Research Of The Method On Wetness Measurement With Micro-strip Gap Resonator

Steam turbine plays a significantly important role within the development of the power sector. To make sure that power can be transmitted constantly to the electricity equipment, steam turbine must function steadily and timelessly. Therefore, to measure the humidity of wet steam accurately is especially important in the steam turbine. Among various methods of testing humidity, the method of humidity measurement by microwave resonant cavity perturbation in becoming mature is applied in actual measurement. Based on present researches of this method, the method of humidity measurement by micro-strip resonant aimed at the disadvantages of metal cylindrical cavity is put forward in this thesis. The humidity sensor made in this method is simple in structure, small in size, light in weight and easy to make. It is an attempt of measuring the humidity of wet steam.First, relations among humidity, temperature, frequency and complex dielectric constant are the focuses of this study. Then, structural characteristics and equivalent circuit of micro-strip line are studied to make a tentative study on the method of measuring the humidity of wet steam. Finally, according to the size of the micro-strip line and the dielectric properties of wet steam, I determined the ideally resonant frequency in this article, chose the port of the simulation model, and determined the parameters of the micro-strip gap resonator. I simulated micro-strip line resonator with the Ansoft HFSS 13.0, and built half-wavelength resonator with open-circuit line and ring micro-strip resonator. To make sure that resonator can meet the requirements of resonance, the article discusses the S parameters of two kinds of structure, and optimize structural parameters. Adjusting the dielectric constant of wet steam in the shielding box and observing the data results, in order to analyze whether frequency offset in two kinds of micro-strip structure can meet the measuring demand of wet steam. The result shows that micro-strip gap resonator meets the theoretical demand and it is can be used to measure humidity of wet steam in steam turbine.