Pressure Fluctuation Measurements In Dilute Polymer Solutions

Measurements of the fluctuating total head in the wake of a flat plate are described with ejection of a dilute polymer solution near the leading edge of the plate. A turbulence probe, consisting of a total-head tube with piezoelectric crystal gage, was specially designed, fabricated and calibrated for this purpose. Turbulence intensities and spectral density distributions were calculated from the measurements, which were made across the wake at a fixed distance downstream of the trailing edge of the plate. The results indicated that the non-dimensionalized profiles of local mean velocity and turbulence intensities in the wake with polymer ejection, are similar to those without any ejection. The shapes of the local spectral density distributions of the turbulent energy over the range of frequencies tested (25-500 cps), are also similar with and without polymer ejection. The total turbulent energy in the wake decreases when polymer solution is ejected and the reduction in total turbulent energy varies with polymer concentration similarly to the reduction in drag on the flat plate. (Author).