Author(s): D. B. Bung; A. Schlenkhoff
Keywords: No Keywords
Abstract: As is known the energy dissipation and oxygen transfer on stepped spillways in skimming flow regime is increased due to earlier self-aeration and slower flow velocities in comparison to smooth spillways. Although, attainment of full energy dissipation is generally not possible neither on steep stepped spillways (BOES, 2000) nor on cascades with moderate slopes (BUNG, 2009). Furthermore, oxygen transfer is only slightly influenced by geometry and discharge on embankment stepped spillways (BUNG, 2009). For these reasons alternatives of influencing the flow properties have been considered with the objective to increase both, the energy dissipation and oxygen transfer potential. This paper presents the results gained on a physical model by adding small micro-roughness elements. The obtained data is compared to a large data set measured on modeled cascades with smooth steps of different heights and varying chute slopes. The results indicate that the arrangement of the micro-roughness has large influence on the flow characteristics.