Application Research Of Electrostatic Induction Technique On Aircraft Engine Gas Path Condition Monitoring

A new condition monitoring method named gas path debris monitoring technology for aircraft engine is discussed. This technology could monitor gas path fault which is"hard to detect"for traditional monitoring methods and provide real time information of component deterioration within the gas path of aero-engines. It is capable to produce early warning of incipient fault and support engine condition state estimation and remaining life prediction. This paper is based on the basis of previous research. An electrostatic sensor is designed and a simulated test environment is built. Several debris monitoring experiments are carried out on both simulated environment and real engine. Removal method of the power interference in monitoring signal is studied. A periodical rub detection model is established to detect blade rub and the model is proven by experiments. The work in this paper could be used to support the health management and logistics for China's big airplane engine in the future. The main contents are list below:1. The mechanism of debris generation and charge principle are analyzed. A probe type electrostatic monitoring sensor is designed based on the common structure of static sensor used in gas-solid two phase flow parameter detection. Simulated experiment facilities are developed to prove the feasibility of this technology. Iron and graphite particles are used to simulate the fault products in gas path. Experiments are carried out at room temperature and high temperature. Signal of charged particles with different materials, different concentration and different diameter are compared and several conclusions are given.2. An exploratory experiment is carried out on a turbo-shaft engine to study the gas path monitoring technology. Based on the 107 hours monitoring signal, the relationship between the shaft power and the electrostatic signal is studied. The relationship between the combustion efficiency deterioration and electrostatic signal is studied too. After that, a parameter baseline is produced based on the affecting factor discussion. The effect of engine washing on monitoring signal, characteristic parameters and overall trend are discussed and the feasibility of parameter baseline is validate clearly.3. Power interference exists in the debris monitoring signal and affects the signal greatly. Removal method of the power interference is studied in the third chapter. Three different methods are used to remove the power interference and the results are discussed. Two orthogonal reference signals are construct in the method based on Independent Component Analysis (ICA) and receive nice result. Comparison show the method based on Independent Component Analysis (ICA) is the best method for power interference removal in the electrostatic monitoring signal.4. An electrostatic based method for rub fault detection in gas path is studied. The generation process and charging mechanism of blade rub debris are analyzed and then the electrostatic probe theory and characteristics of electrostatic induction of a point charge are presented. After that a periodical rub detection model was established. The model shows that a series of characteristic frequency which decay greatly over frequency will appear in the sensor output signal frequency domain when periodical rub happen. This model is validated by several simulated experiments.