Pipe Flow Facility Research Articles

Drag Reduction in Flow of Coal-Oil Suspensions

Pipe flow characteristics of coal-oil mixtures (C.O.M.) are studied by a pipe flow facility consisting of a Tri-Rotor positive displacement pump, which draws fluid from a reservoir tank and discharges through a pipeline at regulated pressures. Pipe flow tests are carried out to study the drag reduction effect of the polymer carboxymethylcellulose (CMC) on the flow of coal-oil mixtures. Addition of CMC reduces friction drag on the average by 10 percent. Preliminary results are presented covering appropriate ranges of operating parameters (coal concentration and temperature) which influence the drag reduction. A brief discussion will evaluate the significance of these results.

Measured Discrimination of Boundary-Layer Pressure Fluctuations by Round, Square, and Rectangular Transducers

Pressure fluctuations obtained in a turbulent air pipe flow facility were measured using 19 flush-mounted transducers that varied in size and shape. The results of these measurements, in the form of spectral density, were then compared with the results obtained using a modified theory on transducer size correction originally proposed by Corcos [J. Acoust. Soc. Amer. 35, 192–199 (1963)]. The modification, by White [J. Acoust. Soc. Amer. 41, 1358–1363 (1967)], consisted of using the measured transducer response kernel. Agreement between the experimental data and theoretical predictions was good. In the midfrequency range, transducers that had their longest dimension parallel to the flow produced the greatest discrimination against pressure fluctuations. At high frequencies, the response becomes a function of size and independent of shape, as predicted.

Longitudinal Space-Time Correlation Function in Turbulent Airflow

The longitudinal space-time correlation function of the fluctuating pressures at the wall in turbulent flow has been measured in the U. S. Navy Underwater Sound Laboratory'a 3.5-in. turbulent pipe-flow facility. Measurements in octave and half-octave frequency bands at zero time delay and at various spatial separations of the transducers are presented and compared with theoretical investigations to illustrate the effect of finite filter bandwidths on the longitudinal space-correlation function.