Experimental Study on the Air Concentration Distribution of Aerated Jet Flows in a Plunge Pool

Weilin Xu,Chunqi Chen,Wangru Wei

doi:10.3390/w10121779

Abstract

There is a lack of knowledge on the air concentration distribution in plunge pools affected by aerated jets. A set of physical experiments was performed on vertical submerged aerated jet flows impinging a plunge pool. The air concentration distribution in the plunge pool was analyzed under different inflow air concentrations, flow velocities, and discharge rate conditions. The experimental results show that the air concentration distribution follows a power-law along the jet axis, and it is independent of the initial flow conditions. A new hypothetical analysis model was proposed for air diffusion in the plunge pool, that is, the air concentration distribution in the plunge pool is superposed by the lateral diffusion of three stages of the aerated jet motion. A set of formulas was proposed to predict the air concentration distribution in the plunge pool, the results of which showed good agreement with the experimental data.

Highlights

The impingement of a jet flow on a floor is a common issue that is important for many engineering applications, such as the flood discharging of hydraulic structures, and heat and mass transfer in industrial operations
In the free jet region, the axial air concentration attenuation followed a power-law distribution, and the air concentration distribution along the lateral cross-sections conformed to the Gaussian distribution law
Both the axial attenuation and the lateral distribution of air concentration in the free jet region were almost unchanged for different initial water velocities, air concentrations, and flow rate conditions

Summary

Introduction

The impingement of a jet flow on a floor is a common issue that is important for many engineering applications, such as the flood discharging of hydraulic structures, and heat and mass transfer in industrial operations. Ervine summarized the characteristics of free turbulent jets, and compared the jet diffusion in the plunge pool with submerged and impinging jets [6]. Ervine collected data for both mean and fluctuating components of the pressure field on a plunge pool floor subjected to jet impingement, and compared the data for circular jets with those for wide rectangular nappes and rectangular slot jets [7]. The research concludes that increasing the air concentration of jet flows and decreasing the initial jet thickness are effective ways to improve the axial velocity attenuation of jet flows. Some researchers focused on the pressure on the floor of the plunge pool by an aerated and non-aerated jet flow [12,13,14,15].

Methods

Results

Conclusion