Research On The Performance Of Turbine Flowmeter Under Different Fluid Conditions

Turbine flowmeter is a kind of velocity-type flowmeter with advantages of high accuracy, good repeatability, wide flow range, and small volume. So it is widely applied in chemical industry, petroleum, metallurgy, light industry, food industry and other flow industry. Because the industry field conditions for turbine flowmeter working is complex, and the flow regime is diversity, it is significant for extending the application field of turbine flowmeter to research on the performance of turbine flowmeter under different flow conditions.The main research works of this dissertation are as following:1. The index number of virtual velocity profile of mixed fluid in the annulus pipe was presented. Based on the analysis of the influence for bubble of mixed fluid to blade by the drag force, the mathematic model of measuring gas-liquid two-phase bubble flow with turbine flowmeter was established. The curve between the index number of virtual velocity profile and gas volume fraction were obtained. The validity of mathematic model was verified by experiments.2. Based on the mixture model, the numerical simulation on gas-liquid two-phase bubble flow (GVF<10%) in a turbine flowmeter was investigated. According to the conclusion of flow field analysis, a method, which can evaluate the performance of turbine flowmeter by simulative value of meter factor variation, was put forward. The rotor's structure of existed flowmeter was improved. It was showed by physical experiment that the performance of the improved meter was better than that of existed meter. The validity of the method of improving design for turbine flowmeter was verified.3. The object function was the minimum of linearity errors of the measurement range. According to four characteristic parameters, the turbine flowmeter's mathematic model and the multivariable nonlinear programming algorithm, a method was presented for reducing the linearity error of a turbine flowmeter. The turbine flowmeters of 50 mm and 25 mm caliber were optimized. The turbine flowmeter with optimal rotor and existed rotor were evaluated on a water flow calibration facility. Through the comparisons of linearity error between the meters with optimal rotor and the meter with existed rotor, the validity of the design reducing the linearity error of turbine flowmeter was verified. 4. Five kinds of turbulence model, S-A model, standard k-εmodel, RNG k-εmodel, Realizable k-εmodel and standard k-ωmodel were applied separately to numerically simulate a turbine flowmeter for measuring liquid. The comparisons between the numerical results and the data of physical experiment showed that standard k-ωmodel was more suitable for 3D numerical simulation on the internal flow fields of the turbine flow sensor and the prediction of the meter factor.5. Three turbine flowmeters, with different lead of rotors, were investigated to measure horizontal gas-liquid two-phase bubble flow on the gas-liquid two-phase flow facility. Results showed that the characteristics curve, measurement relative error and repeatability error were clearly changed with the variation of gas volume fraction. The performance of turbine flowmeter with smaller lead of rotor was better than those of the other two flowmeters. The reasons of the change of measurement performance and error were analyzed and discussed. The physical mechanics that the turbine flowmeter measurement performance was affected by gas volume fraction was also analyzed.