| Turbine apparatus is one of the key power devices in aerospace,gas turbine and steam turbine,in order to improve the overall efficiency of the turbine machinery,it is necessary to accurately measure and analyze the airflow field in the turbine machinery,while the traditional pressure sensor for high-frequency aerodynamic measurement in the turbine engine has problems such as difficult to miniaturize the probe,low measurement accuracy and poor robustness,etc.,while the fiber optic F-P cavity sensor The fiber optic F-P cavity sensor has the features of easy miniaturization of the probe,high sensitivity,and good robustness,which can make up for the shortcomings of the traditional sensor,which makes it a unique advantage in high frequency aerodynamic measurement.With the development of fiber optic F-P cavity sensor in recent years,its signal demodulation technology is also developing,but the dynamic demodulation capability on high frequency pneumatic signal is still lacking,so a new fiber optic F-P cavity sensor demodulation method with high accuracy and dynamic demodulation capability is also needed to meet the demand in high frequency pneumatic measurement.This thesis accomplishing work are as follows:1.To meet the problems of difficult to miniaturize the probe and low measurement accuracy in high frequency pneumatic measurement,the fiber optic F-P cavity sensor is combined with high frequency pneumatic probe for the first time;the research status of fiber optic F-P cavity sensor and its demodulation method is reviewed,the advantages and disadvantages of different demodulation methods are analyzed,and the relationship between air pressure and F-P cavity length is analyzed according to the diaphragm theory of fiber optic F-P cavity sensor.2.Manufacture fiber-optic F-P cavity sensors with PDMS material as the film layer.The sensor has the potential to 20 KHz frequency response,build a platform for high frequency aerodynamic measurements,and measure aerodynamic signals with different frequencies and air pressures,and the signal results show the feasibility of this novel demodulation method.3.In this thesis,a new demodulation scheme is proposed for the first time,mainly for the sparse part of the interferometric signal demodulation,solving the curve of relative cavity length variation against time variation,from which the air pressure and frequency of the aerodynamic signal can be obtained;and this scheme is analyzed from three angles:the jitter of the thin film layer,the repeatability of the structure,and the algorithm error,and also compared with the results of commercial sensor measurement and demodulation.The accuracy of the new demodulation scheme is verified. |
