Research On Numerical Method And Software System Development Of The Vibration Analysis For Propeller Cutting Edge Modification

As an important part of a ship,the propeller is often over-loaded or half-loaded because of various factors during the ship’s navigation,which makes the main engine unable to reach the rated rotational speed or overload.Therefore,the ship-engine-propeller doesn’t in the best working condition,which cause damage to the main engine.In order to solve this problem,researchers often use edge-cutting technology to trim the original propeller,which could reduce the diameter or pitch of the propeller,so that the torque of the propeller is reduced.After cutting edge,the propeller becomes "lighter",and the ship-engine-propeller is re-matched,which makes the ship reach the best working condition.In addition,edgecutting is a convenient and feasible method.So it has great practical significance to transform the propeller by edge-cutting.For the edge-cutting technology,the current research focuses on the influence on the hydrodynamic performance of the propeller,but there are still few of researches about the influence on vibration characteristics.As we all know,the propeller vibration characteristics are very important to the comfort and crypticity of ships.Based on the dynamic model of the propeller,this paper combines MATLAB programming technology,ANSYS secondary development technology and QT user interface technology to carry out the research on the influence of diameter diminishing and trailing edge cutting on the vibration characteristics of the skewed and non-skewed propeller.It reveals the influence of key parameters on the vibration of the propeller,and provides theoretical guidance for seeking the edge-cutting plan which have optimal vibration characteristics under the condition of ship-enginepropeller matching.The research shows:(1)The five-blade propeller has five modes as a group,including umbrella mode and local mode.The higher vibration mode presents more complex bending-torsional phenomena.The natural frequency is also higher.(2)In the diameter cutting case,the greater the cutting amount of the non-skewed propeller,the higher the natural frequency of the umbrella mode,part of the vibration mode changes from torsional vibration to cantilever vibration,the vibration form is simpler;For a skewed propeller,with the increase of the cutting amount,the natural frequency of its blade changes in the same law as that of a non-skewed propeller,but its torsional vibration form is more likely to appear than the cantilever vibration form.(3)In the trailing edge cutting case,the increase in cutting amount has little effect on the natural frequency and mode shape of the non-skewed propeller,and the vibration characteristics of the propeller remain unchanged with increased skew.