Dual Bluff Body Vortex Flowmeter Test

The vortex flowmeter based on measurement of the hydrodynamic vibration generated by the vortex shedding was emerged in the early 70's. Since it has the advantages of no moving components, good linearity, wide measurement range and strong medium adaptability, vortex flowmeter could be used into accurate measurement in different type of fluid. Beside, low-pressure drop across the meter also results in low energy cost. The benefits includes aslo high reliability, low maintenance, and insensitivity for fluid composition, temperature, density, pressure and other factors. Therefore, it is wide accepted that the vortex flowmeter is the ideal flowmeter in the measurement of gas, fluid, steam and mix/cankerous fluid.However, the vortex flowmeter has its own disadvantages! such as poor noise immunity in low flux, low-flowrate sensitivity and adhesion of the sensor surface that affects the meter sensitivity. In order to overcome those defects, lots of work has been done in the recent years. A number of the methods have been developed to improve the performance of vortex flowmeter. For instance, the dual bluff body configurations are tested to strengthen the hydrodynamic vibration, and the differential sensing technique is used to suppress the interferential signals. These works will improve the practicability of the dual bluff body vortex flowmeter greatly.Jn this thesis, the author's contributions can be summarized as follaw:The thesis introduced the history and the actuality of the flowmeter, explained the theory of the vortex flowmeter and outlined the advantage and disadvantage of the vortex flowmeter.The thesis brought out the designing method and choosing principle of the test system component, and introduced composition of test device.Through the plenty of the experiment based on the optimize designing of the one bluff body, the article gave the result of optimizing combination of the bluff body by analyzing the St number and vortex intensity angle, and pointed out the contribution of the bluff body combination to the performance of the vortex flowmeter, and the thesis provided also the method to improve the linearity of the vortex flowmeter. The sensor location and the distance between the two bluff bodies were experimentally optimized. At the same time, the experimental results show that the method of the isolate elasticity has little effect on the anti-jamming performance of the dual bluff body vortex flowmeter.Finally, the thesis provied the best combination of the dual bluff body. That is when the two bluff bodies have the same width and the distance between them is same to the distance L between the two array of the vortex, the vortex flowmeter achieved the maximum intensity of hydrodynamic vibration.