To monitor the velocity of industrial exhaust gas continuously,a parallel double-path flow velocity measurement system was designed,and the related theories on measuring the velocity of stack gas flow was studied based on the light scintillation.A simple phase-screen technique was used to analyze the light scintillation in a turbulent medium,and the expression of optical scintillation cross-correlation was obtained which is used to measure stack gas flow velocity.The path-weighting function of the mean velocity was given.The numerical simulation carried on path-weighting function indicates that it has axially symmetric distribution as Gaussian line shape,and the central velocity of the stack makes greater contribution.The impact of light source spectrum on path-weighting in principle was analyzed,and the preliminary experiments show that,although because the light source spectrum has a certain bandwidth,the path-weighting function has changed,the distribution is still axially symmetric.Based on the path-weighting function,the space distribution of the gas flow velocity in stack can be calculated.
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