Effect of Dilute Solutions of Drag-Reducing Additives on Wall Pressure Fluctuations

Download or read book Effect of Dilute Solutions of Drag-Reducing Additives on Wall Pressure Fluctuations written by R. R. Walters and published by . This book was released on 1970 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments were conducted in a pipe flow facility to determine the effect of drag-reducing polymer additives on turbulent wall pressure fluctuations. The wide-band and power spectral measurements of wall pressure fluctuations for water were in good agreement with measurements presented in the literature. The power spectra of the wall pressure fluctuations for water taken at three different velocities were found to coincide when nondimensionalized with centerline velocity and pipe diameter. Wall pressure fluctuation data were obtained for two different polymer additives at four different concentrations (100 and 1000 wppm Polyhall (P-295) and 85, 100, and 200 wppm Polyox (WSR-301)). The ratio of the wide-band root-mean-square wall pressure to the dynamic pressure remained approximately the same for the Polyhall solutions as for water while the ratio for Polyox solutions was slightly less than water for most velocities. Spectral data showed reductions in the magnitude of the wall pressure fluctuations up to 20 dB for frequencies greater than 2000 Hz for both polymer solutions as compared to water. For the higher frequencies (2-10 kHz) the reductions varied in magnitude from 7 to 16 dB/octave for different additive concentrations. Degradation of the polymer solutions was systematically shown to decrease the effectiveness of reducing the magnitude of the high frequency wall pressure fluctuations. (Author).