Vortex flow meter: It takes 10 seconds for the flow rate to drop to 0 after the valve is closed, and it also takes 10 seconds for it to reach a stable value once the valve is opened
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Hello everyone. I have been doing some debugging recently and encountered a strange phenomenon. I am using an vortex flow meter along with a quick-opening/closing valve that can be opened or closed within 2 seconds. When the valve is opened, it takes 10 seconds for the flow rate to increase; this could be attributed to the gradual buildup of flow. What cannot be explained, however, is that when the valve is closed, it takes about 10 seconds for the flow rate to drop to 0, and roughly 5 seconds for it to fall to 50% of its previous steady-state value. Could some expert explain this? I have searched through various sources, both domestic and international, and all indicate that the response time of vortex flow meters is within 2 seconds, or even 0.5 to 1 second. However, I suspect that this response time refers to situations with normal fluctuations, rather than when there is a sudden change in flow rate – in such cases, the damping time is set at 1 second. Please give some advice
When the valve is opened or closed suddenly, the flow velocity of the fluid changes significantly, resulting in an extremely unstable flow state. Since a vortex flow meter measures the frequency of the vortices generated as the fluid passes through it, the measured frequency becomes unstable; I consider it normal for the frequency to stabilize after about 10 seconds； The parameters given in the data are usually obtained under experimental conditions, which differ significantly from actual operating conditions.
The working principle of the vortex flow meter is to measure flow rate by utilizing the vortices generated by the fluid. After a valve is suddenly opened or closed, there is a significant change in the flow pattern of the fluid; it is normal for there to be a certain reaction time. Moreover, after the valve is closed, disturbances caused by irregular fluctuations of the fluid remaining in the pipeline must also be taken into account.
Considering the time constant, is it possible to adjust parameters such as sensitivity?
Do you have any test data, that is, the response time when there are significant changes in operating conditions while opening and closing valves?
This phenomenon may be normal. When using a vortex flowmeter to measure steam or gases, the compressibility of the gases and the condensation of steam can cause delays, leading to fluctuations in the measurement signals or even incorrect readings. If it is a liquid medium, this phenomenon can also occur due to the accumulation of bubbles in the pipeline.