Numerical Simulation And Design Of Fluidic Flowmeter For Small Flow

Flow rate is an important parameter in the process of industrial production. Flowmeters are widely used in human production and life. With the rapid development of social industry, the emergence of a variety of complex working conditions put forward new requirements for flowmeters. Comparing with other flowmeters, fluidic flowmeter has outstanding advantages that its measurement limit is very low and it can work under harsh conditions. So it has great application value.However, the measurement limit of the existing fluidic flowmeter is much higher than the theoretical value in paractical engineering application. And it lacks of criteria guiding of structural parameters design and optimization design. These shortages limit its application range. Therefore, the fluidic oscillator of small gas flow rate is taken as research object, and the method combining theoretical research, simulation analysis and experimental verification is adopted, in order to explore the principles of flow measurement with jet flow technology, and develop a kind of fluidic flowmeter used for small gas floe rate measurement. Main work done is as follows.(1) The Coanda effect of jet flow was studied. The flow characteristics of three models with tip stream splitter, concave stream splitter, and no stream splitter were simulated with FLUENT respectively. The jet deflection characteristics of concave stream splitter model affected by shoulder distance and splitter distance were analyzed.(2) Combining with the jet flow device characteristics, fluidic oscillator models with concave stream splitter and no stream splitter were designed. The jet flow oscillation characteristics of the two models were compared by numerical simulation. According to the comparison results, fluidic oscillator model with on stream splitter was determined to be experimental model. And the detection method of symmetry differential pressure signal has been put forward.(3) On the basis of numerical simulation results, the integral structure of fluidic flowmeter was designed, including flow totalizer, display device, and mechanical structure, so that the intelligent display can be realized.(4) Experimental platform was built to test the designed fluidic flowmeter. The experimental results show that the velocity of the gas in the pipeline is proportional to the jet flow oscillation frequency within a certain range. While the flow velocity varies in a range of15-50L/min, the fluidic flowmeter has good linearity and stable meter coefficient.