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

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.

1403 Turbulent-Drag Reduction of Polymer Solution and Observation of Microscopic Structure by Freeze Dry

2011 ◽  
Vol 2011.86 (0) ◽  
pp. _14-3_
Author(s):  
Yusuke KATO ◽  
Ibuki IIDA ◽  
Katsushi FUJITA ◽  
Nobuyoshi KAWABATA ◽  
Takashi OHTA
Keyword(s):  
Drag Reduction ◽  
Polymer Solution ◽  
Microscopic Structure ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag

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

Experimental Study on Turbulent Drag Reduction and Polymer Concentration Distribution With Blowing Polymer Solution From the Channel Wall

2010 ◽  
Author(s):  
Masaaki Motozawa ◽  
Taiki Kurosawa ◽  
Hening Xu ◽  
Kaoru Iwamoto ◽  
Hirotomo Ando ◽  
...  
Keyword(s):  
Experimental Study ◽  
Drag Reduction ◽  
Polymer Solution ◽  
Concentration Distribution ◽  
Channel Wall ◽  
Polymer Concentration ◽  
Channel Height ◽  
Wall Region ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag

Experimental study on turbulent drag reduction (DR) and polymer concentration distribution with blowing polymer solution from whole surface of the channel wall was carried out. A set of measurements for drag reduction were performed with blowing rate for the sintered porous metal plate (0.45m × 0.45m × 3) adjusted from 0.5 L/min to 4.0 L/min, and concentration of polymer solution varied from 10 ppm to 200 ppm. Reynolds number based on the channel height was chosen for 20000 and 40000 in this experiment. The polymer concentration distribution in the near-wall region (0.5 mm < y < 20 mm) at three locations of the downstream from the leading edge of the blower wall was also measured. Polymer concentration can be analyzed via Total Organic Carbon (TOC) analyzer. Through the analysis of mass transfer by polymer concentration distribution, we found that polymer which exists in buffer layer (10 < y+ < 70) has important influence on drag reduction.

scholarly journals 0305 Turbulent Drag Reduction with Blowing Polymer Solution from the Wall

2009 ◽  
Vol 2009 (0) ◽  
pp. 159-160
Author(s):  
Masaaki Motozawa ◽  
Kaoru Iwamoto ◽  
Hirotomo Ando ◽  
Tetsuya Senda ◽  
Yasuo Kawaguchi
Keyword(s):  
Drag Reduction ◽  
Polymer Solution ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag

scholarly journals Prediction of Drag Reduction Rate in Turbulent Channel Flow Based on BP Neural Network

2020 ◽  
Vol 194 ◽  
pp. 05049
Author(s):  
Yuchen Cao ◽  
Yongwen Yang
Keyword(s):  
Neural Network ◽  
Drag Reduction ◽  
Polymer Solution ◽  
Channel Flow ◽  
Bp Neural Network ◽  
Reduction Rate ◽  
Turbulent Channel Flow ◽  
Solution Concentration ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag

The technology of turbulent drag reduction by viscoelastic additives cannot be widely applied in practical engineering due to the difficulty in judging the effect of drag reduction. To solve this problem, the experiment of drag-reducing channel flow of polymer solution was carried out based on the comprehensive analysis of the factors affecting the drag reduction rate. Abundant drag reduction rate data were obtained. A three-layer BP neural network prediction model was established with polymer solution concentration, Reynolds number and injection flow rate as input parameters. Based on the test results, the prediction accuracy on drag reduction rate of the model was analysed. The prediction and model validation of drag reduction rate are carried out further according to the historical data in literature. The results show that the predicted drag reduction rate of BP neural network is close to the real drag reduction rate in the drag-reducing flow of polymer solution. The prediction is with high accuracy and with good generalization ability. It is expected to be applied to practical projects and to promote the development of turbulent drag reduction technology by additives.

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