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 velo...