The Effects of Wake Dynamics and Trailing Edge Flap on Wind Turbine Blade

[[abstract]]In the present study, we considered the bladewake interaction (BWI) and the TEF span length, index angle on a turbine blade. The aerodynamic loads and the stresses on the blade were studied. The wake dynamic theory, BEM, and the ANSYS-FORTRAN APDL method were employed. Results were correlation with a small turbine for blade stress distribution. The blade lift distribution was also compared with numerical results from [6]. Finally, the wake and the TEF configuration effects on a 5MW turbine blade in the lift distribution and stresses were presented in this work.[[cooperationtype]]國內[[conferencetype]]國際[[conferencetkucampus]]淡水校園[[conferencedate]]20140623~20140628[[booktype]]電子版[[iscallforpapers]]Y[[conferencelocation]]New Taipei City, Taiwa

On The Vibration Reduction of a Nonlinear Support Base with Dual-shock-absorbers

[[abstract]]The concept of the vibration reduction via position change of the vibration absorbers was introduced in this study. A rigid body plate was taken as the main body. Each of the four corners of the main body was supported by a cubic spring to simulate the transverse-rotate-rotate nonlinear vibrations. Two point-mass shock absorbers were suspended under the body. The positions of these two absorbers could be adjusted to achieve the best vibration reduction effect. The method of multiple scales was used to obtain analytic solutions to this vibration system. Both analytic and numerical results were compared to verify the impacts on system vibration from positions of these two shock absorber devices. This study found that, when natural frequencies of these two shock absorbers are similar, the vibration reduction effect is better. This phenomenon often appears at the endpoint of the rigid body plate when the dual-shock- absorbers are at the same position.[[notice]]補正完畢[[journaltype]]國內[[incitationindex]]EI[[booktype]]紙本[[countrycodes]]TW

The Effect of a Vibration Absorber on a Nonlinear Two-dimensional System in Vibration Reduction

[[abstract]]This study focuses on the vibration of a planar rigid body taking into account the aerodynamic forces and looks at how location or length of the vibration absorber affects system stability. This rigid body is supported by a cubic spring on the elastic axis. The underneath attached vibration absorber is also considered a rigid body, and is mounted with linear spring and damper at both ends. Based on cost efficiency and without changing the main configuration of the vibration system, the absorber’s position and length are adjusted to obtain the combinations for the best vibration damping effect. The Method of Multiple Scales (MOMS) is employed to obtain its fixed point and analytic solutions. Numerical method is directly used to calculate the frequency response of this nonlinear system. The phase plots and frequency response of this nonlinear system are compared to verify the impact of vibration absorber position on the main body vibration. In the case studied, we found that the farther the vibration absorber mass center from 0.3 (non-dimensional chord length) behind the leading edge and longer of vibration absorber, the worse the vibration absorbing effect.[[notice]]補正完畢[[journaltype]]國外[[booktype]]紙本[[countrycodes]]GB

Study of the Positions of Multiple Dampers in a Dual-Plate Mechanism for Vibration Reduction

[[abstract]]This study proposes an economical and effective method of reducing vibration in a dual-plate mechanism. The vibrating mechanism comprises two (upper and lower) rigid body plates joined by a spring at each of the four corners. The lower rigid plate is supported from the ground by the same springs at its four corners. We attached two point-mass Tuned-Mass-Dampers (dual TMDs) to the bottom of each rigid plate, and adjusted their positions to optimize the effectiveness of vibration reduction. Lagrange's equation was used to derive the motion of the dual rigid plates. Vibration reduction effect was analyzed following attachment of the TMDs at different positions in the system. We implemented a practical model, measured the amplitude of vibration, and conducted a comparison between the theoretical and empirical results. The experimental results demonstrate that the optimal vibration reduction effect was achieved when one of the dual TMDs was attached at a position below the applied force point, and the other one was attached at the diagonal quadrant endpoint. This combination was the most effective in reducing the amplitude of vibrations of the plates. The frequency response graph shows that theoretical estimates correspond to experimental results.[[notice]]補正完畢[[journaltype]]國內[[incitationindex]]EI[[booktype]]紙本[[countrycodes]]TW

Lag-damping of the nonlinear blade-wake coupled system in hover

[[abstract]]The lead-lag mode is the most sensitive motion in a helicopter rotoraeroelastic analysis. The stability characteristics of a lag mode in arotor system can be observed through the eigenvalues. The resonancephenomenon can be predicted by eigen-analysis as well. This paper usesanalytic methods to integrate the wake dynamics, blade aerodynamics,and nonlinear composite rotor blade flap-lag-torsion structuraldynamics in the form of a coupled system. Only the homogeneousisotropic material blade will be studied in this paper in order tomake a preliminary investigation of a wake-rotor interaction and thecompatibility of the composite blade equation. The Galerkin's methodand the Duncan's polynomial are used to resolve the equations. Thecoupled nonlinear system is separated into equilibrium and disturbant(dynamic) states. The equilibrium state is solved by using nonlinearsolves. The system's flap-lag-torsion eigen-equations are formulatedby the combination of the equilibrium coefficients and the disturbantequations. The Floquet's theory is used to derive the systemeigenvalues. The nonlinear phenomenon will be investigated througheigen-analysis, especially for quasi-linear resonance. Various lagfrequencies (stiffness) of the isotropic rotor blades are studied inthis paper. The equilibrium results show that the wake has strongeffects in the blade tip displacements in higher blade pitch angles.The eigen-analysis of the lag damping shows the eigenvalue veeringphenomenon occurs when pitch angle is 8 degrees. All of these may bedue to the wake effects in the rotor-wake coupled system.[[abstract]]The lead-lag mode is the most sensitive motion in a helicopter rotoraeroelastic analysis. The stability characteristics of a lag mode in arotor system can be observed through the eigenvalues. The resonancephenomenon can be predicted by eigen-analysis as well. This paper usesanalytic methods to integrate the wake dynamics, blade aerodynamics,and nonlinear composite rotor blade flap-lag-torsion structuraldynamics in the form of a coupled system. Only the homogeneousisotropic material blade will be studied in this paper in order tomake a preliminary investigation of a wake-rotor interaction and thecompatibility of the composite blade equation. The Galerkin's methodand the Duncan's polynomial are used to resolve the equations. Thecoupled nonlinear system is separated into equilibrium and disturbant(dynamic) states. The equilibrium state is solved by using nonlinearsolves. The system's flap-lag-torsion eigen-equations are formulatedby the combination of the equilibrium coefficients and the disturbantequations. The Floquet's theory is used to derive the systemeigenvalues. The nonlinear phenomenon will be investigated througheigen-analysis, especially for quasi-linear resonance. Various lagfrequencies (stiffness) of the isotropic rotor blades are studied inthis paper. The equilibrium results show that the wake has strongeffects in the blade tip displacements in higher blade pitch angles.The eigen-analysis of the lag damping shows the eigenvalue veeringphenomenon occurs when pitch angle is 8 degrees. All of these may bedue to the wake effects in the rotor-wake coupled system.[[sponsorship]]National Science Council; National Cheng Kung University; National Research Council of Canada[[notice]]20130320格式已修正by陸桂英[[conferencetype]]國內[[conferencedate]]20010521~20010523[[booktype]]紙本[[iscallforpapers]]

[[alternative]]The Lead-Lag Damping Analysis of a Nonlinear Rotor-Wake Coupled System

[[abstract]]本論文利用解析的方法將尾流運動方程、葉片空氣動力學及一個非線性的複材葉片的Flap-lag-torsion結構運動方程整合成一耦合的系統。該系統為一極複雜之非線性積分---偏微分方程式，本論文將利用Galerkin及Duncan多項式將其展開，求得平衡項(Equilibrium term)係數，再與擾動項(Disturbant term)合併且線性化之後，利用Floquet理論求解該系統之Flap-lag-torsion阻尼值。由結果得知，本文之Lead-lag阻尼值的預估在低仰角時與前人的實驗結果相比誤差較大，然而整體誤差較前人之數值分析結果為小。此外，本文所建立的數學模式包含尾流及複材葉片之因素且為時域內之方程式，對於旋翼葉片之 Flap-lag-torsion的Damping及穩定性的分析將又邁出一大步。[[abstract]]In this research, a new three-dimensional wake and nonlinear composite rotor blade flap-lag torsion coupled model is developed. The generalized dynamic wake model employed is based on an induced undetermined time dependent coefficients as aerodynamic states. The nonlinear composite beam theory governs the equations of motion of an extensional-flexure-flexure-torsional vibrations of a slewing or rotating beam. The nonlinear equilibrium states results are employed as the coefficients of the linearized disturbant equation. The Floquet Theory is used to find the system dampings. Results show that the error of lag damping for different pitch angles has been reduced from 40.7%~92.1% to 10.2%~34.2%. The present model thus proves to be successful.[[sponsorship]]中正理工學院; 中國航空太空學會; 中華民國燃燒學會[[notice]]20130320格式已修正by陸桂英[[conferencetype]]國內[[conferencedate]]19991204~19991204[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]桃園, 臺

[[alternative]]The effect of wake dynamics on elastic helicopter rotor blades in forward flight

[[abstract]]直昇機的旋翼葉片，當它在懸空或前飛時，誘導尾流會劇烈地影響到它的穩定性。本文的研究即是在探討有關 誘導尾流及旋翼葉片所形成的氣彈系統，它們之間的交互影響及穩定性分析。誘導尾流的理論係採用準確性及偶合 性極佳的彼得斯(Peters) 動力尾流理論。至於和彈性葉片耦合成的氣彈系統，我們使用Galerkin method，做為 求解彈性運動方程的工具，然後再使用修正過的Duncan多項式作為彈性葉片的彎曲模。本氣彈系統是建立在非旋 轉座標系統上，具有週期性的係數，所以必須以"富羅格(Floquet)理論"作為求解特徵值的工具。本研究的結果 即對誘導尾流及剛性葉片和彈性葉片的耦合氣彈系統作特徵值分析，由特徵值分析結果中可以了解誘導尾流對剛性 及彈性葉片Flap 阻尼具有相當程度的影響，而且於前飛時其影響的效應比懸空時更為劇烈。[[sponsorship]]中國航空太空學會; 淡江大學; 中山科學研究院航空工業發展中心[[conferencetype]]國內[[conferencetkucampus]]淡水校園[[conferencedate]]19951217~19951217[[iscallforpapers]]Y[[conferencelocation]]臺北縣, 臺

[[alternative]]Review of Helicopter Rotor Wake Dynamic Theories

[[abstract]]由於旋翼機的升力及推力皆由主旋翼負責,因此直昇機的主旋翼就扮演了重要的角色。本文的目的就是介紹歷年來直昇機主旋翼尾流力學的理論發展。首先就尾流空氣動力學的觀點介紹基本的尾流理論,如動量理論、葉片元素理論等。此外對於電腦上之應用,如自由流法也略加介紹。而對於預設尾流法及較近代之尾流理論--- Peters動力尾流理論及該理論的應用也將詳加介紹。 The development and background of rotary-wing wake dynamics has been briefly reviewed. Several basic wake aerodynamic models have been introduced. The free-wake analysis is also mentioned for the C.F. D. applications. The prescribed wake model has compared with other approach methods. A recently wake model---Peters dynamic wake model is also introduced as well as its applications in aeroelastic systems.[[abstract]]The development and background of rotary-wing wake dynamics has been briefly reviewed. Several basic wake aerodynamic models have been introduced. The free-wake analysis is also mentioned for the C.F. D. applications. The prescribed wake model has compared with other approach methods. A recently wake model---Peters dynamic wake model is also introduced as well as its applications in aeroelastic systems.[[sponsorship]]淡江大學 航空工程系[[conferencetype]]兩岸[[conferencetkucampus]]淡水校園[[conferencedate]]19951214~19951215[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]臺北縣, 臺

[[alternative]]A Flapping Mode Identification of Rotary Wing Blades and Wake Coupled System in Forward Flight

[[abstract]]特徵值的分析可以判定一個系統的穩定性,而對於氣體彈性力學特徵值的分析而言也是很重要的一部分。本文將用富羅格理論對葉片-尾流耦合系統做特徵值分析,並透過此法對四個葉片的旋翼在前飛時做拍撲運動的各組模態( modes)做辨識及探討。本文發現考慮尾流動力影響與不考慮誘導流系統之旋翼葉片特徵值做比較時,即使在很高的前飛率時,誘導流對葉片動力的影響仍然很大。 An eigenvalue study can provide stability information for a system, and it is also and important part of aeroelastic analysis. In this work, the blade-wake coupled system eigen- analysis is studied by the Floquet Theory, and the flapping modes for a four-bladed rotor are investigated and identified through their eigenvalues. The eigenvalues of the Floquet matrix can determine system characteristics. The effect of wake dynamics on rotor blade eigenvalues can be seen by comparison with no inflow case. The results show that the inflow has a profound effect on blade dynamics, even at high advance ratios.[[abstract]]An eigenvalue study can provide stability information for a system, and it is also and important part of aeroelastic analysis. In this work, the blade-wake coupled system eigen- analysis is studied by the Floquet Theory, and the flapping modes for a four-bladed rotor are investigated and identified through their eigenvalues. The eigenvalues of the Floquet matrix can determine system characteristics. The effect of wake dynamics on rotor blade eigenvalues can be seen by comparison with no inflow case. The results show that the inflow has a profound effect on blade dynamics, even at high advance ratios.[[sponsorship]]淡江大學 航空工程系[[conferencetype]]兩岸[[conferencetkucampus]]淡水校園[[conferencedate]]19951214~19951215[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]臺北縣, 臺