Showing 3 results for Aeration
A. Shamsai, R. Soleymanzadeh,
Volume 4, Issue 1 (3-2006)
Abstract
Flow regime in dam's bottom outlet is divided in pressurized flow and free surface flow by
the gate located for discharge control. Down stream tunnel involves high velocity Multi component
Air –water flow studied by mathematical model. In this research work, we used Finite volume
mixture two phase flow model. Because of high Reynolds number, standard two equations k-e
turbulence model was used. Model was verified by backward-facing step flow and results have been
compared with experiments founded by Durst and Schmitt. Air demand ratio has been determined
as function of Froude number at contracted section. Flow patterns have been compared at two
categories of slug & stratified flows, Air mean concentration profile has been obtained at down
stream tunnel. Comparison of flow pattern at two case with and without of aeration was
investigated. Pressure drop behind of the gate and formation of vortex flow after the gate section
have been discussed. Measurement of flow discharge and determination of contraction coefficient
of the gate was outlined.
M.b. Javanbarg, A.r. Zarrati, M.r. Jalili, Kh. Safavi,
Volume 5, Issue 1 (3-2007)
Abstract
In the present study a quasi 2-D numerical model is developed for calculating air concentration distribution in rapid flows. The model solves air continuity equation (convection diffusion equation) in the whole flow domain. This solution is then coupled with calculations of the free surface in which air content in the flow is also considered. To verify the model, its results are compared with an analytical solution as well as a 2-D, numerical model and close agreement was achieved. The model results were also compared with experimental data. This comparison showed that the decrease in air concentration near the channel bed in an aerated flow could be well predicted by the model. The present simple numerical model could therefore be used for engineering purposes.
Shuai Li, Jian-Min Zhang, Wei-Lin Xu, Jian-Gang Chen, Yong Peng, Jun-Ning Li, Xiao-Long He,
Volume 14, Issue 1 (1-2016)
Abstract
The cavitation erosion induced by high flow velocities is very prominent in high head and large unit discharge tunnel. Air entrainment is an effective technology to solve this problem. In this study, numerical simulation and physical model test are applied to the comparative study of air-water flows on bottom and lateral aerator in tunnel. The flow pattern, aeration cavity, air concentration and pressure distribution were obtained and there is a close agreement between the numerical and physical model values. The hydraulic characteristic and aeration effect of anti-arc section are analyzed. The results indicated that added lateral aeration facilities on 1# and 2# aerator can weaken backwater and increase the length of the bottom cavity, but it is limited to improve the air concentration and protect sidewall downstream of the ogee section. Air concentration improved on side walls downstream of anti-arc section when added lateral aeration facility on 3# aerator. The black water triangle zone disappeared and the floor and side walls well protected.
