Sprinkler geometric pattern has been considerd as an important factor of sprinkler irrigation problem. The pattern form of a current sprinkler consists of two parts, namely, physical part that is formed from a main nozzle and mechanical part that is formed from a sub-nozzle and a spray breaker. The latter, mechanical part, supplements the deficit of the former, physical part. But by doing so, the sprinkler geometric pattern cannot be controlled in a widerange. Therefore the author tried to get analytically an arbitrary sprinkler geometric pattern by the method of crossing the two water jets from two nozzles at a proper point in the air.
The summary is as follows:
1) By crossing the two water jets at a proper point in the air, fine droplets are generated at the crossing point. These fine droplets are rapidly reduced in their velocity by the air drag force and fall on the ground.
2) As the discharges coming from the two nozzles are in the same direction, the spray density is raised so that the chance of collision of water droplets to each other in the air is increased.
3) At the moment of collision, each droplet has approximately same trajectory and same velocity. Therfore the division of droplet could not occur by the collision. The combination of fine water droplets is effective for reduction of evaporation and transpiration of the flying water droplets.
4) The condition for the stable flying of combined water droplets was determined theoretically from the balance of force acting on the flying water droplets.
5) Secondary collision of combined water droplets can occur during flight, but the effect on the sprinkler geometric pattern must be clarified experimentally.
6) Effects of the above-mentioned procedures, crossing two water jets in the air and collision of flying water droplets, were confirmed experimentally by the sprinkler geometric patterns of some sprinklers.