Amirkabir University of TechnologyAmirkabir Journal of Civil Engineering2588-297X531020211222Investigation of Flow Characteristics and Pressure Parameters of Free and Submerged Hydraulic Jumps in USBR Stilling BasinsInvestigation of Flow Characteristics and Pressure Parameters of Free and Submerged Hydraulic Jumps in USBR Stilling Basins41254142389310.22060/ceej.2020.17791.6676FASeyed NasrollahMousaviHydraulic Lab Expert, Water engineering Department, Tabriz University, Iran0000-0002-0750-0898FarsadizadehDavoodProf., Dept. of Water Eng., Faculty of Agric., Univ. of Tabriz, Iran0000-0003-1181-8767FarzinSalmasiAssoc. Prof., Dept. of Water Eng., Faculty of Agric., Univ. of Tabriz, Iran0000-0002-1627-8598AliHosseinzadeh DalirDept. of Water Eng., Faculty of Agric., Univ. of Tabriz, Iran0000-0003-2359-3921Journal Article20200125In this study, flow characteristics and pressure parameters of hydraulic jumps have been investigated in a laboratory flume. The results for different incident Froude numbers (Fr<sub>1</sub>), at the downstream of an Ogee spillway on a typified USBR II stilling basin bed were compared with the USBR Type I basins. Dimensions of the Ogee spillway and stilling basin were designed according to the USBR criteria. The pressure data of the points on the basin bed were recorded using pressure transmitters with 20 Hz frequency. Experimental parameters, including flow depths and velocities at the beginning and endpoint of free jumps<em> </em>(<em>Y</em><sub>1</sub>, <em>Y</em><sub>2</sub>, <em>V</em><sub>1</sub> and <em>V</em><sub>2</sub>), and submerged jumps (<em>Y</em><sub>3</sub>, <em>Y</em><sub>t</sub>, <em>V</em><sub>3</sub> and <em>V<sub>t</sub></em>) were measured. In the present study, dimensionless parameters of energy dissipation efficiency (<em>ε<sub>t</sub></em>), mean pressure head (Ψ<sup>*</sup><em><sub>X</sub></em>), the standard deviation of pressure fluctuations (Φ<sup>*</sup><em><sub>X</sub></em>), maximum positive pressure fluctuation coefficient (<em>C<sub>P</sub></em><sup>+</sup>), maximum negative pressure fluctuation coefficient (<em>C<sub>P</sub></em><sup>‒</sup>), total pressure fluctuation coefficient (<em>C<sub>P</sub></em>) and skewness coefficient (<em>A<sub>d</sub></em>) were investigated. Pressure parameters are dependent on Fr<sub>1</sub>, the dimensionless position (<em>Γ<sup>*</sup><sub>X</sub></em>), and the submergence degree (<em>S</em>). The results showed that by reducing the Fr<sub>1 </sub>values, the ε<sub>t</sub> parameter decreases. The Φ<sup>*</sup><em><sub>Xmax</sub></em> value in the USBR Type II basin decreases around 30% compared to the Type I basins in free jumps. The reduction of Φ<sup>*</sup><em><sub>Xmax</sub></em> values in the submerged jump with <em>S</em>=1.4 is about 29% than free jumps. The <em>C<sub>P</sub></em><sup>+</sup><em><sub>max</sub></em> and |<em>C<sub>P</sub></em><sup>‒</sup>|<em><sub>max</sub></em> coefficients in the submerged jump with S=1.4 in comparison with free jumps decrease about 15 and 17%, respectively.In this study, flow characteristics and pressure parameters of hydraulic jumps have been investigated in a laboratory flume. The results for different incident Froude numbers (Fr<sub>1</sub>), at the downstream of an Ogee spillway on a typified USBR II stilling basin bed were compared with the USBR Type I basins. Dimensions of the Ogee spillway and stilling basin were designed according to the USBR criteria. The pressure data of the points on the basin bed were recorded using pressure transmitters with 20 Hz frequency. Experimental parameters, including flow depths and velocities at the beginning and endpoint of free jumps<em> </em>(<em>Y</em><sub>1</sub>, <em>Y</em><sub>2</sub>, <em>V</em><sub>1</sub> and <em>V</em><sub>2</sub>), and submerged jumps (<em>Y</em><sub>3</sub>, <em>Y</em><sub>t</sub>, <em>V</em><sub>3</sub> and <em>V<sub>t</sub></em>) were measured. In the present study, dimensionless parameters of energy dissipation efficiency (<em>ε<sub>t</sub></em>), mean pressure head (Ψ<sup>*</sup><em><sub>X</sub></em>), the standard deviation of pressure fluctuations (Φ<sup>*</sup><em><sub>X</sub></em>), maximum positive pressure fluctuation coefficient (<em>C<sub>P</sub></em><sup>+</sup>), maximum negative pressure fluctuation coefficient (<em>C<sub>P</sub></em><sup>‒</sup>), total pressure fluctuation coefficient (<em>C<sub>P</sub></em>) and skewness coefficient (<em>A<sub>d</sub></em>) were investigated. Pressure parameters are dependent on Fr<sub>1</sub>, the dimensionless position (<em>Γ<sup>*</sup><sub>X</sub></em>), and the submergence degree (<em>S</em>). The results showed that by reducing the Fr<sub>1 </sub>values, the ε<sub>t</sub> parameter decreases. The Φ<sup>*</sup><em><sub>Xmax</sub></em> value in the USBR Type II basin decreases around 30% compared to the Type I basins in free jumps. The reduction of Φ<sup>*</sup><em><sub>Xmax</sub></em> values in the submerged jump with <em>S</em>=1.4 is about 29% than free jumps. The <em>C<sub>P</sub></em><sup>+</sup><em><sub>max</sub></em> and |<em>C<sub>P</sub></em><sup>‒</sup>|<em><sub>max</sub></em> coefficients in the submerged jump with S=1.4 in comparison with free jumps decrease about 15 and 17%, respectively.https://ceej.aut.ac.ir/article_3893_1e1ef99652375149e906097016043ede.pdf