Technology Investigation Of Blade Vibration Measurement Based On Laser Reflect Method

As the chief work component of the steam turbine, the blade played a central role in the industrial development. The blade accident caused by the harmful vibration character was the main reason for the team turbine accident, so the research of vibration character has a great significance for the operation safely. While there were many measurement methods of the blade vibration in China and other countries, but no one could be an effective method for the vibration parameters. This issue has its practical engineering significance.This paper is based on tip-timing measurement method. The blade vibration measurement system based on the laser-reflect-method is designed and built, and the experiment of the entire measurement system is completed in the laboratory.Tip-timing measurement method is a non-contact measurement method. The blade vibration character could be measured by sampling to the time arrival of operating blade. Single-senor measurement method for the paper is summaried by the study of tip-timing which saves the number of sensor mostly. Only one laser sensor can measure the blade parameters.The blade vibration measurement system contains three parts:optical transmission system, photoelectric conversion system and signal acquisition and processing system. According to the requirements of the measurement system, designs the light source, fiber bundle and the probe. The photoelectric conversion system contains two parts:Optical receiving circuit could convert the fiber's output light signal to electrical signal; and signal amplification circuit could amplify the weak electrical signal to the strength that can be acquisited by signal acquisition system.In the end, the blade is sampled by the NI's PXI data acquisition system. There is also description to the design of the speed synchronization sensor in detail. End of the paper, the experiment of the whole measurement system of blade vibration is carried out, it verifies the feasibility of the tip-timing measurement method and receives the vibration parameters of the blade vibration experiment table by measuring. Precision errors could be received by comparison between test data and theoretical data, and then we analyze the causes of error.