open channel flow meter
open channel flow meter
(OP)
Hello everyone
First of all i have to say, i have no knowledge on fluid mechanics. I am encountering a problem with designing a open channel flow meter (through reading level of the fluid from drain). I am intending to set it up on a open drain (12 inch wide and 24 inch deep). While reading theories i found out i need to form a rectangular weir or a notch. I am wondering the drain i also rectangular shaped and without any modification it could also serve the purpose or not? any help would be appreciated.
Thanks
First of all i have to say, i have no knowledge on fluid mechanics. I am encountering a problem with designing a open channel flow meter (through reading level of the fluid from drain). I am intending to set it up on a open drain (12 inch wide and 24 inch deep). While reading theories i found out i need to form a rectangular weir or a notch. I am wondering the drain i also rectangular shaped and without any modification it could also serve the purpose or not? any help would be appreciated.
Thanks





RE: open channel flow meter
suggest the following reference might be useful
http://www.usbr.gov/tsc/techreferences/mands/wmm/W...
RE: open channel flow meter
The standard size flowmeter channel shapes have been empirically correlated to the flow.
If you use a standard weir shape, the depth of a weir is also empirically correlated to flow. You would be better served using a prefabricated weir.
http://www.spitzerandboyes.com/wp-content/uploads/...
Flow meters need to be set up so that backwaters do not interfere with the level measurements.
RE: open channel flow meter
http://www.engineeringtoolbox.com/weirs-flow-rate-d_592.html
RE: open channel flow meter
Those terms are over my head :) . Can you please rephrase that?
@bimr
Thank you for your answer. As you said 'standard size', i am unable to find any. A level vs flow graph can be calculated in any channel. For instance,
q = 3.33 (b - 0.2 h) h3/2 in francis formula of calculating discharge, i can put 'b' as width of the channel and 'h' height of water (measured by level transmitter) to have a discharge. You can consider it Sharp-crested, Suppressed type weir.
what i am not getting by not setting up weir.
RE: open channel flow meter
http://www.fsl.orst.edu/geowater/FX3/help/8_Hydrau...
good primer for hydraulic control, normal depth, super and sub-critical flow
http://mysite.du.edu/~etuttle/tech/opench.htm
this is a good in-depth publication
http://pubs.usgs.gov/of/1988/0707/report.pdf
RE: open channel flow meter
There are a number of considerations. The flow entering the metering flume needs to have a transition into the flume. There has to be a transition on the discharge of the flume. The metering flume is designed such that the flow will be laminar with a level surface, not turbulent.
It is much easier to buy a prefabricated flume than to try to construct one.
http://www.plasti-fab.com/plasti-fab-products/
RE: open channel flow meter