Abstract
In order to lighten the heavy labor of harvesting the lotus-roots by hand, the trial lotus-roots harvester by water jet was built and its performance was tested. The results were summarized as follows.
1. The trial lotus-roots harvester was designed with the object of using on the lotus-roots field flooded with water depth 10-20cm. The main parts of this machine consisted of the boat acted as a float, the jet nozzles doing the fan-shaped reciprocating motion and the pump to suck and supplyw ater, and the machine moved by drawing with wire.
2. In order to havest lotus-roots perfectly, the momentum of water jet per unit area required above 3000kg.s/m2 under variable conditions of lotus-roots and field.
3. In order to keep lotus-roots from broken loss under the constant momentum of water jet, other conditions of water jet and velocity ratio of nozzle (=nozzle velocity/working velocity) had to be considered. The desirable conditions of water jet were two nozzles of the inside diameter 28mm, each nozzle pressure 1.8-2.0kg/cm2, the discharge mass 650l/min, the jet velocity 18m/s in nozzle outlet and the jet force 20kg. The suitable velocity ratio of nozzle was 20-40.
4. The trial machine harvested lotus-roots at the rate 0.3 a to 0.4 a per hour. The values were 4-5 times in comparison with the rate of 0.08 a per hour by hand.
