Study On The Condition Monitoring And Fault Diagnosis Of The Gas Turbine Blade

As a high failure rate power equipment, the proportion of blade fracture of gas turbine is becoming higher year by year. Especially in the high temperature alloy material without effective breakthrough technology, the blade fracture fault seems more prominent, and cause serious production accidents and major economic losses. Currently, the maintenance support on gas turbine almost adopt overhauling after a limited amount of running time, and replace the key components such as blade, etc. However on the account of some problems such as operating environment, the rubbing with casing, corrosion, crack fault and some other faults are happened frequently.Many sets of blade will occur fracture at the short of the scheduled life, or lead to the inefficient operation because of the more wider of blade tip clearance in the process of steady state operation. The blade condition monitoring can improve the efficiency and reliability of unit operation in gas turbine, The blade radial displacement, the blade circumferential displacement and the direction of the blade angle are main state parameters, the radial displacement of the blade tip directly decided the change of the tip clearance value, the change of axial displacement and direction angle of blade can reflect the state of the blade vibration.Comprehensive analysis of tip clearance and blade vibration parameters, can effectively reflect the running condition of the blade. This article through to the running state of the gas turbine rotor blade characteristics and failure mechanism analysis, put forward a kind of blade based on eddy current pulse condition monitoring technology solutions and based on the optimized fault tree analysis fault diagnosis of gas turbine blade.The main works are summarized as follows:1. Based on the eddy current sensor technology, design a kind of tip clearance measurement scheme, On the basis of the static radial calibration, combining with the changing rule of the whole process cycle time waveform, put forward a combination of radial calibration and circumferential static calibration of dynamic sensitivity for solution, it can accurately obtain the dynamic sensitivity and the tip clearance value under different rotational speed were measured, solve the problems of eddy current sensor for owe target area and high-speed undersampling test problem in a certain degree.By the apply of the trigger pulse technique in the tip timing measurement experiment, this method is make up for the blade to the positioning of the deviation problem commendably, compared with the traditional peak tip timing measurement, the blade positioning is more accurate, Ensure the vibration amplitude of the accuracy of measurement, and use the regression tip timing algorithm for blade vibration amplitudeand vibration frequency under different rotational speed. 2. Through the finite element analysis method verifying the results of tip clearance measurement, The results show that under the running speed of5000r/min, the tip clearance value is of high accuracy, but at a higher speed, it need further optimize measurement technology or use higher performance of measuring equipment. According to the actual working condition of unit, adopt the thermal structure coupling technology for different operation conditions of the turbine blade tip clearance change simulation study,complete the analysis of the tip clearance change rule and the influence weights of quantitative under two kinds of centrifugal loads and thermal load.3. At the request of actual engineering project, establish a optimizing method of fault tree based fault diagnosis scheme for gas turbine blade, the scheme was applied to engineering cases, it can be solved respectively blade fracture failure cause analysis and risk assessment.