ANALYSIS OF THE STRESSED STATE OF PROPELLERS OF COMPLEX GEOMETRY IN A WIDE RANGE OF THEIR OPERATION MODES

An analysis of the stress state of the propeller of complex geometry is given depending on the modes of its operation, including emergency control modes. Experimental materials obtained during laboratory tests, and field data are used in this study. It has been shown that for propellers of complex geometry under hydrodynamic loads, deformations of the blades may be sufficient to change their hydrodynamic characteristics. However, in the design mode when the vessel is moving forward, changes in hydrodynamic characteristics are small for propellers with commonly used highly scewed blade contour and have little effect on the prediction of the full forward speed of the vessel. The situation changes in the case of reversing propellers. In this case, the stress state, especially, of highly scewed blade contour propellers can be quite significant and, as a consequence, there can be a significant change in their hydrodynamic characteristics under the action of hydrodynamic load. Such a state of stress affects the reversing characteristics of the vessel, and may cause particular concerns regarding their reliability in reversible modes of operation. As a result of the study, it was concluded that when designing high-speed propellers of complex geometry it is unacceptable to use data as a prototype relating to a low-speed propeller, in order to avoid reducing their reliability.