The authors showed in this report the analysis of flow and pressure charistaristic of ejector pump at lifting sand with water, and compared them with the experimental result by model-ejector pump. The diameter of model ejector is 80.7mm with two built in nozzles. The diameters of nozzle diameter are 6mm, 8mm, 10mm, 12mm. Through experiment, following points were revealed.
(1)When water which contain sand and soil-the diameters of which are comparably so small-are transpored through vertical pipes, sedimentation velocity of particle groups are extremently slow. Accordingly, the velocity difference of water and sand grains are so small that the fluid which contains sandand soil may be regarded appro ximately as homogeneous fluid which has bigger specific gravity than water.
(2)The head of ejector-pump when lifting sand can be determined applicating momentum theory between tip of nozzle and discharge pipes considering only the increace of specific gravity of the fluid. These caluculated values agreed well with the messured data by the sand lifting experiment by the model ejector-pump.