| Flow detection plays an important role in industrial production,scientific experiment and economic accounting and it is an important part of energy measurement.At present,large diameter pipe flow detection is very extensive but most of the flow meter installation need to cut off the pipeline,which often cause inconvenience to industrial production.The traditional plug-in fiber flowmeter can not only realize the disassemblywithout cutting off the pipeline and facilitate the detection of large diameter flow but also has the advantages of good applicability and strong anti-interference ability.However of the fiber optic probe is placed inside the pipeline in the traditional design,the measured fluid cleanliness requirements are higherbased on fiber detection,which brings about a problem that the flow detection accuracyis affectedby properties of measured fluid.In this paper a plug-in vertical axis turbine fiber flow sensing detection system is designed,which improves the turbo mechanism and the reflective intensity modulation fiber optic sensor(RIM-FOS).The optical signal detection unit is designed above the pipeline to avoid the optical signal coming into contact with the direct fluid and solve theproblems thatthe detection accuracy of traditional plug-in fiber flow meter is influenced by the degree of fluid cleaning.Firstly the three-dimensional model of pipeline and turbine mechanism is established by UG software and two kinds of vertical axis turbines are designed.The two models are imported into ANSYS for fluid simulation and the simulation results of the two turbines are compared.A more optimized turbine mechanism is elected according to the simulation results,the turbine simulation coefficient k is obtained at the same time.Then the engineering drawings of the turbine are drawn by CAXA software to manufactureentities.Secondly the optical intensity modulation function of RIM-FOS is simulated by MATLAB and the actual parameter reference value of the fiber is obtained.Fiber amplifier is used as light source equipment and detectorof RIM-FOS and coaxial fiber as the probe.The optical signal is transmitted by the optical fiber amplifier and then received by the detector after reflected by the head face of the axle.The received optical signal is converted by the A/D converter module of ARM to collect the voltage signal.Thirdly the voltage signal is sent to the host computer program through the RS232 serial port and voltage and speed flow rate and flow curves or parameters are displayed by the host computer monitoring platform.Finally an experiment is built to verify the feasibility of the flow detection system.The experimental results show that the design of the turbine is reasonable and turbine has a uniform and stable rotation,which can measure the flow rate from 0.122m/s to 1.203m/s.The detection accuracy of rotate speed through reflected optical fiber is high,which can detect the maximum rotate speed of 336.13r/min.At the same time the results of real-time curve can be displayedin the host computer with good stability.In the end,the advantages disadvantages and future improvement of the system are analyzedin the conclusion part. |
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