The example shown here is an 800mm damper valve. There is a 170kPa pressure drop across the valve and the temperature of the air is 200°C. What is interesting to note in this example is the negative torque on the shaft at ~30° (at which angle the disc acts as an aerofoil) and the maximum torque is at ~60°. The analysis was repeated with water as its medium and what can be seen is the magnitude increase in torque and that the torque-opening curve has shifted to the right.


Work Examples - Butterfly Valves