Design of power-plant mounting systems is mostly based on Modal Decupling at the early development process of a new case of cars. For obtaining a good mounting system, it is important to choose a reasonable coordinate system for modal decoupling and to make an effective modal optimization strategy. In this paper, the correlation between the rigid body modal parameters and dynamic engine mounting force is investigated in detail. Some general principles are proposed to improve the validity of idle shake control based on the method of modal decoupling.

The time-domain method based on the large eddy simulation is applied to predict the flow noise in variable cross-sectional area pipes. For the pipes with sudden area contraction and expansion, the numerical predictions and measured results agree reasonable well. Then the effects of connected structures of pipes on the flow noise is investigated numerically, and the variable cross-sectional area pipes with low flow-generated noise are explored.