Research On The Surface Acoustic Wave Strain Sensor Applied To Gas Pipeline

Surface acoustic wave(SAW) strain sensor is widely used in a variety of measurement environment, especially in some extreme environment, such as that used in the deformation monitoring for the gas pipeline. Gas pipeline transportation of flammable gas, exist for a long time the deformation of pipe gas explosion hazard, SAW strain sensor has, the characteristics of high precision and passive. It can accurately measure gas pipeline surface of small deformation, and avoid introduce security risks in the inflammable and explosive places, may better solve the gas pipeline deformation monitoring problem.Based on the surface acoustic wave sensor technology research, corresponding to gas pipeline SAW strain sensor are studied:Using finite element analysis method, We constructs the simulation model of surface acoustic wave pressure piezoelectric substrates. Based on the perturbation theory, we analysis to calculate the strain sensitivity of deferent cut of the piezoelectric substrate.According to the calculation results, we selected a cut of the substrate which has high sensitivity of strain and low temperature sensitivity. We fabricated the IDT and the reflecting grating on the surface of substrate, and experiment to test the strain sensitivity of the substrate. The experimental results and the theoretical analysis results matched. It verified the accuracy of the simulation results.A temperature compensation of substrate was designed to compensation the additional strain caused by changes in temperature compensated strain measurement process. Before and after the temperature compensation of strain sensor for comparative testing experiments,the results show that the compensated sensor can effectively eliminate the interference temperature and strain measurement effectively.The sensor metal enclosure was research and optimization, through the test of a variety of metal shell structure. Finally we selected a kovar alloy made straight walled metal case.It can protect the sensor in does not reduce the premise of strain sensitivity.Sensors and acquisition circuit and PC software were system, so that the sensor system achieve the rapid and stable strain measurement and data acquisition. It can collect the real-time display on the visual interface, make more suitable for long-term strain monitoring.The sensor system was tested for consistency, reproducibility and accuracy. After a long time test the reliability of the sensor was verified. Sensor was installed and tested in the Beijing Gas Group gas pipeline. After long-term strain monitoring and data acquisition,the monitoring result and experience the value of phase contrast verified the surface acoustic strain sensor used on the feasibility of gas pipeline deformation monitoring.