12 



TABLE 2 



Summary of Test Runs 



Run 



Scheme 



Flow Rate Q 

 cc/min 



Gis Volume K 

 cc 



Tempefatuie 

 deg. C 



Coefficient of 

 Solubility for 

 Nitrogen /3^ 



Mixing 



Efficiency 



1 



Response Time t. 

 min 



Initial 

 Pressure p 



atm 



Equilibrium Pressure P 

 atmospheres 



Indicated 

 by Meter 



VanSlyke 

 Determination 



1 



Fig. 4b 



One nozzle, No. 3 



121 



254 



15 



0.0178 



0.69 



170 



0.92 



0.72 



0.72 

 0.73 



2 



Fig 4b 



One nozzle, No. 1 



110 



250 



22 



0.0162 



0.95 



146 



0.95 



1.25 



U4. 1.26 



3* 

 4 



5 



Fig. 4b 



Three nozzles No. 2 



No spray baffle 



453 

 340 

 333 



147 

 191 

 155 



20 



17.5 



17.5 



0.0166 

 0.0172 

 0.0172 



0.68 

 0.72 

 0.70 



29 

 46 

 39 



1.33 

 0.75 

 1.18 



1.14 

 0.96 

 0.96 





6 



7 

 8 



Fig. 4b 



Three nozzles No. 4 



No spray baffle 



720 

 594 

 511 



152 

 147 

 ~178 



20 

 20 

 19 



0.0166 

 0.0166 

 0.0167 



0.77 

 0.83 

 0.80 



16 

 18 

 26 



1.28 

 1.18 

 1.34 



1.13 

 1.01 

 0.92 





9 



10 

 U 



Fig. 4b 



Three nozzles No. 4 



Spray baffle 



517 

 524 

 527 



170 

 162 

 130 



20 

 22 

 22.5 



0.0165 

 0.0162 

 0.0162 



0.64 

 0.72 

 0.71 



31 

 27 

 22 



0.76 

 0.70 

 1.245 



0.90 

 1.00 

 1.01 



1.00, 1.03 

 1.00, 1.04 



'Measurements affected by clogging of sight tube. 



to the air content indicated by the Van Slyke determination.* 



DISCUSSION 



The data furnished by the test runs and summarized in Table 2 are not as complete as ■ 

 might be desired. Nevertheless, a number of conclusions deducible from the tabulated data 

 or from observations made during the experiments permit the design of a meter chamber ade- 

 quate for measurement of the air content of water employed for cavitation studies in water 

 tunnels and similar facilities. 



A pertinent question affecting the choice of the internal arrangement of the meter 

 chamber is the relative effectiveness of the various means employed for providing Contact be- 

 tween liquid and gas phase. Thus, if it were determined that the "mixing" takes place pre- 

 dominantly in the spray itself, emphasis would be directed toward the employment of finer 

 nozzles and away from the provision of a large area of the inside walls of the chamber. Simi- 

 larly, if the falling film or the helical ramp were determined as the principal area of effective 

 mixing, optimum design would emphasize that feature. In each case the minimum gas-space 

 volume consistent with proper function would be sought. 



In all of the test runs except that indicated as Run 1, a mode of mixing of the air and 

 water was observed which is almost certainly more effective than the combination of all those 

 mentioned above. At and above the level at which the spray impinges upon the inside wall of 



*In converting the indication given by the Van Slyke apparatus to equilibrium pressures, it is, of course, neces- 

 sary to know the relative proportions of the various gases as well as their separate coefficients of solubility. 

 For this purpose, the relative proportions of nitrogen, oxygen, and carbon dioxide in ordinary atmospheric air and 

 their solubility coefficients as given in Reference 5 were used. 



