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· Cavitation refers to the explosive growth of cavitation bubbles (that is, gas nuclei, the radius is generally below 20μm) due to the evaporation of liquid due to the local low pressure of the liquid flow system (lower than the saturated vapor pressure of the liquid at the corresponding temperature). Cavitation bubble collapse will cause a powerful micro-jet impact, produce a very short pressure pulse, the tiny space around the bubble to form a local hot spot to produce extreme high temperature, high pressure, and accompanied by complex physical reactions, chemical reactions, mechanical effects, electrochemical effects and thermal effects. It is estimated that when the free cavitation bubble collapses, the flow rate of the micro-jet near the wall can reach 70 to 180m/s, the impact force generated on the surface of the object is as high as 140 to 170Mpa, the diameter of the micro-jet is about 2 to 3μm, and the number of micro-jet impacts on the surface is about 100 to 1000 times/(s·cm²). Cavitation jet underwater cleaning technology is a new type of underwater facility cleaning technology formed by introducing the cavitation effect into the water jet cleaning technology, that is, artificially produce high-density cavitation bubbles in the water jet beam, and use a large number of cavitation bubbles in the local small area of the surface of the object to achieve the purpose of cleaning the hard dirt and attached Marine organisms. The technology not only has the advantages of high efficiency, energy saving, environmental protection and safety, but also does not harm the base material of the facility, rarely or completely does not harm the original anti-corrosion layer, and can reasonably and effectively clean the thin section area of the ship propeller and other equipment.

· advantage The cavitation jet cleaning method determines in principle that it is very suitable for the cleaning operation in the underwater submerged environment. The use of a lower pressure water source does not harm the operator or the surface being cleaned. There is no limit to the cleaning water source, which can be tap water or seawater (pumps, pipelines, etc., need to be corrosion-resistant), and the materials are convenient. There is no need to add any chemical reagents, no toxic emissions in the operation process, and it is an environmentally friendly cleaning technology. High cleaning efficiency, convenient automatic transformation. The use of cavitation jet technology can achieve high cleaning efficiency, excellent cleaning effect, safety and environmental protection construction requirements and good economy. Compared with the traditional cleaning speed of ten to twenty square meters per hour, the cavitation jet cleaning disk can reach hundreds of square meters to thousands of square meters per hour, which can clean various types of dirt and different pollution levels.

· Application field First, offshore oil structure cleaning The pile and leg oil production platform is the main type of large offshore structures in China, and it is expected that semi-submersible oil production platforms will gradually increase in the future. In order to ensure the safety of the platform, personnel and facilities, it is necessary to carry out effective cleaning in a certain period. With the rapid development of Marine oil industry, there are more and more large Marine structures, and the cleaning task is increasing rapidly. Efficient and safe cavitation jet cleaning technology will become an inevitable need. Second, subsea oil facilities cleaning Offshore oil engineering involves a large number of subsea oil facilities such as subsea oil production systems, which are difficult to be cleaned reasonably and effectively in complex Marine environments. Cleaning by a diver or ROV carrying cleaning equipment is the only effective method at present. The development of modular and automatic cavitation jet cleaning equipment can effectively solve the cleaning problem of underwater facilities.

· Third, ship cleaning FPSO, ships, etc. run in the Marine environment for a long time, and the surface of the hull shell below the waterline will form a rather thick Marine biological attachment layer and dirt layer. The surface of the shell of the ship will inevitably produce a large area of rust during its perennial operation. On this basis, the attachment of algae, shells and other sea organisms will form a tight and hard dirt layer. If it is not effectively cleaned for a long time, the Marine biological attachment layer and dirt layer up to 200mm thick can be formed, which seriously affects the sailing speed of the ship, increases the cost of fuel consumption and reduces the service life of the ship. In the ship cleaning industry, cavitation jet cleaning technology undoubtedly has a broad space for development. Fourth, coastal engineering cleaning In the common coastal engineering, the long-term accumulation of Marine biological dirt and silt directly affects the normal operation of ports and waterways. The long-term erosion of Marine life also has a serious adverse effect on Bridges, moisture-proof lifting, etc., which directly affects the robustness and service life of these facilities. Therefore, it is of great significance to clean coastal engineering, and cavitation jet cleaning technology has broad application space.