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drag reduction via turbulent boundary layer flow control

Science China(Technological Sciences) 2017年第9期60卷 1281-1290页

作者： ABBAS Adel BUGEDA Gabriel FERRER Esteban FU Song PERIAUX Jacques PONS-PRATS Jordi VALERO Eusebio ZHENG Yao School of Aeronautics Escuela Tecnica Superior de lngenierla Aeronautica y del Espacio de la Universidad Politecnica de Madrid (ETS1.4E-UPM) Universidad Politecnica de Madrid Pza. Cardenal Cisneros 3 Madrid E-28040 Spain International Center for Numerical Methods in Engineering (CIMNE) Gran Capita s/n Campus Nord UPC Barcelona 08034 Spain Civil and Environmental Department Universitat Politecnica de Catalunya. BarcelonaTech Gran Capita s/n Campus Nord UPC Barcelona 08034 Spain Centre for Computational Simulation-UPM Scientific and Technological Park (Campus Montegancedo) 28223 Pozuelo de Alarcon Spain School of Aerospace Engineering Tsinghua University Beijing 100084 China School of Aeronautics andAstronautics Zhejiang University Hangzhou 310027 China

Turbulent boundary layer control(TBLC) for skin-friction drag reduction is a relatively new technology made possible through the advances in computational-simulation capabilities,which have improved the understanding of the flow structures of *** in micro-electronic technology have enabled the fabrication of active device systems able to manipulating these *** combination of simulation,understanding and micro-actuation technologies offers new opportunities to significantly decrease drag,and by doing so,to increase fuel efficiency of future *** literature review that follows shows that the application of active control turbulent skin-friction drag reduction is considered of prime importance by industry,even though it is still at a low technology readiness level(TRL).This review presents the state of the art of different technologies oriented to the active and passive control for turbulent skin-friction drag reduction and contributes to the improvement of these technologies.

关键词： turbulent boundary layer flow control drag reduction skin-friction drag reduction

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drag reduction characteristics of recirculation flow at rocket base in an RBCC engine under ramjet/scramjet mode

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Chinese Journal of Aeronautics 2024年第3期37卷 104-115页

作者： Menglei LI Mingbo SUN Peibo LI Daoning YANG Bin AN Yizhi YAO Jikai CHEN Taiyu WANG Jiaoru WANG Hypersonic Technology Laboratory National University of Defense TechnologyChangsha 410073China Department of Aerospace Science and Technology Space Engineering UniversityBeijing 101416China

To reduce the drag generated by the recirculation flow at the rocket base in a RocketBased Combined Cycle(RBCC)engine operating in the ramjet/scramjet mode,a novel annular rocket RBCC engine based on a central plug cone was *** performance loss mechanism caused by the recirculation flow at the rocket base and the influence of the plug cone configuration on the thrust performance were *** indicated that the recirculation flow at the rocket base extended through the entire combustor,which creates an extensive range of the"low-kineticenergy zone"at the center and leads to an engine thrust *** plug cone serving as a surface structure had a restrictive effect on the internal flow of the engine,making it smoothly transit at the position of the large separation *** model RBCC engine could achieve a maximum thrust augmentation of 37.6%with a long plug cone that was twice diameter of the inner ***,a shorter plug cone that was half diameter of the inner isolator proved less effective at reducing the recirculation flow for a supersonic flow and induced an undesirable flow fraction that diminished the thrust ***,the effectiveness of the plug cone increased with the flight Mach number,indicating that it could further broaden the operating speed range of the scramjet mode.

关键词： Rocket-based combined cycle Ramjet/scramjet mode Plug cone drag reduction k-x SST turbulent model

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drag reduction methods at solid‒liquid interfaces

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Friction 2022年第4期10卷 491-515页

作者： Min LIU Liran MA State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China

Friction drag is a nonnegligible matter when relative motion happens between solid and liquid phase,which brings many inconveniences in ship navigation,fluid transportation,microfluid devices,*** various methods have been developed focusing on friction drag *** this article,a review of several widely studied drag reduction methods is given,specially,their advantages and limitations in practical applications are ***,a comparison of different methods is made and the development prospect of drag reduction is concluded.

关键词： drag reduction microstructures superhydrophobic surfaces supercavitation polymer additives

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drag reduction and hairpin packets of the turbulent boundary layer over the superhydrophobic-riblets surface

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Journal of Hydrodynamics 2021年第3期33卷 621-635页

作者： Xin-wei Wang Zi-ye Fan Zhan-qi Tang Nan Jiang School of Mechanical Engineering Tianjin UniversityTianjin300354China Tianjin Key Laboratory of Modern Engineering Mechanics Tianjin300354China

This paper presents experimental measurements by the time-resolved particle image velocimetry(TR-PIV)for the turbulent boundary layer(TBL)over the smooth surface,the superhydrophobic(SH)surface,and the superhydrophobic-riblets(SR)surface in an open-surface recirculating water *** Reynolds number based on the wall friction velocity and the thickness of the TBL over the smooth surface is *** SH surface and the SR surface are manufactured by the laser texturing method on the smooth surface and the riblets surface,*** employing the(modified)Clauser method,a superior efficacy of the drag reduction of about 22.1%is obtained on the SR surface,while the drag reduction rate for the SH surface is about 18.7%.Comparing with the SH surface,the declining 2-order statistics in the near-wall region also indicates a significant drag reduction over the SR *** large-scale structure components extracted by the proper orthogonal decomposition are found to generate a majority of the Reynolds shear stress in the region y^(+)>*** strength of the large-scale features over the rough surfaces(SH and SR surfaces)at disparate wall-normal positions is visualized by the Quadrant splitting method and the conditional *** appearance of the large-scale structures such as the hairpin packets characterized by the two-point correlation shows an excellent consistency with the statistics *** hairpin packets over the SH surface seem always smaller and weaker than those over the smooth *** the SR surface,the hairpin packets in the region 0.1≤y/δ<0.3 are the smallest and weakest among those over the three surfaces,while the scale and the strength of the hairpin packets exceed those over the smooth surface in the region 0.3

关键词： Turbulent boundary layer superhydrophobic riblets drag reduction hairpin packets

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drag reduction characteristics of heated spheres falling into water

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Chinese Physics B 2018年第12期27卷 368-374页

作者： Jia-Chuan Li Ying-Jie Wei Cong Wang Wei-Xue Xia School of Astronautics Harbin Institute of Technology

We experimentally investigate the drag reduction characteristics of heated spheres falling into water by using a highspeed camera. In 25-℃ water, with the increase of the sphere temperature the average velocity increases to a maximum value at a temperature of 400℃ and then decreases until the temperature reaches 700℃, the average velocity will increase while the sphere temperature continually rises until the temperature reaches 900℃. The average and the maximum velocity of the heated sphere are larger than those of the room-temperature sphere. The flow separates at the rear of the heated sphere,leading to low pressure drag. The drag reduction effect of the stable film boiling is lower than that of the nucleate *** the nucleate boiling regime, the average velocity decreases with the increase of water temperature, the drag of the sphere with gentle boiling intensity is smaller. The vapor layer formed in the stable film boiling regime can improve the stability of the fall trajectory. The intense turbulence caused by the nucleate boiling can make the sphere largely deviate from rectilinear motion.

关键词： drag reduction boiling bubbles vapor layer

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drag reduction in the Mouthpart of a Honeybee Facilitated by Galea Ridges for Nectar-Dipping Strategy

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Journal of Bionic Engineering 2015年第1期12卷 70-78页

作者： Chuchu Li Jianing Wu Yunqiang Yang Rengao Zhu Shaoze Yan Division of Intelligent and Biomechanical Systems State Key Laboratory of Tribology Department of Mechanical Engineering Tsinghua University Beijing 100084 China School of Engineering and Technology China University of Geosciences Beijing 100083 China

Some nectarivorous animals have evolved highly specialized tongues to gather nectar from flowers. Here we show that the Italian honeybee, Apis mellifera ligustica, uses the uniformly-distributed ridges on the internal wall of the mouthpart to reduce drag while drinking nectar. We discovered that the tip of the tongue is covered with bushy setae and resembles a brush, and the ridges are parallel distributed on the inner wall of the galeae. Using high-speed camera, we recorded the morphology of the mouthpart when dipping the sucrose water. Considering the ridges and the movement rule of the glossa, we proposed a model for analyzing the mechanism of drag reduction. Theoretical estimation of the friction coefficient with respect to the dipping frequency indicates that the erectable bushy hairs and the ridges can significantly reduce friction when a honeybee drinks nectar. Results show that dimensions of the ridges play a key role in reducing friction. It can be concluded that the ridges on the galeae of honeybee＇s mouthpart can reduce the friction coefficient by 86% compared with the case of the transverse distribution co- efficient S = 40. Finally, the capability of drag reduction in the mouthpart of honeybee may inspire a creative concept for de- signing efficient viscous micropumps.

关键词： honeybee mouthpart ridges drag reduction micropump

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drag reduction IN A TURBULENT CHANNEL FLOW WITH HYDROPHOBIC WALL

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Journal of Hydrodynamics 2012年第3期24卷 458-466页

作者： NOURI Nowrouz Mohammad SEKHAVAT Setareh MOFIDI Alireza Department of Mechanical Engineering Iran University of Science and TechnologyTehran Iran

This paper investigates a theoretical prediction of friction drag reduction in turbulent channel flow which is achieved by using superhydrophobic surfaces. The effect of the hydrophobic surface is considered to be a slip boundary condition on the wall, and this new boundary condition is added to Large Eddy Simulation （LES） equations. The predicted drag reduction at Rer= 180 is approximately 30%, which concurs with results obtained from Direct Numerical Simulation （DNS）. An important implication of the present finding is that the near-wall turbulence structures are modified with streamwise slip velocity. In addition, a noticeable effect on the turbulence structure occurs when the slin lenmh is ereater than a certain vahle

关键词： superhydrophobic surface Large Eddy Simulation (LES) drag reduction slip length turbulence structures

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drag reduction OF A CATIONIC SURFACTANT SOLUTION AND ITS SHEAR STRESS RELAXATION

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Journal of Hydrodynamics 2012年第2期24卷 202-206页

作者： CAI Shu-peng Institute of High Pressure Water Jet Hunan University of Technology Zhuzhou 412007 China

In order to study the mechanisms of the turbulent frictional drag reduction by surfactant additives,the drag reduction,the shear viscosity and the shear stress relaxation were measured for solutions of a cationic surfactant cetyltrimethyl ammonium bromide （CTAB） with the same molar sodium salicylate as a *** is found that the first step relaxation time decreases with increasing concentration and,thus,with the maximum drag-reducing rates,which indicates that the stiffness of the micellar structures with the first relaxation time,increases with the increase of the concentration of ***,for this surfactant,a viscoelastic property is necessary for reducing drag,while a stronger viscoelasticity characterized by a tail relaxation time does not necessarily mean a higher drag-reducing rate.

关键词： drag reduction shear stress relaxation relaxation time viscoelasticity

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drag reduction behavior of hydrolyzed polyacrylamide/xanthan gum mixed polymer solutions

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Petroleum Science 2017年第2期14卷 412-423页

作者： Mehdi Habibpour Peter E. Clark School of Chemical Engineering Oklahoma State University Stillwater OK 74078 USA

Partially hydrolyzed polyacrylamide（HPAM）as the main component of slickwater fracturing fluid is a shear-sensitive polymer,which suffers from mechanical degradation at turbulent flow *** different concentrations of HPAM as well as mixtures of polyacrylamide/xanthan gum were prepared to investigate the possibility of improving shear stability of *** reduction（DR）measurements were performed in a closed flow *** HPAM solutions,the extent of DR increased from 30%to67%with increasing HPAM concentration from 100 to1000 *** the HPAM solutions suffered from mechanical degradation and loss of DR efficiency over the shearing *** indicated that the resistance to shear degradation increased with increasing polymer *** efficiency of 600 wppm xanthan gum（XG）was 38%,indicating that XG was not as good a drag reducer as *** with only 6%DR decline,XG solution exhibited a better shear stability compared to HPAM *** HPAM/XG solutions initially exhibited greater DR（40%and 55%）compared to XG,but due to shear degradation,DR%dropped for HPAM/XG *** to 200 wppm HPAM solution,addition of XG did not improve the drag reduction efficiency of HPAM/XG mixed solutions though XG slightly improved the resistance against mechanical degradation in HPAM/XG mixed polymer solutions.

关键词： Slickwater Polyacrylamide Xanthan gum drag reduction Shear stability

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drag reduction characteristics and flow field analysis of textured surface

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Friction 2016年第2期4卷 165-175页

作者： Qingshun BAI Jinxuan BAI Xiangpan MENG Chengcheng JI Yingchun LIANG School of Mechanical and Electrical Engineering Harbin Institute of Technology Harbin 150001 China Shanghai Satellite Equipment Research Institute Shanghai 200000 China

A textured surface with a micro-groove structure exerts a distinct characteristic on drag reduction behavior. The fluid dynamic models of four textured surfaces are constructed in various profile geometries. Computational fluid dynamics is used to study the friction factors and drag reduction properties with various flow speeds on the textured surfaces. The friction coefficient varieties in the interface between the fluid and the textured surface are examined according to the simulation of the four geometries with V-shaped, saw tooth, rectangular, and semi-circular sections. The drag reduction efficiencies decrease with the increase in water velocity while it is less than a certain value. Moreover, the simulation results of the velocity, shear stress, energy, and turbulence effect on the V-shaped groove surface are presented in comparison with those of the smooth surface to illustrate the drag reduction mechanism. The results indicate that the peaks of the V-shaped grooves inhibit the lateral movement of the turbulent flow and generate the secondary vortex, which plays a key role in the impeding momentum exchange, thereby decreasing turbulent bursting intensity and reducing shear stress in the near-wall flow field. The kinetic energy and turbulence analysis shows that the vortex in the near-wall flow field on the textured surface is more stable compared to that on the smooth surface.

关键词： textured surface drag reduction micro-groove computational fluid dynamics (CFD)

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