| 摘要 |
The velocity of a liquid jet, such as the headbox (10) jet of a paper making machine, is measured by cross-correlation of a.c. signal components produced by a pair of light beams received by a pair of photodiodes (24, 26). The light is supplied by a single source (28), an incandescent lamp, and is guided by a pair of bifurcated fiber optics mounted above the jet and spaced apart in the flow direction. The a.c. components are filtered to remove low frequencies, amplified and then analyzed in a spectrum analyzer (48). |
