Numerical modelling of flow over spillways

Abstract

The spillway of Sarpfossen hydropower plant has been studied numerically and experimentally. The physical model was built in the Vassdragslaboratoriet at the Norwegian University of Science and Technology, NTNU. The model consists of the Sarpfossen dam and the river Glomma upstream of the dam. On the spillway crest are three gates installed - two flap gates and a sector gate. In addtion is further upstream of the dam a bridge for cars and trains. Two of the bridge piers are fixed in the water and has an influence in the flow pattern. The model was run with a certain discharge and the velocities in the river were measured with a Flow Meter and VectrinoVelocimeter. Besides of the velocity measurements the water levels between bridge and dam were measured. These measurements were conducted to investigate the occuring wave phenomena, shock wave. The simulations were carried out by a commercial program, STAR-CCM+. The results from the simulation have been verified by the measurements from the model.

Simulation were performed to replicate the flow phenomenas in the physical model and to find out how well STAR-CCM+ is suited to cope the complex flow structures. Three simulations were performed - two for the velocity distribution and one for the water level measurements with generated shock waves. The results of the simulations show quite good correlations. The velocity measurements show satisfying results. The shock wave could also be replicated quite well and the results are quite promising.

Future studies are recommended to get more experience with simulating complex free-surface flows. Especially simulations of shock wave are not very frequent and well tested and should be included in further studies.