Optimization of the taper angle of the jetter confuser used for reversible blast cleaning of propellers from corrosion

It is shown that it is very effective to remove corrosion products from various surfaces, including the metal surface of the propeller, using the new technology of reverse-jet cleaning (RJC) developed by the authors. The RJS technology is based on the physical principle that the jet of the working fluid (pulp based on river sand or bentonite clay), upon impact with the surface to be cleaned, turns 180°, which leads to an increase in the jet effect on the surface to be cleaned by 1.5–2 times due to the occurrence of the reactive component. To ensure the marked turn of the jet, an original design of the body was developed, which is distinguished by a patent novelty. One of the main elements in this design is a jet-forming device in the form of a confuser. The presented theoretical studies of the pressure loss of the working fluid in the confuser channel, based on the study of the pressure loss function to the extremum, which made it possible to obtain a dependence for calculating the optimal taper angle in a wide range of Reynolds numbers characterizing the turbulent mode of motion taking into account the influence of the working fluid density and its dynamic viscosity, the average speed of movement of the working fluid, the radius of the confuser, as well as the coefficient of equivalent roughness, i.e. from gradual wear of the confuser channel. The resulting dependence can be recommended for calculation in the design of jet cleaning devices and other installations of jet technology.

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