Collection And Analysis Of The Acoustic Signals During The State Monitoring Of Gas Turbines

Fault diagnosis technology has now been widely used in the rotary machine around the world. Currently there occur a lot of new methods to diagnose the running state of gas turbines, such as infrared monitoring, ultrasound monitoring and acoustic emission monitoring etc. Acoustic monitoring method applied in gas turbines not only causes no damage to the monitored object, but also saves money for state monitoring. So this paper mainly deals with how to use acoustic monitoring method to evaluate the working state of turbines.Centrifugal blower is the main object being researched in this paper. The air intake volume of the centrifugal blower is changed in order to control the running state of the blower. And then the acoustic signals generated by the blower are collected. Through the way of extracting the feature of the signals the health state of the blower can be monitored. In the whole process of the experiments, 2 representative testing points for the signal collecting have been laid. One of them is located near the air inlet area of the blower and the other is located near the air outlet of the blower. At the same time, a set of acoustic signal collecting system which collects the signals generated by the blower has been established and this system facilitates the offline signal analysis, using software LabVIEW. Besides, another set of acoustic signal analysis system for real time analyzing using software LabVIEW has also been established. This system can do some online power spectrum analyzing. As to the data collected, probabilistic density analyzing method and power spectral density analyzing method are used to do some offline data analysis. The analyzing program is compiled by using the software MATLAB.To realize using the acoustic emission monitoring method for the health monitoring of gas turbines, a set of equipment simulating the scraping between the blades and the shell inside the gas turbines has been designed. Besides, another set of equipment simulating the scraping between the blades and the shell inside the centrifugal blower for the acoustic emission monitoring has also been designed.In the end, the difficulties and disadvantages of acoustic monitoring method have been analyzed. And a plan for the future experiments has been made.