هيدروليك رژيم جريان ريزشي از روي سرريزهاي پلكاني

Nappe Flow Hydraulics In the Stepped Spillway

A stepped spillway includes several vertical drops, which are jointed to each other in a rectangular open channel from the reservoir upstream to its stilling basin (downstream). The flow over stepped spillway can be classified in to the Nappe and Skimming flows. The Nappe flow takes place in low flow discharge, which may be followed by the hydraulic jump over the horizontal part of each step. In the present study based upon the dimensional similitude, two models have been developed for calculation of energy dissipation, which are correlated with some non-dimensional parameters. To find the unknown coefficients of these equations, several physical models have been established in the Shahid Chamran University (SCU), Hydraulic Laboratory and several small and large stepped spillways (with average slope of 15 and 25 degrees) have been installed in the laboratory flume. Several hydraulic parameters have been measured which are used for optimization of noted unknown coefficients. Results of the developed models have been compared with the observed data and results of the previous studies cited in the literature. The comparative study shows that a very good agreement exists between the results of this study with those from observation and reported in the literature.