Temperature and concentration influence on drag reduction of very low concentrated CTAC/NaSal aqueous solution in turbulent pipe flow
Introduction
In pipe or channel flows, a great part of the energy is lost by the friction of the fluid on the wall, especially for a turbulent flow. A major objective of a lot of works is to find a way to reduce this loss of energy. The modification of the fluid properties seems to be a promising technique for the flow in pipes. Thus, dissolving in a liquid small amounts of additives (some ppm), such as polymers or surfactants, can reduce frictional drag (drag reduction, DR) in pipe or channel flow by 70–80% in turbulent regime ([1], [2] and references therein). For industrial applications using pumping systems, such an effect leading to power saving could be beneficial.
Numerous research efforts have focused on the mechanism of drag reduction. Recent reviews [3], [4], [5] give a good overview of the drag reduction by additives. In the case of polymer additives, Lumley [6], and Seyer and Metzner [7], attributed simultaneously the DR phenomenon to the high extensional deformation rate in radial flow pattern in turbulent flows. Indeed, some drag reducing solutions are presented as non-viscoelastic fluid [8], [9], [10]. Gyr and Bewersdorf [11] suggested that the shear induced structure (SIS) is responsible for drag reduction with surfactant additives. Therefore, local shear-thickening has been explored [12]. A local action near the wall is also suspected for this kind of additive. So [13], [14] studied the impact of a wall slip. Some other questions are asked in the review paper of Drappier et al. [15]. Direct Numerical Simulations have been made during the last 15 years ([16], and cited by [3], [4], [5]). They support the hypothesis of a great elongational effect for polymer solutions. This mechanism is also suspected to be operative when micellar surfactant solutions are used ([2], [5] and references therein).
The common feature of these studies is that additive structures which impact rheological properties interact with turbulence in the flow and cause DR for specific conditions. For surfactant-counterion solutions, more or less complex micelles and chains could be formed depending on concentration and temperature [11]. Both parameters act oppositely on the size of the structure: the concentration increases the size and the temperature decreases it [17], [18]. Temperature dependence for drag reducing solutions has been investigated [19], [20], [21], [22], showing that an upper temperature limit leads to DR effect extinction. This observation could be due to an evolution from spherical micelles to rodlike shape, as reported by Zakin et al. [2] for surfactant solutions. As far as the influence of concentration is concerned, the onset of DR is obtained above the Critical Micelle Concentration (CMC). Most of the studies about DR for surfactant solution concern relatively high concentration ones (higher than 500 ppm, [11]). However, it was shown that a relatively low concentrated aqueous solution of CTAC/NaSal (less than 100 ppm) leads to an effective drag-reduction [23], [24].
Recently, it has been shown for bounded flow (rectangular channel) that the concentration influences the turbulence characteristics (vortex structures and occurrence of bursting events) even for identical levels of the macroscopic parameter characterising DR effectiveness [23]. Interactions between surfactant chains and structures turbulent flow are then strongly dependent on the temperature and the concentration. These remarks suggest that the description of the DR phenomenon for a given surfactant system and a fixed wall bounded geometry requires the identification of flow behaviour according to flow intensity and also temperature and concentration.
The present work is an experimental study which aims at characterizing the Reynolds dependence of the frictional drag for the pipe flow of aqueous CTAC/NaSal surfactant solutions. This study investigates the influence of the temperature (10–50 °C) and the concentration (25–150 ppm) on flow characteristics.
Section snippets
Measurement set-up
The experiments were performed on a horizontal closed loop system (Fig. 1). The system consists of two long linear sections (22.5 mm diameter pipe). The first one is a stainless steel pipe equipped with a differential pressure transducer connected to two pressure taps 6.2 m apart. The first pressure tap is located far enough from the pipe entrance (1.3 m) to eliminate entrance effects [25]. The fluid flow is driven by a volumetric pump from the tank. At the outlet of the pump, a pressure damper is
Results and discussion
Fig. 2 presents the friction factor versus the Reynolds number for a 75 ppm CTAC/NaSal solution flow for a temperature of 20 °C. The different flow regimes, described by Bewersdorff and Ohlendorf [24] for a high concentrated surfactant solution (930 ppm), are found in this configuration. The Onset Reynolds number ORN (first critical Reynolds numbers) is the one for which the drag reduction phenomenon begins (here about 10,600), as indicated by the end of the linear fall of the friction factor. For
Conclusions
The temperature (10–50 °C) and the concentration (25–150 ppm) effects on drag reduction of a very low concentrated CTAC/NaSal aqueous solution are investigated with experiments in a 22.5 mm pipe by measuring the linear pressure drop. From rheological measurement, it is found that the shear viscosity for the different solutions is very close to the water's viscosity for all shear rates.
There exists a DR effect in all cases, but differences appear in the range of Re for which it appears and for
References (29)
- et al.
A non-viscoelastic drag reduction cationic surfactant system
J. Non-Newton. Fluid Mech.
(1997) - et al.
Influence of surfactant concentration and counterion to surfactant ratio on rheology of wormlike micelles
J. Colloid Interface Sci.
(2001) - et al.
Direct numerical simulation of viscoelastic drag-reducing flow: a faithful finite difference method
J. Non-Newton. Fluid Mech.
(2004) - et al.
Effect of a shear-thickening rheological behaviour on the friction coefficient in a plane channel flow: a study by direct numerical simulation
J. Non-Newton. Fluid Mech.
(2007) - et al.
Réduction de la traînée avec une solution de CTAC-NaSal: Etude du glissement à la paroi en géométrie de Couette
Comptes Rendus Mécanique
(2010) - et al.
Experimental study of drag-reduction mechanism for dilute surfactant solution flow
Int. J. Heat Mass Transfer
(2008) - et al.
New limiting drag reduction and velocity profile asymptotes for nonpolymeric additives systems
AIChE J.
(1996) - et al.
Surfactant drag reduction
Rev. Chem. Eng.
(1998) Drag reduction in turbulent flow of polymer solutions
- et al.
Mechanics and predictions of turbulent drag reduction with polymer additives
Annu. Rev. Fluid Mech.
(2008)
Computational viscoelastic fluid mechanics and numerical studies of turbulent flows of dilute polymer solutions
Drag reduction by additives
Annu. Rev. Fluid Mech.
Turbulence phenomena in drag-reducing systems
AIChE J.
Drag Reduction of Turbulent Flows by Additives
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