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Implementation of a Roughness Element to Trip Transition in Large-eddy Simulation

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Journal of Thermal Science 2015年第1期24卷 30-36页

作者： J.Boudet J.-F.Monier F.Gao LMFA Ecole Centrale de Lyon Université de Lyon–UMR CNRS 5509 69134 Ecully Cedex France PhD.Candidate Université de Lyon–UMR CNRS 5509 69134 Ecully Cedex France

In aerodynamics, the laminar or turbulent regime of a boundary layer has a strong influence on friction or heat transfer. In practical applications, it is sometimes necessary to trip the transition to turbulent, and a common way is by use of a roughness element(e.g. a step) on the wall. The present paper is concerned with the numerical implementation of such a trip in large-eddy simulations. The study is carried out on a flat-plate boundary layer configuration, with Reynolds number Rex=1.3×106. First, this work brings the opportunity to introduce a practical methodology to assess convergence in large-eddy simulations. Second, concerning the trip implementation, a volume source term is proposed and is shown to yield a smoother and faster transition than a grid step. Moreover, it is easier to implement and more adaptable. Finally, two subgrid-scale models are tested: the WALE model of Nicoud and Ducros(Flow Turbul. Combust., vol. 62, 1999) and the shear-improved Smagorinsky model of Lévêque et al.(J. Fluid Mech., vol. 570, 2007). Both models allow transition, but the former appears to yield a faster transition and a better prediction of friction in the turbulent regime.

关键词：大涡模拟 Smagorinsky模型跳闸执行情况粗糙元平板边界层空气动力学表面粗糙度

Numerical Investigation of Flutter Stability in Subsonic Space Turbine Blisk with Emphasis on Cut-on/Cut-off Modes and Interblade Phase Angles

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热科学学报：英文版 2012年第6期21卷 492-499页

作者： Hakim Ferria Pascal Ferrand Franois Pacull Stéphane Aubert Laboratoire de Mécanique des Fluides et d'Acoustique CNRS UMR 5509 Université de LyonUniversité Claude Bernard Lyon 1INSA Lyon 36avenue Guy de Collongue69134 EcullyFrance Fluorem 64 chemin des Mouilles69134 EcullyFrance

The so-called blisks,*** bladed disks,are characterized by very low viscous material damping and make the flutter prediction much more *** that framework,a two-dimensional numerical study of a space turbine blisk featuring complex deformation of blades and high eigenfrequency(>40kHz)is *** simulations are based on unsteady Reynolds Averaged Navier Stokes computations linearized in the frequency domain and consist in the superposition of an unsteady linear(in time)pressure field,generated by a harmonic perturbation,upon a steady nonlinear(in space)*** aerodynamic damping coefficient is calculated over a range of nodal diameters,and the blades are predicted aeroelastically ***,violent changes occur and are rather critical since sudden and large deviations in stability *** that context,the nature of the waves propagating from the cascade are *** an approach provides fundamental knowledge about the perturbations which can either propagate to the far-field(cut-on mode)or decay(cut-off mode).It is expected that the ability of the flow to damp or to amplify the blade motion is strongly affected by the way unsteady perturbations are transferred from the cascade to the *** nature of the waves are first assessed from the aforementioned linearized results,then they are evaluated analytically and finally compared.A good agreement is found despite the strong assumptions of the analytical *** results show a clear correlation between the cut-on/cut-off conditions and *** least stable configuration corresponds to cut-off mode at the inlet and no wave at the *** outgoing waves from the cascade,the blade is prone to be less stable:the energy from the blades vibration is necessarily dissipated or sent out by the cascade.

关键词：颤振稳定性数值模拟涡轮叶盘空间相位角亚音速非定常扰动叶片振动

Investigation of dynamics of discrete framed structures by a numerical wave-based method and an analytical homogenization approach

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Chinese Journal of Aeronautics 2017年第1期30卷 66-74页

作者： Zhou Changwei Sun Xiangkun Mohamed Ichchou Abdel-Malek Zine Jean-Pierre Lainé Stephane Hans Claude Boutin Laboratory of Tribology and Systems Dynamics Ecole Centrale de Lyon Ecully 69134 France Institut Camille Jordan Ecole Centrale de Lyon Ecully 69134 France Laboratory of Tribology and Systems Dynamics Ecole Nationale des Travaux Publics de l'Etat Vaulx-en-Velinx 69518 France

In this article, the analytical homogenization method of periodic discrete media（HPDM）and the numerical condensed wave finite element method（CWFEM） are employed to study the longitudinal and transverse vibrations of framed structures. The valid frequency range of the HPDM is re-evaluated using the wave propagation feature identified by the CWFEM. The relative error of the wavenumber by the HPDM compared to that by the CWFEM is illustrated in functions of frequency and scale ratio. A parametric study on the thickness of the structure is carried out where the dispersion relation and the relative error are given for three different thicknesses. The dynamics of a finite structure such as natural frequency and forced response are also investigated using the HPDM and the CWFEM.

关键词： Framed structures Homogenization method Periodic structures Wave finite element method Wave propagation

Mechanism of superlubricity of a DLC/Si_(3)N_(4) contact in the presence of castor oil and other green lubricants

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Friction 2022年第10期10卷 1693-1706页

作者： Yun LONG Yang WANG Volker WEIHNACHT Stefan MAKOWSKI Momoji KUBO Jean Michel MARTIN Maria-Isabel DE BARROS BOUCHET Ecole Centrale de Lyon Laboratory of Tribology and System DynamicsUniversity of LyonEcully 69134France Institute for Materials Research Tohoku UniversitySendai 980-8577Japan Department of Mechanical Systems Engineering Graduate School of EngineeringTohoku UniversitySendai 980-8579Japan Fraunhofer Institute for Material and Beam Technology(IWS) Dresden 01277Germany

To meet the surging needs in energy efficiency and eco-friendly lubricants,a novel superlubricious technology using a vegetable oil and ceramic materials is *** coupling different hydrogen-free amorphous carbon coatings with varying fraction of sp^(2) and sp^(3) hybridized carbon in presence of a commercially available silicon nitride bulk ceramic,castor oil provides superlubricity although the liquid vegetable oil film in the contact is only a few nanometres thick at *** a partial liquid film possibly separating surfaces in contact,local tribochemical reactions between asperities are essential to maintain superlubricity at low *** local pressure activates chemical degradation of castor oil generating graphitic/graphenic-like species on top of asperities,thus helping both the chemical polishing of surface and its chemical passivation by H and OH ***,the formation of the formation of–(CH_(2)–CH_(2))n–noligomers have been evidenced to have a major role in the friction *** simulation unveils that formation of chemical degradation products of castor oil on friction surfaces are favoured by the quantity of sp^(2)-hybridized carbon atoms in the amorphous carbon ***,tuning sp^(2)-carbon content in hydrogen-free amorphous carbon,in particular,on the top layers of the coating,provides an alternative way to control superlubricity achieved with castor oil and other selected green lubricants.

关键词： superlubricity diamond-like carbon(DLC) sp^(2)-hybridized carbon hydrogen passivation castor oil

Assessment of Linear and Non-Linear Two-Equation Turbulence Models for Aerothermal Turbomachinery Flows

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Journal of Thermal Science 2006年第1期15卷 14-26页

作者： Pascale KULISA Cedric DANO Laboratoire de Mecanique des Fluides et d'Acoustique UMR5509 Ecole Centrale de Lyon 69134 ECULLY Cedex France

三线性二方程的骚乱为 k 建模吗？蔚， k？蠅和 k？1 并且非线性的 k？1 个模型被用于空气动力学、热的汽轮机流动预言。在片上的 wake 和热转移系数的压力侧面与试验性的数据相比。好同意与线性 k 被获得吗？1 当模特儿。没有重要修正... 详细信息

三线性二方程的骚乱为 k 建模吗？蔚， k？蠅和 k？1 并且非线性的 k？1 个模型被用于空气动力学、热的汽轮机流动预言。在片上的 wake 和热转移系数的压力侧面与试验性的数据相比。好同意与线性 k 被获得吗？1 当模特儿。没有重要修正与非线性的模型一起被观察。在片的条款弄醒的运输方程的平衡也被介绍。线性、非线性的 k？1 个模型被评估预言描述汽轮机流动的三维的旋涡。模拟证明经过旋涡是损失的主要起源。关键词骚乱模型 - 数字模拟 - turbomachinery CLC 数字 O357.

关键词：湍流模型数字模拟涡轮机械线性方程

Mechanism of friction reduction of unsaturated fatty acids as additives in diesel fuels

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Friction 2013年第3期1卷 252-258页

作者： Jean Michel MARTIN Christine MATTA Maria-Isabel De Barros BOUCHET Cyrielle FOREST Thierry Le MOGNE Thomas DUBOIS Michael MAZARIN Laboratory of Tribology and System Dynamics Ecole Centrale de Lyon69134 EcullyFrance TOTAL CReSBP2269360 Solaize CedexFrance

This paper investigates the effect of unsaturated fatty acid additives on the lubricating properties of a biodiesel,composed of a blend of fatty acid methyl esters(FAMEs)and a conventional diesel *** presence of fatty acids as additives for biodiesel improves their lubricating properties at elevated temperature *** formation of a protective lubricating tribochemical film on the steel contact surfaces has been *** temperature conditions and possibly oxygen are needed to form this film that reduces friction and limits *** analytical tools have revealed the insulating nature of the formed tribofilm and its chemical ***-induced reticulation is thought to play a major role in the growth of this insulating film.

关键词： biodiesel low friction fatty acids tribochemistry surface analysis

Numerical Analysis of the Tip Leakage Flow Field in a Transonic Axial Compressor with Circumferential Casing Treatment

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Journal of Thermal Science 2010年第3期19卷 198-205页

作者： G.Legras N.Gourdain I.Trebinjac LMFA-UMR CNRS 5509 Ecole Centrale de Lyon /Université Lyon 1 /INSA69134EcullyFrance CERFACS Computational Fluid Dynamics Team31057ToulouseFrance

This paper reports on numerical investigations aimed at understanding the influence of circumferential casing grooves on the tip leakage flow and its resulting vortical *** results and conclusions are based on steady state 3D numerical simulations of the well-known transonic axial compressor NASA Rotor 37 near stall operating *** calculations carried out on the casing treatment configuration reveal an important modification of the vortex topology at the rotor tip *** grooves limit the expansion of the tip leakage vortex in the direction perpendicular to the blade chord,but generate a set of secondary tip leakage vortices due to the interaction with the leakage mass ***,a deeper investigation of the tip leakage flow is proposed.

关键词：叶尖泄漏涡轴流压缩机数值分析套管跨音速治疗流场美国宇航局

Experimental Study of Corner Stall in a Linear Compressor Cascade

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Chinese Journal of Aeronautics 2011年第3期24卷 235-242页

作者： MA Wei OTTAVY Xavier LU Lipeng LEBOEUF Francis GAO Feng Laboratoire de Mecanique des Fluides et d'Acoustique Ecole Centrale de Lyon Ecully 69134 France School of Jet Propulsion Beihang University Beijing 100191 China

In order to gain a better knowledge of the mechanisms and to calibrate computational fluid dynamics （CFD） tools including both Reynolds-averaged Navier-Stokes （RANS） and large eddy simulation （LES）, a detailed and accurate experimental study of comer stall in a linear compressor cascade has been carried out. Data are taken at a Reynolds number of 382 000 based on blade chord and inlet velocity. At first, inlet flow boundary layer is surveyed using hot-wire anemometry. Then in order to investigate the effects of incidence, measurements are acquired at five incidences, including static pressures on both blade and endwall sur- faces measured by pressure taps and the total pressure losses of outlet flow measured by a five-hole pressure probe. The maxi- mum losses as well as the extent of losses of the comer stall are presented as a function of the investigated incidences.

关键词： comer separation compressor cascades incidence hot-wire anemometry computational fluid dynamics

Study of Transition from Laminar to Turbulent Boundary Layer on a Tilted Flat Plate Using Heat Transfer Measurements

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Journal of Thermal Science 2007年第2期16卷 186-191页

作者： E.Sanz C.Nicot R.Point F.Plaza Laboratoire de Mécanique des Fluides et Acoustique LMFA(ECL-UCB-INSA Lyon-CNRS)36Avenue Guy de Collongue69134 Ecully.France.

边界层转移一个完全倾斜的盘子借助于热转移大小被学习了。一个热流动传感器被开发了，为表面或流动的各种各样的类型转以便测量对流的热的效率。它在经常的温度的操作允许热流动的直接、快的大小。现在的纸报导传感器的发展并且在取决... 详细信息

边界层转移一个完全倾斜的盘子借助于热转移大小被学习了。一个热流动传感器被开发了，为表面或流动的各种各样的类型转以便测量对流的热的效率。它在经常的温度的操作允许热流动的直接、快的大小。现在的纸报导传感器的发展并且在取决于外部流动的入射角的边界层介绍它的应用程序给转变的学习。在批评雷纳兹数字和压力坡度参数之间的一种指数的关系被发现了。

关键词：层流湍流边界层传热测量斜板对流压力梯度