Pallabazzer 



The previous equations allow the complete solution when some of the param- 

 eters are given, v^, j3^, m^ have generally been chosen as fundamental pa- 

 rameters (the choice of M^,, which appeared very useful from the point of view 

 of the numerical procedure, turned out to be very ineffective from the point of 

 view of the physical meaning) and /S^/Sf , a.^ as auxiliary parameters for the 

 powerplant solution. 



NUMERICAL DATA AND SOLUTIONS 

 The parametric range chosen was 



'V, 



V^ = to 50 m/s, (0 to 97 knots) ' ^ 



^Gp = to 21, (0 to 210 m water) 



■ M^ = 0.4 to 3, 



/3 = 1 to 20, ''"■ '" ' '■-'-■' ■ '-' - 



Hj = to 1. 



Moreover, the dimensionless valve pressure loss of hp, was 



8/3=0,1. 



All the hydrojectors and pumpjectors have been studied in the aligned con- 

 figuration (zj = z^ = 1 m), while the water jet was analyzed in the s config- 

 uration (zq = 1 m, Zi = -3 m). To the loss coefficient £. there was assigned 

 a mean value of 0.2 for all the aligned propulsors and of 0.3 for the s propul- 

 sors; these values were deduced from similar cases (Refs. [7,8,20,23]). The 

 coefficient >/; was everywhere assumed equal to 0.9, but some attempts were 

 made with different values. All other fundamental numerical coefficients are 

 listed in Table 1. 



On the basis of the previously examined equations and of the numerical co- 

 efficients which have been listed, the fourteen powerplants represented in Figs. 

 23 - 26 were analyzed; the most significant results are plotted in Figs. 28-40 

 for the power-plants which proved to be the most interesting. The fundamental 

 functions which have been mostly represented are the overall efficiency -n^ 

 and the inflow mass ratio 7; the last one is, in fact, the ratio between air and 

 water flow rates; it represents the air flow rate which can involve the unit 

 water flow rate and therefore it is an important figure of merit among power- 

 plants, because it represents the water driving availability of the turbine. 



Since the specific thrust a indicates the thrust which can be obtained at a 

 fixed speed by the unit water flow rate, this information is completed by the 

 necessary knowledge of how large an air flow rate can drive the unit water 

 flow rate, that is by y. In other words, y provides information about the tur- 

 bine potentiality which is needed to provide the thrust a. (In such powerplants 

 the turbine potentiality can never be represented by the net power but by the 

 air inflow rate.) 



1144 



