the channel in the present study were swimming downstream, suggesting that this could be the normal route to return from an ascent.…”

“…The horizontal distribution of salmon from this study provides support for this pattern. As Andersson et al (2012) also proposed, the nearer the shoreline the salmon swim, the easier it is for them to locate fishway entrances.…”

Numerical Investigation of Turbulent Flow through Rectangular and Biconvex Shaped Trash Racks

“…For instance in hydro-electrical engineering there is a desire to minimize the energy losses (Marjavaara and Lundström 2006 [1], Marjavaara et al 2007 [2], Andersson et al 2013 [3] and Andersson et al 2014 [4]) at the same time as there are demands on safe fauna passage and low maintenance costs [5], Laine et al 1998 [6], Lundström et al 2010 [7], Lundström et al 2015 [8], Green et al 2011 [9] and Andersson et al 2012 [10]). To avoid damaging of the water turbines from large floating trash in the waterways, the turbine intakes are protected by grids of racks, so called trash racks as exemplified in Figure 1 being a sketch of one of the turbine intakes in Bruksfors a Power-station in Rickleån, Västerbotten, Sweden own by Skellefteå Kraft.…”

Effect of Spatial Resolution of Rough Surfaces on Numerically Computed Flow Fields with Application to Hydraulic Engineering

“…One such concept is to combine partially resolved roughness with a numerical model for roughness. For natural roughness, e. g. for river beds, there is not always an obvious difference in geometrical scale between what is considered a flow domain and roughness elements respectively, (Andersson et al, 2012;Lundström et al, 2010). The topology of the river bed changes with time due to bed erosion and sediment transport.…”