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Mechanism of wavy vortex and sign laws in flow past a bluff body:vortex-induced vortex 认领 引用 被引量：4
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作者 L.M.Lin S.Y.Shi +1 位作者 X.F.Zhong Y.X.Wu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2019年第1期1-14,I0001,共14页
As reported in a previous work by Lin et al.(Acta Meeh Sin, 2018. http://gffzzd3cc09b8251d45dfsqnfnk9bwbf696knw.ffgz.tsg.suse.edu.cn/10.1007/s 10409-018-0758-z), an interesting phenomenon was discovered based on the analysis of wavy vortex and vorticity distribution i... As reported in a previous work by Lin et al.(Acta Meeh Sin, 2018. http://gffzzd3cc09b8251d45dfsqnfnk9bwbf696knw.ffgz.tsg.suse.edu.cn/10.1007/s 10409-018-0758-z), an interesting phenomenon was discovered based on the analysis of wavy vortex and vorticity distribution in the shear layers and near wake of a peak-perforated conic shroud, and two sign laws were summarized. In the present paper, the theory of a vortex-induced vortex is introduced to explore mechanisms in a wavy vortex and applicable sign laws for uniform and incompressible flow past a fixed bluff body. Based on the analysis of the nearest-wall How, two vortex-induced models for streamwise and vertical vortex pairs, respectively, are proposed under two boundary cases, denoting the induced vorticity introduced or distributed on and near the walls. As a result, the first sign law, for only streamwise and vertical components of vorticity, and the second sign law, for three components of vorticity, are obtained under their own particular conditions. The first sign law reveals the intrinsic physical relationship between streamwise and vertical vorticities, independent of the distribution of spanwise vortices in the whole flow field. It is also confirmed that the spanwise vortices, as well as the shear layers and wake width, distributed wavily across the span, are attributed to the introduced streamwise or vertical vortices. The two sign laws for vorticity are independent of the disturbed spanwise wavelength and the Reynolds number. Through the analysis of flow past the conic shroud, the two sign laws are successfully used to summarize typical spacial distributions of vorticity in three flow regions: on and near the front cylinder surfaces, the separated shear layers and the near wake. 展开更多
关键词 Wavy vortex Sign law Vortex-induced vortex Wake Bluff body
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Hydrodynamics and Lateral Gas Dispersion in a High-Density Circulating Fluidized Bed Reactor with Bluff Internals 认领 引用 被引量：4
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作者 杨艳辉 贾新莉 +1 位作者 魏飞 金涌 《Chinese Journal of Chemical Engineering》 SCIE EI CAS 2001年第3期291-296,共6页
Effect of bluff internals on the hydrodynamics and lateral gas mixing was studied in a 0.186m ID high-density riser. With the bluff internals, the extremely non-uniform radial profiles of solid fraction and particle v... Effect of bluff internals on the hydrodynamics and lateral gas mixing was studied in a 0.186m ID high-density riser. With the bluff internals, the extremely non-uniform radial profiles of solid fraction and particle velocity become flat and the dense downflow layer near the wall disappears, indicating the significant enhancement of solid turbulence introduced by the internals. The fluctuation velocity and solid fraction transient signal analysis indicates a significant increase in fluctuation intensity near the wall region. The length influenced by the internals on the flow structure is about 1 meter. The lateral gas dispersion coefficient increases significantly as the bluff internals exist in the riser. 展开更多
关键词 high-density riser bluff internal solid fraction particle velocity transient analysis gas mixing gas dispersion model
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Numerical investigations on effects of bluff body in flat plate micro thermo photovoltaic combustor with sudden expansion 认领 引用 被引量：3
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作者 鄂加强 黄海蛟 赵晓欢 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第4期975-982,共8页
In order to reveal combustion characteristics of H_2/air mixture in a micro-combustor with and without bluff body, the effects of inlet velocities, equivalence ratios and bluff body's blockage ratios on the temper... In order to reveal combustion characteristics of H_2/air mixture in a micro-combustor with and without bluff body, the effects of inlet velocities, equivalence ratios and bluff body's blockage ratios on the temperature field, pressure of the combustor wall, combustion efficiency and blow-off limit were investigated. The numerical results indicate that the sudden expansion plate micro combustor with bluff body could enhance the turbulent disturbance of the mixed gas in the combustion chamber and the combustion condition is improved. Moreover, a low-speed and high temperature recirculation region was formed between the sudden expansion step and the bluff body so that the high and uniform wall temperature(>1000 K) could be gotten. As a result, it could strengthen the mixing process, prolong the residence time of gas, control the flame position effectively and widen the operation range by the synergistic effect of the bluff body and steps. When the blockage ratio ranged from 0.3 to 0.6, it could be found that the bluff body could play a stabilizing effect and expand combustion blow burning limit, and combustion efficiency firstly was increased with the inlet velocity and equivalence ratio, and then was decreased. 展开更多
关键词 micro combustor bluff body sudden expansion numerical investigations
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Study on Hydrodynamic Vibration in Dual Bluff Body Vortex Flowmeter 认领 引用 被引量：5
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作者 傅新 杨华勇 《Chinese Journal of Chemical Engineering》 SCIE EI CAS 2001年第2期123-128,共6页
The characteristics of the dual bluff body vortex shedding is investigated, and the possibility to use dual bluff body combinations to strengthen the hydrodynamic vibration around the bluff body objects is explored. T... The characteristics of the dual bluff body vortex shedding is investigated, and the possibility to use dual bluff body combinations to strengthen the hydrodynamic vibration around the bluff body objects is explored. The numerical and experimental approaches were utilized to examine the time dependent flow field and the pressure oscillation around the bluff bodies. The numerical data were obtained by the advanced large eddy simulation model. The experiment was conducted on a laboratory scale of Karman vortex flowmeter with 40 mm diameter. It is revealed that the optimized dual bluff body combinations strengthened the hydrodynamic vibration. It was also found that the hydrodynamic vibration with 180° phase difference occurred at the axisymmetric points of circular pipe on the lateral faces of the equilateral triangle-section bluff bodies. Using the dual bluff body configuration and the differential sensing technique, a novel prototype of vortex flowmeter with excellent noise immunity and improved sensibility was developed. 展开更多
关键词 flowmeter vortex shedding dual bluff body hydrodynamic vibration
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Intrinsic relationship of vorticity between modes A and B in the wake of a bluff body 认领 引用 被引量：2
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作者 L.M.Lin S.Y.Shi Y.X.Wu 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2018年第5期320-325,362,共6页
The intrinsic physical relationship of vorticity between modes A and B in the three-dimensional wake transition is investigated.Direct numerical simulations for the flow past a square-section cylinder are carried out ... The intrinsic physical relationship of vorticity between modes A and B in the three-dimensional wake transition is investigated.Direct numerical simulations for the flow past a square-section cylinder are carried out at Reynolds numbers of 180 and 250,associated with modes A and B,respectively.Based on the analysis of spacial distributions of vorticity in the near wake,characteristics of the vertical vorticity in modes A and B are identified.Moreover,the relationship of three vorticity components with specific signs is summarized into two sign laws,as intrinsic physical relationships between two instability modes.By the theory of vortex-induced vortex,such two sign laws confirm that there are two and only two kinds of vortex-shedding patterns in the near wake,just corresponding to modes A and B.In brief,along the free stream direction,mode A can be described by the parallel shedding vertical vortices with the same sign,while mode B is described by the parallel shedding streamwise vortices with the same sign.Finally,it is found out that the|-type vortex is a basic kind of vortex structure in both modes A and B. 展开更多
关键词 Mode A Mode B Wake Bluff body Sign law
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Energy Harvesting in the Wake of An Inverted C-Shaped Bluff Body 认领 引用 被引量：1
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作者 WANG Jun-lei LI Shen-fang +2 位作者 Md.Mahbub ALAM ZHU Hong-jun HU Guo-biao 《China Ocean Engineering》 SCIE EI CSCD 2024年第1期68-80,共13页
This paper proposes a novel wake-induced vibration(WIV)-based energy harvesting system consisting of two bluff bodies.An inverted C-shaped bluff body is stationary installed at the upstream position to generate an int... This paper proposes a novel wake-induced vibration(WIV)-based energy harvesting system consisting of two bluff bodies.An inverted C-shaped bluff body is stationary installed at the upstream position to generate an interference wake street,and a cylinder bluff body equipped with a transducer is elastically suspended at the downstream position to harness WIV energy.The hydrodynamics and energy harvesting(EH)performance of the proposed system are investigated via experimental studies.The reduced velocity(U*)ranging from 2 to 14(the corresponding Reynolds number ranging from 15100 to 106200)is considered in the present study.It is found that the wake generated by the inverted C-shaped bluff body significantly affects the EH performance.Enlarging the opening angle(α)of the C-shaped bluff body increases the vibration amplitude of the downstream cylinder,thereby increasing the harvested power.When the spacing(L)between two bluff bodies is two times the cylinder diameter(D),the wake-induced vibration(WIV)mode is observed,while the combined WIV and wake galloping(WG)mode occurs whenαis 150°,and L equals 3D or 4D.The average drag coefficient becomes negative when L is 2D,3D,or 4D.By carefully configuring a C-shaped bluff body,the wake generated by it can bring an augmenting effect on the vibration of the downstream EH cylinder.For example,the RMS power output of the proposed EH system reaches a maximum of 0.31 W at U*=8 and L=4D,which is 300%greater than that of its traditional counterpart.Furthermore,after a number of case stud-ies,it is identified that the proposed EH system can achieve the best performance whenαis 150°and L=2D. 展开更多
关键词 wake-induced vibration vortex-induced vibration galloping energy harvesting bluff body
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Recent development of vortex method in incompressible viscous bluff body flows 认领 引用 被引量：1
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作者 刘兰 嵇峰 +1 位作者 樊建人 岑可法 《Journal of Zhejiang University-SCIENCE A》 CAS 2005年第4期283-288,共6页
Vortex methods have been alternative tools of finite element and finite difference methods for several decades. This paper presents a brief review of vortex method development in the last decades and introduces effici... Vortex methods have been alternative tools of finite element and finite difference methods for several decades. This paper presents a brief review of vortex method development in the last decades and introduces efficient vortex methods developed for high Reynolds number bluff body flows and suitable for running on parallel computer architectures. Included in this study are particle strength exchange methods, core-spreading method, deterministic particle method and hybrid vortex methods. Combined with conservative methods, vortex methods can comprise the most available tools for simulations of three-dimensional complex bluff body flows at high Reynolds numbers. 展开更多
关键词 Vortex methods Simulation of flows Bluff body
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Simulation of bluff body stabilized flows with hybrid RANS and PDF method 认领 引用 被引量：4
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作者 Minming Zhu Xingsi Han Haiwen Ge Yiliang Chen 《Acta Mechanica Sinica》 SCIE EI CAS 2007年第3期263-273,共11页
The motivation of this study is to investigate the turbulence-chemistry interactions by using probability density function （PDF） method. A consistent hybrid Reynolds Averaged Navier-Stokes （RANS）/PDF method is use... The motivation of this study is to investigate the turbulence-chemistry interactions by using probability density function （PDF） method. A consistent hybrid Reynolds Averaged Navier-Stokes （RANS）/PDF method is used to simulate the turbulent non-reacting and reacting flows. The joint fluctuating velocity-frequency-composition PDF equation coupled with the Reynolds averaged density, momentum and energy equations are solved on unstructured meshes by the Lagrangian Monte Carlo （MC） method combined with the finite volume （FV） method. The simulation of the axisymmetric bluff body stabilized non-reacting flow fields is presented in this paper. The calculated length of the recirculation zone is in good agreement with the experimental data. Moreover, the significant change of the flow pattern with the increase of the jet-to-coflow momentum flux ratio is well predicted. In addition, comparisons are made between the joint PDF model and two different Reynolds stress models. 展开更多
关键词 Hybrid algorithm Unstructured mesh Finite volume method PDF method Bluff body stabilized flow
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Simulation of vortex shedding behind a bluff body flame stabilizer using a hybrid U-RANS/PDF method 认领 引用
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作者 Min-Ming Zhu Ping-Hui Zhao +1 位作者 Hai-Wen Ge Yi-Liang Chen 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2012年第2期348-358,共11页
The present study aims at the investigation of the effects of turbulence-chemistry interaction on combus- tion instabilities using a probability density function （PDF） method. The instantaneous quantities in the flo... The present study aims at the investigation of the effects of turbulence-chemistry interaction on combus- tion instabilities using a probability density function （PDF） method. The instantaneous quantities in the flow field were decomposed into the Favre-averaged variables and the stochastic fluctuations, which were calculated by unsteady Reynolds averaged Navier-Stokes （U-RANS） equations and the PDF model, respectively. A joint fluctuating velocity- frequency-composition PDF was used. The governing equa- tions are solved by a consistent hybrid finite volume/Monte- Carlo algorithm on triangular unstructured meshes. A non- reacting flow behind a triangular-shaped bluff body flame stabilizer in a rectilinear combustor was simulated by the present method. The results demonstrate the capability of the present method to capture the large-scale coherent struc- tures. The triple decomposition was performed, by divid- ing the coherent Favre-averaged velocity into time-averaged value and periodical coherent part, to analyze the coherent and incoherent contributions to Reynolds stresses. A sim- ple modification to the coefficients in the turbulent frequency model will help to improve the simulation results. Unsteady flow fields were depicted by streamlines and vorticity con- tours. Moreover, the association between turbulence produc- tion and vorticity saddle points is illustrated. 展开更多
关键词 Vortex shedding PDF method Unsteady RANS Finite volume. Bluff bodies
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Numerical Simulation of Turbulent Swirling Pipe Flow with an Internal Conical Bluff Body 认领 引用 被引量：5
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作者 Jinli Song Nabil Kharoua +1 位作者 Lyes Khezzar Mohamed Alshehhi 《Fluid Dynamics & Materials Processing》 EI 2021年第2期455-470,共16页
Turbulent swirling flow inside a short pipe interacting with a conical bluff body was simulated using the commercial CFD code Fluent.The geometry used is a simplified version of a novel liquid/gas separator used in mu... Turbulent swirling flow inside a short pipe interacting with a conical bluff body was simulated using the commercial CFD code Fluent.The geometry used is a simplified version of a novel liquid/gas separator used in multiphase flow metering.Three turbulence models,belonging to the Reynolds averaged Navier-Stokes(RANS)equations framework,are used.These are,RNG k-ε,SST k-ωand the full Reynolds stress model(RSM)in their steady and unsteady versions.Steady and unsteady RSM simulations show similar behavior.Compared to other turbulence models,they yield the best predictions of the mean velocity profiles though they exhibit some discrepancies in the core region.The influence of the Reynolds number on velocity profiles,swirl decay,and wall pressure on the bluff body are also presented.For Reynolds numbers generating a Rankine-like velocity profile,the width and magnitude of flow reversal zone decreases along the pipe axis disappearing downstream for lower Reynolds numbers.The tangential velocity peaks increase with increasing Reynolds number.The swirl decay rate follows an exponential form in accordance with the existing literature.These flow features would affect the performance of the real separator and,thus,the multiphase flow meter,noticeably. 展开更多
关键词 Swirling pipe flow conical bluff body CFD separator
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Investigation of vortical flow over bluff bodies with base cavities 认领 引用 被引量：3
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作者 Shu-Cheng Pan Jin-Sheng Cai 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2012年第5期1238-1247,共10页
Based on our previous research about drag reduction in term of the base cavity length using two dimensional simulations, this paper describes a numerical study of a bluff body of which the number of base cavities is s... Based on our previous research about drag reduction in term of the base cavity length using two dimensional simulations, this paper describes a numerical study of a bluff body of which the number of base cavities is successively increased and the cavity geometries are also modified to assume different shapes. Here we attempt to find an effective configuration to reduce the drag by increasing the number of base cavities. The numerical simulations examining varied number of base cavities reveal the presence of different strength of vortices in the wake zone which is the reason why the drag coefficients are distinctly different for different cases. In the case with double and triple rectangular cavities, we use the pressure contours snapshots at successive time instants to describe the wake evolution. We further investigate the effect of variable base cavity shapes for a constant cavity length at an identical time instant. A total of two different geometries of base cavities are discussed here： the rectangular and the sinusoidal cavities with sharp and rounded trailing edges, respectively. The numerical results reveal that the for- mer is an effective drag reduction configuration which can produce a significant base pressure recovery corresponding to the strength of the vortices shown in the pressure contour figures. While the latter shows no obvious reduction in drag coefficient and a similar intensity of vortex in the wake zone compared with the unmodified case. Reductions in drag are observed for all the investigated cavity configurations, and additionally it is found that the magnitude of the reduction bears a direct relationship with the number of the cavities up to a certain minimum value. 展开更多
关键词 Flow control Drag reduction. Bluff body Basecavity
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Prediction of Fluid Force Exerted on Bluff Body by Neural Network Method 认领 引用 被引量：2
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作者 ZHAO Yong MENG Yang +2 位作者 YU Pengyao WANG Tianlin SU Shaojuan 《Journal of Shanghai Jiaotong university(Science)》 EI 2020年第2期186-192,共7页
With the development of artificial intelligence,artificial neural network(ANN)has been widely used in recent years.In this paper,the method is applied to the prediction of the fluid force exerted on the bluff body whe... With the development of artificial intelligence,artificial neural network(ANN)has been widely used in recent years.In this paper,the method is applied to the prediction of the fluid force exerted on the bluff body when flow passes around.Firstly,back propagation(BP)model and convolutional neural network(CNN)model are introduced;then the mapping relation between the shape of bluff body and the fluid force,which is calculated by computational fluid dynamics(CFD),is established by sample training.Finally,it is used to predict the fluid force of the new shape bluff body.By taking the CFD results as benchmark,CNN model is capable of predicting both the resistance and lift force,while BP model is incompetent to predict lift force.Furthermore,both CNN and BP models have a significant advantage in prediction efficiency,compared by CFD calculation method. 展开更多
关键词 convolutional neural network(CNN)model back propagation(BP)model computational fluid dynamics(CFD) bluff body flow fluid force
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Drag of a D-shaped bluff body under small amplitude harmonic actuation 认领 引用
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作者 Yaqing Li Honglei Bai Nan Gao 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2015年第1期35-38,共4页
Open-loop flow control method was used to affect the development of a turbulent wake behind a D-shaped bluff body.Loud speakers were embedded inside the bluff body to produce two zero-net-mass-flux jets through 2 mm-w... Open-loop flow control method was used to affect the development of a turbulent wake behind a D-shaped bluff body.Loud speakers were embedded inside the bluff body to produce two zero-net-mass-flux jets through 2 mm-wide span-wise slots located along the upper and lower edges on the rear wall.The drag forces for different actuation amplitudes(Cμ,the ratio between the momentum of the actuating jets and the moment deficit caused by the bluff body)and frequencies(StA)were examined.The effects of the phase difference in the two jets(0 andπ)were also studied.It was found that when Cμwas 0.1%,a drag reduction up to 5%was achieved when the velocities of the two jets varied in phase at a frequency of 5tA=0.16.When the velocities of the two jets variedπout of phase,significant drag increase was observed. 展开更多
关键词 D-shaped bluff body Open-loop flow control Synthetic jet
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Performance of 32 Hybrid Rice Varieties at Pine Bluff of Arkansas 认领 引用 被引量：1
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作者 Bihu Huang Zongbu Yan 《American Journal of Plant Sciences》 CAS 2016年第15期2239-2247,共9页
Yield test of 41 entries, 32 new hybrids, 8 male parents restore lines and 1 inbred variety, was conducted on the farm of University of Arkansas at Pine Bluff (UAPB) in 2012. The only inbred Francis in this experiment... Yield test of 41 entries, 32 new hybrids, 8 male parents restore lines and 1 inbred variety, was conducted on the farm of University of Arkansas at Pine Bluff (UAPB) in 2012. The only inbred Francis in this experiment was used as the check. Francis is a popular variety and widely used in Arkansas rice production. Results showed that the yields of 7 hybrids were 25.7% - 30.7% higher than check Francis. Hybrid 28s/BP23R had the highest yield, 10846.6 kg/hectare and over check by 30.7%. The yield of hybrid 28s/PB-24, was 10628.9 kg/hectare and over check by 28.1%. The yields of hybrid 28s/PB-22 and 33A/PB24 were 10549.8 and 10539.8 kg/hectare and over check by 27.1% and 27.0%, respectively. The sterile lines 28s, 29s, 30s and 33A have good combinability. PB2, PB5, PB12, PB22, PB23, PB24, and PB25 are good restorers and most of their hybrids were over check more than 17%. Sterile 28s has DEMG (Dominant Early Maturity Gene) which can make earlier heading hybrids by crossing with late restorer lines. Sterile 30s and 33A have no DEMG but have heat resistant gene. They can make late heading hybrids by crossing with late restorer lines PB24 and PB22 and the late heading hybrids can resistant to hot temperature. These results showed that these sterile lines, restorer lines and hybrids can be used in rice production of Arkansas in the future. 展开更多
关键词 Performance Hybrid Rice Variety Pine Bluff Arkansas
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Developing a virtual physical system for vortex-induced vibration studies of a bluff body 认领 引用
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作者 Haojie Ren Shixiao Fu +2 位作者 Mengmeng Zhang Yuwang Xu Hao Ren 《Journal of Ocean Engineering and Science》 SCIE CSCD 2025年第5期678-691,共14页
A virtual physical system(VPS)for VIV studies of a bluff body is developed to replace the actual physical systems.It can arbitrarily and accurately control and edit the physical parameters,including mass,damping ratio... A virtual physical system(VPS)for VIV studies of a bluff body is developed to replace the actual physical systems.It can arbitrarily and accurately control and edit the physical parameters,including mass,damping ratio and spring stiffness,specifically for the mass-spring-damper system.The recursive Duhamel integral method(DIM)with unconditional stability was used for the VPS control system,addressing real-time noise filtering problem and simplifying the system as a single input and single output(SISO)one.Delay compensation and inertial force elimination methods were investigated and proposed to overcome the crucial unwanted damping effects.An experimental facility for VIV model tests by VPS was manufactured,and the bluff body model with a measurement system was specially designed to accurately sense the hydrodynamic force during VPS operation.Systematic verification experiments for parameter editing and control of an actual physical target system were conducted,showing that the VPS can reproduce the equivalent spring-damper-mass system in high fidelity with an accuracy error of less than 5%.VIV model tests for a bluff body at Reynolds numbers(Re=UD/υ,where U is the flow velocity,D represents the diameter of cylinder model,andυis the kinematic viscosity coefficient)of 5.7E4 and 2.3E5 were performed using the VPS experimental facility,presenting well-Repeated VIV responses at low Re and unexpected VIV response with a large amplitude of 2.4 D at high Re,which can cause severe fatigue damage for relevant structures.The present VPS will provide promising and powerful experimental tools for VIV studies of a bluff body to reveal the related sensitive parameter effects. 展开更多
关键词 Vortex-induced vibration Virtual physical system High Reynolds number Experiments in fluids Bluff body
Experimental studies of the effects of hydrophobic coatings on flow separation around 3D bluff bodies 认领 引用
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作者 Naseeb Ahmed Siddiqui Martin Agelin‑Chaab 《Advances in Aerodynamics》 EI 2025年第4期136-158,共23页
This study explores how hydrophobic coating influences the structure of the flow separation at the rear end of 3D bluff bodies.Two 3D representative bluff bodies,namely the standard Ahmed body(SAB),which features flow... This study explores how hydrophobic coating influences the structure of the flow separation at the rear end of 3D bluff bodies.Two 3D representative bluff bodies,namely the standard Ahmed body(SAB),which features flow separation and reattachment at its slant surface,and the elliptical Ahmed body(EAB),which exhibits fully separated flow,are employed.The bluff bodies were coated with Ultra Ever Dry hydrophobic paint.Experiments were carried out on pairs of coated and uncoated SABs and EABs in a water tunnel utilizing time-resolved and standard particle image velocimetry(PIV)at a Reynolds number of 4.3×104based on the model height.The results show that hydrophobic coatings influence the flow features of these bluff bodies.For the SAB,the coating alters the slant separation bubble,increasing the reattachment length by 80%and reducing the shear stress.The Strouhal number on the slant surface of the SAB also increases,with a dominant value of St=0.24.Proper orthogonal decomposition(POD)analysis shows dominant Strouhal numbers of St=0.36 and St=0.48 for the first and second POD modes,respectively.Additionally,dynamic mode decomposition(DMD)analysis identifies a dominant Strouhal number of St=0.3 in the wake.Conversely,the EAB,which already has a fully separated flow,is less affected by the coating.The wake recirculation length is reduced by 6%.Strouhal numbers on the coated EAB's slant surface range from 0.40 to 0.55,and those in the wake vary from 0.25 to 0.85.The POD analysis does not reveal dominant Strouhal numbers in the EAB's wake,while the DMD analysis indicates a dominant Strouhal number of St=0.013,pointing to energetic modes due to the fully separated flow.These findings demonstrate that hydrophobic coatings affect the flow characteristics of 3D bluff bodies differently,depending on their inherent flow separation properties. 展开更多
关键词 Hydrophobic surfaces Bluff body Drag reduction Flow control
Numerical aerodynamic analysis of bluff bodies at a high Reynolds number with three-dimensional CFD modeling 认领 引用 被引量：6
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作者 BAI YuGuang YANG Kai +4 位作者 SUN DongKe ZHANG YuGuang KENNEDY David WILLIAMS Fred GAO XiaoWei 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2013年第2期277-289,共13页
This paper focuses on numerical simulations of bluff body aerodynamics with three-dimensional CFD(computational fluid dynamics) modeling,where a computational scheme for fluid-structure interactions is implemented.The... This paper focuses on numerical simulations of bluff body aerodynamics with three-dimensional CFD(computational fluid dynamics) modeling,where a computational scheme for fluid-structure interactions is implemented.The choice of an appropriate turbulence model for the computational modeling of bluff body aerodynamics using both two-dimensional and three-dimensional CFD numerical simulations is also considered.An efficient mesh control method which employs the mesh deformation technique is proposed to achieve better simulation results.Several long-span deck sections are chosen as examples which were stationary and pitching at a high Reynolds number.With the proposed CFD method and turbulence models,the force coefficients and flutter derivatives thus obtained are compared with the experimental measurement results and computed values completely from commercial software.Finally,a discussion on the effects of oscillation amplitude on the flutter instability of a bluff body is carried out with extended numerical simulations.These numerical analysis results demonstrate that the proposed three-dimensional CFD method,with proper turbulence modeling,has good accuracy and significant benefits for aerodynamic analysis and computational FSI studies of bluff bodies. 展开更多
关键词 bluff body aerodynamic analysis fluid-structure interaction three-dimensional CFD modeling flutter
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南极利文斯顿岛上三叠统Miers Bluff组及其与相当地层对比 认领 引用 被引量：4
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作者 沈炎彬 邓希光 +2 位作者 欧阳舒 郑祥身 刘小汉 《地层学杂志》 北大核心 2000年第4期291-296,共6页
南极南设得兰群岛利文斯顿岛 Miers Bluff组 (MBF)是一套岩层倒转、强烈变形、浅变质的浊流沉积地层 ,主要由砂岩、泥岩、粉砂岩及含砾砂岩组成 ,具有很好的韵律层 ,形成鲍玛序列 ,通常被认为属于近海底扇浊流沉积 ,并当作中新生代火山... 南极南设得兰群岛利文斯顿岛 Miers Bluff组 (MBF)是一套岩层倒转、强烈变形、浅变质的浊流沉积地层 ,主要由砂岩、泥岩、粉砂岩及含砾砂岩组成 ,具有很好的韵律层 ,形成鲍玛序列 ,通常被认为属于近海底扇浊流沉积 ,并当作中新生代火山岩的基底。最近发现的孢粉化石指明其时代属晚三叠世 ,从而解决了久来时代的疑问(石炭—三叠纪 ,二叠—三叠纪 ,或前侏罗纪 )。分布在南极半岛格雷厄姆地的特里尼蒂半岛群、南奥克尼群岛的杂砂岩—页岩组、智利南部乔诺斯群岛乔诺斯变质杂岩的 Potranca组以及新西兰惠灵顿的 Torlesse杂岩应是时代相当、岩性及沉积环境相似的岩层。三叠纪末受太平洋板块俯冲影响 ,这一浊流地层褶皱、变形、隆升 ,具有相同的构造风格 。 展开更多
关键词 MiersBluff组 浊流沉积 上三叠统 地层对比 南极
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氢燃料钝体火焰的热声振荡机理及主动控制研究 认领 引用
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作者 张龙 梁勇 +2 位作者 王智辉 周华 任祝寅 《推进技术》 EI CAS CSCD 北大核心 2026年第3期72-84,共13页
以氢燃料钝体火焰为研究对象,探索其热声振荡过程的内在物理机制和抑制振荡的有效控制策略。通过大涡模拟复现了氢燃料钝体火焰的热声振荡特性,其压力脉动振幅约为1 kPa,脉动主频为195 Hz,并通过特征根分析,识别出不稳定燃烧区域起始于... 以氢燃料钝体火焰为研究对象,探索其热声振荡过程的内在物理机制和抑制振荡的有效控制策略。通过大涡模拟复现了氢燃料钝体火焰的热声振荡特性,其压力脉动振幅约为1 kPa,脉动主频为195 Hz,并通过特征根分析,识别出不稳定燃烧区域起始于钝体下游两侧的剪切层位置,并集中于回流区末端和计算域下游,不稳定燃烧过程的关键组分为自由基H,关键反应为H2的链分支反应H2+M⇔H+H+M。构建了降阶模型和神经网络相耦合的热声振荡预测模型,模型预测结果同LES仿真数据间的相对误差低于10%,实现了对压力脉动动态特性的高精度预测。设计了滑动多频段移相控制模型,有效抑制了氢燃料钝体火焰的振荡过程,使压力脉动幅值降低了约15%,主频峰值降低了约52%。 展开更多
关键词 氢燃料 钝体火焰 热声振荡 主动控制 燃烧优化
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基于海流涡激振动的压电俘能特性数值模拟研究 认领 引用
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作者 周阳 朱令乾 +2 位作者 陈诺言 周秉乾 钟圣杰 《太阳能学报》 EI CAS CSCD 北大核心 2026年第5期410-420,共11页
为实现海流驱动压电俘能器振动发电,给海洋中的各类低功耗监测传感器供能,基于涡激振动原理,设计一种采用改良阻流体的压电俘能系统,以提高发电性能。分别对阻流体和压电悬臂梁结构进行优化设计,基于COMSOL Multiphysics软件,仿真分析6... 为实现海流驱动压电俘能器振动发电,给海洋中的各类低功耗监测传感器供能,基于涡激振动原理,设计一种采用改良阻流体的压电俘能系统,以提高发电性能。分别对阻流体和压电悬臂梁结构进行优化设计,基于COMSOL Multiphysics软件,仿真分析6种不同阻流体结构诱导产生的涡街特性,并选用最优阻流体结构开展流-固-电全耦合仿真。研究海流流速、阻流体尺寸对阻流体和压电悬臂梁上的升阻力系数以及压电悬臂梁输出电压的影响。仿真结果表明,优化设计的压电俘能结构可提高俘能系统的输出电能,在海流流速0.5 m/s、阻流体尺寸0.02 m条件下压电悬臂梁开路电压为0.8 V。 展开更多
关键词 海流能 涡激振动 能量收集 压电悬臂梁 多物理场耦合 阻流体
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