How can one determine the coefficient of discharge for oscillating helium flow from 22 bar to 8 bar? The oscillation is produced by a rotary valve which generates the sinusoidal pressure waveform to create an oscillating flow. Which instrument can be helpful? Coriolis meter can be useful but I do not know whether it can be suitable for 22 bar to 8 bar pressure variation with to and from motion of gas?
In fact, there is a variety of distinct technologies to flowmetering, each one presenting the respectives advantages and disadvantages.
The fact that you work with pure He is an advantage to use thermal technology, which is strongly dependent of the fluid properties knowledge.
On the other hand, usually thermal meters are less sensitive to flow variations due to the its own thermal principle, which should to warm and cool in the same frequencie of the flow.
I confess that I am not a specialist in thermal technologies, so I suggest a consultation join to supplier, as well.
My suggestion for a PVT or a gravimetric method refers to a customize flow calibration procedure by your own, considering this particular pressure fluctuations and meter instalation.
Unfortunately, I don´t have any literature in English, but I am sure that it is not represent a hard task to get some, since it is a widely known calibration procedures.
I think you need to be more specific. Do you want to measure the flow rate? What is your estimated flow rate, velocity and flow section. Is the gas clean? (in that case you might use a thermal device, if not maybe an ultrasonic)
I want to measure the flow rate/mass flow rate of gas which is Helium 99.999 % clean. The estimated maximum flow rate can be 2 gram per second. Hope now you understand it.
The flow measurement in such conditions represent a real challenge!
First of all, you have to consider that "coefficient of discharge" usually is a concept applied to legal metrology in order to compare flow rate calculated by theoretical inferences versus an accredited flow rate. Usually such comparision is carried under steady state flow condition.
Otherwise, in distinct flow conditions, you have to check if the flowmeter is able to operate and you have to provide by your own a comparision method that you trust.
The estimated flow rate: 2g/s = 7,2 kg/h is a very small rate. Probably, ultrasonic flowmeter may be the best selection due to the high pressures involved, but I am not sure if such technology is able to operate with pure He (to be checked...) Have you considered PVT / gravimetric methods ?
Good luck for you!
Thank you Rogerio Ramos sir for your time. Sorry sir, I do not know about PVT/Gravimetric methods. Can you suggest me some readings?
You say the flow is fluctuating, what is the characteristic time/frequency of the oscillation.
The flow of 2gr/s is not that small, you probably may use a mass flow meter based on thermal measurement, look at: http://www.aalborg.com/index.php/main_page/product_overview/id_product_overview/20.
This one is up to 70 bar but there is a wide variety of models and makers.
Good luck.
In fact, there is a variety of distinct technologies to flowmetering, each one presenting the respectives advantages and disadvantages.
The fact that you work with pure He is an advantage to use thermal technology, which is strongly dependent of the fluid properties knowledge.
On the other hand, usually thermal meters are less sensitive to flow variations due to the its own thermal principle, which should to warm and cool in the same frequencie of the flow.
I confess that I am not a specialist in thermal technologies, so I suggest a consultation join to supplier, as well.
My suggestion for a PVT or a gravimetric method refers to a customize flow calibration procedure by your own, considering this particular pressure fluctuations and meter instalation.
Unfortunately, I don´t have any literature in English, but I am sure that it is not represent a hard task to get some, since it is a widely known calibration procedures.
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