Vibration Analysis And Improved Design Of Marine Diesel Generator’s Top Module

As land resources continue to decrease, more and more countries begin to turn their attention to the sea, so a large number of ships have been put into the snatch of marine resources. As the power plant and power supply device of the ship, generator plays a key role in the fierce competition. It is very important to maintain the good performance of the generator with high speed under harsh environment. The top module consists of a cooling system, a control system, a detection system and an output system, its structural strength determines the performance of the whole generator.This topic comes from the improvement and optimization design of the vibration of marine diesel generator which is produced by a company. The top module has low natural frequency, and is close to the low order ignition frequency of the diesel engine, which is very easy to cause the resonance damage. In order to improve on its natural frequency, the top module can be thickened, but this is contrary to the light trend which may cause the decline in the competitiveness of products. According to these problems, this paper makes a preliminary improvement design and the final optimization design for the top module. Consulted relevant references and compared advantages and disadvantages of former vibration technology then designed a new top module: Vibration isolation of the cooler with low natural frequency is carried out to reduce its vibration; the relatively weak parts of the top module’s housing part on the way through the improvement of the structure to improve its natural frequency. By the way of combined finite element modal analysis software with LMS experimental modal testing equipment to calculate the natural frequency of the top module, the cost of the improvement and optimization design was substantial saved. In order to verify the rationality of the design, we have collected optimized top module’s vibration data under the rated load and the result show that: combined with the damping methods(isolation and structure improvement) has obvious effect on reducing top module’s vibration.The main research contents of the article are as follows:(1) Widely consult the domestic and foreign research on vibration reduction technology and vibration isolator design, compare the advantages and disadvantages of various vibration control technology, combined with the actual situation of the box and select a reasonable method of vibration reduction.(2) Rigid modal test had done for the cooler to acquire its natural frequency and vibration mode. Designed a hanging type installation and corresponding rubber isolator for protect cooler from resonance.(3) Combine the method of finite element modal analysis with experimental modal analysis for aided design, comparing to the experimental modal analysis data and adjusting the finite element modal analysis makes the analysis more accurate and reasonable.(4) The vibration date of the top module and stator are acquired by vibration test on the generator which installing optimized top module under the rated load. The result shows that the improved design is reasonable. At the same time, the date p rovides the reference basis for the finite element analysis of the top module and the parts to be improved.