Does anyone know where i can get the calculations for sizing an inverted screw pump. Inverted being that there is no screw but the fins art attached to the inside of a pipe and the pipe is rotating. I am moving any where from 150 to 400 lbs of dry powder per minute, depending on the amount of powder being produced. I dont have the exact length yet, hence why i just need the formulas. The idea is to find the diameter, fin height, spiral patern, and speed. If anyone knows where i can get the calculations i would apreciate the help.