Experimental Study of Energy Dissipation in Sudden Contraction of Open Channels

The study of energy dissipation in hydraulic structures has an essential role in providing safety to these structures and providing plans to protect them during different releases of flow.The purpose of this research is to determine the impact of sudden constriction that occurs in open channels on the dissipated energy.Therefore, experimental work was conducted on models that were built based on dimensional analysis for the parameters impacting the dissipated energy in an open channel.Eighty experiments were conducted on these models.In each experiment, several readings for water depth were measured along the contraction zone.Through analyzing the laboratory results, several findings were established.First, it was found that the contraction length has an inverse effect on energy dissipation, with the energy dissipation increasing at the smallest contraction length.Second, the results obtained in the laboratory showed that the dissipation of energy increases with the increase in the discharge.Third, the greatest energy dissipation was obtained at the greatest amount of contraction, and the least energy dissipation was obtained at the lowest amount of contraction in all cases of flow and length of contraction.Finally, an empirical equation was built based on the experimental outcomes statically using the non-linear regression analysis in SPSS software.The calculated dissipated energy by the empirical equation showed a great fitting with experimental findings, and this was confirmed by statistical measurement of the Coefficient of Determination (R 2 ) and Nash-Sutcliff Efficiency (NSE), which they found 0.995 and 0.986, respectively.