Multi-loaded operation is always a feature of marine equipment. Experiments were done on marine centrifugal pumps to study the influence of the shifting-load. Variation of parameters related to rotation speed and flow rate was analyzed. Results of experiments confirmed the empirical formula of the rotation speed against vibration. It was concluded that the vibration level of the centrifugal pump is proportional to the forth to ninth power of the rotation speed. Changing of flow rate has a greater influence on low and high frequency vibration than that on intermediate frequency vibration. The influence even becomes much larger at the characteristic frequency of blades of the centrifugal pump. The general conclusion is that when low flow rate operation condition is required, the rotation speed of the pump should be lowered to reduce the operation noise instead of adjusting the valve of the pump.

In order to increase the lifespan and efficiency of micromotors, the damping effect of the metal brushes of micromotors is studied. The relationship between Rayleigh damping model and dissipation factor of materials is established. The location of rubber damper in the structure is simulated and optimized by means of the transient dynamic analysis module of MSC.Marc. Meanwhile, the vibration magnitudes of the metal brushes are measured with Polytec Scanning Vibrometer when the rubber damper attached at the original and optimal locations respectively. The results show that the vibration magnitude of triple frequency after the optimization can be reduced to 12.1 % (clockwise rotation) and 11.2 % (counterclockwise rotation) respectively. This method can improve the vibration performance of metal brushes. It is of significance for engineering practice.

Aiming at the rotor test rig，the rotor-bearing system is modeled for different types of lubrication bearings, the dynamical behaviors of the rotor system are then investigated. The dynamical stiffness and damping coefficients for different bearing key parameters are also studied. Via comparison, the dynamical supporting characteristics under different bearing parameters are discussed. With consideration of the different foundation support stiffness, the critical speeds of the rotor-bearing system are also investigated.

In order to develop and improve the technique of identification and measurement of aircraft noise source, and to understand the essential properties of the noise source deeply, a large planar microphone array for the landing process of large civil aircraft has been developed. This plane array is composed by 104 microphones whose positions in the plane are determined by the computer aided optimization design. Meanwhile, the spectrum characteristics of the array have been tested by means of numerical simulation. The plane array has been used to measure the noise sources of 20 landing aircrafts in the Xi’an Xianyang International Airport. In the experiment, a noise source identification and measurement system for large civil aircraft has been built and developed, and the microphone array technique and its data processing software also have been verified.

Feed water pump is one of important auxiliary equipments of steam turbine. In tuning up the feed pump of a steam turbine, over-vibration phenomena were found. In this paper, the vibration characteristic of the feed pump is analyzed carefully according to the vibration measurement data. It is found that the oil whip is the main cause of the over-vibration. The results provide a reference for tuning up and design of the feed pumps.