Pre-aerated classic hydraulic jump downstream a partly-stepped chute

ABSTRACT

Study of hydraulic jumps following aerated supercritical flow has been limited, although this is a common scenario in stilling basins preceded by open-channel spillways. New experiments were performed in a concrete stilling basin model downstream of a sloping stepped chute, where hydraulic jumps were generated on the horizontal stilling basin bed and characterized by bubbly approach flow with Froude numbers 7.6 and 9.3 and Reynolds numbers in the order of 10⁵. Measurements were focused on the jump toe oscillations, jump roller length, and air–water flow property distributions. Comparison of the results with literature data under non-aerated inflow conditions suggested overall insignificant pre-aeration effects on the investigated air–water flow properties, although some comparative analyses were subject to scale effects. The streamwise evolution of air flux suggested that the pre-entrained air did not intrude deeply into the jet-shear layer beyond 1/5 to 1/3 roller length from the jump toe.

Keywords:

• Air entrainment
• hydraulic jump
• pre-aeration
• roller length
• scale effect

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The research was financially supported by the National Key Plan for Research and Development of China [grant no. 2022YFC3203902] and the National Natural Science Foundation of China [grant nos. 51909180, 51709192].