Vehicle Exhaust System Dynamics Research With Pulsating Flow Incentive

The exhaust system is indispensable as well as one of the most important parts of the vehicle. Its main function is leading exhaust gas smoothly export into the air, and purification of harmful substances and reduction noise at the same time. Dynamic characteristics, including natural character and response with certain incentive, is an important characteristic of the exhaust system, it directly related to the formation of cracks on the vehicle exhaust system and diving comfort, and affects the reliable and safe operation of the vehicle. Among the factors influencing the exhaust system on dynamic character, vibration of engine emission is a very obvious and important one. This study is on the dynamic character of automotive exhaust system under the pulsation flow incentive. The main research including four aspects are as follows:Firstly, in the basic of accurately analyzing exhaust system structure, the motion differential equation in cylindrical coordinates were constructed with thin straight tube, thin bending tube unit and changing diameter tube unit in the use of the symmetric rectangular unit, and lay the foundation for the establishment of dynamic model of the exhaust system.Then, according to the different structure of exhaust system, gathering thin straight tube, thin bending tube unit and changing diameter tube unit together into a complete exhaust system, and establishment its dynamics model, it provides the basis for the natural character and dynamic response analysis of the system.Thirdly, the motion characteristics of pulsating gas flow are analyzed by the plane wave theory, the method of the radial displacement of nodes on the incentive is set to the pulsation pressure pulsation of the incentive system, proved the dynamic characteristics of automobile exhaust system in the pulsating flow incentive.Finally, prove the symmetric rectangular element in computing and analyzing dynamic character of the exhaust system feasibility and validity through examples, analysis the dynamic character of the exhaust system under the incentive of pulsating flow, and obtain some beneficial conclusions.