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Theoretically analysed design features of the working section of a hydrodynamic cavitation device with swirling input. Using the numerical methods of SolidWorks software and the Flow simulation module, fluid flow modeling was performed to describe similar processes. The comparison of the results of visual and experimental studies has been carried out. Visual observations indicate that the life cycle of vapor-gas bubbles and cavities in the design under study can be divided into several periods, in particular the formation of vapor-gas bubbles, their growth, generation of cavities, their volume increase, transformation and destruction. The influence of input and output hydrodynamic and technological parameters of the flow and design features on the character of the cavitation area and the form of cavitation were studied. According to the results of theoretical and experimental research, rational mode of operation of the cavitation device is proposed.

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The following paper analyses selected problems regarding the impact of technological parameters and the type of adherend material on the strength of adhesive-bonded steel sheet joints. The subject of the test was a single-lap adhesive joint of S235JR steel sheet. Joints were formed on two types of substrates: with or without corrosion products on the surface. The surface of steel sheet adherends was pre-treated with three cleaning solutions: acetone, Wiko industrial degreasing agent and Cortanin F anti-corrosion agent, depending on the state of the surface. Adhesive joints were formed with Epidian 53/ET/100:15 epoxy adhesive. The formed joints were subjected to one of three ageing variants: 14 days, two months and 3 months, which were followed by destructive testing to determine the shear strength of joints. The analysis of results obtained in the tests indicates that the strength performance of adhesive joints of corrosion-free adherends was characterised by higher values than in corroded steel sheets, regardless of ageing time.

Disinfective action of physical-chemical effects accompanying hydrodynamic cavitation on the microorganisms sanitary indices in water has been studied. Disinfection kinetics was found to be dependent on the cavitation field characteristics and the microbes population. Based on the structural-morphological investigation of the E.coli bacteria it was found that antimicrobial effect is obtained due to the mechanical rupture of cells and chemical disinfection, which results from the hydroxyl radicals and hydrogen peroxide effect. Mathematic model that allows predicting the disinfection result under the hydrodynamic cavitation has been developed. The effect of chemicals on E.coli microorganisms under hydrodynamic cavitation has been investigated. Adding of AgNO 3 or hydrogen peroxide in the cavitation installation makes it possible to reduce the disinfection time and to decrease the chemical oxides concentration by 50-70 %, which is caused by the synergism effect.

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