Finite disturbances were generated in a pipe containing water or a 20 ppm solution of Separan AP-30 in water by oscillating a sleeve at the wall. The sleeve amplitude in the axial direction varied from 0.5 to 2.0 inches and the frequency from 0.25 to 1.0 Hz. Downstream of the sleeve oscillations in the fluid velocity were measured with a laser Doppler flowmeter at various axial and radial positions to determine behavior at the lower frequency part of the stability curve for water. The response amplitude, phase angle and the mean velocities were measured for both fluids at Reynolds numbers from 500 to 2100. The water response was frequency dependent in the experimental range. Transitions from well defined velocity fluctuations following the disturbance frequency to random responses were noted as the frequency changed from 0.25 Hz to 1.0 Hz. The dilute polymer solutions showed reduced response amplitudes and always had well defined fluctuations indicating that the stability limit is at a higher frequency than that for water.
Berman, Neil S. and Cooper, Eugene E., "Laser-Doppler Measurements of the Decay of Velocity Fluctuations in Dilute Polymer Solutions" (1969). Symposia on Turbulence in Liquids. 41.
Symposium on Turbulence Measurements in Liquids (1969: Sep., Rolla, MO)
Chemical and Biochemical Engineering
Article - Conference proceedings
Light Transmission Techniques
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