Air Flow Noise Analysis For The Intake Manifold Based On The Secondary Development Of STAR-CCM+

Intake manifold plays a key role in dynamic and economical performance ofengine. High speed air flow through the intake manifold causes air flow noise whichincreases the noise of the intake system. An excellent intake manifold can improve theintake performance and decrease the air flow noise.At beginning of the development of intake manifold design, people used test andexperience to design intake manifold, which caused a lot of time and money. What’smore, this method can’t find the key problem. However, CFD and CAA can solve thisproblem. To improve analysis efficiency, this paper uses CAA and CFD to developmentthe automated systems of flow field simulation and acoustic field simulation, which canhelp the simulation and analysis of flow field and acoustic field execute in order andregularly. When changing several conditions or coordinates of points, these systems canachieve by just one click. They improve the analysis efficiency, make the results havethe same property and avoid mistakes.The calculation accuracy of the air flow noise is based on the calculation accuracyof the flow field. This paper uses different turbulence models, different number of prismlayers and thickness to simulate the intake manifold flow field, and contrast thesimulation results with the test results. The results show that realized k turbulencemodel with0.01mm’s prism layer thickness makes the simulation results closer to thetest results. This paper uses them to simulate air flow noise for its accuracy.This paper simulates4modification models of some kind intake manifold with thedeveloped air flow noise simulation system. By applying Proudman and Curle model toanalyze the distribution of noise sources, we can find that the main noise source isquadrupole source caused by the pressure gradient. Increasing the volume of pressurestabilizing cavity，radius of curvature and transition fillets can improve the intakeperformance and decrease the noise. In unsteady simulation, the relationship betweensound pressure level and frequency can be obtained by applying detached eddysimulation in near field, FW-H in far field and fast Fourier transform on data. Theresults show that the noise decreases8dB in7.5m away as the optimization of theintake manifold’s structure, and the peak value appears on specific frequency whichhelps noise identification.