scholarly journals Research Progress on the Collaborative Drag Reduction Effect of Polymers and Surfactants

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 444 ◽  
Author(s):  
Yunqing Gu ◽  
Songwei Yu ◽  
Jiegang Mou ◽  
Denghao Wu ◽  
Shuihua Zheng
Keyword(s):  
Drag Reduction ◽  
Reynolds Numbers ◽  
Research Progress ◽  
Polymer Additives ◽  
Factors Affecting ◽  
Mechanism Model ◽  
Reduction Effect ◽  
Reduction Characteristics ◽  
Degradation Properties ◽  
Degradation Ability

Polymer additives and surfactants as drag reduction agents have been widely used in the field of fluid drag reduction. Polymer additives can reduce drag effectively with only a small amount, but they degrade easily. Surfactants have an anti-degradation ability. This paper categorizes the mechanism of drag reducing agents and the influencing factors of drag reduction characteristics. The factors affecting the degradation of polymer additives and the anti-degradation properties of surfactants are discussed. A mixture of polymer additive and surfactant has the characteristics of high shear resistance, a lower critical micelle concentration (CMC), and a good drag reduction effect at higher Reynolds numbers. Therefore, this paper focuses more on a drag reducing agent mixed with a polymer and a surfactant, including the mechanism model, drag reduction characteristics, and anti-degradation ability.

scholarly journals A Study of Drag Reduction on Cylinders with Different V-Groove Depths on the Surface

Water ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 36
Author(s):  
Jiyang Qi ◽  
Yue Qi ◽  
Qunyan Chen ◽  
Fei Yan
Keyword(s):  
Drag Reduction ◽  
Drag Coefficient ◽  
Vortex Structure ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Reynolds Numbers ◽  
Groove Surface ◽  
Smooth Cylinder ◽  
Groove Structure ◽  
Reduction Effect

In this study, the drag reduction effect is studied for a cylinder with different V-groove depths on its surface using a k-ω/SST (Shear Stress Transport) turbulence model of computational fluid dynamics (CFD), while a particle image velocimetry (PIV) system is employed to analyze the wake characteristics for a smooth cylinder and a cylinder with different V-groove depths on its surface at different Reynolds numbers. The study focuses on the characteristics of the different V-groove depths on lift coefficient, drag coefficient, the velocity distribution of flow field, pressure coefficient, vortex shedding, and vortex structure. In comparison with a smooth cylinder, the lift coefficient and drag coefficient can be reduced for a cylinder with different V-groove depths on its surface, and the maximum reduction rates of lift coefficient and drag coefficient are about 34.4% and 16%, respectively. Otherwise, the vortex structure presents a complete symmetry for the smooth cylinder, however, the symmetry of the vortex structure becomes insignificant for the V-shaped groove structure with different depths. This is also an important reason for the drag reduction effect of a cylinder with a V-groove surface.

scholarly journals Effect of SDBS on the drag reduction characteristics of polyacrylamide in a rotating disk apparatus

2015 ◽  
Vol 4 (3) ◽  
pp. 326 ◽  
Author(s):  
Hayder A. Abdul Bari ◽  
Zainab Yousif ◽  
Zulkefli Bin Yaacob ◽  
Edward Oluwasogaakindoyo
Keyword(s):  
Drag Reduction ◽  
Rotating Disk ◽  
Reynolds Numbers ◽  
Aggregate Structure ◽  
Surfactant Micelle ◽  
Micro Particles ◽  
Transmission Electron ◽  
Speed Up ◽  
Reduction Characteristics

<p>This paper focuses on the determination of the interaction between polymer (Polyacrylamide (PAM)) and surfactant (Sodium dod benzene sulfonate (SDBS)) as a drag reducer using Rotating Disk apparatus (RDA) at various concentrations (500, 700, 1000, 1500 and 2000) ppm individually and in the combined form under turbulent conditions at different rotation speed up to 3000 rpm, as well as studying their mechanisms as a drag reducer. The results show that the maximum percent drag reduction increases to (40, 41, 43, 45 and 48)% by using the combined additives of surfactant and polymer at the above concentrations respectively, with slower degradation and display drag reduction for a larger range of Reynolds numbers. The nano and micro particles formed from the combined PAA and SDBSA was studied using cryo-transmission electron microscopy (cryo-TEM) techniques. The images show the surrounding of polymer chain to the surfactant micelle to form an aggregate structure. A hexagonal crystalline form was suggested to describe the shape of the aggregate structure.</p>

scholarly journals Experimental Study on Drag Reduction Characteristics of Bionic Earthworm Self-Lubrication Surface

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Guomin Liu ◽  
Xueqiao Wu ◽  
Meng Zou ◽  
Yuying Yan ◽  
Jianqiao Li
Keyword(s):  
Drag Reduction ◽  
Flow Rate ◽  
Experimental Testing ◽  
Reduction Rate ◽  
Normal Pressure ◽  
Secondary Effects ◽  
Quadratic Regression ◽  
Regression Test ◽  
Reduction Effect ◽  
Reduction Characteristics

In the present study, a coupling bionic method is used to study the drag reduction characteristics of corrugated surface with lubrication. In order to test the drag reduction features, bionic specimen was prepared inspired by earthworm surface and lubrication. Based on the reverse engineering method, nonsmooth curve of earthworm surface was extracted and the bionic corrugated sample was designed, and the position of lubrication hole was established by experimental testing. The lubricating drag reduction performance, the influence of normal pressure, the forward velocity, and the flow rate of lubricating fluid on the forward resistance of the bionic specimens were analyzed through a single factor test by using the self-developed test equipment. The model between the forward resistance and the three factors was established through the ternary quadratic regression test. The results show that the drag reduction effect is obvious, the drag reduction rate is 22.65% to 34.89%, and the forward resistance decreases with the increase of the forward velocity, increases with the increase of the normal pressure, and decreases first and then becomes stable with the increase of flow rate of lubricating fluid. There are secondary effects on forward resistance by the three factors, and the influencing order is as follows: normal pressure>flow rate of lubricating fluid>forward velocity.

Numerical Research about Drag-Reduction Characteristic of Riblet Structure on Aerofoil Blade of Centrifugal Fan

2013 ◽  
Vol 655-657 ◽  
pp. 105-108 ◽  
Author(s):  
Song Ling Wang ◽  
Rui Rong ◽  
Xiao Fei Hao
Keyword(s):  
Drag Reduction ◽  
Smooth Surface ◽  
Design Flow ◽  
Wall Region ◽  
Centrifugal Fan ◽  
Mean Velocity ◽  
Numerical Research ◽  
Reduction Effect ◽  
Fan Blade ◽  
Reduction Characteristics

The drag reduction characteristics of riblet structure on aerofoil blade of centrifugal fan were numerically simulated with Fluent. Riblet structure still has good drag reduction effect on the surface of aerofoil blade. The best drag reduction effect has been gotten with appropriate riblet structure size, with the greatest drag reduction efficiency of 9.65%. And under the design flow of the fan, the drag can be reduced by 2.96%. The mean velocity of near-wall region on riblet surface has a significant increase than smooth surface. Turbulent kinetic energy and turbulent intensity are lower than smooth surface obviously, the drag reduction effect of riblet structure on aerofoil blade is verified. The present results can be used to provide a valuable reference for optimization of centrifugal fan blade modification.

scholarly journals Polymers and Plastrons in Parallel Yield Enhanced Turbulent Drag Reduction

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 197 ◽  
Author(s):  
Anoop Rajappan ◽  
Gareth H. McKinley
Keyword(s):  
Drag Reduction ◽  
Couette Flow ◽  
Turbulent Flows ◽  
Polymer Additives ◽  
Frictional Drag ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag ◽  
Reduction Effect ◽  
Friction Measurements ◽  
Wall Bounded Turbulence

Despite polymer additives and superhydrophobic walls being well known as stand-alone methods for frictional drag reduction in turbulent flows, the possibility of employing them simultaneously in an additive fashion has remained essentially unexplored. Through experimental friction measurements in turbulent Taylor–Couette flow, we show that the two techniques may indeed be combined favorably to generate enhanced levels of frictional drag reduction in wall-bounded turbulence. We further propose an additive expression in Prandtl–von Kármán variables that enables us to quantitatively estimate the magnitude of this cooperative drag reduction effect for small concentrations of dissolved polymer.

Diffusion of a Tangential Drag-Reducing Polymer Injection on a Flat Plate at High Reynolds Numbers

1976 ◽  
Vol 20 (03) ◽  
pp. 171-180 ◽  
Author(s):  
Daniel H. Fruman ◽  
Marshall P Tulin
Keyword(s):  
Drag Reduction ◽  
Flat Plate ◽  
Concentration Distribution ◽  
Reynolds Numbers ◽  
Polymer Injection ◽  
High Reynolds Numbers ◽  
Pure Solvent ◽  
Reduction Effect ◽  
High Reynolds ◽  
Drag Reducing Polymer

The diffusion of a thin tangential jet of an aqueous solution of drag-reducing polymer injected into the water-turbulent boundary layer of a flat plate at a freestream Reynolds number, 3.6 × 107, and the accompanying drag reduction are investigated for a variety of initial concentrations and ratios of injection to freestream velocities. The concentration distribution along the wall is found to be mainly represented by two regions. In the first region the wall concentration is practically constant and equal to the injected one; in the second region the concentration varies approximately as the inverse of the distance from the injection slit. The length of the first region is significantly increased by the polymer solution injection as compared with the pure solvent injection. The drag-reduction effect associated with the polymer injection depends on the trailing-edge concentration achieved as a result of the diffusion process.

Numerical Analysis of Drag Reduction Characteristics of Biomimetic Puffer Skin: Effect of Spinal Height and Tilt Angle

2021 ◽  
Vol 21 (9) ◽  
pp. 4615-4624
Author(s):  
Hong-Gen Zhou ◽  
Chang-Feng Jia ◽  
Gui-Zhong Tian ◽  
Xiao-Ming Feng ◽  
Dong-Liang Fan
Keyword(s):  
Drag Reduction ◽  
Tilt Angle ◽  
Fluid Velocity ◽  
Viscous Drag ◽  
Total Drag ◽  
Pressure Drag ◽  
Reduction Efficiency ◽  
Distribution Parameters ◽  
Reduction Effect ◽  
Reduction Characteristics

Based on the migratory phenomenon of the puffer and the cone-shaped structures on its skin, the effects of spinal height and tilt angle on the drag reduction characteristics is presented by numerical simulation in this paper. The results show that the trend of total drag reduction efficiency changes from slow growth to a remarkable decline, while the viscous drag reduction efficiency changes from an obvious increase to steady growth. The total and viscous drag reduction efficiencies are 19.5% and 31.8%, respectively. In addition, with the increase in tilt angle, the total drag reduction efficiency decreases gradually; the viscous drag reduction efficiency first increases and then decreases, finally tending to be stable; and the total and viscous drag reduction efficiency reaches 20.7% and 26.7%, respectively. The flow field results indicate that the pressure drag mainly originates at the front row of the spines and that the total pressure drag can be effectively controlled by reducing the former pressure drag. With the increase in low-speed fluid and the reduction in the near-wall fluid velocity gradient, the viscous drag can be weakened. Nevertheless, the drag reduction effect is achieved only when the decrement of viscous drag is greater than the increment of pressure drag. This work can serve as a theoretical basis for optimizing the structure and distribution parameters of spines on bionic non-smooth surfaces.

scholarly journals Noise Reduction Effect of Superhydrophobic Surfaces with Streamwise Strip of Channel Flow

2021 ◽  
Vol 11 (9) ◽  
pp. 3869
Author(s):  
Chen Niu ◽  
Yongwei Liu ◽  
Dejiang Shang ◽  
Chao Zhang
Keyword(s):  
Reynolds Number ◽  
Drag Reduction ◽  
Noise Reduction ◽  
Channel Flow ◽  
Superhydrophobic Surface ◽  
Sound Field ◽  
Flow Noise ◽  
Slip Boundary ◽  
Eddy Simulation ◽  
Reduction Effect

Superhydrophobic surface is a promising technology, but the effect of superhydrophobic surface on flow noise is still unclear. Therefore, we used alternating free-slip and no-slip boundary conditions to study the flow noise of superhydrophobic channel flows with streamwise strips. The numerical calculations of the flow and the sound field have been carried out by the methods of large eddy simulation (LES) and Lighthill analogy, respectively. Under a constant pressure gradient (CPG) condition, the average Reynolds number and the friction Reynolds number are approximately set to 4200 and 180, respectively. The influence on noise of different gas fractions (GF) and strip number in a spanwise period on channel flow have been studied. Our results show that the superhydrophobic surface has noise reduction effect in some cases. Under CPG conditions, the increase in GF increases the bulk velocity and weakens the noise reduction effect. Otherwise, the increase in strip number enhances the lateral energy exchange of the superhydrophobic surface, and results in more transverse vortices and attenuates the noise reduction effect. In our results, the best noise reduction effect is obtained as 10.7 dB under the scenario of the strip number is 4 and GF is 0.5. The best drag reduction effect is 32%, and the result is obtained under the scenario of GF is 0.8 and strip number is 1. In summary, the choice of GF and the number of strips is comprehensively considered to guarantee the performance of drag reduction and noise reduction in this work.

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