【作者】 王岩；

【导师】 朱程香；

【作者基本信息】 南京航空航天大学 ， 飞行器设计， 2022， 硕士

【摘要】 快速精准地探测飞机表面结冰特性能够有效保障飞行安全、提高防除冰效率。本文针对压电超声传感器、蒙皮和冰层组成的多层结构,基于超声脉冲回波测厚原理,定量保型地测量铝制蒙皮表面冰层厚度。本研究针对飞机表面结冰探测需求,采用理论与实验相结合的方法,对超声传感器压电层、匹配层和背衬层等内部结构进行了优化设计,实现了铝板表面冰层0.2mm高精度探测的要求。首先,基于超声波在多层介质中传播规律以及脉冲回波测厚的理论基础,建立压电超声传感器-铝板-冰层的多层探测结构。对超声传感器内部结构进行理论分析,主要包含以下三点:(1)由目标冰层探测精度确定超声传感器中心频率,基于压电材料频率和厚度关系确定压电材料厚度;(2)根据平面压电传感器聚焦理论进行探测范围研究,由目标探测冰层范围确定传感器直径大小;(3)基于声阻抗匹配原理确定匹配层和背衬层材料声阻抗值。其次,根据探测理论建立的结构模型进行仿真研究,针对3mm铝板的超声传感器设计采用COMSOL和Piezo CAD对传感器内部结构压电材料、背衬材料和匹配材料计算。传感器结构仿真研究包括:(1)压电材料厚度即中心频率研究,获得不同中心频率下探测信号;(2)不同直径压电材料探测范围计算分析;(3)不同声阻抗背衬材料和匹配材料仿真研究;(4)不同厚度背衬层和匹配层对探测信号的影响分析,通过以上分析获得铝板表面结冰探测的超声传感器最优结构参数。最后,根据传感器仿真设计结果进行试验制备,并对自主制备的未封装超声传感器性能测试,通过未结冰的铝板厚度探测试验验证理论设计;搭建地面低温箱结冰探测试验平台,对封装好的超声传感器探测冰层精度和最大范围进行测试验证,通过脉冲回波信号的幅值分析得到最终冰层厚度探测结果,与实际模具中冰层厚度对比,得到超声传感器结冰探测误差。结果表明,针对铝板表面冰层厚度保型探测可简化超声传感器内部结构,无需匹配层;所设计中心频率10MHz、直径6mm的超声传感器对冰层探测精度可达0.2mm,最大冰层探测厚度可达10mm,冰层探测误差控制在10%以内。更多还原

【Abstract】 Rapid and accurate detection of icing characteristics on aircraft surface can effectively guarantee flight safety and improve the efficiency of anti-icing and de-icing.In this paper,the thickness of ice layer on the surface of aluminum skin is measured quantitatively and non-contact based on the principle of ultrasonic pulse-echo thickness measurement.This research mainly adopts the method of combining theory and experiment to design the internal structure of ultrasonic transducer for ice detection,including piezoelectric layer,matching layer and backing layer,so as to achieve the requirement of high-precision of 0.2mm ice detection on the surface of aluminum plate.Firstly,based on the propagation law of ultrasonic wave in multilayer media and the theory of pulse-echo thickness measurement,the multilayer detection structure of piezoelectric ultrasonic transducer,aluminum plate and ice layer is established.Secondly,the internal structure of ultrasonic transducer is theoretically analyzed,mainly including the following three points :(1)the center frequency of ultrasonic transducer is determined by the detection accuracy of target ice,and the thickness of piezoelectric material is determined based on the relationship between frequency and thickness of piezoelectric material;(2)The detection range is studied according to the focusing theory of planar transducer,and the diameter of transducer is determined by the target detection of ice range;(3)The acoustic impedance of matching material and backing material are determined based on the principle of acoustic impedance matching.Then,according to the structural model established by the detection theory,the simulation study is carried out.For the ultrasonic transducer design of 3mm aluminum plate,COMSOL and Piezo CAD are used to calculate the piezoelectric materials,backing materials and matching materials of the transducer internal structure.The simulation study of transducer structure includes :(1)the thickness of piezoelectric material,i.e.the center frequency,is studied to obtain the detection signals at different center frequencies;(2)Calculation and analysis of detection range of piezoelectric materials with different diameters;(3)Simulation of different acoustic impedance of backing material and matching material;(4)Analysis of the influence of different thickness backing layer and matching layer on the detection signal.Through the above analysis,the optimal structural parameters of ultrasonic transducer for ice detection on aluminum plate surface are obtained.Finally,experimental preparation was carried out according to the simulation result of transducer design,and the performance of the self-prepared unpackaged ultrasonic transducer was tested and studied,and the theoretical design was verified by the unfrozen aluminum plate thickness detection test.The ice detection test platform of the ground cryobox was built,and the ice detection accuracy and maximum range of the encapsulated ultrasonic transducer were tested and verified.The final ice thickness detection result was obtained through the amplitude analysis of pulse echo signal,and the detection error of the transducer was obtained by comparing with the ice thickness in the actual mold.The results show that the non-contact detection of the thickness of ice on the surface of aluminum plate can simplify the internal structure of ultrasonic transducer without the need of matching layer,the designed ultrasonic transducer with a center frequency of 10 MHz and a diameter of 6mm can reach the precision of 0.2mm of ice and the maximum thickness of ice up to 10 mm,and the error of ice detection can be controlled within 10%.更多还原