The discussion centers on the differences between nozzles (or venturis) and flow control valves, particularly in how they affect fluid flow characteristics such as velocity, pressure, and flow rate. The scope includes theoretical aspects of fluid dynamics and practical implications of these devices in fluid control.
Participants express differing views on the operational principles of nozzles and flow control valves, with some asserting that they function differently in terms of flow rate and energy preservation, while others argue for their similarity under certain conditions. The discussion remains unresolved with competing perspectives.
There are assumptions regarding fluid incompressibility and the specific conditions under which the devices operate, which may not be universally applicable. The discussion also lacks definitive mathematical formulations to support the claims made.
Could you please explain how the flow area differs for the case of flow rate reduction from the case where velocity increases(flow rate maintained the same)?JBA said:For any identical flow area and coefficient both the nozzle/orifice and the control valve act exactly in the same manner, reducing the size of the flow area in either case equally reduces the mass flow through the device.
Nice answer.So, in case of flow control valves, sudden reduction in cross sectional area is a reason for reduction in flow rate.Dullard said:I may misunderstand your question, but:
A nozzle 'attempts' to preserve total energy by reducing cross-section gradually, with a minimum of friction/turbulence. Much of the potential energy due to pressure is converted to kinetic energy (velocity). Control valves reduce cross-section, but make no attempt to be gentle.