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.

Abstract : Transfer path analysis (TPA) is an effective method for structure vibration performance optimization, evaluation and fault diagnosis. The basic theory and characteristic of TPA method is mainly described in the paper. The experiment system is established for TPA method to verify the TPA method. Comparison of simulation calculation value with experiment value shows that simulation result and experiment result are basically consistent. TPA method is used in four improved structures separately and reasonable structure is confirmed. The analytical results showed that the TPA method is a good way to find the vibration transmission path which provides the evidences to control the vibration transmission effectively.

The marine equipment includes seawater marine pump, drainage pump, screw pump, hydraulic pressure pump, air-conditioning chilled water pump etc. These pumps work with various forms including rotation, reciprocation, meshing etc., and vibrate with different frequency characteristics. In this paper，the vibration levels, characteristics and causes of different rotational marine pumps were analyzed. Some measures for vibration reduction were proposed and applied to the improvement design of some pumps. The results of testing showed that the vibration level of these pumps was reduced as the expected.

The paper intends to analyze quantitatively the correlation between the NASTRAN finite element (FE) model and a testing model for a middle raft frame of a floatingraft isolation system. The first five vibration modes of the raft frame are estimated by finite element method (FEM) and measured by testing. The modal assurance criterion (MAC) matrix is established in LMS virtual lab for relativity analysis between the FE model and the testing model. The MAC estimated by LMS virtual lab shows that the modal computed by FEM is basically correct and the method can be used for dynamic esponse analysis of the structure.

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.