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Multidisciplinary Design and Verification of the HB Flatback Airfoil Family

AIAA JOURNAL 2019年第11期57卷 4639-4649页

作者： Doosttalab, Mehdi Frommann, Olaf Univ Appl Sci Bremen Fac Natur & Tech Dept Mech Engn Inst Aerosp Technol Flughafenallee 10 D-28199 Bremen Germany Nordex Energy GmbH Langenhorner Chaussee 600 D-22419 Hamburg Germany

This paper presents the design, multidisciplinary optimization, and verification of 6 different flatback airfoils with different maximum thickness ranging from 35 to 50% with various trailing edge gap using 2D flow conditions for large multi-megawatt wind turbine blades. Because the design of the airfoil sections is a multidisciplinary field, involving several aerodynamic and structural parameters, the Simulated Annealing algorithm was used to design the optimized shape of the flatback airfoil sections. Computational fluid dynamics calculations in the optimization process were performed using the commercial Fluent code. The design Reynolds number was 6.0x106 and the optimized airfoil sections have 35, 40, 45, and 50% maximum thickness with a trailing edge gap ranging from 12.5 up to 20.0%. The wind tunnel test was performed on the HB-FB-350-150 airfoil at a Reynolds number of 0.950x106. The results show that the optimized flatback airfoils have several benefits compared with currently applied flatback airfoils. The results for these new optimized flatback airfoils are mainly a higher lift coefficient, higher stall angle of attack, higher sectional moment of inertia, and lower sensitivity to leading edge roughness compared with the current flatback airfoils.

关键词： Airfoil Sections Aerodynamic Performance Lift to Drag Ratio Aerodynamic Characteristics Transitional Flow simple algorithm Wind Tunnel Tests Turbine Blades Annealing Wind Turbine Airfoil

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Numerical simulation of oscillating lid driven square cavity

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ALEXANDRIA ENGINEERING JOURNAL 2018年第4期57卷 2609-2625页

作者： Indukuri, Jagadeesh Varma Maniyeri, Ranjith Natl Inst Technol Karnataka Dept Mech Engn Mangalore 575025 Karnataka India

This paper aim to develop a two-dimensional computational model to study the fluid dynamic behaviour in a square cavity driven by an oscillating lid using staggered grid based finite volume method. Firstly the developed computational model is validated with that of other researcher's results for the case of finite wall motion. Later the numerical simulations are performed for the case of top wall oscillations for various combinations of Reynolds number and frequencies. From these simulations an optimum frequency is chosen and then with the optimum frequency the simulations are carried out to explore the vortex behaviour for the cases of parallel wall oscillations (both top and bottom walls moving in the same direction) and anti-parallel wall oscillations (both top and bottom walls moving in the opposite direction). From these simulations it may be concluded that Re = 1000 is medium range of operation for better mixing inside the cavity for the cases of parallel and anti-parallel wall oscillations. (C) 2017 Faculty of Engineering, Alexandria University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://***/licenses/by-nc-nd/4.0/).

关键词： Finite volume method First order upwind scheme Oscillating lid driven cavity simple algorithm

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Computational analysis of two-dimensional wing aeroelastic flutter using Navier-Stokes model

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AIN SHAMS ENGINEERING JOURNAL 2018年第4期9卷 3459-3472页

作者： Hussin, Magdy Saeed Ghorab, Ashraf El-Samanoudy, Mohamed A. Arab Org Industrializat Cairo Egypt Ain Shams Univ Mech Power Engn Dept Cairo Egypt

All flying vehicles are not stiff enough, and its flexibility can interact with the flow around it to create self- sustaining vibrations, so interaction between Computational Fluid Dynamic (CFD) and Computational Structure Dynamic (CSD) need to be considered. In the present work the aero-elastic model has been implemented and evaluated for symmetrical NACA 0012. This is because of the abundance of section aero-elastic characteristics that leads to validation of the solution model. Navier Stokes Equations were integrated in time for aerodynamic forces. Then, at each time step forces were coupled with airfoil equations of motion to numerically simulate its flutter. Compressible N-S equations were discretized using finite volume method (FVM) and solved by Semi-Implicit Method for Pressure Linked Equations (simple) algorithm on unstructured grid by creating a MATLAB algorithm. In addition to that numerical method, classical methods have been used to investigate the flutter and the results have been compared. (C) 2018 Ain Shams University.

关键词： Flutter N-S Equations simple algorithm CFD Two-dimensional wing

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Numerical study of forced convection heat transfer in an oscillating lid driven cavity with heated top wall

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INTERNATIONAL JOURNAL OF HEAT AND TECHNOLOGY 2018年第4期36卷 1378-1387页

作者： Indukuri, Jagadeesh, V Maniyeri, Ranjith NITK Dept Mech Engn Mangalore 575025 Karnataka India

The present work is aimed to study the fluid flow and heat transfer behaviour in an oscillating lid-driven cavity using finite volume method by developing a two-dimensional computational model. Firstly, the developed computational model is validated by comparing our numerical results with that of the other researcher's results for the case of wall moving with finite motion. Next, the simulations are conducted for oscillating cavity problem with top wall oscillation for Reynolds number (Re = 5 00) and frequency (omega=2 pi/6). Later, the simulations are carried out for cases of oscillating parallel wall (upper and lower walls oscillating with sync) and oscillating anti-parallel wall (upper and lower walls oscillating with reverse sync) with the same optimum frequency and fixed Reynolds number (Re = 500). Secondly, the same optimum frequency is used to study the heat transfer characteristics in an oscillating lid-driven square cavity with heated top wall and lower cold wall for various Reynolds numbers (Re = 100-1000) and Prandtl numbers (Pr = 0.2 to 1.0). From this study, it is found that for high Prandtl number case (Pr = 1.0) the flow of high temperature isotherms inside the cavity is more when compared with low Prandtl number cases due to increase in molecular diffusion of momentum.

关键词： finite volume method simple algorithm oscillating lid-driven cavity Reynolds number Prandtl number

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Summary of Wind Speed Time Series Prediction algorithms

Summary of Wind Speed Time Series Prediction Algorithms

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作者： Xian-hui ZHU Nan SHI Xun-wen SU Pin LV Yue YU School of Electrical and Control Engineering Heilongjiang University of Science and Technology

Accurate prediction of wind speed is an important prerequisite for wind power *** hackle the large number of wind prediction outcomes in recent years,based on simple discussion of the wind power generation principle,wind speed predicted classification was summarized,the characteristics of a single algorithm wind speed forecast model was generalized,and the advantages and disadvantages of typical combination algorithm of wind speed forecast model was trying to scientific evaluated,the prediction effects of wind speed based on numerical weather prediction(NWP) was given *** last,in order to provide a research reference for future the main direction that should pay more attention to predict wind speed is given.

关键词： Wind speed prediction Classification simple algorithm Combination algorithm NWP

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Fourier analysis of the effect of non-constant terms on the convergence properties of simple algorithm formulated on a staggered grid

Fourier analysis of the effect of non-constant terms on the ...

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International Conference on Civil, Architectural and Hydraulic Engineering (ICCAHE 2012)

作者： Wang, Fei Zheng, Li Li, Yitian Wuhan Univ State Key Lab Water Resources & Hydropower Engn S Wuhan 430072 Peoples R China Changjiang Waterway Planning Design & Res Inst Wuhan 430011 Peoples R China

ISBN: (纸本)9783037854846

The Fourier analysis is employed to study the effect of non-constant terms on the convergence properties of simple (Semi-Implicit Method for Pressure Linked Equations) algorithm formulated on a staggered grid in two-dimension. The results indicate the non-constant items can broaden the convergence range of pressure relaxation factor for a given velocity under-relaxation factor. What's more, the non-constant items do well to the damping of the lowest error and can accelerate the convergence rate.

关键词： Fourier analysis non-constant terms simple algorithm error relaxation factor

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Efficient parallel implementation of incompressible pipe flow algorithm based on simple

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CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2016年第6期28卷 1751-1766页

作者： Zhang, Ji-Lin Yuan, Jun-Feng Wan, Jian Mao, Jie Zhu, Li-Ting Zhou, Li Jiang, Cong-Feng Di, Peng Wang, Jue Hangzhou Dianzi Univ Sch Comp Sci & Technol Hangzhou 310018 Zhejiang Peoples R China Hangzhou Dianzi Univ Sch Mech Engn Hangzhou 310018 Zhejiang Peoples R China Univ New S Wales Sch Mech Engn Sydney NSW 2052 Australia Chinese Acad Sci Comp Network Informat Ctr Supercomp Ctr Beijing Peoples R China

Parallel semi-implicit method for pressure-linked equations(simple) algorithm is used to solve the 3-D incompressible pipe flow problem. In this paper, we proposed a novel parallel simple algorithm that uses the alternate tiling technique. Firstly, a parallel simple algorithm based on domain decomposition method was established, and the implementation of domain partition and data exchange was presented. Then, we presented serial finite difference stencil algorithm based on alternate tiling. Furthermore, an iteration space parallel two-way finite difference stencil algorithm based on alternate tiling was proposed, introducing the sequence of iterative space tiles as the sequence of execution and using time skewing technique to partition the iteration space, thus to improve the data locality of algorithm. The cache misses and the cost of communication and synchronization are reduced by reordering the tiles of iteration space. Finally, the effectiveness of the two parallel simple algorithms were compared. The results showed that the parallel simple algorithm that uses the two-way finite difference stencil algorithm based on alternate tiling has good data locality, performance, and scalability in the Deepcomp7000 cluster computing environment. Copyright (C) 2013 John Wiley & Sons, Ltd.

关键词： domain decomposition incompressible pipe flow simple algorithm TDMA alternate tiling finite difference stencil

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LAMINAR PULSATING CONFINED JET FLOW OF NANOFLUIDS IN A DUCT WITH ISOFLUX WALL

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HEAT TRANSFER RESEARCH 2017年第11期48卷 1007-1024页

作者： Rahgoshay, M. Ranjbar, A. A. Ramiar, A. Rahimi, M. Arya, A. Babol Univ Technol Sch Mech Engn POB 484 Babol Sar Iran

Pulsating flows have a potential for research in many aspects. A pulsating unsteady confined jet is still unclear and requires further investigation because of many upcoming applications. In the past decade, nanofluids have attracted much interest because of their reported superior thermal performance and many potential applications. Also, a pulsating confined jet in a nanofluid is a new idea in fluid mechanics and heat transfer. In this paper, two-dimensional pulsating confined jet flow of nanofluids through a duct with isoflux walls is investigated numerically. In order to solve the Navier-Stokes and energy equations, the finite volume approach with collocated grid is employed. The momentum interpolation technique of Rhie and Chow is applied in simple algorithm. The simulation is performed at different pulse parameters (amplitude, Strouhal and Reynolds numbers) and volume fractions of nanoparticles for unsteady flow and also various values of the duct-to-jet width ratio (aspect ratio). Increasing both the frequency and amplitude leads to a slight increase in the Nusselt number but by increasing the Reynolds number, aspect ratio, and volume fraction the average Nusselt number will increase more. By increasing the Reynolds number and volume fraction, a higher rate of heat transfer is observed. The authors have not found in the open literature any records similar to the present work. One of the advantages of using pulsation in a nanofluid is a delay in the sedimentation process of nanoparticles.

关键词： pulsating flow Strouhal number volume fraction recirculation zone Nusselt number simple algorithm nanofluid

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Optimum Interaction Between Magnetohydrodynamics and Nanofluid for Thermal and Drag Management

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JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER 2017年第1期31卷 218-229页

作者： Bovand, M. Rashidi, S. Esfahani, J. A. Islamic Azad Univ Energy & Sustainable Dev Res Ctr Semnan Branch POB 35196-97951 Semnan Iran Ferdowsi Univ Mashhad Dept Mech Engn Mashhad 917751111 Iran

The magnetohydrodynamic technique has a positive impact upon the reduction of the unsteady flow forces, and a negative effect on the thermal performance. Adding nanoparticles to the base fluid is a common technique for thermal-performance improvement that can lead to an increase in drag forces. This paper is an attempt to control and optimize the interactions between two techniques by response surface methodology for nanofluid flow around a triangular obstacle. Also, a sensitivity analysis is performed to determine which parameters are the key drivers of a model's results. Orientations of the obstacle, Stuart number, and volumetric concentration of nanoparticles are selected as the operational parameters. A finite volume method with computational fluid dynamics techniques is used to solve the governing equations. The ranges of Stuart number N, orientations of the triangular obstacle , and volumetric concentration of nanoparticles phi are 0-5, 0-60deg, and 0-0.05, respectively. The Reynolds number Re is fixed at Re=100. The obtained results indicate that the Nusselt number Nu is more sensitive to the Stuart number rather than the orientations of the obstacle or the volumetric concentration of nanoparticles. Also, the optimized parameters for the minimum drag coefficient C-D are N=0.1697, theta=54.543deg, and phi=0.0225. These values for the maximum Nusselt number are N=0, theta=35.151deg, and phi=0.05.

关键词： Nanofluids Magnetohydrodynamics Enhancing Heat Transfer Rate Drag Coefficient Stuart Numbers Nanoparticles simple algorithm Sensitivity Analysis Finite Volume Method Unsteady Flows

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A new numerical method for solution of boiling flow using combination of simple and Jacobian-free Newton-Krylov algorithms

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PROGRESS IN NUCLEAR ENERGY 2017年 95卷 48-60页

作者： Hajizadeh, A. Kazeminejad, H. Talebi, S. Nucl Sci & Technol Res Inst Res Sch Reactor POB 11365-3486 Tehran Iran Nucl Sci & Technol Res Inst Res Sch Radiat Applicat POB 11365-3486 Tehran Iran Amirkabir Univ Technol Tehran Polytech Dept Energy Engn & Phys 424 Hafez AvePOB 15875-4413 Tehran Iran

In this paper, an efficient and stable numerical approach is developed in which a different combination of Jacobian-free Newton-Krylov (JFNK) and simple methods are introduced for solution of two-phase flow in both steady state and transient conditions. It is shown that, combination of Krylov subspace methods and simple type preconditioner give a fast convergence in the solution of the Drift Flux Model (DFM). It is demonstrated that the stability problem with simple approach, for two-phase flow problems, can be avoided by combining with JFNK. RELAP5 code and experimental data are considered for verification study. For all benchmarks, the proposed methods predictions are in good agreement with experiment and RELAP5 results. The accuracy of the proposed schemes were studied and compared with the classical simple method. It was found that the present approach to two-phase flow simulation predicts accurate results over a wide pressure range;whereas the classical simple algorithm underestimated the void fraction at low pressures. Finally, a typical power transient is considered to derrionstrate how the problem fastest time scale can change during the course of a transient. The present assessment of the numerical method showed that the time step control is not based on a stability time step restriction, like the material Courant limit. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Drift flux model simple algorithm Jacobian-free Newton-Krylov method

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