Turbulence energy and intensity spectra in a baffled, stirred vessel

The radial components of the turbulence energy and intensity spectra within a stirred, baffled tank are measured with a transducer probe of the type developed by Eagleson et al. (9). The spectra are normalized because absolute levels of the intensity in these high intensity velocity fields cannot be measured with the present technique. Average velocities are also measured with Pitot and Prandtl tubes. Range of measured energy and intensity spectra was 19 to 1,100 cycles/sec. The measured energy spectra show a k−5/3‐relation in the low wave number range where the wave number k is less than 100 ft.−1 and a k−10/3‐relation in the wave number range of 100 to 1,000 ft.−1. This behavior is found regardless of impeller size, motor speed, and position in tank, in particular radial distance, indicating that the decay of energy spectra is self‐preserving. Increasing the viscosity from 0.80 to 103 centipoises results in a progressively steeper slope in the high wave number range. The shape of the intensity spectra is the same as that of the concentration spectra measured by Manning (26, 27).