Research On Measurement Of Particles Motion Parameters In Aero-engine Exhaust Plume

In the field of aero-engine condition monitoring,the abnormal particles in the exhaust plume is the direct product of the early failure of the engine gas path,and the measurement of its parameters is of great significance for evaluating the damage degree of the engine gas path and establishing the perfo rmance degradation prediction mechanism.At present,there are many advanced measurement methods,such as laser doppler,particle image velocimetry and digital holography,etc.,but they can’t be directly applied to industrial sites because of the limitations of measurement accuracy,test efficiency and environmental requirements.Therefore,in this paper,high speed camera technology is used to measure the particles motion parameters in aero-engine exhaust plume.The high speed imaging process of partic les in aero-engine exhaust plume is analyzed,the geometric imaging model of the high speed camera system is constructed,and the calibration principle of the systematic internal and distortion parameters under the nonlinear model is further expounded,and the basic performance parameters of high speed imaging of particles is discussed.An algorithm for detecting the particles motion parameters with different density distribution in the aero-engine exhaust plume is proposed.For sparse particle groups,the motion speed is detected through particle identification and location,feature matching and speed detection,and the motion trajectory is obtained according to the feature matching results and interpolation.For dense particle groups,the velocity is detected by the processes of region dispersion,cross-correlation matching of gray distribution,peak locking,etc.,and the trajectory is characterized by describing streamline by Euler method.A measurement system of particles parameters in high speed combustion field based on simulated aero-engine exhaust plume experiment platform is constructed,and the particles image acquisition experiment is carried out with graphite and high purity iron particles as objects.At the same time,in order to compare the accuracy of particles velocity measurement,a high speed combustion field particle image velocimetry system is set up,and the combustion field images with uniform tracer particles is obtained.The feasibility of applying the detection algorithm to the measurement of particles parameters in high speed combustion field is verified.Based on the pretreatment process of particles images,the parameters of graphite and high purity iron particles images under various working conditions are detected,and the results are further compared with the combustion field velocity.The results show that the proposed algorithm can accurately obtain their movement velocity and trajectory.A software for measuring the particles motion parameters in high speed combustion field is designed,and the parameters can be measured more quickly and efficiently.Therefore,it is proved that high speed camera technology combined with image processing technology is suitable for measuring the particles motion parameters in high speed combustion fields such as exhaust plume.