The Analysis And Optimization Of Vibration And Noise About The Marine Medium-speed Diesel Engine

Engine vibration and noise are important parameters which determine the qualityof the diesel engine performance. Noise and vibration control technology is animportant research direction of modern diesel technology. Mastering engine noise andvibration characteristics in the design phase, the analysis of engine vibration andnoise transmission path based on engine noise prediction and optimization of theacoustic simulation model, ensuring the engine noise and vibration to meetincreasingly stringent requirements, improving product competitiveness, have veryimportant significance. This paper makes a medium-speed marine diesel enginemodel, respectively, using the finite element software and boundary element softwarecalculate vibration response and radiation noise, thus to optimize and validate themodel, specific work is as follows:1. A perfect three-dimensional solid model of the diesel engine is made. On thebasis of the original three-dimensional model of the diesel engine, the writercompletes cover plate which has a greater impact on the overall noise and vibration,increasing the accuracy of the analysis.2. Build diesel machine finite element model to calculate the oil pan and the whole(no isolator and has isolators) in free mode, get their natural frequencies and modeshapes, analysis of its dynamic characteristics which provides guidance for futureresearch.3. Engine vibration response calculation and transfer path analysis. Load theexisting major driving forces to the finite element mode which has isolator and noisolator, calculating and analyzing the vibration response in both cases, in order toevaluate the intensity of the isolation effect. The results are obtained by the analysisof boundary conditions for noise frequency domain. Various parts of the typical nodeare selected to calculate the three transmission paths (force head, cylinder side thrustand main bearing force). The model is loaded by a single cylinder pressure causedwhen vibration response of the situation and vibration intensity of the evaluation criteria, getting their share energy percentage of the four transmission paths.4. Build diesel boundary element model for calculating engine radiated noise.Engine noise tests are conducted, comparing the measured and calculated results toverify the correctness of the model and methods. Model is reconstructed by method ofusing diesel cylinder head covers, body side cover plate and oil pan structurestructural acoustic sensitivity analysis. The results show that the modified dieselmodel SPL space field point decline, reaching the purpose of reducing vibration andnoise.