Design And Finite Element Analysis Of Medium-speed Marine Diesel Engine Block

Medium speed diesel engine has been widely used in marine power.This paper compares and analyzes domestic marine medium-speed diesel engines with the same cylinder diameter.Comparing with each index,many problems are exposed,such as low power,large volume,economy and unsatisfactory emissions.In order to solve the problems of low power,economy and exhaust emission,a new design and development of a medium speed marine diesel engine with double supercharged high pressure ratio and Miller cycle system is carried out.Based on this,this paper takes its body as the research object,mainly from the body design,the body dynamics analysis,the body strength and the body mode to solve the problem of large volume,heavy weight and high manufacturing cost.According to the development requirements of a medium-speed marine diesel engine,the overall layout scheme is determined and the block design is carried out according to the overall scheme.Referring to domestic and foreign marine medium-speed diesel engines,combined with the concept of thin-walled strong back,the integrated design of the body and gear box is carried out.Geometric multi-section arc surface is used to design the crankcase section of the engine block,which reduces the overall volume and weight,reduces the production cost,and ensures that the overall stiffness and strength meet the application requirementsThe crank and connecting rod parts are assembled by three-dimensional software,and the envelope diagram of crank and connecting rod is analyzed and calculated.By using this method,the design efficiency can be improved,and the in-cylinder pressure curve can be calculated by AVL BOOST software,which provides a reference for finite element analysis.By establishing the finite element models of the parts of the R&D machine,applying the corresponding bads and constraints,the finite element analysis is carried out under the pre-tightening force and the maximum explosive pressure.By analyzing the natural frequencies and mode shapes of the modal,combining with the calculation of the excitation frequency of the diesel engine,and comparing the calculated results,it is verified that the possibility of resonance of the engine is small.Through the bench performance and reliability test of the R&D model,it is verified that the performance of the R&D model is stable,the machine body and its components run reliably under long-term full load and variable load,and the design of the machine body meets the application requirements.