Study On Noise And Vibration Characteristics Of Low-speed Diesel Engine And Control Method

Marine diesel engine is the most important source of vibration and noise. The vibration and noise performance itself is an important reference index in diesel engine selection. Diesel power density and improve incentives so that it produces a corresponding increase in the force. Because of that, diesel engine radiated noise levels increases at the same time. The International Maritime Organization recently revised the ship noise level rules that working and living cabin noise limits descends 5dB (A). The new specification is expected to be July 1,2014 for new ships enforcement. Under such a severe form, to carry out low-speed diesel engine noise and vibration characteristics analysis has important theoretical significance and application value.With the support of national high-tech shipbuilding projects, the paper vibration and noise problems of small-bore low-speed marine diesel engine with independent intellectual property rights carry out a detailed study. According to assemble the whole three-dimensional model, finite element analysis model including a cylinder block, a frame, a base, air cooler, turbocharger is built. The characteristics of diesel each excitation source is considered. The main bearing loads, the exhaust valve striking force of the law and the frequency domain characteristics of the in-cylinder combustion pressure, crosshead striking force is analyzed. Using the finite element method, based on the actual position of incentives, encourage each individual is loaded to the corresponding position of the finite element model. The transient response is analyzed under a single excitation obtaining the vibration characteristics of the machine. The vibration machine vibration intensity is respectively calculated.The acoustic transient boundary element method is used. The whole acoustic boundary element analysis model to the whole surface of the acoustic vibration displacement node calculation input conditions, access to the whole of the surface radiation noise characteristics. The average sound pressure level is got by using"energy superposition method".Some local optimizations are proposed. The optimization results show local optimization measures could significantly reduce the vibration of the local structure.And the vibration and noise reduction effect is not obvious. But reducing crosshead gap can be significantly reduced noise and vibration of the machine. Thus, results of this analysis can provide important theoretical support and practical engineering value to two-stroke low-speed marine diesel engine in low-noise design techniques.