Angle of divergence of a gas flow 1

[vic56]

I have a gas flow through an 8" pipe into a 14" diameter cylinder over a length of approx. 16" then emerging into a pressure vessel. We have used similar configurations for the past 30 odd years. I have always used 7.5 degrees as the approx. half angle of divergence as the flow emerges from a smaller diameter into the next larger one. This has never been a critical part of the analysis. However for the analysis of a particular unit malfunction, I would like to check if this angle is in the right ballpark or if I should be using something else.
I realise that this is perhaps not the correct forum for this, however having spent half the morning searching through detailed descriptions of jet nozzles, turbines and garden hoses, I wondered if anyone had any thoughts on this or could point me in the right direction for a suitable site to consult.
Appreciate any help,

Vic

 

[MikeHalloran]

The ASHRAE handbook has pressure loss estimating tools for ductwork, including conical diffusers. If memory serves, the 7.5 degree half-angle conical diffuser is pretty close to being a lossless transition.



Mike Halloran
Pembroke Pines, FL, USA