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<br />Our first ground tests with this system showed a very low air pressure <br />of 15 psi (and, correspondingly, a very high MAlA operating temperature). <br />Obviously the 100 nozzles required too much flow for the system. \Ve <br />blocked off 50 nozzles with wood/ rubber plugs which sealed both the air <br />and liquid outlets, and ended up with what we considered the best final <br />system compromise -- the MAlA handling 50 nozzles at a 32 psi pressure. <br />and a liquid flow rate of 15 gpm. A lower liquid flow rate "opened" the <br />nozzles more and reduced the air pressure apparently decreasing the <br />efficiency of small droplet generation rather than increasing it. On <br />ground tests with this final configuration using the fertilizer solution, <br />the visual cloud which drifted off was satisfyingly dense and not too <br />much material was wasted by being in droplets so large they fell immediately <br />(perhaps 15- 350/0 of the liquid being wasted). On one occasion earlier we <br />used an MAlA generator to operate the FTR 30 nozzle dispenser with the <br />C- 97 on the ground. The water spray at about 7 gpm looked quite good. <br />The air pressure at this low air volume flow rate was 35 psi and higher. <br /> <br />In summary, the dispensing system was as anticipated; apparently <br />satisfactory for the program, but not ideal. Major gains in hygroscopic <br />seeding can be derived from improved dispensing equipment (and <br />calibration techniques). The ultimate system would operate without <br />an air supply requirement and would be adjustable as to droplet size range. <br />Calibration of the present system is of course desirable. This is a large <br />task which is most efficient to do as part of a longer term dispenser system <br />optimization program. <br /> <br />A study by Carroz (1971) tells of trying to develop and calibrate a high- <br />volume spray dispenser for hygroscopic material for warm fog dissipation. <br />The flow rates and desired particle sizes are closely comparable to what is <br />required in warm rain augmentation, but while for rain augmentation the <br />small particles under 5 pm diameter are merely wasted, for warm fog <br />dissipation they are actually harmful. For either goal the particles over <br />100 11m diameter are wasted. Carroz notes the value of spraying crosswind <br />rather than back along the wind, reviews quantitative aspects of atomization, <br />notes the difficulty of calibration, and does not find any spraying method whic h <br />is really promising for producing large quantities of small particles in a narrow <br />size range. <br /> <br />16 <br />