[dovber]

Hi,
Im trying to calculate resistance coefficiants of simple perforated plate by using idelchik handbook. the plate is 1mm thick, 70% open, with 7mm dia. holes, and around 150x150mm in size. the approach air velocity is around 5 m/s.
i want to clarify some things as this is the first time i do this calculation :


1. Hydraulic dia. Dh is defined as 4*fo/Pio , where Pio is the perimeter. perimeter of what - a single 7mm hole or the whole channel section (150*4) ?

2. Can you point me to a reference/table where i can find resistances of perforated plates ? i didnt find somthing like this on the web.

thanks!