Measurements of Turbulence Characteristics in Water and in Dilute Polymer Solutions

Measurements of turbulence characteristics were made inside a boundary layer in external flow of water and in water with polymer additives of the Polyox type. Flush mounted hot-film sensors and wedge, parabolic, and cylindrical sensors were used to measure the turbulent velocity fluctuations. Graphs are given of energy density, dissipation, turbulence shear correlation spectra, and microscale of turbulence distribution. Tests were run in an open channel flow at one Reynolds number and two rates of polymer injection to give 20 and 40 ppm average concentration in the boundary layer. The results indicate that the advent of the quartz insulated hot-film sensor permits many useful measurements to be made in conducting liquids. The general application has to be, however, carefully considered since the calibration in liquids with impurities or with additives, especially drag reducing polymers, is still a very difficult and uncertain procedure. The most reliable results available at present are the ones obtained from the data arranged in the form of a ratio of two measurements thus cancelling out the calibration factors. Even so a direct quantitative comparison cannot be made between measurements in water and in polymer without accurate calibration of the hot-film sensors, which is not yet possible