flow of the total can be switched proportionately from one output 

 port to the other. However, in an actual amplifier this is not true 

 because corresponding to 10 percent of the total flow the flow velocity 

 through the output port is so small that its velocity head is not 

 enough to cause any flow. 



THE PROTOTYPE AMPLIFIER 



Design of the Amplifier 



Based upon the theory developed in the previous section, a 



double leg elbow amplifier was designed to handle 5 gpm of water 



flow rate. The geometric parameters of the active and passive 



legs, the control port and the power jet separation of the amplifier 



were kept the same as that of the experimental element (Table 1). 



However, the depth h, of the flow passages was reduced to 3/8-inch 



to increase the power jet momentum for a given combination of active 



and passive leg flows. It was assumed that the designed values of 



Q and Q were 2.5 gpm each such that resulting in a 



a p 



U (x ) /jc 

 value of 3.59 for the parameter „ _ o h V 



It was further assumed that to force the f low tirou^the output ports, 



the stagnation pressure of the power jet based upon its axial 



velocity U(xn) , i.e., ,,2^„ . should not be less than three inches 

 ^ U (■'^ o) 



2g 



corresponding to U(xo) of four ft/sec. Using this data, Xq was found 

 to be 5.6 inches. Due to other practical considerations, however, x 

 was chosen to be 3.25 inches. The maximum deflection of the power jet 

 was assumed to be 18°. Further, using Equation (12) the width Wq of 

 the output ports for Xq = 3.25, was computed as one inch. For this 

 configuration of the output ports, U(x ) was calculated by using the 

 value of p and was found to be four ft/sec. Table 7 lists the values 

 of all the key geometric parameters of the amplifier. The vents 

 were provided on either side of the power jet to prevent wall attach- 

 ment effects. The vents were designed such that they can be connected 

 to the output ports, if desired. A sketch of thu amplifier's element 

 is shown in Figure 26. 



21 



