Laboratory Study of SimultaneousCoarse-gradient Roughness and Positive Slope on Hydraulic Jump Length in Classical Stilling Basin

Subject Areas : hydraulic structures

Roozbeh AGHA MAJIDI ¹ (1) Professor Assistant, civil Department , Islamic Azad university , Sepidan branch , Sepidan , iran)
Amir hossein Nozari ² (Msc of civil engineering , Islamic Azad university , Marvdasht branch , Marvdasht , iran)

Received: 2019-03-16 Accepted : 2020-09-09 Published : 2020-03-10

Keywords: hydraulic jump, Overflow, Classical stilling basin, Physical modelr roughness,

Abstract :

Hydraulic structures such as stilling basins, mainly are used for the purpose of energy dissipation in the lower zone of overflows, chute and diversion dams, in order to control hydraulic jump. In this research, the rate and effect of the jump is determined by laboratory tests. In these experiments, the sharp roughness of the bed of basin and also the change in the slope of the basin( structure ) from 0 to 0.3 percent were tested and parameters such as flow rate, initial depth, secondary depth, jump length of water surface profile, water head on overflow crown and water head prior to overflow were accurately measured. The analysis of data showed that the sharp roughness can effectively reduce the length of jump to to 35.5%. For sharp shape roughness, with an increase in the landing rate, the ratio y2 / y1 increases by an average of 6.5%. For a Froude number with a sharp roughness setting, the Lj / y2 ratio decreases by an average of 1.2%.