The Design And Performance Analysis For B15-Engine Intake System

With the development of economy, the automobile industry has been changing with each passing day. China became the biggest automobile consumer market of the world at one jump, and the annual production and sales have been increasing by30%for several years. The increasing demand for automobiles results in the rapid development of components and vehicle industry. At present, the design of engines must meet the criteria of emission and noise level besides the power performance and economy, which makes it very necessary to make an exhaustive study on engine intake and exhaust systems. The intake system is made up mainly by inlet manifold and the pipe before inlet manifold. The pipe before inlet manifold can cut down the induction noise. How to design the intake system components and analyze the combination property is a topical issue of the current engineering projects. In this thesis, the intake system is designed, and the performance is analyzed, after which the working level of the intake system is evaluated comprehensively.Firstly, the principles of variable valve timing and variable intake manifold are introduced, then the simulation model of B15engine is established in GT-Power, after which the model is calibrated by the test results and the error is less than5%.This lays preliminary groundwork for the subsequent calculation, the parametric sensitivity of Helmholtz resonator,1/4Wave tube and air cleaner is calculated, and the influence of parameter changing on Acoustic attenuation performance is summarized, based on which the silencer elements of intake system are designed. The design procedure and method of silencer element are explained thoroughly, and the detailed design scheme is put forward. Then in order to make the order noise lower than the target value at certain speed, the silencer elements are optimized. The optimized intake system reduces the noise level, and the pressure loss is less than2.5kPa, which meets the demand value.Secondly, three methods are put forward in this thesis to analyze the performance of inlet manifold, and they are simplified simulation built up with zero or one dimensional models, steady or transient calculation by CFD and coupled simulation by one dimensional with three dimensional software. After the comparison of these three methods, it is found that the coupling process can provide more accurate boundary conditions for the calculation. The problems of coupling between GT-Power and STAR-CCM+are solved, and then the simulation is carried out. It can be seen from the pressure field that the results of the three-dimensional software accord with those of the one-dimensional software very well. Then the velocity field of every branch pipe in different time is analyzed, and the suggestion is that the curvature of the branch pipe should be reduced.Lastly, in order to evaluate the performance of the silencer elements, the acceleration running noise model is built up based on the coupling model. The result shows that the noise of the intake system is lower than61.8dB(A), which satisfies the demand for contribution rate to the acceleration running noise.