Characteristics Simulation And Optimization Onthe Flow Field Of U-channel Ultrasonic Flowmeter With A Flow Conditioner

Flow field distribution characteristics on the measuring pipe is the key issue for themeasuring reliability of ultrasonic flowmeter(USFM). With the title “CharacteristicsSimulation and Optimization on the Flow Field of U-channel Ultrasonic Flowmeter with aFlow Conditioner”,the thesis focuses on structure parameter analysis and optimization of flowvelocity stability on the ultrasonic track of U-channel USFM and analysing method forrectifying effect of flow conditioner based on computational fluid dynamics(CFD),whichleads to the progress of design and optimization for USFM. Thesis has important academicvalue and practical significance on developing of ultrasonic measuring study and Subject ofMeasuring and Controlling.Measuring mechanism of USFM are summarized and systematically analyzed;meanwhile, the research situation of measuring performance optimization technology forUSFM and flow field analysis and optimization technology for flowmeter base on CFD,isdiscussed in the thesis.The thesis content is determined combining with the demand of flowadaptability analysis for U-channel USFM and practical significance of the flow conditionerapplications. The main work includes the following parts:①The overall procedure of flow field simulation is presented,CFD numerical simulationmechanism and flow state, flow control equation are introduced.The measuring mechanismand structure features of U-channel USFM is discussed, meanwhile, structure parameterissues that influencing flow velocity stability on the ultrasonic track are analysed. Frameworkof characteristics simulation and optimization on the flow field of U-channel USFM with aflow conditioner is arisen.②Flow field distribution is obtained by using CFD tool-FLUENT simulation softwareand the flow rate correction coefficient-K is arisen for judging flow velocity stability on theultrasonic track.Structure parameter issues such as middle pipe diameter-D,middle pipelength-L1,spacing of ultrasound reflecting device and the middle pipe inlet-L2and the shapeof diffluence hole,which may influence flow velocity stability on the ultrasonic track,are analysed respectively based on FLUENT. The structure optimized USFM-model A isobtained.③Based on the analysis of USFM inlet flow field stability improving effect caused byflow conditioner，judgement method for rectifying effect of flow conditioner based on CFD isproposed which including stability of flow pipe cross-section judgement method and judgestandard of rectifying effect-Lmin. Calculation procedure of the judgement mehod is presentedaccording to the contrast verification of two different flow conditioner model-model I andmodel II using CFD tool.It’s of important reference value using this judgement method fordesign and optimization of flow conditioner.④Flow velocity stability on the ultrasonic track of the structure optimized USFM-model A is studied under different conditions of inlet velocity aim at obtaining the optimalultrasonic channel selection.Meanwhile, the flow velocity stability on the ultrasonic track ofmodel A with prepositive flow conditioner model I and model II are analysed respectively soas the judgement method for rectifying effect of flow conditioner is proved to be feasible.Flow field of U-channel USFM with a flow conditioner is studied and the structureparameter dimensions are changed so as the flow field distribution is optimized.The CFD testresults show that: flow velocity stability on the ultrasonic track of the USFM is significantlyimproved while D=15mm,L1=32mm,L2=12mm and the diffluence hole is enlarged.It’sproved that prepositive flow conditioner has a remarkable effect on improving flow velocitystability on the ultrasonic track and the judgement method is feasible on design andoptimization of flow conditioner.