Polyox WSR Research Articles

Flow of dilute polymer solutions about circular cylinders

Experiments on fully attached flows of aqueous solutions of Polyox WSR-301 and pure solvent (tap and distilled water) about circular cylinders were carried out in the range 5 × 104<Re< 3 × 105for the initial purpose of providing definitive experimental information on drag reduction with additives in external flows.During the course of the investigation, a critically degraded polymer solution was observed to cause, at a particularRe, an unforseen instability in the separation line, similar to that first observed by Brennen (1970 in fully developed cavity flows. This instability, which most easily manifest edit self in the form of an abrupt drag-force jump (here called a drag crisis) from a high subcritical to a low supercritical value, became the central issue in the investigation. Efforts to isolate the causes of this instability led to further experiments with suspensions of nearly neutrally buoyant spherical and non-spherical particles. The measurements have shown that fibres and polymer hasten transition, spherical particles do not appreciably affect the characteristics of the flow and that neither the spherical particles nor fibres give rise to a drag crisis.

Diffusivity of oxygen in a non-Newtonian saline solution

The mass transport of oxygen to a rotating disc has been measured in a non-Newtonian saline solution using electrochemical polarization techniques. The diffusivity has been obtained from a comparison of the experimental results with the theoretical expression for the mass flux of Hansford and Litt. Results are presented for Polyox WSR301 concentrations varying from 0 to 10 000 parts per million by weight.

Some Storage and Shear History Effects on Polymeric Friction Reduction

The drag reducing properties of two dilute polymer solutions were studied using a simple turbulent pipe flow apparatus under various conditions of storage and mechanical degradation. Aqueous solutions of Polyox WSR-301 (polyethylene oxide) and Separan AP-30 (polyacrylamide) were prepared at 500 ppmw (parts per million by weight) and then diluted into weak concentrations for storage and testing on a day-by-day basis. At concentrations of 10, 25, 50 and 100 ppmw, aged samples showed the same peak effectiveness as freshly prepared ones. However, the aging process reduced the ability to resist mechanical degradation. Anomalies were found in which solutions tend to partially recover from shear degradation under certain conditions, and in other cases tend to improve their friction-reducing efficiency after continuous shearing. Experimental results suggest that entanglement or aggregation of polymer molecules could be one of the important mechanisms involved in friction reduction.

Stability studies in pipe flows unsing water and dilute polymer solutions

AbstractThe response of water and 20 ppm. solutions of Separan AP‐30 and Polyox WSR 301 to the periodic motion of a thin sleeve was measured using a laser Doppler velocimeter. The sleeeve was moved in an axial direction by an external coupling at frequencies from 1/4 to 1.O Hz and at amplitudes of 1/2 to 2 in. The flow filed downstream of the distrbance was found to consist of three regions: 1. a near field with a separation wake from the sleeve moving toward the piep centerline; 2. an intermediate field in which alternate laminar and turbulent slugs passed a point; and 3. a far field with decaying turbulent lfow. Defferences in the behavior of water flows and polymer flows appeared in each region. In the near field, wakes spread faster in water flows. In the intermediate field, the laminar slugs disappeared into turbulence more rapidly in water flows. And in the far field, the turbulence was not as developed in the polymer flows.Detailed statistical evaluations were made on the signals in each region for a Reynolds number of 2000. The response of the dilte polymer polymer solutions appeared to be governed by the initial interaction with the sleeve. Fewer high frequencies were generated than in the pure solvent so the periodic disturbance persisted downstream. In pure water the eddies from the separation wake interacted strongly with the periodic distrurbance leading to rapid decay of the periodic portion. Shear rates were not high enough to attribute the dilute polymer differences to viscoelastic effects.

Transition of Mixtures of Polymers in a Dilute Aqueous Solution

Data are presented for the flow of deionized water solutions of linear, unbranched polymers—Separan AP-30, Polyox WSR-35 and Polyox WSR-301, and mixtures of the latter two in a 0.0235 in. tube. The Reynolds numbers vary from about 1200 to about 12,000. Measurements were made at 4 deg C and near room temperature. Occurrence of transition is confirmed by oscillograph traces and pressure ratio calculations in addition to the usual “break” on a friction factor-Reynolds number graph. From the calibration data, it appears that for small tubes there is a critical parameter, such as molecular weight or polymer length, below which transition occurs as for water, but above which the transition Reynolds number depends on polymer concentration. The low and high polymers were mixed to vary molecular weight distribution of samples. It was found that the higher molecular weight polymer dominates the transition process, but in the turbulent regime the effects are roughly additive.

Heat Transfer Characteristics of Dilute Polymer Solutions in Fully Rough Pipe Flow

DILUTE polymer solutions which exhibit detectable elastic effects can produce large reductions of fractional drag over fully rough surfaces in the absence of any viscous sublayer1. We have carried out some heat transfer experiments with polyethylene oxide (Union Carbide Polyox WSR301) solution in a rough bore pipe and derived some interesting results.

Molecular Model of Drag Reduction by Polymer Solutes

TOMS1 has shown that in turbulent flow above the critical Reynolds number the drag is substantially reduced by adding a small amount of high polymer solute to the liquid2–14. In some cases, there is also a remarkable shift of the onset of turbulence to higher Reynolds number15,16 with a corresponding reduction of drag. Typical drag reductions of over 50 per cent have been achieved in pipes, on immersed moving bodies and on ship hulls by the addition of 20 p.p.m. by weight of ‘Polyox WSR 301’, which is an unbranched polyethylene oxide of approximate molecular weight 4 × 106. Larger doses of polymer solute produce little additional effect. A minor effect of this type—about 4 per cent drag reduction—can also be achieved by the addition of a relatively large amount of very fine sand17–19.

Effects of Shear Treatment on Drag-reducing Polymer Solutions and Fibre Suspensions

NUMEROUS workers have put forward models which attempt to explain the complex behaviour of drag reducing polymer solutions, but no explanation has been universally accepted. The ability of apparently identical batches of a polymer to give widely varying results has now been ascribed to variations in mixing procedures, though apparently no systematic investigation of the reason for such behaviour has been made. In the experiments reported here, concerning drag reduction in ‘Polyox WSR 301’ solutions and asbestos fibre dispersions, attention is focused on the differences in behaviour in large and small bore pipes and the changes in this behaviour brought about by shear thinning treatment.

Design, in vitro and in vivo Evaluation of Gemifloxacin Mesylate Floating Matrix Tablets

Objective of the investigation was to develop gastro retentive dosage form of gemifloxacin mesylate for local action in the stomach as it has antibacterial activity against Helicobacter pylori. Gemifloxacin mesylate is a synthetic broad-spectrum antibacterial agent for oral administration, having 7 hrs half-life and 71% oral bioavailability. In present study, gemifloxacin mesylate floating matrix tablets were prepared by direct compression method using polymers (HPMC K4M, HPMC K15M and polyox WSR 1105) and evaluated for various parameters like drug content, floating behavior (floating lag time and total floating time), in vitro drug release, swelling index, weight variation, friability, hardness and thickness. Sodium bicarbonate was incorporated as gas generating agent in all formulations. Drug-excipients compatibility was studied by Differential Scanning Calorimetry. Results have shown that the amount of polymer in the formulation affected the drug release. Optimized formulation (F8 containing polyox WSR1105 as release retarding agent) was selected based on in vitro drug release, floating lag time, floating time and other parameters. This formulation followed zero order kinetics and non-Fickian mechanism of drug release. In vivo radiographic study was conducted in healthy human volunteers using tablets containing BaSO4 as radio opaque agent. The average residence time was found to be 4.5± 0.86 h (n=3). This design of gastro retentive drug delivery system helps in increasing the local delivery of drug in patients with Helicobacter pylori infection

Turbulent and Transition Pipe Flow of Dilute Aqueous Polymer Solutions

The addition of minute quantities of high molecular weight polymers to water can produce a large reduction in the turbulent pipe flow friction. A laser-Doppler instrument for measuring local velocity is used to study transition and turbulent pipe flow of a 50-WPPM aqueous solution of Polyox WSR 301 (polyethylene oxide) at the center of a 14-mm diam pipe. The addition of the polymer to water does not significantly alter the level of the longitudinal turbulence intensity at the center line over the range of Reynolds numbers studied. A surprising result of polymer addition occurs below a Reynolds number of 2,500 in the region of the hump. The increased relative band widths of the frequency spectra in this region imply an uncertainty in the fluid velocity. This result, together with the observed concurrent decrease in the ratio of center line to bulk velocity relative to pure water, shows that the flow is no longer of the steady Poiseuille type after the addition of Polyox WSR 301. The absence of spikes from the frequency spectra further implies that the flow is not intermittent in the sense that laminar and turbulent slugs are alternately passing the point of measurement. At these Reynolds numbers,more » the flow is probably laminar but unsteady. (18 refs.)« less

Grid Turbulence in Dilute Polymer Solutions

THE effect of long-chain polymer additives on turbulent water flows has been widely studied1–5 because it lessens hydrodynamic drag. For this reason past efforts have been centred principally on flow in pipes6–9, the boundary layers on immersed moving bodies10,11 and ship hulls12. Typically drag reductions of over 50 per cent have been achieved in pipes by the addition of 20 parts per million by weight (w.p.p.m.) of ‘Polyox WSR 301’, which is an unbranched chain molecule of approximate molecular weight 4 × 106. Larger doses produce little additional effect. The effect of polymer additives on “free-stream” turbulence has not received much attention, and there is conflicting evidence whether the turbulent structure is affected at all in the absence of the shear associated with boundary layer flows. On the one hand Virk et al.6, studying flow at the centreline of a pipe carrying a 1,000 w.p.p.m, ‘Polyox’ solution, found only slight modification of the normal turbulence structure while Gadd13, on the other hand, observed eddy suppression in an unconfined turbulent jet expansion.

Drag of Spheres in Dilute High Polymer Solutions

WHITE1 showed that the drag on spheres in water, at Reynolds numbers exceeding the critical value (vd/ν > about 2 × 105), could be increased by dissolving a very small quantity of polyethylene oxide (Union Carbide ‘Polyox WSR301’) in the water, and suggested that this effect resulted from suppression of turbulence in the boundary layer by the additive, which caused earlier separation and a corresponding increase in the wake size.

Turbulent Flow of Dilute Aqueous Polymer Solutions

This paper summarizes some of the research into the effect of polymer additives on turbulent shear flow, which was conducted at the University of Liverpool between October, 1964, and October, 1966. The paper contains a brief description of the research together with a summary of the principal results and conclusions. The present work was devoted to a detailed examination of the mechanism of a particular flow by gathering information on friction drag, velocity distribution, concentration distribution, and correlation with Reynolds number and polymer concentration level. The particular flow chosen was the fully developed turbulent flow in a 2-in-dia pipe of Polyox WSR-301 solutions. A maximum drag reduction of 71 percent was obtained at a Reynolds number of 1.5 × 105 for solutions having polymer concentration of 10 weight parts per million. The drag reduction effect occurred only above some “critical” Reynolds number which was independent of concentration. The polymer additives were found to influence the flow in the neighborhood of a solid boundary. In this zone of the flow, the eddy viscosity was found to be much lower than that of water. In the absence of a boundary, as in free jet flow, the polymer additives had no effect on the flow characteristics. The experiments showed for the first time that the polymer molecules were uniformly distributed across the pipe diameter under all turbulent flow conditions investigated. A method of determining polymer concentration was devised for this purpose.