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Object and purpose of research. The object of the research is the cavitation noise of transport vessels propellers. The purpose is to analyze and generalize modern research and methods for predicting broadband noise induced by the operation of the transport vessels cavitating propellers. Materials and methods. A review of the research materials (published in the XXI century) on the cavitation noise of transport vessels propellers, in particular broadband noise, as well as the author's own research on the causes and physical aspects of the occurrence of broadband noise is carried out. Based on the Fourier analysis of the time functions of velocities and pressures in the flow near the propeller, the conditions for the occurrence of broadband noise at (4–10)-blade harmonics and the parameters that relate this noise to various types of cavitation on the propeller are found. Main results. A review of recent studies results devoted to the cavitation noise of transport vessels propellers has shown that the levels of the so-called broadband noise that occurs when the cavitating propeller operates in nonuniform flow at high (4–10)-blade harmonics are used as the basis for modern noise predicting methods. At the same time, the authors of the methods consider broadband noise only as a result of the tip vortices development. The paper considers and generalizes an alternative hypothesis of the broadband noise occurrence caused by the occurrence and collapse of cavities within the blade with the formation of a double-headed peak on the time function of pressures. The analysis of publications on the development of the vortex wake behind the propeller and the modeling of pressures at the buckling failure of the tip vortex spirals allowed to show that double pressure peaks can be formed in the flow during the development of the vortex wake behind the propeller. This made it possible to combine both hypotheses of the broadband noise formation – from the development of the tip vortex and from the occurrence and collapse of cavities on the blades – and to link the assessment of the growth possibility of high blade harmonics with the cavitation parameters. Conclusions. It is shown that modern research methods have made it possible to obtain new data on the mechanism of the occurrence and collapse of cavitation both on the blade and in the tip vortex. At the same time, the currently used methods for predicting cavitation and, in particular, broadband noise are very approximate and require refinement to assess the effect of various cavitation characteristics on broadband noise. The hypotheses of broadband noise occurrence and the proposed physical model covering both vortex cavitation and the formation and collapse of cavities can serve as a basis for such clarification.

Object and purpose of research. This research was intended to design and manufacture a dummy test rig for self-propulsion testing of various in-hull propulsors. This test rig will be used to test waterjet designs for underwater objects. Materials and methods. Analytical assessments on geometry of propeller and stator blades, numerical simulation of operational condition for two-row blade system operating in the water duct as per in-house KSRC techniques. Main results. Interaction of internal waterjets with the hull of underwater object has never been studied before. To estimate this interaction, it was decided to perform self-propulsion tests with a suitable hull model. This work included design and manufacturing of a dummy test rig representing a hull of underwater object and enabling hydrodynamic measurements for an in-hull waterjet. Another result of this work was design and manufacturing of a four-row in-hull propulsion unit. Conclusion. The dummy test rig manufactured in this work could be further used to optimize in-hull waterjets of various configurations. Apart from the configuration described in this paper, it could also be feasible to design, manufacture and apply a combined rim-driven propulsion motor in the initial part of the water duct.

Object and purpose of research. This research was intended to check if a pre-swirl stator installed before an open propeller of moderate skew could be a viable solution for non-cavitation hydrodynamic noise mitigation. This solution was compared with a typical open skewed silent propeller. Materials and methods. Design and verification calculations have been performed in a given wake field of pre-swirl stator. Pre-swirl stator was designed considering the wake field turn at the skew angles of typical propeller. Wake field behind the pre-swirl stator and design calculation of open propeller considering the heterogeneity of inflow were determined using the calculation methods. The tests and calculations of vibroacoustic parameters have been performed for evaluation of propulsion, cavitation and acoustic parameters of propellers with pre-swirl stators in comparison with open propeller. Main results. This work was also intended to answer the question if a moderate-skew propeller with pre-swirl stator could be an alternative to a silent skewed open propeller. To this effect, a model of propulsion system (propeller + pre-swirl stator) was designed and manufactured. This model was further used for comparative cavitation, hydrodynamic and acoustic testing in the cavitation tunnel, as well as for self-propulsion tests in deep-water towing tank. Conclusion. The tests have shown that propellers with pre-swirl stators have lower noise emission at high frequencies than open propellers. Cavitation and propulsion performance remain the same for both options.

Object and purpose of research. Effects of the vane hub cap are investigated regarding hydrodynamic, cavitation and acoustic performance of a ducted propeller as propulsion system. Materials and methods. In the work process two versions of the vane hub cap have been designed to take account of the wake field behind propeller. Experimental investigations of the propulsion system model with a smooth hub cap and designed hub cap are given. Additionally, positions of hub cap vanes with respect to propeller blades (in-between the blades or in wake of the blades) were studied. Main results. The thrust and torque coefficients as well as cavitation numbers were obtained, and the acoustic radiation was measured for the investigated propulsion system arrangements. Conclusion. Comparisons were made and conclusions drawn regarding the efficiency of vane hub cap application.