Benoulli.

Anything flowbench related

Re: Benoulli.

Postby Chad Speier » Mon Dec 10, 2012 12:56 pm

I'm not debating that an orifice "should" flow different at different locations. I'm saying a properly calibrated bench with a set of certified plates, calibrated to each hole, should net you the same results. The flow calibration numbers for each bench might be different, but should result in the same cfm rating..

I've had heads in Oregon and Denver and California, flow what my properly calibrated SF600 does here. Now my head was lower at Meauxs but Larry says all heads are 10+ low, by his choice.

Harold Bettis told me the ASME flow standards for flow benches are MFC-3M-1990 or MFC -3M-2004. This states if the Reynolds number is less than 2,000 the flow is considered to be laminar. If the Reynolds number is greater than 4,000 the flow is considered to be totally turbulent.

Also a point of interest, bench flow = scfm = acfm at 60ºF and 29.92 in. HG.

PS, your chart shows "flow through a square edge orifice".. wrong for calibrating a bench!!!!!!!!!!!! This is one of the flaws I find in a SF bench. The rotating disk is of square edge design. The dc for a sharp edge vs a square edge is considerably different. I put a sharp edge plate in my PTS bench vs a square edge and the square totally turbulent at higher rates.
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Re: Benoulli.

Postby MaxRaceSoftware » Wed Dec 12, 2012 2:47 am

Chad Speier wrote:I'm not debating that an orifice "should" flow different at different locations. I'm saying a properly calibrated bench with a set of certified plates, calibrated to each hole, should net you the same results. The flow calibration numbers for each bench might be different, but should result in the same cfm rating..

I've had heads in Oregon and Denver and California, flow what my properly calibrated SF600 does here. Now my head was lower at Meauxs but Larry says all heads are 10+ low, by his choice.

Harold Bettis told me the ASME flow standards for flow benches are MFC-3M-1990 or MFC -3M-2004. This states if the Reynolds number is less than 2,000 the flow is considered to be laminar. If the Reynolds number is greater than 4,000 the flow is considered to be totally turbulent.

Also a point of interest, bench flow = scfm = acfm at 60ºF and 29.92 in. HG.

PS, your chart shows "flow through a square edge orifice".. wrong for calibrating a bench!!!!!!!!!!!! This is one of the flaws I find in a SF bench. The rotating disk is of square edge design. The dc for a sharp edge vs a square edge is considerably different. I put a sharp edge plate in my PTS bench vs a square edge and the square totally turbulent at higher rates.




1) I've had heads in Oregon and Denver and California, flow what my properly calibrated SF600 does here.


2) This is one of the flaws I find in a SF bench. The rotating disk is of square edge design.
The dc for a sharp edge vs a square edge is considerably different.
I put a sharp edge plate in my PTS bench vs a square edge and the square totally turbulent at higher rates

--------------------------------------

these things are easy to test in real world .

1) weather changes quickly and drastic at times in southern Louisiana,
likewise different seasons of the year,
so basically thats like flow testing the Cyl Head in different parts of the USA or at different elevations or densities,
yet , under various weather conditions, Cyl Heads on my Flowbench Flow test the same CFM numbers ... no Flow difference to weather !
(as long as its the very same Cyl Head Ports tested different times a year)

so for a Ratiometric device like an Orfice you don't need to correct for Weather conditions
with a SF-600 Orfice-centered bench
the SF-110 needs temp weather corrections because Orfice is after electric motors on intake flow and vice/versa on exhaust flow.

where you are going to see the big difference in Flow CFM concerning weather conditions
is with a LFE Laminar Flow Element ...which you must always correct for weather with LFE Bench

2)this is quick and easy !
just test the sharp-edged Orfice vs square edge Orfice , its easy to do,
and its like Chad says , significant flow differences !

SuperFlow designed the large rotating disc with square edge on both sides so you could Flow test
in both directions, then added a plexiglass plate to divert Flow so it measure correctly
as it flows to and enters Orfice .

if you did not do it that way, it ends up sort of what NASCAR tricks were with restrictor plate
if you let flow enter directly straight into the Orfice, its better to split it around a plate in a container

almost same reason for square edge Calibration plates SuperFlow gives you with Flowbench,
it has sealing tape on one side, so you bolt it down,
and the square edge on both sides allows you to Flow test in both directions
without unbolting and flipping over the plate

or you could just use sharp edge both int and exh sides and create your own SF calibration values
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Meaux Racing Heads
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Re: Benoulli.

Postby johnta1 » Fri Dec 23, 2016 7:50 pm

In the last pic/chart, shouldn't the orifice inlet pressures be in the same units?
28 in/H2O is not equal to 28 in/Hg?
(need to convert baro to in/H2O or the other way)

:?:
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