My question relates to the design of parallel blade dampers (installed just before a c-fan inlet in most cases). I have in the past utilized several "rules of thumb" related to the damper blade surface area (4 in-lb per sq.ft., etc...) to determine the required torque for opening. In addition, several different methods have been employed by vendors in determining this torque. I question the accuracy of these various methods, due to problems that have arose from time to time. It is my intention to determine the most accurate rule of thumb or absolute method for calculating this torque.
This is essentially a special case of an airfoil with the air flow stream normal to the surface. My background in both computational fluid dynamics and aeronautical engineering is limited. Any ideas and/or feedback on this topic is duly appreciated.