Calculating flow volume for whole house fan
unless the fan is shrouded or ducted and sealed to your ceiling it will be quite hard to tell how much air is moved because much of the air could just recirculate around the fan.

the simplest way is to

Area = pi * radius^2

B = fan pitch in inches / 12

C = fan rpm

1 rpm = air moved so many feet at 0% slippage or 100% efficiency

max theoretical cubic feet per min = A * B * C  

i don't know what % slippage would occur, that would be based on how well the fan blade is designed.  Then account for however much regurgitation of air around the fan due to no shroud gap and not sealed to ceiling.  this also doesn't account for any varying blade pitch (i.e. more pitch near center less near tip).

the easiest and cheapest way might be to build a 1-2 foot duct on output side of fan and grab some cheap wind speed gauge to measure the output air speed from fan.  then math would be Area * speed; with wind speed converted to feet per sec.