Abstrakt

Flow Characteristics and Energy Dissipation Losses in Different Configurations of Steps of Stepped Spillway

Prof. Dr. Abdul-Hassan K. Al-Shukur , Dr.Safaa K. Hashim Al-Khalaf , Ishraq M. Ahmed Al-sharifi

This study based on laboratory experiments aims to investigate the flow characteristics and energy dissipation rates on six different configurations of steps of stepped spillway which are: (Inclined and endsills which were fixed on the downstream of the horizontal face of all steps, alternative endsills and horizontal steps, steps combined with endsills and inclined started with endsills and steps combined with endsills and inclined but started with inclined), at physical model with ratio height to length of step (h/l= 0.8391) and (h=3cm) at skimming flow regime. Flow discharge variations were applied in each configuration and the hydraulic changes were investigated and energy dissipation rates were calculated and compared with conventional type of step of stepped spillway. The results showed that the using of different types of steps have the most influence on the amount of energy losses, they are increased the energy losses by about (1.6%-18.6%) at different runs and configurations in comparison of horizontal steps. The results indicated also that the energy dissipation rate at configuration of alternative inclined and horizontal steps show increased by about (6.2% at q=0.02119 m3/s/m) more than the configuration of alternative endsills and horizontal steps and by about (5.3% at q=0.02119 m3/s/m) more than configurations of inclined on all steps. Furthermore, use of compound horizontal and inclined steps alternatively has better performance in dissipating the flow energy in comparison with the horizontal steps, it is increased in the energy dissipation rate up to about (18.6 %) at (q=0.02119 m3/s/m).