Simulation And Optimization Of The Effect Of Typical Flow - Blocking Components On Ultrasonic Flowmeter Performance

Best-possible accurate measurement and effective control have become more strigent to ensure profitability in the process of flow measurement.Ultrasonic flow meters’non-contact measurement, high repeatability, wide breadth of measurement, simple testing methods and easy installation enable a more advanced and widely used approach compared with conventional flow meters.In fact,the ultrasonic flow meters can not be configured fully to meet the flow development length demands of site-specific requirements limited by space and cost in the field with all kinds of choked flow elements.Thus, ultrasonic flow meters performance must be affected as the inlet fluid is notanideal fluidflow when reach the flow meters. The paper mainly focuses on optimization on ultrasonic flow meters used in the situation of confinedspaceinstallation to achieve sustained stability and reliability.Throughout the paper, theoretical analysis, field experiment and CFD numerical simulation methods are brought in that highlight the features discussed.(1)The measurements reported here therefore provide a case study from a gas distribution station in Nanjing allowing for installation restrictions. Choose the standard k-s turbulence model in FLUENT for the numerical simulation according to the installation structure. Compare the simulation results with the experimental results which get from the same pipe section with the same throughput. The experimental flow rate is estimated to be0.16%-3.73%by indication error compared with simulation results, consistent with the simulation results, which will be refered to verify the feasibility and reasonalibity of CFD numerical simulation. It can be easily concluded that the gas distribution station in Nanjing configuration conditions can not meet the demands of site-specific requirements and flow development length range.(2)Take a series of experiment on site under non-chokedconditionsin order to get benchmark results for follow up studies; Set up geometric models consists of two kinds of common choked flow elements and respectively simulate those two kinds segment using FLUENT.Compare the above results from the following3aspects within the scope of measurement:Ideal flow pattern and non-ideal flow pattern (installed with choked flow elements); The same Reynolds number wih different diameters; Different size of choked flow elements In addtion, analyze its effect on the distribution of gas velocity field and the measurement performance of ultrasonic flow meter.The results demonstrate that portal tracts have higher disturbance intensity on gas velocity field than reducing pipe. There is no Law of Similitude in the downstream of portal tracts, and contrasitively Law of Similitude can be found in the downstream ofreducing pipe. The most significant disturbance on gas velocity field is portal tracts of DN300X2600among the different size of choked flow elements.(3)A impoved rectifier is introduced to solve the above problemsand put forward flow adjustment assessment methodsas well as evaluate optimum scheme using CFD numerical simulation. Analyze measurement performances of ultrasonic flowmeter under the following 3different conditions:With portal tracts; Non-choked flow element benchmark experiments; With portal tracts and rectifier.The results suggest that gas velocity field in the downstream of portal tracts and rectifier is ideal and indication error of simulation flow rate trends to be steady when portal tracts DN300X2600exsits in the upstream of flow meter and the length of straight pipe in the downstream of rectifier is greater than8D.Also,flow rate indication error’s variation trends are typically the same with when consider the portal tracts and rectifierexperiment with benchmark experiments.The error is0.03%-0.2%. Both flow rate indication error comply withtheminimum performance requirementof ultrasonic flow meters prove the rectifiercomprehensively.