FLOW OF DILUTE POLYMER SOLUTIONS THROUGH CURVED PIPES (2ND REPORT, PRESSURE LOSS IN 360 degree BENDS).

Experiments on flows of water and dilute aqueous solution of polyethylene oxide are carried out over the Reynolds number range of 10**3 to 5 multiplied by 10**4. Concentration of polymer solutions is varied from 1 ppm to 100 ppm. The ratios of curvature radius to pipe radius R/a are 18. 7, 34. 3 and 47. 3. Measured pressure distributions along a bend axis are classified in three types by their patterns. Flow property of each pattern is clarified by using the method of flow visualization. Drag reduction in bend flow is smaller than that in straight pipe flow. Pressure loss coefficients are correlated with the Reynolds number, the ratio of radius R/a, and the Weissenberg number. The empirical formulas presented for the bend loss coefficient are useful from an engineering viewpoint.