Papers by Keyword: Gas Flow Meter

Abstract: Based on Bernoulli law, a average flow meter for short duct is usually designed with a rectifying grille, a series of sectional distributed pressure points and a large pressure-averaging vessel. As rectification is one of the key characteristics of this method, the effect of grille on rectifying is numerically simulated. The predicted results show that the grille in the 800mm×500mm section is very effective on regulating the originally disordered flow in the wind box branch duct. The velocity distribution tends to be uniform when the arrayed pitch is decreased while the rectifying effect is not closely associated with the relative location of the grille. The grille thickness plays a determining role as the rectifying becomes gradually weakened when the thickness is over 200mm. When a 5×4 grille with a thickness of 200mm is mounted at 200mm from the main duct outlet horizontally in downstream duct of the main wind box, the averaged pressure of each subsection is in good linear relation with the average gas velocity in the branch duct. The linear relationship is well maintained when the static pressure is measured at specific position and the dynamic pressure point is installed with error of 4o. This indicates that the grille-type flow meter is very reliable on measuring average gas velocity in short ducts. The application of this method on a 200MW industrial boiler shows that it possess promising potentials on optimizing combustion and emission, which could bring admirable environmental, economic and social benefits.

Abstract: In order to study the effects of velocity distribution of ultrasonic gas flow meter based on wall roughness, , a full developed turbulence model is established based on the theory of prandtl mixing length and flow loss coefficent λ has been calculated by using Colebrook friction correlation formula after analyzing time interval difference measuring method of ultrasonic flow meter. Through Matlab calculating and simulating velocity distribution in different conditions of wall roughness about the model shows and through Fluent simulating, velocity vector and pressure distribution in smooth and rough tube have been compared and analyzed. The experimental results shows that quantification of velocity distribution based on wall roughness can been solved with the model, and the analysis results have certain instructive significance to the development of ultrasonic gas flow meter.