Research On The Structural Radiation Noise Prediction Techniques Of Internal-combustion Engine

The structural noise prediction has been an important aspect in the field of internal-combustion engine research. Knowing the radiant level of engine noise at the stage of design and doing optimization of whole engine structural noise control based on simulative model have great significance to insure internal-combustion engine satisfing more and more strict requirements of engine noise and to promote the product competitive capability. Based on 90°V8 diesel engine, the research of internal-combustion engine structural noise prediction is done systematically by using FEM and BEM, and the research on structural noise prediction of 90°V8 diesel engine is achieved. In detail, the main work is as follows:(1) The actuality of the research of internal-combustion engine structural noise prediction is reviewed firstly after referring to some literature, and then the method and technical path of this research is gived.(2) The 3-D entity models of main constructs of 90°V8 diesel engine are established. Based on the convergence analysis of discrete errors, a diesel's finite element models of its chief components and assembly have been established. Adopting the Lanczos method, their modal computations have been conducted, and the natural frequencies and mode shapes were obtained which establish the base to structure response analysis and noise prediction.(3) The main loads of 90°V8 diesel engine are calculated, such as cylinder pressure, main bearing force, piston impact force and side push force. Then the values and positions of these loads have been determined. Mode superpostition is adopted to calculate dynamic response analysis on 90°V8 diesel. Modal response functions of all modes are obtained, which offer boundary conditions for the computation of radiation noise from engine surface by ATV technique. (4) The boundary element model of 90°V8 diesel engine is built, and then the response of engine exterior is imported into the boundary element model. Afterward, we can predict 90°V8 diesel engine structural noise and calculate the main acoustic result, such as sound pressure, and radiation power by software of LMS.Sysnoise.