Environmental Fluid Mechanics

, Volume 19, Issue 6, pp 1455–1468 | Cite as

Experimental investigation of bubbly flow and air entrainment discharge downstream of chute aerators

  • Ruidi BaiEmail author
  • Shanjun Liu
  • Zhong Tian
  • Wei Wang
  • Faxing ZhangEmail author
Original Article


In a chute aerator flow, a large air discharge that is introduced through an air supply duct is entrained into the flow and transported to the downstream zone. In this study, a series of experiments were conducted to quantify the two–phase flow properties, including air concentration, bubble frequency, and bubble diffusivity, and air entrainment flux for a wide range of Froude numbers (3.3 ≤ F0 ≤ 7.4) at relatively large Reynolds numbers (5 × 105 ≤ R ≤ 1.2 × 106). The distributions of air concentration and bubble frequency, which demonstrated two competitive turbulent processes, were presented. The air transport process of the chute aerator flow was quantitatively described based on the approach flow conditions and the aerator geometry. According to the characteristics of air discharge in the equilibrium zone, and based on the previous equation, qa = KV0L, the experimental results indicated that the dimensionless coefficient K was independent of the aerator structure and significantly increases with the flow Froude number.


Chute aerator Air entrainment Air–water flows Physical modelling 

List of symbols


Air concentration


Bottom air concentration


The air diffusivity coefficient in the cavity zone


The air diffusivity coefficient in the impact and equilibrium zones


Air bubble frequency


Froude number


Acceleration of gravity


Flow depth at the emergence


Offset height


Cavity length


Distance between of x = 0 and the impact point of P = Pm


Distance between of x = 0 and the intersection of the upper and the lower aeration regions


Dimensionless air discharge coefficient


Bottom pressure


Maximum bottom pressure


Cavity subpressure


Air dicharge


Water discharge


Reynolds number


Correlation coefficient


Flow velocity at the emergence


Weber number


The stream–wise coordinate along the chute bottom


The perpendicular coordinate


The location of C = 0


The location of C = 0.50


The location of C = 0.90


The location of maximum air concentration


The location of maximum air bubble frequency


Chute bottom angle


Air entrainment coefficient


Emergence angle


Density of water


Surface tension of water


Kinematic viscosity of water



This work was supported by the National Key Research and Development Program of China (2016YFC0401707), the National Natural Science Foundation of China (Grant Nos. 51709293 and 51679157), and the Fundamental Research Funds for the Central Universities (Grant No. 20826041A4305). Many thanks to Ning Sun and Mingcong Lv for helping in experiments.


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Copyright information

© Springer Nature B.V. 2019

Authors and Affiliations

  1. 1.State Key Laboratory of Hydraulics and Mountain River EngineeringSichuan UniversityChengduChina

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