Noise Measurement And Prediction Of Single Cylinder Diesel Engine

The control of structure noise has played an important role in the field of internal-combustion engine designing. It is significant that the prediction and optimization are carried out through the designing process to satisfy the more and more strict requirements of engine noise, even affecting the survival of engine in the market competition. Because the radiant sound level is one of most concerned targets of a engine.Based on TC118D diesel engine, the research contains test measurement and diesel engine structural noise prediction by FEM and BEM. The purpose of test is to obtain the surface vibration and radiation sound intensity during both engine working and it being driven by electrical machine. The noise prediction task includes loads calculation and response analysis using multi-body, and prediction of sound radiation based on BEM.1. Fix the experiment equipment and measure the block surface vibration velocity and sound intensity of surfaces out of the engine. Study the contribution of engine parts and compare with the simulation results.2. Research the method and technique routine of noise prediction. In detail, the main work is as follows:First, establish the3-D entity models and simplify some tiny features without influencing the modal analysis, in order to get better finite element models. Set up point to point contact interface between any two of parts. Run a finite element analysis using ABAQUS to receive the natural frequencies and mode shapes, which is for the structure response analysis and noise optimization. Then, get the exciting force source by means of simplified simulation modals which are provided by AVL-/GLIDE/EXCITE/TYCON. These needed forces include piston impact force, bearing loads, seat force of intake and exhaust valve and pressure acting on the bottom of the cylinder head. Adding the boundary, carry out a dynamic response analysis and get the whole surface vibration results by NASTRAN. Build the boundary element model of TC118D diesel. Accomplish FEM-BEM data transfer by use of geometry interpolation method. Achieve radiation acoustic intensity spectrum of space points at different frequency. Compare the results of simulation with the ones of test. Finally, according to the information exacting from the research, modify the structure of parts which make more noise and provide a way for structure optimization and noise control of the whole engine.