检索结果-南通市图书馆

A Study on Relationship among Blade Camber Direction and pitch angle and Performance of a Small Straight-Blade Darrieus Wind Turbine by Using Scale Test Model and Gurney Flap

维普期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Journal of Flow Control, Measurement & Visualization 2021年第2期9卷 28-44页

作者： Tadakazu Tanino Keisuke Hara Ryo Yoshihara Takeshi Miyaguni Advanced Engineering School National Institute of Technology Kurume College Fukuoka Japan Department of Mechanical Systems Engineering University of Kitakyushu Fukuoka Japan

Straight-blade Darrieus vertical axis wind turbines are used as medium and small size wind turbine because of higher power output in vertical axis wind turbine (VAWT). In our previous study, the relationship between the performance and Reynolds number based on airfoil chord length had been investigated by using small-scale test models of lift-type VAWT, and the results showed that the performance of tested wind turbine models with small diameter was clearly lower than that of the large-scale field test machine, and its performance also varies significantly with the blade pitch angle. In this study, we focused on the performance of a small-scale straight-blade Darrieus VAWT, the relationship among the blade airfoil camber direction and the pitch angle, and the performance of the small-scale VAWT was examined experimentally by using a small-scale VAWT test model with Gurney flap which was a small flat plate. Gurney flaps with its height h, as a ratio to the blade chord length c, h/c = 0.036 to 0.055, were attached to the blades of the VAWT test model, in addition, the attaching direction of the Gurney flap on the blade was examined for both inward and outward of the rotor, and the pitch angle was also examined for a range of −5 to 10 degrees. These results are discussed comparing with the result of the VAWT without Gurney flap and considering the numerical results for the single blade with/without the Gurney flap. The results showed that the performance of the tested VAWT was reversed between the inward and outward Gurney flaps around a pitch angle of 10 degrees. That is, the inward Gurney flap was superior at a pitch angle of less than 10 degrees, while the outward Gurney flap was effective at a pitch angle of more than 10 degrees. Furthermore, for the tested small-scale VAWT model, the optimum pitch angle was about 5 degrees, and the inward and shorter Gurney flap showed higher power performance of the VAWT under this pitch angle condition.

关键词： Darrieus VAWT Gurney Flap Camber Direction pitch angle Power Performance

Horizontal Motion Control for Variable Vector Propeller of Submarine Based on pitch angle Varying

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Horizontal Motion Control for Variable Vector Propeller of S...

Geometric effects of cross sections on equilibrium of helical and twisted ribbon

第36届中国控制会议

作者： ZHENG Xiuli SUN Rong CHEN Mingjie ZHAO Jie FU Huixuan Academy of Automatication Harbin Engineering University Harbin Engineering University

ISBN: (纸本)9781538629185

In order to decrease both the weight and the size of submarine,the variable vector propeller（i.e.,VVP） has been applied on it.In this paper we will study the horizontal motion control for submarine with variable vector propeller.Firstly,we will build the reasonable simplification of the horizontal motion equations about submarine with variable vector propeller according to the need of control system.Secondly,we will build the rules of pitch matching for the variable vector propeller,so we can get the pitch state of WP,and we will give the thrust of WP in this pitch state.Thirdly,considering the characteristic of nonlinearity,time-variation,coupling,stochastic disturb of wave and ocean current,and dubious parameters in horizontal motion control system of submarine with variable vector propeller,the backstepping sliding mode controller based on model reference adaptive is designed for it.The adaptive rules are introduced in the backstepping sliding mode control during the design of controller.By applying the backstepping sliding mode controller based on adaptive rules for horizontal motion of submarine with WP,we can overcome the influence caused by some factors such as uncertainty and complexity of control system,and hold the performance of control.The formulation consults proved that backstepping sliding mode controller based on model reference adaptive can have better adaptive ability for uncertainty and complexity than the fuzzy sliding controller.

关键词： Variable Vector Propeller pitch angle Horizontal Motion Control Backstepping Sliding Mode Controller and Model Reference Adaptive

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2017年第4期38卷 495-504页

作者： Ye XIAO Zaixing HUANG State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

In the framework of elastic rod model, the Euler-Lagrange equations characterizing the equilibrium configuration of the polymer chain are derived from a free energy functional associated with the curvature, torsion, twisting angle, and its derivative with respect to the arc-length. The configurations of the helical ribbons with different cross-sectional shapes are given. The effects of the elastic properties, the cross-sectional shapes, and the intrinsic twisting on the helical ribbons are discussed. The results show that the pitch angle of the helical ribbon decreases with the increase in the ratio of the twisting rigidity to the bending rigidity and approaches the intrinsic twisting. If the bending rigidity is much greater than the twisting rigidity, the bending and twisting of the helical ribbon always appear simultaneously.

关键词： Euler-Lagrange equation twisting angle pitch angle elastic rod model helical and twisted ribbon

Ray Tracing for Doppler Backscattering System in the Experimental Advanced Superconducting Tokamak

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2015年第9期17卷 728-732页

作者：周楚刘阿娣胡建强王明远张小辉李弘俞昌旋刘万东兰涛谢锦林 CAS Key Laboratory of Geospace Environment Department of Modern PhysicsUniversity of Science and Technology of China

The Doppler backscattering system has been widely used for turbulence measurements,and the microwave beam will be backscattered near the cut-off layer when the Brag condition is fulfilled.In tokamak,the ray-tracing code is used to obtain the radial position and perpendicular wave number of the scattering layer for turbulence velocity measurement and the WKB（Wentzel-Kramers-Brillouin） approximation should be satisfied for optical propagation.To calculate the backscattering location and wave number at the cut-off layer only,a single ray tracing in the cross section is enough,while for spatial and wave number resolution calculation,multiple rays reflecting the microwave beam size should be used.Considering the angle between the wave vector and the magnetic field,a three-dimension quasi-optical Gaussian ray tracing is sometimes needed.

关键词： Doppler backscattering system ray tracing wave number resolution pitch angle

DYNAMIC CHARACTERISTICS OF LAG VIBRATION OF A WIND TURBINE BLADE

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2013年第6期26卷 592-602页

作者： Yinghui Li Liang Li Qikuan Liu Haiwei Lv School of Mechanics and Engineering Southwest Jiaotong University College of Mathematics Chengdu University of Information Technology

Lagwise dynamic characteristics of a wind turbine blade subjected to unsteady aero- dynamic loads are studied in this paper. The partial differential equations governing the coupled longitudinal-transverse vibration of the blade with large bending deflection are obtained by ap- plying Hamilton＇s principle. The modal problem of the coupled vibration is handled by using the method of numerical integration of Green＇s function. Influences of the rotating speed, the pitch angle, the setting angle, and the aerodynamic loads on natural frequencies are discussed. Results show that：（I） Lagwise natural frequencies ascend with the increase of rotating speed; effects of the rotating speed on low-frequencies are dramatic while these effects on high-frequencies become less. （2） Influences of the pitch angle on natural frequencies are little; in the range of the normal rotating speed, the first frequency ascends with the increase of the absolute value of the pitch angle, while it is contrary to the second and third frequencies. （3） Effects of the setting angle on natural frequencies depend on the rotating speed; influences are not significant at low speed, while they are dramatic on the first frequency at high speed. （4） Effects of the aerodynamic loads on natural frequencies are very little; frequencies derived from the model considering aerodynamic loads are smaller than those from the model neglecting aerodynamic loads; relative errors of the results corresponding to two models ascend with the increase of the absolute value of the setting angle.

关键词： wind turbine blade lag dynamic characteristics rotating speed pitch angle setting angle aerodynamic load

Turbulent Melt Flow in a Helical Channel of an Inductive Pump

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research(International) 2012年第S1期19卷 566-568页

作者： A.Kapusta B.Mikhailovich L.Reymal B.Tilman Center for MHD Studies Ben-Gurion University of the NegevBeer-ShevaIsrael Department of Mechanical Engineering Ben-Gurion University of the NegevBeer-ShevaIsrael Mahyd and Co TallinnEstonia

In contrast to Ref.[1]studying MHD processes in a helical channel induced by a vertical rotating electric current layer,in the present report we examine another version with the rotating electric current layer orthogonal to the helical channel axis,which leads to an increase in melt velocity with the growing pitch angle α of the helical channel.

关键词： vertical coordinate system helical channel pitch angle external friction model electromagnetic body force flow velocity.

Advanced Control of a PMSG Wind Turbine

在线全文

学校读者我要写书评

暂无评论

International Journal of Modern Nonlinear Theory and Application 2016年第1期5卷 1-10页

作者： Hafsi Slah Dhaoui Mehdi Sbita Lassaad National Engineering School of Gabes Photovoltaic Wind and Geothermal Systems Research Gabes Tunisia

In this work, an intelligent artificial control of a variable speed wind turbine (PMSG) is proposed. First, a mathematical model of turbine written at variable speed is established to investigate simulations results. In order to optimize energy production from wind, a pitch angle and DC bus control law is synthesized using PI controllers. Then, an intelligent artificial control such as fuzzy logic and artificial neural network control is applied. Its simulated performances are then compared to those of a classical PI controller. Results obtained in MATLAB/Simulink environment show that the fuzzy and the neuro control is more robust and has superior dynamic performance and hence is found to be a suitable replacement of the conventional PI controller for the high performance drive applications.

关键词： Wind Turbine Variable Speed pitch angle Pi Controller Fuzzy Logic Controller Neural Networks Controller