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Pressure Loss Through Flattened Pipe End

Pressure Loss Through Flattened Pipe End

RE: Pressure Loss Through Flattened Pipe End

How would you determine that pressure loss for a normal cross section pipe? Once it's out of the pipe, it's at atmospheric pressure.

I think what you want to do is calculate (or measure) the increase in backpressure from the nozzle, compared to an open pipe?

RE: Pressure Loss Through Flattened Pipe End

(OP)
Yes, correct. I need to calculate the backpressure from the nozzle in order to predict velocity at nozzle end. Hope that makes sense. Tapered orifice best approach?

RE: Pressure Loss Through Flattened Pipe End

Area ratio: Area of "squished nozzle = 1/8 inch x nozzle width (not on the prf!)/Area of the 6 inch (nominal OD) pipe

BUT! The nozzle bending will NOT be very uniform nor consistent unless you "machine out" the end after bending (squishing) the pipe. Most of the time, you will get a collapsed pipe end that is closed in the center, and rather more open (much larger than 1/8 inch!) at both ends.

Thus, completely squish the small pipe end completely closed. THEN, cut the irregular squished end to a uniform width and height so you get a uniform spray. And, of course, after testing proves you aren't getting enough fluid or too much fluid, then you simply change the regular, squared machined opening to be either higher, longer, or thinner or narrower.

RE: Pressure Loss Through Flattened Pipe End

(OP)
How does one get from area ratio to differential pressure?

RE: Pressure Loss Through Flattened Pipe End

(OP)
I'm guessing the Bernoulli Equation....q = cd A2 [ 2(p1 - p2) / ρ(1 - (A2 / A1)2) ]1/2

RE: Pressure Loss Through Flattened Pipe End

The simple method is empirical. Put a pressure gauge and flow meter on the pipe.

RE: Pressure Loss Through Flattened Pipe End

Looks a bit complex to me but for what it's worth, your "hydraulic diameter" is equivalent to about 6mm - 1/4" Going for an orifice calc with a 6mm hole would seem like a good first start point, but as said above, your chance of getting a nozzle exactly as drawn looks interesting.

Testing looks like a requirement to me.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

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