A state-of-the-art review on drag reduction has been presented in order to bring out some important aspects of the drag reduction phenomenon and its potential for practical use. The review is biased towards micellar systems and discusses in detail the morphological differences between drag reducing polymeric and micellar systems. Work relating to polymeric systems has not been dealt in detail as it has been the subject of earlier reviews. Studies relating to biological additives as well as suspensions have been briefly mentioned without detailed discussion as their potential for practical use presently appears] to be limited.

A review on drag reduction with special reference to micellar systems

A comprehensive study of the rheological properties of aqueous polyacrylamide solutions was carried out. A RheoStress RS100 Haake rheometer was used in the measurements. The concentration of polyacrylamide ranged from 0.25 to 1.0% by weight. This range is sufficiently wide to cover many of the rheological features of polyacrylamide in the lower range of concentration. The study included measurements of steady shear flow parameters, transient shear stress response, yield stress, thixotropic behavior, creep recovery, dynamic responses, and temperature effects in the range 10–50°C. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1587–1597, 1998

Rheological properties of aqueous polyacrylamide/NaCl solutions

Long-term degradation tests for dilute polymer solutions flowing turbulently in circular pipes were conducted in a closed recirculatory flow loop at room temperature. The polymeric additives used were Polyox WSR-301 and Separan AP-273 at 200 ppm wt. in deionized water. The degradation run for Separan was conducted for 730 h, which is considerably longer than any of the earlier degradation studies reported in the literature. The degradation run for Polyox was conducted for only 22 h because of the extreme sensitivity of Polyox to shear degradation. Effects of degradation on turbulent friction and heat transfer coefficients are presented. It was found that dilute Polyox solution cannot be used in recirculatory systems because it degraded completely in less than 24 h. However, dilute Separan solution did not degrade completely under a typical flow shear condition but maintained a plateau value of about 25% friction reduction after the initial rapid degradation period. The existence of a plateau for the dilute Separan solution is an important finding because it implies that this solution may be a good candidate for use in practical closed-loop thermal systems.

Degradation effects of dilute polymer solutions on turbulent friction and heat transfer behavior

Flow behavior in terms of shear stress and viscosity versus shear rate is investigated for aqueous solutions of Alcoflood polymer materials. Rheostress RS100 is employed for operating, measuring, and analyzing this experimental investigation. Polymer concentration in the range of 100–10,000 ppm was covered. Fitting analysis is carried out for all the examined polymer solutions. Casson and Ostwald-de-Waele correlations can be employed for predicting flow behavior, depending upon polymer type. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2896–2904, 2002

Flow behavior of enhanced oil recovery Alcoflood polymers

The effects of viscoelastic fluid on the cavitation inception and development within a centrifugal pump: An experimental study

Apparent viscosity over a range of 106 s−1 in shear rate and first normal stress difference functions for dilute drag‐reducing solutions of Separan AP‐30 in distilled water were measured for both freshly prepared and shear‐degraded solutions, for concentrations from 100 to 500 wppm. A nonlinear integral constitutive equation is proposed which accurately represents these data, and the effects of concentration and shear degradation on the properties (e.g., the model parameters) is shown. Shearing has a greater effect on the low shear viscosity of these solutions than it has on the elastic properties, resulting in a greater degree of drag reduction for the sheared than the fresh solutions.

Hsun‐Fu David Chang

Papers

Effect of Shear Degradation on the Rheological Properties of Dilute Drag‐Reducing Polymer Solutions