The Computer Simulation Analysis Of Diesel Engine Combustion Noise

With the development of industry and transportation, the noise of engine has become more critical. Noise index is an aspect in evaluating engine's performance. Analysis and control of engine noise has the significance.Take an engine with four cylinders as an example, and apply computer simulation technology to analyze engine structure vibration and noise. It aims at reducing the noise of engine, and supplying the thought and method for the acoustic analysis of engine.First establish finite element model of engine. The engine structure is a very complicated mechanical system, so there are too many dispersed units of the finite element model. Which increases the calculating amount, and calculation can still be limited by computer hardware. Then this paper has adopted the matrix condense and recovery. The choice of the main node of degree of freedom decides the calculating accuracy.The noise of engine is mainly caused by gas eruption pressure which is transmitted through cylinder head and piston, con-rod, crankshaft, body outwards to radiate noise. So the noise of engine is analyzed considering block, cylinder head, oil pan. In addition, in order to close to true operating situation of engine, the influence of crankshaft, bearing, oil film damping is considered. Therefore, the noise analysis of engine is a multi-body dynamics problem. This paper combines multi-body dynamics methods with the finite element method, considering the non-linear factor between the structures, and analyzes the engine dynamics response better.Calculate the noise of engine at speed 2600rmp, and get the surface vibration speed stage of engine. Though improving the structure of engine, the surface vibration speed stage of engine is reduced.