Influence Of Nozzle Structure On Erosion Ability Of Submerged Cavitating Water Jet

With the continuous exploitation of oil and other resources,shallow geological resources are gradually depleted,and the development of deep underground and deep seabed resources is urgent.The task of mining deep underground or deep seabed oil and gas and other geological resources is to break the surface rock under the deep water environment and extract the oil and gas resources under the rock,and breaking the deep underwater surface rock is the first problem to be solved.Due to the efficient performance of the cavitation water jet technology in the deep water environment,the cavitation water jet technology has become the key to solving the problem of deep underwater surface rock formation.The key to the formation of an efficient cavitation water jet lies in cavitation nozzle.In order to study the influence of different nozzle structures on the erosion ability of submerged cavitation water jets,a submerged jet erosion experiment device and three different types of cavitation nozzles were developed by ourselves,which realized adjustable back pressure,pump pressure and target distance,In the laboratory simulated deep water environment,the cavitation jets of different nozzle structures are used to carry out experimental research on the erosion of terracotta brick.The effect of different nozzle structures on the erosion ability of cavitation water jets is studied,the relationship between different nozzle structures and the erosion ability of cavitation water jets is obtained,and the influence of changes in jet parameters on the erosion ability of cavitation water jets is explored.Collect the erosion pit depth,erosion damage area and the quality of the iron powder filled in the erosion pit after the erosion,combined with the observation of the morphological changes of the erosion pit,and analyze the erosion of the terracotta brick by the cavitation jet with different nozzle structures Different mechanisms.Further unveiling the mystery of the erosion mechanism of the cavitation water jet has great theoretical significance and engineering application value.The research results show that: as a kind of cavitation nozzle,the cavitation effect of ordinary nozzles is the most unsatisfactory;the cavitation performance of the gradual contraction-sudden expansion nozzle is the most prominent,and it is easy to shear between the incoming flow and the accompanying flow to form a high-strength vortex.The erosion ability of gradual contraction-gradual expansion nozzle is the most prominent.The density and distribution of cavitation bubbles in the flow field are better than those of the other two nozzles,which is beneficial to the stable output of the jet flow field.The jet erosion ability of gradual contraction-sudden expansion nozzle and gradual contraction-gradual expansion nozzle is significantly better than that of the ordinary nozzle;the cavitation water jet erosion ability of gradual contraction-sudden expansion nozzle and gradual contraction-gradual expansion nozzle has the best back pressure value;The gradual contraction-gradual expansion nozzle has longer optimum standoff and the gradual contraction-sudden expansion nozzle has stranger ability of resisting back-pressure.Ordinary nozzle erosion pits are usually regular "funnel pits",gradual-expanding nozzle erosion pits are usually irregular "ellipsoidal pits",and gradualincreasing nozzles are usually "cylindrical pits",and gradually decreasing-"Rainbow pits" often appear in the erosion pits of gradual nozzles.