Engine Room ventilation - Air out issue

Let's Assume a Fan Diameter of say , 2.5 feet . 0.75 Metres would work as well . What the equation is then missing is , at normal fan operating speed ,
what amount of air is transferred from inside the Engine room , through the fan ( times two ).
Volume of a Sphere won't work , because the fan cutouts are cylindrical , not spherical . You need the Volume of the Circle contained within the 0.75
Metre Circular Fan Cutout .

 

Now what is needed is the Volumetric Efficiency of each of the Two Fans .

 

If these Evacuator Fans were emptying a mineshaft , they would have to be very large , maybe larger than O.75 Metres , and they would probably be better than 1.0 Horsepower , much more would be needed . 2.5 HP , Rotating a 2.5 Meter Diameter Fan , you need to find out how many Cubic Meters per Second
or CFM , Cubic Meters per Minute , the fans could move .