Analysis of Propeller Design Methods and Validation With the CFD Computation of a Propeller-Pump

There is a large variety of axial propellers available, ranging from very small devices with only millimeters in diameter to ship propellers being several meters in size. Also they are applicable in several different ways, from low pressure propellers when actually used as fans or high pressure differences when used for propulsion purposes. Several theories have been developed to calculate and predict propeller performance. The basic theory is the linear momentum theory which takes only the axial motion into account. The theory can be refined taking the rotational motion and hence the angular momentum into account and also segmenting the propeller into several blade elements, to which classical airfoil theory can be applied. However, common literature does not include any precise verification of these theories. The present work shows with CFD computations the validation and hence accuracy of the blade element theory and its predecessors on a specific axial machine, namely the blood assist Reitan catheter propeller-pump. The propeller-pump is evaluated in a large operational range, using a commercial CFD code. The theory is then applied to the CFD results calculating the stream tube, in which all the necessary parameters, like interference factors, are evaluated. Those will deliver the machine characteristics thrust, torque and efficiency according to these theories. Comparison of this data to the CFD values shows good agreement, especially when segmenting the propeller and therefore using multiple stream tubes. Thus, the validity of these theories and its range of applicability was verified showing in detail how these theories can be employed as reliable design tools coupled with CFD verification.