Study On Relationship Between Solid Particles And Bubble In Submerged Water Jets

In order to satisfy the needs of exploiting ocean resources and incising under water , cavitation water jets and abrasive water jets have been developed. The cavitation of waterpower mechanism (such as pump and water motor) and water project construction through water current with sand need studying. The research of three multiphase of solid and liquid and gas has not been perfect. The research of the relationship between solid particles and bubble of abrasive water jets in the condition submerged by water has not been done at present all over the world.This paper will study systematically and theoretically the relationship of solid particles and bubble in submerged water jets, and the cavitation characteristic of abrasive water jets. Then it will experiment the capability of rock-erosion by cavitation water jets and by abrasive water jets with bubble. The important findings are as follows.①By analyzing bubble athletics characteristic, the bubble athletics equation in abrasive water jets was established. On the basis of the force analysis of single particle, athletics equation of the group abrasive particles has been set up. The study suggests that the time that a bubble collapses varies with the concentration of abrasive particles, and the fluid pressure, and shows the velocity distribution of the abrasive particles.②The momentum equations of liquid, bubble and solid particle have been set up after the athletic disciplinarian of abrasive water jets with bubble was analyzed from microcosmic movement theory. It were simulated for the velocity and the pressure of the submerged abrasive water jets. Show that the velocity of solid particles is smaller than water phase , and its dynamic pressure is bigger than water phase . The characteristics of the turbulent and the overflow, and the cavitation characteristic of abrasive water jets with bubble have been studied. Then it is pointed out that the cavitation number of abrasive water jets with bubble is bigger than that of cavitation water jets under the same condition, and the ability of cavitation of abrasive water jets decreases slightly. The cavitation water jets erodes the target by the bubble collapsing while the abrasive water jets with bubble incise and break the target by the erosion and abrasion. The bubble collapse pressure of cavitation water jets is bigger than that of abrasive water jets with bubble slightly.③The growth of bubble cloud experiences swelling and compressing, reinflating and recompressing, collapsing and falling in the cavitation water jets or abrasive water jets with bubble. The length of bubble cloud produced by cavitation water jets increases with pump pressure and as it does, it has a best ambient pressure. In the low–concentration abrasive water jets with bubble, the length of bubble cloud firstly increases and then decreases with the increase of pump pressure and it is unsteady as ambient pressure increases.④The experiment shows : With the same pump pressure, the capability of cavitation water jets produced by wenqiuli nozlle is stronger than common water jets. The average depth of erosion on gritstone for cavitation water jets is 2 times as much as common water jets, and its mass erosion is 7 times as much as common water jets, and its diameter of erosion is 2.3 times as much as common water jets.The erosion experimentation of abrasive water jets with bubble indicates: The noise of cavitation decreases with ambient pressure, while it increases with pump pressure. The depth and mass erosion on granitic decrease with the increasing of ratio of efficient standoff distance to diameter. At the best erosion time, the work efficiency is three times as much as cavitation water jets. The mass erosion and depth erosion on granitic increase with pump pressure, while they decrease with ambient pressure, and have a best ambient pressure which is the same as cavitation water jets.The main innovation of the dissertation is that: By analyzing the relationship between solid particles and bubble of abrasive water jets submerged by water, the bubble athletics equation in abrasive water jets and the group abrasive dynamic equation have been established . The momentum equations of abrasive water jets with bubble has been investigated based on microcosmic movement theory . The change domain of cavitation number and bubble collapse pressure have been gained . These provide the theoretical and experimental basis for the application of abrasive water jets with bubble in deep water and deep sea.