Minimum venturi diameter

[TheLucifer]

Hi all.

We have a supplier who will provide us air flow sensors for some air ventilation lines. They require us to provide minimum venturi diameter/pipe diameter ratio avoiding a shock wave. I haven't been working in aerodynamics field for years and couldn't find a quick calculation method. do you know a way to calculate the minimum venturi tube diameter?

 

[sreid]

What you need to provide is the "pipe" diameter and the air flow velocity (or air flow volume). In general you need to keep the venturi air flow velocity Reynold's Number below 2000. These equations and tables are available in hydrodynamic texts. You used the term "Shock Wave" which implies near or above the speed of sound. Are your ventilation flow rates this high?