Fig. 1- Schematic of the general pattern of flow and aeration process in the aerators

Investigation of the Effect of Ramp Angle on Chute Aeration System Efficiency by Two-Phase Flow Analysis


1 Associate Professor, Civil Engineering Department, Jundi-Shapur University of Technology, Dezful, Iran

2 Instructor in Civil Engineering Department Jundi-Shapur University of Technology, Dezful,Iran.



Flow aeration in chute spillway is one of the most effective and economic ways to prevent cavitation damage. Surface damage is significantly reduced when very small values of air are scattered in a water prism. A structure known as an aerator may be used for this purpose. Besides, ramp angle is one of the factors influencing aerator efficiency. In this research, the value of air entraining the flow through the Jarreh Dam’s spillway at the ramp angles of 6, 8 and 10 degrees, as three different scenarios, was simulated using the Flow-3D software. In order to validate the results of the inlet air into the flowing fluid at a ramp angle of 6 degrees, the observational results of the dam spillway physical model from the laboratory of TAMAB Company in Iran were used. According to the results, raising the ramp angle increases the inlet air to the water jet nappe, and a ten-degree ramp angle provides the best aeration efficiency. The Flow-3D model can also simulate the two-phase water-air flow on spillways, according to the results.

슈트 여수로의 흐름 폭기는 캐비테이션 손상을 방지하는 가장 효과적이고 경제적인 방법 중 하나입니다. 수중 프리즘에 아주 작은 양의 공기가 흩어지면 표면 손상이 크게 줄어듭니다. 이를 위해 폭기 장치로 알려진 구조를 사용할 수 있습니다. 또한, 램프 각도는 폭기 효율에 영향을 미치는 요인 중 하나입니다. 이 연구에서는 FLOW-3D 소프트웨어를 사용하여 3가지 다른 시나리오인 6, 8 및 10도의 램프 각도에서 Jarreh 댐의 방수로를 통해 흐름을 동반하는 공기의 값을 시뮬레이션했습니다. 6도의 경사각에서 유동 유체로 유입되는 공기의 결과를 검증하기 위해이란 TAMAB Company의 실험실에서 댐 방수로 물리적 모델의 관찰 결과를 사용했습니다. 결과에 따르면 램프 각도를 높이면 워터제트 기저귀로 유입되는 공기가 증가하고 10도 램프 각도는 최고의 폭기 효율을 제공합니다. Flow-3D 모델은 결과에 따라 여수로의 2단계 물-공기 흐름을 시뮬레이션할 수도 있습니다.


Fig. 1- Schematic of the general pattern of flow and aeration process in the aerators
Fig. 1- Schematic of the general pattern of flow and aeration process in the aerators
(a) The full-scale map of the Jarreh spillway’s plan and profile.
(a) The full-scale map of the Jarreh spillway’s plan and profile.
Fig. 2- Experimental setup (Shamloo et al., 2012)
Fig. 2- Experimental setup (Shamloo et al., 2012)


1- Baharvand, S., & Lashkar-Ara, B. (2021). Hydraulic design criteria of the modified meander C-type
fishway using the combined experimental and CFD models. Ecological Engineering, 164.
2- Bayon, A., Toro, J. P., Bombardelli, F. A., Matos, J., & López-Jiménez, P. A. (2018). Influence of VOF
technique, turbulence model and discretization scheme on the numerical simulation of the non-aerated,
skimming flow in stepped spillways. Journal of Hydro-Environment Research, 19, 137–149.
3- Brethour, J. M., & Hirt, C. W. (2009). Drift Model for Two-Component Flows. Flow Science, Inc., FSI09-TN83Rev, 1–7.
4- Chanson, H. (1989). Study of air entrainment and aeration devices. Journal of Hydraulic Research, 27(3),
5- Dong, Z., Wang, J., Vetsch, D. F., Boes, R. M., & Tan, G. (2019). Numerical simulation of air-water twophase flow on stepped spillways behind X-shaped flaring gate piers under very high unit discharge. Water
(Switzerland), 11(10).
6- Flow-3D, V. 11. 2. (2017). User Manual. Flow Science Inc.: Santa Fe, NM, USA;
7- Hirt, C. W. (2003). Modeling Turbulent Entrainment of Air at a Free Surface. Flow Science, Inc., FSI-03-
TN6, 1–9.
8- Hirt, C. W. (2016). Dynamic Droplet Sizes for Drift Fluxes. Flow Science, Inc., 1–10.
9- Hirt, C. W., & Nichols, B. D. (1981). Volume of fluid (VOF) method for the dynamics of free boundaries.
Journal of Computational Physics, 39(1), 201–225.
10- Kherbache, K., Chesneau, X., Zeghmati, B., Abide, S., & Benmamar, S. (2017). The effects of step
inclination and air injection on the water flow in a stepped spillway: A numerical study. Journal of
Hydrodynamics, 29(2), 322–331.
11- Kramer, M., & Chanson, H. (2019). Optical flow estimations in aerated spillway flows: Filtering and
discussion on sampling parameters. Experimental Thermal and Fluid Science, 103, 318–328.
12- Mahmoudian, Z., Baharvand, S., & Lashkarara, B. (2019). Investigating the Flow Pattern in Baffle
Fishway Denil Type. Irrigation Sciences and Engineering (JISE), 42(3), 179–196.
13- Meireles, I. C., Bombardelli, F. A., & Matos, J. (2014). Air entrainment onset in skimming flows on
steep stepped spillways: An analysis. Journal of Hydraulic Research, 52(3).
14- Parsaie, A., & Haghiabi, A. H. (2019). Inception point of flow aeration on quarter-circular crested stepped
spillway. Flow Measurement and Instrumentation, 69.
15- Richardson, J. F., & Zaki W N. (1979). Sedimentation and Fluidisation. Part 1. Trans. Inst. Chem. Eng,
32, 35–53.
16- Shamloo, H., Hoseini Ghafari, S., & Kavianpour, M. (2012). Experimental study on the effects of inlet
flows on aeration in chute spillway (Case study: Jare Dam, Iran). 10th International Congress on
Advances in Civil Engineering, Middle East Technical University, Ankara, Turkey.
17- Wang, S. Y., Hou, D. M., & Wang, C. H. (2012). Aerator of stepped chute in Murum Hydropower
Station. Procedia Engineering, 28, 803–807.
18- Wei, W., Deng, J., & Zhang, F. (2016). Development of self-aeration process for supercritical chute
flows. International Journal of Multiphase Flow, 79, 172–180.
19- Wu, J., QIAN, S., & MA, F. (2016). A new design of ski-jump-step spillway. Journal of Hydrodynamics,
05, 914–917.
20- Xu, Y., Wang, W., Yong, H., & Zhao, W. (2012). Investigation on the cavity backwater of the jet flow from the chute aerators. Procedia Engineering, 31, 51–56.
21- Yakhot, V., & Orszag, S. A. (1986). Renormalization group analysis of turbulence. I. Basic theory.
Journal of Scientific Computing, 1(1), 3–51.
22- Yang, J., Teng, P., & Lin, C. (2019). Air-vent layouts and water-air flow behaviors of a wide spillway
aerator. Theoretical and Applied Mechanics Letters, 9(2), 130–143.
23- Zhang, G., & Chanson, H. (2016). Interaction between free-surface aeration and total pressure on a
stepped chute. Experimental Thermal and Fluid Science, 74, 368–381.