Gas-Turbine Powerplants For Two-Phase Hydropropulsion 



OA 



1.6 



2 A 



Zi 



(c) the same, as a function of a {^ = 

 0.9, p = 12, a. p.) 



Fig. 28 - IR-(l) powerplant performances 

 (Continued) 



the hot-gas pumpjector, the cold-air hydrojector, and the water jet. The last 

 two systems have been introduced just with the aim of comparison, because 

 actually realized (see Sec. 2). 



In Sec. 4, the pure propulsive performances {a, Vp, A^/A^, etc.) were dis- 

 cussed, while here the powerplant performances {v^, y, e ) will be considered; 

 however, some of the results of Sec. 4 will be reviewed here. 



(a) On the whole, all the hot- gas powerplants showed very close peak 

 performances. It was already shown that the thrust a and all the other propul- 

 sive parameters do not depend on the powerplant configuration; it can be seen 

 now that both hydrojector and pumpjector powerplants are able to provide a 

 peak over-all efficiency of about 22%, and the only difference consists in the 

 advance speed range, where that efficiency is available, or in the discharge 

 pseudo-Mach number and consequently in the thrust and in the discharge cross 

 section which need it. 



IR-(2) provides overall efficiency above 0.21 at a speed comprised 

 between 25 m/s and 40 m/s, by regulating a^^ between 0.2 and 0.6, but no solu- 

 tions are available above 40 m/s. However, since ni-(l) and IR-(2) actually 

 are the same powerplant (the IR-(2) chamber pressure has been imposed equal 

 to the H.P. turbine discharge pressure (also when a^ = 0), while the IR-(l) 

 chamber pressure is equal to the highest powerplant pressure; this configura- 

 tion can be obtained by cutting out the mean-pressure extraction), operating 

 ranges up to 50 m/s can be obtained by IR-(l) configuration at same efficiency. 



1147 



