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CROSS-STACK OPTICAL CONVOLUTION VELOCIMETER DEVELOPMENT AND EVALUATION OF A BREADBOARD DESIGN
Citation:
Rudd, M. CROSS-STACK OPTICAL CONVOLUTION VELOCIMETER DEVELOPMENT AND EVALUATION OF A BREADBOARD DESIGN. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/2-79/192.
Description:
A new type of instrument has been designed and evaluated for the measurement of a line average of a stack gas velocity. The light output from a lamp is collimated and projected across the stack. A shadowgraph image of the turbulence in the stack is produced on the far side and this image is convected by the stack gas flow. A grating is placed over the image and the light transmitted falls on a photodetector. The frequency output from the photodetector is the rate at which the shadow graph image crosses the grating. A breadboard design of this cross-stack optical convolution velocimeter (OCV), as it is called, was built and evaluated over a wide range of environmental conditions. Agreement between the OCV and a corrected pitot tube was within 1.3% (root mean square error). Position sensitivity of the OCV was extensively studied and a configuration was found that is completely insensitive to position. Laboratory tests showed that the cross-stack OCV is an effective, accurate velocity monitoring instrument that is simple to build and operate.