Foa 



'V. 



Fig. 11 - Static performance of a bladeless propeller 

 for P2^P\ = 1-0 



results, the thin-jet-strip theory is probably overly pessimistic as a basis for 

 prediction of potential performance. If the primary jet were of sufficient radial 

 width to span the entire interaction space, the upper limit of performance would 

 (apart from the effect of mixing during deflection) be that predicted by the two- 

 dimensional theory. 



In the analysis of Ref. 9, a constant-area mixing phase is added to the de- 

 flection phase, which is again treated as a plane -flow interaction. With this ad- 

 dition, the analytical model reduces to the ideal constant-area ejector when the 

 spin angle is zero. Typical results of this analysis, for static operation with an 

 area ratio of 15, a ratio of primary total pressure to ambient static pressure of 

 2.8, and two primary -to -secondary stagnation temperature ratios, are presented 

 in Fig. 12. These results confirm that the superiority of the bladeless propeller 

 over the ejector increases as the primary -to -secondary temperature ratio —or 

 the secondary -to -primary density ratio — is increased.* They also show that 

 the effect of mixing following the deflection phase may be favorable or unfavor- 

 able, depending on the spin angle and on the temperature ratio. 



=As the spin angle is increased from 0° (ejector) to 20° , the calculated energy- 

 transfer efficiency (ratio of mechanical energy gained by the secondary to 

 mechanical energy lost by the primary) increases from .40 to .53 if the tem- 

 perature ratio is 1.0; whereas it increases from .22 to .55 if the temperature 

 ratio is 4.0. 



1362 



