Prediction of Drag Reduction Effect of Pulsating Control in Turbulent Pipe Flow by Machine Learning

2019 ◽  
Author(s):  
Wataru Kobayashi ◽  
Takaaki Shimura ◽  
Akihiko Mitsuishi ◽  
Kaoru Iwamoto ◽  
Akira Murata
Keyword(s):  
Machine Learning ◽  
Drag Reduction ◽  
Reduction Rate ◽  
Automatic Measurement ◽  
Turbulent Pipe Flow ◽  
Working Fluid ◽  
Circulation System ◽  
Validation Data ◽  
Acceleration And Deceleration ◽  
Reduction Effect

Abstract It has been widely expected that the pulsating control can reduce friction drag in various fluid systems. In order to maximize its effect, a prediction tool of drag reduction using pulsating control is required. The present study aims at the prediction of the drag reduction rate by machine learning. Multilayer perceptron (MLP) was applied as the machine learning method. Water was used as the working fluid. First, an automatic measurement system was constructed and drag reduction effect was evaluated by an experiment with various pulsation waveforms. The flow pulsation was generated by giving periodical acceleration and deceleration by a centrifugal pump in a closed circulation system. The bulk Reynolds number Reb ranges between 3400 and 3800. Next, the experiments were performed with over 5000 kinds of waveforms to make training and validation data for MLP. Within the data, the maximum drag reduction rate of 38.6% was observed. The friction coefficient Cf decreased during the acceleration period and increased during deceleration period. Finally, the drag reduction rate was predicted in three cases with different input parameters of MLP. The relationship between pulsation waveforms and the drag reduction effect was successfully predicted.

LDV Measurement of Turbulent Pipe Flow With Traveling Wavy Elastic Wall for Drag Reduction

2019 ◽  
Author(s):  
Seiya Nakazawa ◽  
Takaaki Shimura ◽  
Akihiko Mitsuishi ◽  
Kaoru Iwamoto ◽  
Akira Murata
Keyword(s):  
Drag Reduction ◽  
Pipe Flow ◽  
Reduction Rate ◽  
Streamwise Velocity ◽  
Turbulent Pipe Flow ◽  
Deformation Control ◽  
Wall Deformation ◽  
Maximum Drag Reduction ◽  
Reduction Effect ◽  
Ldv Measurement

Abstract Drag reduction effect by traveling wavy wall deformation control in turbulent pipe flow was experimentally investigated. From the visualization, we confirmed the downstream traveling wave although it was not uniform in the circumferential direction. When the frequency is 110 Hz, the wall deformation amplitude and the wavelength indicated that the effective values for drag reduction. The wavespeed is approximately effective values for drag reduction. As a result, the maximum drag reduction rate of 6.8 % is obtained. The result of a LDV measurement shows that the mean streamwise velocity gradient decreased near the wall by the control, which leads to drag reduction.

scholarly journals An investigation on the drag reduction performance of bioinspired pipeline surfaces with transverse microgrooves

2020 ◽  
Vol 11 ◽  
pp. 24-40 ◽  
Author(s):  
Weili Liu ◽  
Hongjian Ni ◽  
Peng Wang ◽  
Yi Zhou
Keyword(s):  
Numerical Simulation ◽  
Drag Reduction ◽  
Pressure Loss ◽  
Fluid Transport ◽  
Reduction Rate ◽  
Orthogonal Analysis ◽  
Maximum Drag Reduction ◽  
Reduction Effect ◽  
Save Energy ◽  
Microgrooved Surface

A novel surface morphology for pipelines using transverse microgrooves was proposed in order to reduce the pressure loss of fluid transport. Numerical simulation and experimental research efforts were undertaken to evaluate the drag reduction performance of these bionic pipelines. It was found that the vortex ‘cushioning’ and ‘driving’ effects produced by the vortexes in the microgrooves were the main reason for obtaining a drag reduction effect. The shear stress of the microgrooved surface was reduced significantly owing to the decline of the velocity gradient. Altogether, bionic pipelines achieved drag reduction effects both in a pipeline and in a concentric annulus flow model. The primary and secondary order of effect on the drag reduction and optimal microgroove geometric parameters were obtained by an orthogonal analysis method. The comparative experiments were conducted in a water tunnel, and a maximum drag reduction rate of 3.21% could be achieved. The numerical simulation and experimental results were cross-checked and found to be consistent with each other, allowing to verify that the utilization of bionic theory to reduce the pressure loss of fluid transport is feasible. These results can provide theoretical guidance to save energy in pipeline transportations.

Experimental Study on Drag-Reduction Effect of a New Sinusoidal Riblet

2012 ◽  
Author(s):  
Monami Sasamori ◽  
Kaoru Iwamoto ◽  
Akira Murata
Keyword(s):  
Experimental Study ◽  
Drag Reduction ◽  
Flat Surface ◽  
Reynolds Shear Stress ◽  
Three Dimensional ◽  
Reduction Rate ◽  
Physical Mechanisms ◽  
Image Velocimetry ◽  
Reduction Effect ◽  
Riblet Surface

An experimental study of a new three-dimensional (3-D) riblet has been carried out. The lateral spacing of our 3-D riblet surface is sinusoidally varied in the streamwise direction (see Fig. 3). In the comparison of the optimal two-dimensional (2-D) blade riblet which shows 9.9% drag reduction rate [1], the riblet height, thickness and averaged lateral spacing are respectively 0.83, 5 and 2.5 times larger than those of the optimal 2-D riblet in wall units. The net drag reduction rate of 11.7% has been confirmed in a low-speed wind channel at the bulk Reynolds number of 3400. The flow structure over the 3-D riblet mounted a wall was also analyzed in the velocity field by using 2-D Particle Image Velocimetry and was compared with the corresponding flow over the flat surface in an attempt to identify the physical mechanisms for the drag reduction. The normal turbulent intensities on the present riblet are almost same as those of the flat surface, whereas the Reynolds shear stress is much decreased, and especially becomes negative near the riblet height. These are different phenomena from those of all the previous riblets [1–7].

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.

Drag Reduction Effect of Turbulent Pipe Flow with Traveling Wavy Elastic Wall

2019 ◽  
Vol 2019 (0) ◽  
pp. OS1-10
Author(s):  
Seiya NAKAZAWA ◽  
Takaaki SHIMURA ◽  
Akihiko MITSUISHI ◽  
Kaoru IWAMOTO ◽  
Akira MURATA
Keyword(s):  
Drag Reduction ◽  
Pipe Flow ◽  
Turbulent Pipe Flow ◽  
Elastic Wall ◽  
Reduction Effect

scholarly journals Fabrication of Zinc Substrate Encapsulated by Fluoropolyurethane and Its Drag-Reduction Enhancement by Chemical Etching

Coatings ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 377 ◽  
Author(s):  
Yuanzhe Li ◽  
Zhe Cui ◽  
Qiucheng Zhu ◽  
Srikanth Narasimalu ◽  
Zhili Dong
Keyword(s):  
Drag Reduction ◽  
Superhydrophobic Surface ◽  
Chemical Etching ◽  
Flow Resistance ◽  
Reduction Rate ◽  
Low Flow ◽  
Rolling Angle ◽  
Standard Design ◽  
Reduction Effect ◽  
Nanoscale Roughness

A fluoropolyurethane-encapsulated process was designed to rapidly fabricate low-flow resistance surfaces on the zinc substrate. For the further enhancement of the drag-reduction effect, Cu2+-assisted chemical etching was introduced during the fabrication process, and its surface morphology, wettability, and flow-resistance properties in a microchannel were also studied. It is indicated that the zinc substrate with a micro-nanoscale roughness obtained by Cu2+-assisted nitric acid etching was superhydrophilic. However, after the etched zinc substrate is encapsulated with fluoropolyurethane, the superhydrophobic wettability can be obtained with a contact angle of 154.8° ± 2.5° and a rolling angle of less than 10°. As this newly fabricated surface was placed into a non-standard design microchannel, it was found that with the increase of Reynolds number, the drag-reduction rate of the superhydrophobic surface remained basically unchanged at 4.0% compared with the original zinc substrate. Furthermore, the prepared superhydrophobic surfaces exhibited outstanding reliability in most liquids.

Flexible Turbulence Absorbers for Enhancing the Liquid Flow in Pipelines

2014 ◽  
Author(s):  
Hayder A. Abdulbari ◽  
Rosli Bin Mohd Yunus ◽  
Ashwin Charles
Keyword(s):  
Drag Reduction ◽  
Liquid Flow ◽  
Viscoelastic Behaviour ◽  
New Technique ◽  
Circulation System ◽  
Liquid Circulation ◽  
Diameter Pipe ◽  
Flow Enhancement ◽  
Reduction Effect

In the present work, an additive-free new technique for enhancing the flow in pipelines is introduced. Such technique depends on inserting Turbulence Altering Pseudo-Surface, TAPS with certain dimensions inside the pipe (adjacent to the inner wall). Such technique is meant to simulate the viscoelastic behaviour of soluble additives to enhance the flow in pipelines. Liquid circulation system with a testing section divided into four subsections was used to test the drag reduction effect of the new technique. The results showed that almost 60% flow enhancement is achievable when inserting 12 strips with 60 cm length into 0.0381 m diameter pipe.

A tracer dispersion study of the drag-reduction effect in a turbulent pipe flow

1971 ◽  
Vol 47 (2) ◽  
pp. 209-230 ◽  
Author(s):  
A. W. Bryson ◽  
Vr. Arunachalam ◽  
G. D. Fulford
Keyword(s):  
Molecular Weight ◽  
Drag Reduction ◽  
Pipe Flow ◽  
Viscous Sublayer ◽  
Turbulent Pipe Flow ◽  
Reduction Mechanism ◽  
Response Curves ◽  
Pipe Flows ◽  
Tracer Dispersion ◽  
Reduction Effect

Remarkable differences in dispersion of a tracer material injected into turbulent pipe flows of water and water containing as little as 2·5 parts per million by weight of a soluble high-molecular-weight drag-reducing polyoxyethylene additive have been measured. Analysis of the tracer response curves in terms of a simple one-parameter model shows that the observed results are compatible with a drag-reduction mechanism based on thickening of the viscous sublayer adjoining the wall. Other experiments, reported briefly, suggest that polymer adsorption on to the wall is responsible for this thickening.

20704 Friction-Drag Reduction Effect in Pulsating Turbulent Pipe Flow with a Branch

2013 ◽  
Vol 2013.19 (0) ◽  
pp. 367-368
Author(s):  
Nobuaki IDO ◽  
Kaoru IWAMOTO ◽  
Akira MURATA ◽  
Hiroya MAMORI
Keyword(s):  
Drag Reduction ◽  
Pipe Flow ◽  
Turbulent Pipe Flow ◽  
Friction Drag ◽  
Reduction Effect ◽  
Friction Drag Reduction
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