Abstract
The paper presents the results of an experimental study carried out to investigate the effect of geometric and hydraulic parameters on energy dissipation and location of the hydraulic jump, with a change in the height of roughness elements and the divergence of walls in different discharges. Experiments were conducted in a horizontal rectangular basin with gradual expansion 0.5 m wide and 10 m long. Four physical models were fixed in the flume. The measured characteristics of the hydraulic jump with different divergences ratio (B = b1/b2 = 0.4, 0.6, 0.8, 1) and the inflow Froude numbers (6 < Fr1 < 12) were compared with each other and with the corresponding values measured for the classical hydraulic jump. The results showed that the tailwater depth required to form a hydraulic jump and also the roller length of the hydraulic jump and the length of the hydraulic jump on a gradual expansion basin with the rough bed were appreciably smaller than that of the corresponding hydraulic jumps in a rectangular basin with smooth and rough bed. With the experimental data, empirical formulae were developed to express the hydraulic jump characteristics relating to roughness elements height and divergence ratio of wall. Also, the applicability of some empirical relationships for estimating the roller length was tested.
Highlights
In an open channel, a hydraulic jump is a sudden and rapid transition from a supercritical to a subcritical flow
The hydraulic jump is often applied as an energy dissipator below weirs or spillways of dams, chutes, gates, drops and other structures might be utilized in this regards
In order to investigate the S-jump on gradually expanding basin with roughened bed, its characteristics such as length of the hydraulic jump, sequent depth, roller length of the hydraulic jump, bed shear stress, and energy loss were evaluated
Summary
A hydraulic jump is a sudden and rapid transition from a supercritical to a subcritical flow. The hydraulic jump is often applied as an energy dissipator below weirs or spillways of dams, chutes, gates, drops and other structures might be utilized in this regards. The water depth increases abruptly and some of the kinetic energy is transformed into potential energy, with some energy irreversibly losses through the turbulence. The first main experimental and theoretical works about the hydraulic jump were conducted by Bidone (1819) and Bélanger (1841). Bélanger (1841) developed a theoretical solution for the ratio of the conjugate depths based upon the momentum principle [2]: y2∗
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