The Method For Crack Of Metal/Temperature Detection Based On Antenna Sensor

With the steady progress of aerospace goals,researchers have become more stringent in their technical indicators.As an important power of aerospace vehicles,aero engines can directly affect the flight performance of aerospace vehicles.Therefore,it is very important to ensure the stability of power.As the core of power supply,the engine often works in the harsh environment of high temperature and high pressure,which makes it difficult to monitor the temperature of the engine and the health of its parts.Among them,the most vulnerable areas of aero engines are the high-pressure compressor,combustion chamber and high-pressure turbine.There are many challenges in the traditional test system: the wiring of the aero engine monitoring system is cumbersome and the space utilization is low,which greatly increases the difficulty of engine design;The base material in the detection sensor system is easily affected by the harsh environment inside the engine,which reduces the sensitivity and accuracy of the test results;Long-term in a high temperature and high pressure state,the sensor detection system is prone to aging,short service life and other problems.These problems have restricted the development of performance testing for aero engines to varying degrees.In response to the above-mentioned problems,an antenna sensor based on a high-temperature co-fired ceramic substrate is proposed,which combines the thermal/electric-wave conversion structure in electromagnetic wave sensing under high temperature environment and the principle of electromagnetic coupling in electromagnetic signals to construct a model of microwave sensor;Using alumina and aluminum nitride as high-temperature resistant and sensitive dielectric materials,through screen printing and multi-layer co-firing process,a sensitive structure is formed,and the integrated manufacturing of high-temperature resistant ceramic materials is completed;Using the radio frequency resonance coupling and principle,the change in the resonance frequency f caused by the sensitive change in capacitance is used as the measurement transfer factor to test the prepared sensor.The details are summarized as follows:1.Based on electromagnetic wave transmission and feeding theory,using planar transmission line and electromagnetic resonance technology,and systematically analyzing different planar transmission line schemes,and finally selecting impedance matching eccentric feeding method for model construction;the advantages of electromagnetic coupling technology are analyzed,which can make the space electromagnetic wave replace the traditional transmission line method and make the transmission method more flexible.2.Based on the test principle of the electrical length in the crack detection sensor and the temperature characteristics of the dielectric material characteristics of the temperature sensor,the design model is imported into the HFSS software for design simulation,and the model is compared with multi-dimensional parameters to obtain an optimized physical model.The simulation results and functional relationships of electrical length,dielectric constant and return loss are used as references to simulate the experimental environment and provide parameter guidance for process preparation and actual testing.3.Because platinum and ceramics have good performance in high temperature and high pressure environments,platinum slurry has high practical value for ceramic-based microwave sensors.The thick film technology combined with the screen printing process is used to complete the preparation of the sensor,and the influence of the sensitive factor on the sensor is used to establish the relationship between the sensitive factor and the resonant frequency of the sensor.Among them,the crack antenna sensor adopts the detection principle of the patch antenna,which can carry out high-sensitivity testing of the cracks of the metal device,and is expected to be produced in large quantities in engineering;the temperature antenna sensor uses a wireless passive LC circuit structure.Compared with the traditional LC circuit structure,this design adopts a planar structure in which the sensitive capacitor is separated from the inductor at the signal receiving end,thereby increasing the service life of the sensor.4.Use network analyzer,precision translation platform,high temperature muffle furnace,etc.to build two sets of test platforms to test and verify the prepared antenna sensor.The results show that the resonant frequency of the crack detection sensor decreases with the increase of cracks.For metal cracks with a width of less than 2mm,the minimum sensitivity is 72MHz/mm.When the coupling distance between the external antenna and the sensor in the temperature sensor is 10 mm,the reading effect is the best.In the temperature range of100℃-1500℃,the resonance frequency of the sensor decreases regularly with the increase of temperature,and the highest sensitivity of measurement is 7KHz/℃,and the lowest is 2KHz/℃.