Experimental Study on Variation of Pressure in Transient Two-phase Flow (Water and Air)

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Shafiei Shiva, Javad | 2010

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 40417 (09)
University: Sharif University of Technology
Department: Civil Engineering
Advisor(s): Borghei, Mahmoud
Abstract:
Based on the air entrainment, the water conveyance tunnels can be categorized as pressurized, two-phase flow. When the flow is controlled by gates, sudden closure of gates would produce unsteady two-phase flow. The most important effect of such an event is the sudden change in the pressure which can be a function of channel slope, air and water inflow and their ratio. In this thesis the pressure change in unsteady two-phase in an experimental set up using rectangular tunnel is studied. About 100 tests were carried out for single and two-phase flow with various water and air discharges causing unsteady flow with different slopes. It was observed that in a defined slope the ratio of the maximum observed pressure in the unsteady flow to the initial pressure is minimum and is independent of the flow conditions and Also in an air concentration of 45% (air discharge /water discharge), for all cases, the ratio of the maximum observed pressure in the unsteady flow to the initial pressure is minimum. Finally, relations regarding pressure variations due to effect of different variables are presented as graphs and equations.
Keywords:
Water Hummer ; Unsteady Flow ; Froude Number ; Dynamic Pressure ; Two Phase Flow ; Rectangular Flume

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