부산대학교 도서관

Small pitot tubes are known to give erroneous results when used in dilute polymer solutions. Large errors were noted by Smith et al. for partially degraded polyethylene oxide solutions and by Astarita and Nicodemo for fresh Dow ET 597 solutions. Friehe and Schwartz showed that the errors could be small when large diameter pitot tubes were used. The influence of velocity and terminal relaxation times is reported. Although the polymer terminal relaxation time, the fluid velocity, and the pitot tube diameter have been shown to affect the measurements, the exact dependence on these variables is still unknown. The onset of pitot tube errors in fresh and degraded solutions of Polyox WSR 301 was found to be related to drag reduction onset. A linear dependence of the pressure error on strain rate, U/D, also is noted.