stack effect

[struct_eeyore]

Hi all,

Not a fluid engineer, so forgive my ignorance. I'm hoping someone can direct my to the proper way to calculate air flow rate in a open ended stack. Stack is 100' high, bottom is about 10' away from ground surface, 10' in diameter; a 6 ft/sec wind is blowing across the top. Temperature differential is negligible.

 

[georgeverghese]

Flow through this stack can only be due to this "negligible temp difference". Run the calcs for say 1-2degC delta T and see what flow you get. Delta T may be higher is summer when ground temps are warmer. For example, for ground temp at 27degC and a delta T of 2degC, I get 150kg/hr through the 10inch stack (exit velocity 0.75m/sec).