A Numerical Investigation On Structure Strength Of Marine Podded Propulsor

Currently, the international shipbuilding industry is closely paying attention to the ship Energy Efficiency Design Index(EEDI) standard changes. Marine propeller design requires a more comprehensive and in-depth consideration to propulsive efficiency, cavitation performance, stern pulse pressure, vibration and noise, strength.To design to meet the international standards of the new marine propulsion device is important. Hydrodynamic performance research methods of the domestic marine propulsion continue to mature, simultaneously structural strength research of propeller under special conditions is also underway. In marine propulsion, due to controllable pitch propeller and podded propulsor respective characteristics, both of which have a huge potential market. This paper uses numerical method to calculate structural strength of blade of controllable pitch propeller and pod of podded propulsor based on unidirection fluid-construction interaction theory. Specific research contents are as follows:Select MAU4-54 blade of bulk carriers as the research object and calculate its hydrodynamic performance at different advance coefficient, and compare with the experimental results, both are consistent,simultaneously analyze the pressure field of the blade. Then extract the pressure coefficient data of blade at the design case, using TECPLOT software to interpolate the pressure coefficient onto finite element nodes of real blade, and get hydrodynamic loads of real blade calculated by the law of similarity. Finally, use ANSYS software to load hydrodynamic loads, centrifugal load of real blade, and solving and strength check, and detailed analysis of the blade stress and distortion, while comparing with CCS rules checking, the results of two methods are consistent. This method validates that the numerical calculation method of structural strength check of blade based on unidirectional fluid-structure coupling theory is reasonable. Compared with the specification checking method, this method provides the more comprehensive stress distribution information.Matching design for ship-engine-propeller with JDC3-65 spectrum, and respectively obtain geometric parameters, runnig speed, hydrodynamic performance under the design case, the bollard case based design pitch and the maximum thrust case of the designed controllable pitch propeller. Then calculate the pressure distribution based CFD numerical method under the three conditions and analyze the pressure distribution. Then use the finite element method to calculate and analyze strength of blade under the three conditions, simultaneously compare with CCS rules checking, both results are consistent. The results show: the design case to meet the structural strength requirement, and the bollard case and the maximum thrust case not to meet the strength requirement.Use numerical calculation method based on the unidirectional fluid-structure interaction theory to check pod. Firstly, do numerical calculation on hydrodynamic performance of podded propulsor at different advance coefficients and different flowing directions, simultaneously analyze the pressure distribution on the surface of pod. Then use the finite element method to calculate the strength under the two conditions, and analyze the surface stress and distortion distribution. The results showed: the maximum equivalent stress occurs at the upper end, the front and the rear end of bracket.When the podded propulsor is rotated at the small angle, its stress distribution is similar and magnitude of stress does not change significantly.