| When the aircraft passes through the cloud layer containing supercooled water drops,there will be ice accretion on the surface,which will seriously affect the flight safety and cause enormous casualties and economic losses.In order to solve this problem,an ice detection system based on ultrasonic pulse echo is established in this paper,which is used to detect the physical parameters of the ice layer on the aircraft surface and control the switch of the anti / de icing system according to the measurement,reduce the energy consumption and ensure the flight safety.In this paper,the non-contact ultrasonic pulse echo measurement technology is used,and the ultrasonic transducer is arranged inside the wing skin.Firstly,based on the skin / ice multilayer structure,the reflection,transmission and attenuation characteristics of ultrasonic pulse wave across different materials are studied.The ice thickness measurement method is established by measuring the time interval of the echo signal of the top and bottom surface of the ice layer,combining with the propagation speed of the ultrasonic wave in the ice layer to calculate the ice thickness;the ultrasonic pulse echo will produce a certain attenuation when crossing the porous ice layer,according to the relationship between the ice density and the ultrasonic pulse echo attenuation,the ice density measurement method is established to study the effect of the ice density on the ultrasonic signal in the ice detection ground experiment,the echo signal will be superposed with certain noise signal,and the signal will be decomposed into several modes according to the frequency by the complete total empirical mode decomposition method,and the effective information will be extracted to restrain the measurement noise and improve the accuracy.Secondly,PZFlex software is used to simulate the selection of ultrasonic probe parameters,ice thickness and density measurement.The influence of the parameters of the ultrasonic probe on the ultrasonic wave is analyzed by modeling,and the physical size and excitation frequency of the probe are determined;the ice / skin model is established,and the influence of the thickness on the measurement accuracy and acoustic attenuation is studied by adjusting the thickness of the ice layer.The results show that the time interval of the echo from the upper and lower surface of the ice layer is linear with the thickness of the ice,which can be used for the detection of the thickness of the ice;the bubble is added to the ice layer to simulate the thickness of the ice layer In the real ice layer,by adjusting the parameters of bubbles in the ice layer,the effect of ice density on acoustic attenuation is studied.It is found that the attenuation of ultrasonic pulse amplitude is linear with the density in a certain range.Finally,the experimental platform of ultrasonic ice detection in cold ground environment is established to verify the feasibility of ultrasonic pulse echo detection method.In the experiment,the ice layer preparation system in the cold environment on the ground is built and calibrated to prepare ice layers with different parameters for the experimental research of the detection system;the ultrasonic pulse echo detection system is built to measure the acoustic signals of different ice layer thickness and density,and the attenuation law of the echo signal changes with the physical properties of the measured ice layer is obtained.The experimental results are compared with the simulation results,and the error is less than.This study can provide theoretical support for aircraft icing detection. |
