self inducing impeller
 

I'm working in a stirred tank with a self inducing impeller,a pitched blade turbine downflow, and i have few question about this problem: 1-what's the gas and liquid used in such tank? 2-is the hollow shaft open in its top to induce air or the impeller just induce the gas? 3-how we calaculate the pressure loss between the gas inlet and the holes of impeller blade outlet? 4-what's their boundary conditions I would be very grateful for your response Thx