For the purpose of noise control, the sources and mechanism of the HVAC (Heating Ventilation and Air Conditioning) system noise on offshore platform were analyzed. It is shown that besides the HVAC system noise there are ambient noise and the secondary noise radiated by piping system, and based on the theory of noise control, the measures of noise reduction were proposed. Results of this research provide some reference for noise control of offshore platform HVAC system, and also have a guiding significance for HVAC system design in the field of marine engineering.

The LES technique was used to simulate the 3-D unsteady full flow-field of a contra-rotating axial fan. Several monitoring faces were arranged in the flow-field between the two impellers. The monitoring points were arranged in each monitoring face. The FW-H technique was used to simulate the aerodynamic noise of the flow-field between the two impellers. The contours of vorticity magnitude of the monitoring faces and the sound pressure levels of the monitoring points were processed. The vortex and the aerodynamic noise characteristics in the monitoring faces were analyzed. This study may be useful for the analysis of fan’s aerodynamic noise.

A multi-body dynamics model for analyzing power-train mounting system is established by adopting MSC ADAMS/View. The correctness of the model is verified by the measurement data of the vibration response of each component of the mounting system in idling condition. According to energy decoupling theory, the stiffness of each component of the mounting system is considered as the design variable, and the reasonable matching of natural frequency is taken as the restraint. Then, the best improvement of the energy decoupling of the power-train in the direction of stimulation is selected as optimization target to improve the vibration characteristics of an economic car in idling condition. The result shows that, considering stiffness as the design variable only can realize the improvement of decoupling property. To gain the complete decoupling, some other influencing factors should be taken into consideration.

The factors which affect steering wheel shimmy are briefly introduced in this paper. The causes of steering wheel shimmy are investigated by road reappearance test. Frequency spectrum analysis, coherence analysis and order analysis are applied to locate some defective parts, which are optimized and validated later on. The results show that the steering wheel shimmy is reduced effectively.

The metal magnetic memory technique is very effective in early damage detection for metal parts. However, information of disturbing magnetic fields also exists in the magnetic memory signals so that the characteristic signals in the stress concentration area can not be recognized easily. This paper puts forward a new filtering method based on wavelet packet decomposition and reconstruction. Wavelet packet decomposes signals according to different frequency ranges. The goal to filter the disturbing signals can be achieved through intercepting the interested frequency ranges and reconstructing signals. Simulation analysis verifies the feasibility of this method. Then, this method is used to decompose and reconstruct actual magnetic memory signals and a preferable effect is gained. It makes the signal characters in stress concentration area more clear and depresses the probability of damage misjudgment.

Numerical simulation of a threedimensional steady turbulent flow in the overall flow field, from the inlet of the collector to the outlet of the diffuser, of a counterrotating axialflow fan is performed. Unstructured grid is used to discrete the domain for computation. Pressure boundary conditions are specified to the inlet and the outlet. The SIMPLE algorithm in conjunction with the RNG kε turbulence model is used to solve the threedimensional NavierStokes equations. The moving reference frame is adopted to transfer data across the interface between the rotating field and the stationary field. The broadband noise source model based on the Lighthill noise analogy theory is introduced to simulate the aerodynamic noise field of the fan. The sound intensity distribution inside the fan, on the impellers, the blades and the shell of the fan are predicted. The pressure fluctuation of three interfaces around impellers caused by the rotating impellers and blades vibration is studied by the Fast Fourier Transform (FFT) method. The simulation results are of important significance to the optimal design and noise control of the fan.

Based on the actual measuring and analyzing, we evaluate the validity for using an Htype nog between return cooling pipe and turbocharger to alleviate the vibration level for pipeline systems of a nuclear power plant under nog relaxed and fixed conditions. The results will provide technical supports for further improvement of system vibration reduction.

The testing of drivers attention quality and reaction character under vehicles interior noise condition are performed by means of psychometric detecting method. By analyzing the test data measured, the differences of these two parameters under different noise levels is obtained. The analysis and conclusion may have practical significance for improving driver’s traffic safety.