Hi,
References: http://en.wikipedia.org/wiki/Venturi_effect , http://en.wikipedia.org/wiki/Orifice_plate
image: http://benvalle.com/Picture39.png
Keyword: Venturi air flow rate, volume measurement.
I have a differential pressure sensor.
I want to measure flow and the volume using the sensor.
Which I think will require a Venturi tube to develop two different pressure points. I have tried several tubes with different dimensions.
All the given equations have been tried but none of them are close to give good result.
Venturi tubes do not need to return back to D again as shown in the attached image.
Any pointer will be helpful.
I tried with http://benvalle.com/Picture39.png :
__________________________________________
D , d , converging angle from D to d
__________________________________________
30mm 20mm, 28 degrees.
38mm, 3mm, 90 degrees.
10mm, 5mm, 21 degrees.
__________________________________________
More info: I am using a 100mL syringe to get measured volume based on availability.
Thanks.
Dear Rahul
To get a good reading of the static pressures and thus calculation of the dynamic pressure and the flow rate, the folowing might help: 1. add the divergent section to minimise drag. 2. Use a device that will give a more accurate and constant air flow that a 10ml syringe. Perhaps a large syringe on a constant rate syringe pump.
Regards
Deon
People make these, actually they make converging/diverging nozzles with pressure taps to use as flow meters.
And yes, I have seen them very small.
Try google
Is the flow rate constant or varying?
To get accurate results you either need steady flow with the method you are using. (For example, removing any dynamic flow with a large volume)
Or if oscillating flow at one frequency, you need to use the two microphone method.
If transient flow, you need quite clever mathematical interpretation of the pressures to infer flow rate. Look at
http://scitation.aip.org/content/asa/journal/jasa/83/6/10.1121/1.396322
http://scitation.aip.org/content/asa/journal/jasa/79/2/10.1121/1.393542
Why do you think the current way you measure flow is wrong?
Regards
Paul
I have an example of the application of venturi tube in the kitchens, which helps reduce pressure and increase flow rate. For this to work you need to make a window in the final part of the reduction of the venturi to increase airflow.
- Badges
- Science topic
- Similar topics
- Engineering