Turbulent Drag Reduction Effect by Hydrogen and Oxygen Microbubbles Made by Electrolysis

2006 ◽  
Author(s):  
Xinlin Lu ◽  
Hiroharu Kato ◽  
Takafumi Kawamura
Keyword(s):  
Drag Reduction ◽  
Void Fraction ◽  
Bubble Diameter ◽  
Water Electrolysis ◽  
Air Injection ◽  
Air Bubbles ◽  
Turbulent Drag Reduction ◽  
Circulating Water ◽  
Turbulent Drag ◽  
Reduction Effect

Turbulent drag reduction by very small hydrogen microbubbles was investigated experimentally. The method for generating microbubbles of 10–60 μm by water electrolysis was established firstly. Experiments were carried out using a circulating water tunnel, and it was observed that the small microbubbles generated by electrolysis can achieve the same drag reduction as the injected air bubbles at much lower void fraction. The distribution of microbubble was examined using the microscope photography. The peak of local void fraction was found to be very close to the wall, while no correlation was found between the average bubble diameter and the distance from the channel wall. The present experimental results suggest that the very small microbubbles produced by electrolysis are 10∼100 times more effective in terms of the drag reduction than large bubbles made by air injection. So it is considered that the diameters of microbubbles play an important role to drag reduction.

Turbulent Drag Reduction by Hydrogen Microbubbles Made by Electrolysis

2007 ◽  
Author(s):  
Takahisa Endo ◽  
Hiroharu Kato ◽  
Xinlin Lu
Keyword(s):  
Drag Reduction ◽  
Void Fraction ◽  
Water Electrolysis ◽  
Experimental Results ◽  
Air Injection ◽  
Air Bubbles ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag

Turbulent drag reduction realized by hydrogen microbubbles was investigated experimentally. A method of generating microbubbles of 10–60μm diameter by water electrolysis was established. Experiments were performed using a water circulating tunnel. Microbubbles generated by electrolysis can achieve the same drag reduction as the injected air bubbles at a much lower void fraction. The present experimental results suggest that microbubbles produced by electrolysis are 10∼100 times more effective in terms of drag reduction than large bubbles generated by air injection. Thus, it is considered that the diameters of microbubbles play an important role in drag reduction.

0304 Turbulent Drag-Reduction Effect by Blowing Polymer Solution from a Wall using Discrete-Element Model

2009 ◽  
Vol 2009 (0) ◽  
pp. 157-158
Author(s):  
Masahiko KOSHI ◽  
Kaoru IWAMOTO ◽  
Akira MURATA ◽  
Yasuo KAWAGUCHI ◽  
Hirotomo ANDO ◽  
...  
Keyword(s):  
Drag Reduction ◽  
Polymer Solution ◽  
Element Model ◽  
Discrete Element ◽  
Discrete Element Model ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag ◽  
Reduction Effect

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.

scholarly journals Turbulent Drag Reduction. Effect of Implanted Fiber.

1996 ◽  
Vol 62 (596) ◽  
pp. 1383-1387 ◽  
Author(s):  
Takashi TAKATA ◽  
Keiji KYOGOKU ◽  
Tsunamistu NAKAHARA
Keyword(s):  
Drag Reduction ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag ◽  
Reduction Effect

scholarly journals Fibre-induced drag reduction

2008 ◽  
Vol 602 ◽  
pp. 209-218 ◽  
Author(s):  
J. J. J. GILLISSEN ◽  
B. J. BOERSMA ◽  
P. H. MORTENSEN ◽  
H. I. ANDERSSON
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Reynolds Number ◽  
Drag Reduction ◽  
Elastic Layer ◽  
Turbulent Drag Reduction ◽  
Rigid Polymer ◽  
Fibre Concentration ◽  
Induced Drag ◽  
Turbulent Drag

We use direct numerical simulation to study turbulent drag reduction by rigid polymer additives, referred to as fibres. The simulations agree with experimental data from the literature in terms of friction factor dependence on Reynolds number and fibre concentration. An expression for drag reduction is derived by adopting the concept of the elastic layer.

Sign in / Sign up

Export Citation Format

Share Document