The Bladeless Propeller 



y 



Fig. 4 - Velocity vector diagram. 



flows come in contact, i.e., simultaneously with the start of the pressure ex- 

 change phases, but can be expected to proceed at a slower rate. In an ex- 

 treme idealization, mixing can be regarded as the third and last phase of the 

 interaction. 



It is possible, and sometimes desirable, to separate the two fluids after 

 pressure exchange, before mixing between them has progressed too far. One 

 obvious way to do this is to extract them from the interaction zone through sep- 

 arate ports suitably arranged in fixed positions in the relative frame. Another 

 way is suggested by the observation that u^^ and u^^ have different orienta- 

 tions. If the exit from the interaction zone is made up of two sets of stationary 

 passages, one with the orientation of Ui^ and the other with the orientation of 

 Oj^, then a predominant portion of each of the two fluids will flow out through 

 that set of passages which matches the orientation of its motion. 



The simplest embodiments of the cryptosteady pressure exchange concept 

 are those in which frame f ^ rotates at a constant angular velocity relative to 

 frame f . Figures 5 and 6 show two such arrangements. The primary fluid is 

 discharged into the interaction space through skewed orifices on the periphery 

 of a rotor. If no external torque is applied to the rotor — i.e., if the rotor spins 

 freely, with negligible friction, and is solely driven by the reaction of the issu- 

 ing jets — and if no prerotation is imparted on the flows by fixed vanes or by 

 other external means, then the deflection phase of the interaction takes place 

 essentially in the manner discussed above. 



At every instant, the primary fluid which has emerged during a brief and 

 immediately preceding time interval from each rotating orifice, occupies in 

 space a spiral or helical region which rotates about the same axis and at the 

 same angular velocity as the rotor. Although the fluid particles within this re- 

 gion do not follow the same motion, its boundaries are the interfaces separating 

 the primary from the secondary fluid, and their relation to the flow of this sec- 

 ondary fluid is therefore substantially the same as that of blade or vane sur- 

 faces of the same shape, rotating at the same angular velocity. Thus the driving 

 fluid forms a cascade of "pseudo blades," the action of which on the driven fluid 



1357 



