Simulation Study On Noise Of Engine Structure Surface

At present, with consumer increasing NVH (noise, vibration, comfort)levels ofvehicle, especially the control on noise radiation of engine structure surface increasinglybrought to the attention of the vehicle and engine manufacturers.As rapid developmentof the theory and computer technology, know about noise radiation level of the enginesurface and the regional contribution to the amount of noise radiation has becomepossible,in the design phase of the engine,It provides a convenient and efficient methodfor structure design on reduction of engine vibration and noise.Computer-based simulation on engine structure surface noise, there are mainlyfinite element method, boundary element method and multi-body dynamics. This paperuse the method described above to explore structure surface noise of JS ATV400engine.The noise from the vibration, the vibration source is the exciting force. Highprecision calculations based on the the accurate excitation force to get the idea, thethesis around the driving forces carried out an in-depth study. The exciting force of theengine under load is more complex, it is only for the exciting force in-depth study andcalculations, these incentives include the power to the main bearing force, the strikingforce of the piston on the cylinder liner, valve cylinder head force, including thecamshaft bearing, intake and exhaust valves seated force. And then create the enginethree-dimensional model and finite element model, modal analysis, modal calculationresults that the left and right engine cover and the cylinder head has a largerdisplacement mode shape. Then, based on the calculated excitation force, frequencyresponse analysis, found that the left and right engine cover and cylinder head vibrationvelocity, which is consistent with the modal analysis results. The establishment of theengine surface boundary element and boundary element block to frequency responsecalculation results for the boundary conditions the surface of the engine noise acousticsimulation, to draw cylinder head noise contribution right cylinder head noisecontribution, by calculating the sound intensity data were compared with the measureddata, the results agree well with the surface calculation results with higher precision.Using CAD/CAE technology, based on the measured cylinder pressure curve andthe two-dimensional drawings, It can predict the noise radiation in engine design stage,without time-consuming test. Meanwhile, the prediction on a larger area acousticradiation can clear direction to optimization design of structure parts and reducing on vibration and noise of engine.