Influence of backflow on skin friction in turbulent pipe flow

2018 ◽  
Vol 30 (6) ◽  
pp. 065104 ◽  
Author(s):  
Razieh Jalalabadi ◽  
Hyung Jin Sung
Keyword(s):  
Skin Friction ◽  
Pipe Flow ◽  
Turbulent Pipe Flow

The Combined Drag Effects of Riblets and Polymers in Pipe Flow

1993 ◽  
Vol 115 (2) ◽  
pp. 213-221 ◽  
Author(s):  
G. W. Anderson ◽  
J. J. Rohr ◽  
S. D. Stanley
Keyword(s):  
Drag Reduction ◽  
Skin Friction ◽  
Pipe Flow ◽  
Guar Gum ◽  
Rough Surfaces ◽  
Turbulent Pipe Flow ◽  
Low Concentration ◽  
Friction Effect ◽  
Low Concentrations ◽  
Riblet Surface

The additional skin friction effect produced by a 3M riblet surface, used in conjunction with low concentration polymer solutions, is investigated in fully developed, turbulent pipe flow. Generally at the low concentrations of Polyox 301 and guar gum studied, the absolute drag reduction of the 3M riblets appears to be independent of the polymer presence, with a maximum between 5 and 7 percent occurring around h+ = 12. Comparisons with previous polymer studies with 3M riblets, sand roughened and commercially rough surfaces are made.

Drag Reduction Characteristics of Solutions of Macromolecules In Turbulent Pipe Flow

1964 ◽  
Vol 4 (03) ◽  
pp. 203-214 ◽  
Author(s):  
J.G. Savins
Keyword(s):  
Pressure Drop ◽  
Pressure Gradient ◽  
Drag Reduction ◽  
Skin Friction ◽  
Boundary Layers ◽  
Pipe Flow ◽  
Single Phase ◽  
Turbulent Pipe Flow ◽  
Turbulent Motion ◽  
Flow Rates

Abstract Certain types of macromolecules added to otter and salt solutions flouting in turbulent motion can reduce the pressure gradient. Alternatively, the volumetric capacity of a pipe for these fluids is increased by the presence of these material. Examples presented show that the drag reduction can become significant. Thus, the presence of 0.28 per cent of a gum derivative in a solution of sodium chloride flowing at 200 gal/min in a 1.89- in. pipe yields a pressure drop which is 0.44 of the single-phase drop measured under the same conditions of turbulent flow; the addition of 0.1 per cent of a vinyl derivative to a 1-in. water line yields a through put capacity which is 1.78 of the single-phase capacity at the same pressure drop. It is further shown that these phenomena are distinctly different from previous observations with other classes of non-Newtonian systems. There a simple lowering of friction factors below the levels predicted from the resistance laws for Newtonian fluids is associated with a suppression of turbulent motion. A rational physical explanation for drag reduction is advanced. Briefly, the proposed mechanism is a storage by the molecular elastic elements of the macromolecules in solution of the kinetic energy of the turbulent motion. Introduction This study was inspired by a recent review of some paradoxical drag reduction phenomena in turbulent pipe flow. Under very moderate conditions of turbulent flow, the pressure gradient necessary to pump solutions containing certain specific kinds of polymers, fibers and metallic soaps may become appreciably lower than that required to pump the solvent, i.e., water or a low-viscosity hydrocarbon, under identical flow rates in the same conduit. As shown by our review, this phenomenon of drag reduction in turbulent duct flow was first noted during the second world war, apparently arising in connection with the development of flame warfare weapons. Since that time several papers illustrating this phenomenon have appeared: Toms, Oldroyd, Agoston et al., Bundrant and Matthews, Robertson and Mason, Ousterhout and Hall, Daily and Bugliarello, Lummus, Anderson, and Fox. That there are practical applications for techniques which increase discharge or decrease the pressure necessary to transport a liquid through a pipeline is illustrated in the patents which have issued which take advantage of this peculiar phenomenon, e.g., Mysels, Dever, Harbour, and Seifert. One also finds fragmentary evidence of this effect in the data pertaining to a few of the polymeric solutions studied by Shaver and Dodge. However, these investigators were concerned with the development of friction factor vs Reynolds number correlations for a variety of non-Newtonian solutions and suspensions, rather than in a study of drag reduction. A similar kind of drag reduction effect has been observed in gases. Sproull, for example, reports that adding dust to air flowing in turbulent motion through a pipe results in a lowering of the pressure gradient at identical flow rates. There are also military applications for reducing the drag on hydrodynamic vehicles. For example, the possibility of injecting a rheologically complex fluid into the boundary layers of bodies to reduce the skin friction has been investigated by Fabula and Granville. Along somewhat different lines are the drag reduction studies of Kramer. He has shown that skin friction can be reduced by covering the surface of a vehicle with a flexible skin. The effect is apparently due to the boundary layer being stabilized by the presence of the skin. Drag reduction by means of coexisting gas and liquid boundary layers, e.g., film boiling and continuous gas injection, has been proposed by Bradfield, Barkdoll, and Byrne, Cess and Sparrow, Sparrow, Jonsson, and Eckert. Here the skin friction occurs between a vapor and a surface rather than between a liquid and a surface. There are several references in the literature to friction-factor correlations for non-Newtonian solutions and suspensions: Shaver and Merrill, Dodge and Metzner, Clapp, and Thomas. SPEJ P. 203ˆ

The Preston tube as a means of measuring skin friction

1962 ◽  
Vol 14 (1) ◽  
pp. 1-17 ◽  
Author(s):  
M. R. Head ◽  
I. Rechenberg
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Skin Friction ◽  
Pipe Flow ◽  
Large Diameter ◽  
Turbulent Pipe Flow ◽  
Pitot Tube ◽  
Diameter Pipe ◽  
Flow Similarity ◽  
Considerable Doubt

Preston's method of measuring skin friction, which makes use of a Pitot tube resting on the surface, depends upon the assumption of a region of flow similarity, adjacent to the wall, common to fully developed turbulent pipe flow and the turbulent boundary layer. Experiments performed elsewhere have cast considerable doubt on the validity of this assumption, and the present investigation was undertaken to establish whether or not it is justified.Experiments were carried out in a short length of large-diameter pipe which could either form part of a very much longer pipe, giving fully developed turbulent pipe flow, or could be preceded by a conventional contraction and screens, giving a developing turbulent boundary layer.Final results showed that for a given skin friction the Pitot tube reading was the same for both boundary layer and pipe flows, thus vindicating Preston's method and confirming the existence of a universal region of wall similarity. Initial experimental difficulties were found to be due to unexpectedly large circumferential variations in skin friction in the growing boundary layer.

Skin Friction following BLADE manipulation in a turbulent pipe flow

1993 ◽  
Vol 15-15 (4-5) ◽  
pp. 274-278 ◽  
Author(s):  
B. C. Khoo ◽  
Y. T. Chew ◽  
Y. A. Mah
Keyword(s):  
Skin Friction ◽  
Pipe Flow ◽  
Turbulent Pipe Flow

Particle Destabilization in Turbulent Pipe Flow

1989 ◽  
Vol 21 (6-7) ◽  
pp. 435-442 ◽  
Author(s):  
B. Döll
Keyword(s):  
Pipe Flow ◽  
Reaction Rate ◽  
Turbulent Pipe Flow ◽  
Cationic Polymers ◽  
Flow Conditions ◽  
Polyelectrolyte Adsorption ◽  
Charge Neutralization ◽  
Silica Suspensions ◽  
Kinetics Of ◽  
Turbulent Flow Conditions

Silica suspensions (pH = 6.8) and three different cationic polymers were used to study the kinetics of charge neutralization by polyelectrolyte adsorption. The experiments were performed in a continuous flow pipe reactor under steady state turbulent flow conditions. The charge neutralization was monitored by electrophoretic mobility (EPM) measurements of the suspended particles as a function of time after polyelectrolyte audition. The results show the dependency of the destabilization reaction rate on flow and polymer characteristics.

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