output flow can be switched completely from one port to the other. It 

 is therefore concluded that the amplifier can be designed using the 

 theoretical procedure described in the report, but its output flow 

 characteristics should be derived experimentally. 



In summary, it can be stated that as desired a double leg elbow 

 amplifier capable of delivering about five gpm of water flow rate has 

 been developed. The amplifier has a flow amplification factor of 50 

 and is capable of switching flow completely from one output to the 

 other proportionately. The output flow characteristics of the 

 amplifier are nearly linear. Finally, a theory to predict the output 

 flow and useful in designing an amplifier of given capability has 

 been developed. The theory predicts amplifiers outflow within 10 

 percent of its actual value. 



THE FLUIDIC MIXING SYSTEM 



The mixing system shown in Figure 1 employs amplifiers that operate 

 on suction type controls only. But the proportional amplifier developed 

 here required a blowing type control thus the concept needs modification. 

 Therefore the design of a system must be modified accordingly. 

 One such system design is shown in Figure 33 in which two modulating 

 amplifiers are manually controlled by connecting the control port of 

 each amplifier to a source of fluid source throu^ variable resistors to 

 vary the flow. A given mixture flow at a certain mixture ratio is 

 obtained simply by adjusting the control flow for each amplifier. 

 Similarly, the mixture ratio at a certain mixture flow rate can be 

 varied simply by adjusting the needle valves settings. Fluidic 

 variable resistors such as variable length, variable area, or variable 

 curvature type for a given application can be fabricated. However, 

 their resistance can not be varied uniformly from zero to no flow. 

 Mechanically operated needle valves suffer from maintenance problems, 

 however, their resistance characteristics are such that they can modulate 

 flows from a predetermined value to zero. Such valves can be fabricated 

 from corrosion resistant materials to reduce frequent maintenance. 

 These valves because of their low flow carrying capacity (up to 0.2 gpm) 

 are small and cost of replacing them is much lower than those of 

 capacities up to 5 gpm. In the light of the foregoing discussion it 

 was decided to use needle valves on the control lines of the mixing 

 system. Such a mixing system is free from water hammer problems 

 (in case of liquids) because there is no sudden closure of valves 

 during operation. Furthermore, becasue of sensitive amplifiers, the 

 system has a fast response. Consequently, it was decided to test 

 the system by mixing water with water. 



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