Research On Testing Technology Of Displacement Variation Resonance Method

With the development of science and technology, the requirement of the aviation engine is constantly improving. Tip displacement variation is an important parameter of engine; it will have a great impact on the engine’s work safety and performance. Therefore, the study of tip displacement variation automatic test can provide the technical basis and foundation for the improvement of engine design, the determination of the optimum gap, the research engine tip clearance automatic control technology and engine failure prediction.In this paper, it analyzes the research status of engine blade tip displacement variation test method at home and abroad, lists the different displacement variation test principle, and based on the advantages and disadvantages of various test methods and test requirements of the system, finally chooses microwave resonance method to test the displacement variation. Based on the basic principle of dielectric resonator, 01TEdmode dielectric resonator sensor was designed to work at 4~6GHz. In order to carry out the relevant test experiment of the engine blade, we developed a set of engine rotor model. According to the deduced algorithm, the corresponding test software is written in C++ programming language, so that it can achieve automatic, simple and rapid test. Taking the dielectric resonance sensor as the core, the heating device, the circulating water cooling system, the automatic temperature measuring device, the engine rotor drive system and other components are combined to form a set of displacement variation measurement system of dielectric resonator method, which can work at room temperature ~500℃.In this paper, we have made the following improvements and innovations: first, in order to achieve the demand for testing, the single-ended short-circuited dielectric resonator is developed as a sensor, which is applied to the measurement of displacement variation. Compared with the traditional method, it has the advantages of strong energy storage and good stability, and it has the advantages of miniaturization, light weight and high test precision compared with the microwave resonant cavity; second, the displacement variation is measured by the microwave resonance method, in essence, it is based on the interaction between the relative position of the measured object and the electromagnetic wave. Therefore, based on the field distribution of the dielectric resonator, the formula for calculating the displacement variation is derived by the shift of the resonant frequency.The test system has been used to complete the relevant test of tip displacement variation. The test error of the test results is analyzed, the corresponding error sources are found, and the error formula of displacement variation is given.The testing index:Temperature: room temperature ~ 500℃Frequency: 4~6GHzTesting range:0~5mmTest accuracy:0.02mmTest error:Indoor temperature: DL/ L ≤2.0%High temperature(500℃): DL/ L ≤4.4%...