Development of Fluidics-Type Sprinkler to Remove the Fallen Volcanic Ash from Mt.Sakurajima

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As a part of the investigation on the device to remove the volcanic ash fallen on the sun-heat collector, new type of sprinklers applied the flow mechanism in the fluidic devices have been designed and developed. In this study, by using the video camera and the image processing system, the spread angle of the sprinkled water have been investigated. Moreover, the distribution of the sprinkled water have been measured quantitatively. Inthis investigation, the diameter of the air hole set in the developed sprinkler were changed variously. The obtained concludions in this study are as follows.(1) As the diameter of the air holes becomes large, the spread angle of the sprinkled water widens. However, at a certain diameter the spread angle has a maximum value, and then it lessens gradually.(2) The distributions of the sprinkled water change greatly with the diameter of the air hole. In the case of small diameter, water is distributed around the water jet center-line mainly and its distribution is shaped like a sharp edge cone. However, as the diameter increases the distribution of the sprinkled water changes into the saddle-shape one. The maximum depth of the sprinkled water shows at the outer edge of the water jet.(3) In order to estimate the distirbution of the sprinkled water quantitatively, the mean depth of the sprinkled water was introduced newly. As a result, the mean depth is large in the case that water distributes in the shape of cone. However, it becomes small according to the uniformity of the sprinkled water distribution.