The Analysis And Research About Torsional Vibration Of Marine Diesel Engine's Shafts

Torsional vibration of marine diesel engine is an important factor for safe navigation.Nowdays high-power marine diesel engines are widely used in large vessels. During the operation of marine diesel engine, the shaft carrys and deliverys more powerful load, which means, the state of torsional vibration become more complex. It makes the marine engine torsional vibration calculation and research more important.To achieve efficient and accurate calculation of torsional vibration,on the one hand, more new researches of torsional vibration are needed,on the other hand,intergrating and applying reasonable methods to develop calculation software are also needed.Based on this,the auther did systematic analysis on various factors of torsional vibration and compared a wide range of torsional vibration calculation methods and developed a torsional vibration calculation software as well as its interface. Torsional vibration of 6S50MC-C marine diesel engine's shaft was calculated and compared with the raw date of calculation reports, the rationality of the calculation software was verified.The content of the paper was involed with free vibration calculation,forced vibration calculation ,the influence of firing order to torsional vibration,torsional vibration calculation under the conditon of single cylinder misfire and a trial discussion about the influence of single cylinder misfire to marine diesel engines which have different numer of cylinders.The main work included establishing mathematical model ,the comparison among Holzer Mothed,Matrix Method and Jacobian Method,the discussion and calculation of harmonic coefficients as well as damping,the improvement of torsional vibration amplitude calculation and synthetic method,the impact to shaft's torsional vibration under the condition of different single cylinder misfire and removal of the piston rod assembly which caused the imbalance of shaft,tosional vibration calculation software programming and interface development.By calculating and verifying.It was proved that making Holzer Method and Energy Method programmed and calculated by computer still had practical significance.Through analysis and comparison and reasonable proposal was put forward to the optimization of tirsional vibration,at the same time,the influence of firing order and single cylinder misfire to torsional vibration was explained from principle.In addition, a useful exploration about single cylinder misfire's impact to diesel engine with different number of cylinders was also started.