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NUMERICAL PREDICTION OF VORTEX FLOWIN HYDRAULIC TURBINE DRAFT TUBE FOR les

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Journal of Hydrodynamics 2005年第4期17卷 448-454页

作者： LIU Xiao-bing ZENG Yong-zhong CAO Shu-you School of Energy and Environment Xihua University Chengdu 610039 China State Key Hydraulics Laboratory of High Speed Flows Sichuan University Chengdu 610065 China

The three-dimensional unsteady turbulent flow is studied numerically in the whole flow passage of hydraulic turbine, and vortex flow in the draft tube is predicted accurately in this paper. The numerical prediction is based on the Navier-Stokes equations and Large-Eddy Simulation （les） model. The SIMPLE algorithm with the body fitted coordinate and tetrahedroid grid system is applied for the solution of the discretization governing equations.

关键词： vortex flow hydraulic turbine draft tube numerical prediction les

les investigation of swirl intensity effect on unconfined turbulent swirling premixed flame

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Chinese Science Bulletin 2014年第33期59卷 4550-4558页

作者： Zhihua Wang Yanwei Xu Yu L Zhijun Zhou Junhu Zhou Kefa Cen State Key Laboratory of Clean Energy Utilization Zhejiang University

A finite reaction rate model is presented as a closure of large eddy simulation(les) to numerically study an open premixed methane/air swirling flame. The resultant model is firstly validated by comparing with reported data and then employed to investigate the effect of swirling intensity on flow field, flame characteristics and combustion instability of the swirling flame. Three different swirl numbers are considered. The les results show that as swirling intensity increases, the vortex entrainment and micro-mixing are enhanced, leading to more lean equivalent ratios at flame front; consequently, higher swirling number causes lower flame temperatures and slower CO oxidization; for all simulated swirl numbers,flame fronts are completely located out of the recirculation zones and anchored at the inner surface of the annular swirling steams; swirl number has a crucial effect on swirling flame extension toward radial and tangential dimensions and then significantly affects streamwise flame length, which is a great influencing factor on combustion instability; vortex-induced disturbance on flame in streamwise plays a critical role in combustion instability.

关键词：预混火焰旋流强度 les 漩涡燃烧不稳定性潜水大涡模拟速率模型

A novel dynamic coherent eddy model and its application to les of a turbulent jet with free surface

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Science China(Physics,Mechanics & Astronomy) 2010年第9期53卷 1671-1680页

作者： LU Jun,TANG HongWu,WANG LingLing & PENG Feng College of water conservancy of hydro-power engineering,Hohai University,Nanjing 210098,China 1. College of water conservancy of hydro-power engineering Hohai University Nanjing 210098 China

We has developed a novel dynamic coherent eddy model,in which the coherent structure-Q criterion introduced by Hunt et al(1988)-is taken into account in the subgrid-scale turbulent viscosity based on the eddy viscosity *** proposed method is to combine the resolved-scale velocity-gradient tensor in the classical Smagorinsky model with Q criterion weighted.A kind of dynamic procedure which was averaged in a general process at temporal direction based on the autocorrelations of the characteristic resolved scales of turbulence was taken for the coefficient of subgrid *** model is implemented in the σ-coordinate and the filtered Navier-Stokes equations are solved by the operator splitting *** validation was explored to 2-D turbulent slot jet both in ambient environment and in regular *** prediction of the present model was compared with the experiment data,including the averaged velocity profiles,the velocity fluctuations and the Reynolds *** model performance is shown to be satisfactory.

关键词： les subgrid-scale modeling σ-coordinate turbulent jet

Experimental and les investigation of flame propagation in a hydrogen/air mixture in a combustion vessel

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Chinese Science Bulletin 2014年第20期59卷 2496-2504页

作者： Huahua Xiao Zhanli Mao Weiguang An Jinhua Sun State Key Laboratory of Fire Science University of Science and Technology of China Department of Fire Protection Chinese People’s Armed Police Force Academy

This work presents an experimental and numerical investigation of premixed flame propagation in a hydrogen/air mixture in a closed combustion *** the experiment,high-speed schlieren video photography and pressure sensor are used to examine the flame dynamics and pressure *** the numerical study,a large eddy simulation(les)based on a RNG sub-grid approach and a les combustion model is applied to reproduce experimental *** effects of four physical phenomena on the burning velocity are considered in the combustion model,and the impact of grid type on the combustion dynamics is examined in the les *** flame experiences four stages both in experiment and les calculations with structured and unstructured grids,i.e.,spherical flame,finger-shaped flame,flame with its skirt in contact with the sidewalls,and tulip-shaped *** flame speed and pressure in the vessel develop with periodical oscillations in both the experiment and les simulations due to the interaction of flame front with pressure *** numerical simulations compare well with the detailed experimental measurements,especially in term of the flame shape and position,pressure build-up,and periodical oscillation *** les combustion model is successfully validated against the bench-scale *** is put into evidence that mesh type has an impact to a certain extent on the numerical combustion dynamics,and the les calculation on structured grid canpredict the flame dynamics and pressure rise more accurately than that on unstructured grid with the same mesh *** flame shape is more asymmetrical in the les on an unstructured grid than that on a structured grid,and both the flame speed and the pressure rise at the later flame stage are underestimated in the les on the unstructured grid.

关键词：火焰传播实验测量空气混合物燃烧器 les 非结构化网格燃烧动力学数值模拟

Comparative Study of Three High Order Schemes for les of Temporally Evolving Mixing Layers

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Communications in Computational Physics 2012年第10期12卷 1603-1622页

作者： Helen C.Yee Bjorn Sjögreen Abdellah Hadjadj NASA-Ames Research Center Moffett FieldCA94035USA Lawrence Livermore National Laboratory LivermoreCA94551USA CORIA UMR 6614&INSA de Rouen 76800 St-Etienne du RouvrayFrance

Three high order shock-capturing schemes are compared for large eddy simulations(les)of temporally evolving mixing layers for different convective Mach numbers ranging from the quasi-incompressible regime to highly compressible supersonic *** considered high order schemes are fifth-order WENO(WENO5),seventh-order WENO(WENO7)and the associated eighth-order central spatial base scheme with the dissipative portion of WENO7 as a nonlinear post-processing filter step(WENO7fi).This high order nonlinear filter method of Yee&Sjogreen is designed for accurate and efficient simulations of shock-free compressible turbulence,turbulence with shocklets and turbulence with strong shocks with minimum tuning of scheme *** les results by WENO7fi using the same scheme parameter agree well with experimental results compiled by Barone et al.,and published direct numerical simulations(DNS)work of Rogers&Moser and Pantano&Sarkar,whereas results by WENO5 andWENO7 compare poorly with experimental data and DNS computations.

关键词： High order numerical methods numerical methods for turbulencewith shocks DNS les mixing layer

用les方法对斜拉桥斜拉索风雨振的机理的研究

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工程力学 2007年第9期24卷 134-139页

作者：刘庆宽石家庄铁道学院大型结构健康诊断与控制研究所石家庄050043

在特定的风雨条件下,斜拉桥的斜拉索会发生激烈的风雨振现象。这种振动会造成索-梁和索-塔锚固区结构的疲劳损伤等一系列问题,因此,研究并明确斜拉索风雨振的机理,从而找到这种振动的控制方法,已经成为紧迫的研究课题。该文从流场分析入... 详细信息

在特定的风雨条件下,斜拉桥的斜拉索会发生激烈的风雨振现象。这种振动会造成索-梁和索-塔锚固区结构的疲劳损伤等一系列问题,因此,研究并明确斜拉索风雨振的机理,从而找到这种振动的控制方法,已经成为紧迫的研究课题。该文从流场分析入手,利用数值分析的Large-eddy simulation方法,研究了索面存在水线的情况下水线位置不同时流场分布的变化和卡尔曼涡强度的变化,提出水线后侧"小涡"的脱落是影响卡尔曼涡强度的原因。在风速高于卡尔曼涡致振动风速的条件下,当卡尔曼涡受到小涡影响变得足够弱时,索容易发生振动。

关键词：斜拉索风雨振 les 卡尔曼涡振动机理

基于les和BPBE的舰船气泡尾流数值分析方法

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船舶力学 2015年第1期19卷 28-34页

作者：金良安闫雪飞迟卫陈明荣海军大连舰艇学院航海系辽宁大连116018

提出一种基于大涡模拟(les)和气泡群平衡方程(BPBE)的舰船气泡尾流特征参数研究的数值分析法:首先建立舰船尾流场les控制方程,结合实船初边始条件,对流向的速度进行数值模拟;然后再将les计算得到的速度代入BPBE方程进行尾流中气泡数密... 详细信息

提出一种基于大涡模拟(les)和气泡群平衡方程(BPBE)的舰船气泡尾流特征参数研究的数值分析法:首先建立舰船尾流场les控制方程,结合实船初边始条件,对流向的速度进行数值模拟;然后再将les计算得到的速度代入BPBE方程进行尾流中气泡数密度分布(BND)的求解。计算结果表明:BND沿尾流流向的分布基本符合指数分布,在500 m以内的区域衰减速度很快,500 m以外的区域衰减速度缓慢;在离船尾越近的地方,小气泡的相对BND越大;在3 000 m距离处BND最大的气泡尺寸约为70μm。该方法计算效率较高、占用空间较少,可望为舰船气泡尾流特征的研究提供新的有效手段。

关键词：舰船尾流 les 气泡聚并 BPBE BND

超声速湍流流场的RANS/les混合计算方法研究

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空气动力学学报 2009年第6期27卷 723-728页

作者：袁先旭邓小兵谢昱飞张志成中南大学轨道交通安全教育部重点实验室湖南长沙410075 中国空气动力研究与发展中心四川绵阳621000

采用对接/拼接网格技术,建立了基于分区混合和基于湍流尺度混合的双重RANS/les混合计算模型,并对环翼低速绕流、翼型跨声速绕流和球锥带凹窗外形二维超声速绕流进行了初步的数值模拟。环翼和翼型绕流计算表明,该混合模型可给出较合理的... 详细信息

采用对接/拼接网格技术,建立了基于分区混合和基于湍流尺度混合的双重RANS/les混合计算模型,并对环翼低速绕流、翼型跨声速绕流和球锥带凹窗外形二维超声速绕流进行了初步的数值模拟。环翼和翼型绕流计算表明,该混合模型可给出较合理的湍流宏观平均量;球锥带凹窗外形二维超声速绕流计算表明,该混合模型可得到超声速瞬态湍流脉动流场,凹窗处存在复杂的旋涡结构和波系结构,呈现较大尺度的脉动。但该模型还需要进一步的考核验证。

关键词：气动光学效应 RANS les RANS/les

弱可压缩移动粒子半隐式方法(WC-MPS)与湍流大涡模型(les)模拟溃坝流动(英文)

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船舶力学 2014年第12期18卷 1415-1423页

作者：刘永涛马宁朱仁庆顾解忡上海交通大学船舶海洋与建筑工程学院上海200240 江苏科技大学船舶与海洋工程学院江苏镇江212003

应用弱可压缩移动粒子半隐式法(WC-MPS)结合湍流大涡模型(les)模拟了自由液面流动问题。该方法通过流体状态方程实现流场压力的直接计算,并根据大涡模拟Smagorinsky模型来计算湍流项。最后应用该方法,针对两个溃坝自由液面流动问题,特... 详细信息

应用弱可压缩移动粒子半隐式法(WC-MPS)结合湍流大涡模型(les)模拟了自由液面流动问题。该方法通过流体状态方程实现流场压力的直接计算,并根据大涡模拟Smagorinsky模型来计算湍流项。最后应用该方法,针对两个溃坝自由液面流动问题,特别考虑不同粒子直径以及湍流Smagorinsky系数,进行数值对比研究以及实验对比分析,得到了采用较小粒子直径和较大湍流Smagorinsky系数模拟大变形自由液面具有较好结果的结论。

关键词： WC-MPS les 自由表面溃坝