Numerical analysis of gate and butterfly valves of flow characteristics used in drinking water facilities

The proper selection of the valves used in drinking water facilities according to the network system plays an important role in the healthy and efficient operation of the system. The most important parameters to consider when selecting a valve are the flow characteristics of the valves: operation pressure, velocity of flow and head loss. In this thesis study, the flow characteristics of gate and butterfly valves which are used widely in drinking water systems have been investigated in two dimensions through ANSYS FLUENT program. The velocity, static pressure and loss coefficient K values were determined separately in these valves in the valve opening rates 10%, 20%, 40%, 50%, 60%, 80% of DN 200 gate valve and the disc opening angles 20◦, 40◦, 60◦, 80◦ and 90◦ of DN 200 double eccentric butterfly valve with 1, 2 and 3 m/s inlet velocities. At the result of the study, it was found out that in some parts of these valves the static pressure falls under the evaporation pressure of the water at 20◦C in the opening rate % 8 that corresponding to 20◦ disc opening angle of butterfly valve with the inlet velocity 3 m/s and in the opening rate 10% with the inlet velocities 2 and 3 m/s of gate valve. The head loss coefficient of butterfly valve is lower than that of gate valve up to valve opening rate of 50%. In general approach, the graphics for loss coefficient of both valves show similarity. The increase of input velocity does not cause a change in the valve loss coefficient.