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Aeroelastic analysis of a rotating wind turbine blade using a geometrically exact formulation

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Abstract

In this paper, an aeroelastic analysis of a rotating wind turbine blade is performed by considering the effects of geometrical nonlinearities associated with large deflection of the blade produced during wind turbine operation. This source of nonlinearity has become more important in the dynamic analysis of flexible blades used in more recent multi-megawatt wind turbines. The structural modeling, involving the coupled edgewise, flapwise and torsional DOFs, has been performed by using a nonlinear geometrically exact beam formulation. The aerodynamic model is presented based on the strip theory, by applying the principles of quasi-steady and unsteady airfoil aerodynamics. Compared to the conventional steady aerodynamic model, the presented model offers a more realistic consideration of fluid–structure interactions. The resulting governing equation, expanded up to the third-order terms, is analyzed by using the reduced-order model (ROM). The ROM is developed by employing the coupled mode shapes of a cantilever blade under free loading condition. The specifications of the 5MW-NREL wind turbine are used in the simulation study. After verifying the ROM results by comparing them with those of the full FEM model, the model is used in additional static, modal and transient dynamics analyses. The results indicate the important effect of geometrical nonlinearity, especially for larger structural deformations. Moreover, nonlinear analyses reveal the important effects of torsion induced by lateral deformations. It is also found that the governing equation is more efficient, and sufficiently accurate, when it is developed by using the second-order kinetic terms, third-order potential terms and the second-order aerodynamic terms together with third-order damping. Finally, the effects of nonlinearities on the flutter characteristics of wind turbine blades are evaluated through frequency and dynamic analyses.

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Correspondence to M. Behzad.

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Appendix

Appendix

Considering the two Euler angles, the transformation matrix between the deformed and undeformed local coordinate systems is as follows [1]:

$$\begin{aligned} T=\left( {{\begin{array}{ccc} {1-\frac{1}{2}({v}'^{2}+{w}'^{2})}&{} {{v}'}&{} {{w}'} \\ {-{v}'-{w}'\phi +\frac{{v}'\phi ^{2}}{2}}&{} {1-\frac{\phi ^{2}}{2}-\frac{{v}'^{2}}{2}-\frac{{v}'{w}'\phi }{2}}&{} {\phi -\frac{{v}'{w}'}{2}-\frac{\phi ^{3}}{6}-\frac{{w}'^{2}\phi }{2}} \\ {-{w}'+{v}'\phi +\frac{{w}'\phi ^{2}}{2}}&{} {-\phi -\frac{{v}'{w}'}{2}+\frac{\phi ^{3}}{6}+\frac{{v}'^{2}\phi }{2}}&{} {1-\frac{\phi ^{2}}{2}-\frac{{w}'^{2}}{2}+\frac{{v}'{w}'\phi }{2}} \\ \end{array} }} \right) \nonumber \\ \end{aligned}$$
(A.1)

Matrices \(\left[ {H_1 } \right] \) and \(\left[ {H_2 } \right] \) in Eq. (4) are defined as [21]:

$$\begin{aligned} \left[ {H_1 } \right] =\left( {{\begin{array}{ccc} 1&{}\quad 0&{}\quad 0 \\ 0&{}\quad 0&{}\quad 0 \\ 0&{}\quad 0&{}\quad 0 \\ 0&{}\quad 1&{}\quad 0 \\ 0&{}\quad 0&{}\quad 0 \\ 0&{}\quad 0&{}\quad 0 \\ 0&{}\quad 0&{}\quad 1 \\ 0&{}\quad 0&{}\quad 0 \\ 0&{}\quad 0&{}\quad 0 \\ 0&{}\quad 0&{}\quad 0 \\ 0&{}\quad 0&{}\quad 0 \\ \end{array} }} \right) , \left[ {H_2 } \right] =\left( {{\begin{array}{ccc} 0&{}\quad 0&{}\quad 0 \\ 0&{}\quad 0&{}\quad 0 \\ 0&{}\quad 0&{}\quad 0 \\ 0&{}\quad 0&{}\quad 0 \\ {\frac{1}{2}{w}'+\frac{1}{4}{w}'^{3}-\frac{1}{4}{w}'\phi ^{2}+\frac{1}{2}{v}'^{2}{w}'}&{}\quad {\phi -\frac{1}{2}{v}'{w}'+\frac{1}{2}{v}'^{2}\phi -\frac{1}{6}\phi ^{3}}&{}\quad {1+\frac{1}{2}{v}'^{2}-\frac{1}{2}\phi ^{2}+\frac{1}{2}{w}'{v}'\phi } \\ 0&{}\quad 0&{}\quad 0 \\ 0&{}\quad 0&{}\quad 0 \\ {-\frac{1}{2}{v}'-\frac{1}{4}{v}'\phi ^{2}+\frac{1}{4}{v}'{w}'^{2}}&{}\quad {-1-\frac{1}{2}{w}'^{2}+\frac{1}{2}\phi ^{2}+\frac{1}{2}{v}'{w}'\phi }&{}\quad {\phi +\frac{1}{2}{w}'{v}'+\frac{1}{2}{w}'^{2}\phi -\frac{1}{6}\phi ^{3}} \\ 0&{}\quad 0&{}\quad 0 \\ {1-\frac{1}{2}{v}'{w}'\phi }&{}\quad 0&{}\quad 0 \\ 0&{}\quad 0&{}\quad 0 \\ \end{array} }} \right) \nonumber \\ \end{aligned}$$
(A.2)

By applying the Green–Lagrange strain theory, matrix \(\left[ {H_3 } \right] \) in Eq. (8) is obtained as [21]:

$$\begin{aligned} \left[ {H_3 } \right] =\left( {{\begin{array}{ccc} 0&{}\quad 0&{}\quad 0 \\ 0&{}\quad 0&{}\quad 0 \\ 0&{}\quad 0&{}\quad 0 \\ 0&{}\quad 0&{}\quad 0 \\ {-{v}''{v}'y-\frac{1}{2}{v}''{w}'z-\frac{1}{2}{w}''{w}'y-\frac{1}{2}{\phi }'{w}''(y^{2}+z^{2})}&{}\quad {\frac{1}{2}{w}''z}&{}\quad {-\frac{1}{2}{w}''y} \\ {-y+\phi z+y{w}''z-\frac{1}{2}{v}'{w}'z-\frac{1}{2}{v}'^{2}y+\frac{1}{2}\phi ^{2}y-2\phi {v}''yz+{v}''y^{2}+\frac{1}{2}{w}'{\phi }'(y^{2}+z^{2})+{w}''\phi (y^{2}-z^{2})}&{}\quad {-\frac{1}{2}{w}'z}&{}\quad {\frac{1}{2}{w}'y} \\ 0&{}\quad 0&{}\quad 0 \\ {-{w}''{w}'z-\frac{1}{2}{v}''{v}'z-\frac{1}{2}{w}''{v}'y+\frac{1}{2}{\phi }'{v}''(y^{2}+z^{2})}&{}\quad {-\frac{1}{2}{v}''z}&{}\quad {\frac{1}{2}{v}''y} \\ {-z-\phi y-\frac{1}{2}{w}'^{2}z+\frac{1}{2}\phi ^{2}z-\frac{1}{2}{w}'{v}'y+{w}''z^{2}+{v}''yz+2{w}''\phi yz+\phi {v}''(y^{2}-z^{2})-\frac{1}{2}{v}'{\phi }'(y^{2}+z^{2})}&{}\quad {\frac{1}{2}{v}'z}&{}\quad {-\frac{1}{2}{v}'y} \\ {-{w}''y+{v}''z+{w}''\phi z+{v}''\phi y+{w}''^{2}zy+{w}''{v}''(y^{2}-z^{2})-{v}''^{2}yz}&{}\quad 0&{}\quad 0 \\ {{\phi }'(y^{2}+z^{2})+\frac{1}{2}({w}'{v}''-{v}'{w}'')(y^{2}+z^{2})}&{}\quad -z&{}\quad y \\ \end{array} }} \right) \nonumber \\ \end{aligned}$$
(A.3)

Blade acceleration vectors \(\left\{ {Q_1 } \right\} \)and \(\left\{ {Q_1 } \right\} \) in Eq. (6) are expressed as [21]:

$$\begin{aligned} \left\{ {Q_1 } \right\}= & {} \left[ {P(\left\{ {s,0,0} \right\} ^{t})} \right] \left\{ {\vec {\alpha }_{{\textit{XYZ}}} } \right\} \nonumber \\&+\left[ {P(\vec {\omega }_{{\textit{xyz}}} )} \right] ^{t}\left[ {P(\left\{ {s,0,0} \right\} ^{t})} \right] \left\{ {\vec {\omega }_{{\textit{xyz}}} } \right\} \nonumber \\ \left\{ {Q_2 } \right\}= & {} \left\{ {\ddot{u},\ddot{v},\ddot{w}} \right\} +2\left[ {P(\left\{ {\dot{u},\dot{v},\dot{w}} \right\} ^{t})} \right] \left\{ {\vec {\omega }_{{\textit{xyz}}} } \right\} \nonumber \\&+\left[ {P(\left\{ {u,v,w} \right\} ^{t})} \right] \left\{ {\vec {\alpha }_{{\textit{xyz}}} } \right\} \nonumber \\&+\left\{ {\vec {\omega }_{{\textit{xyz}}} } \right\} ^{t}\left[ {P(\left\{ {u,v,w} \right\} ^{t})} \right] \left\{ {\vec {\omega }_{{\textit{xyz}}} } \right\} \end{aligned}$$
(A.4)

where antisymmetric matrices \(\left[ {P(\vec {\omega }_{{\textit{xyz}}} )} \right] \) and \( \left[ {P(\vec {\omega }_{\xi \eta \zeta } )} \right] \), which represent the corresponding angular velocity of each coordinate system, are written as:

$$\begin{aligned} \left[ {P(\vec {\omega }_{{\textit{xyz}}} )} \right] =\dot{T}_r T_r^t ; \left[ {P(\vec {\omega }_{\xi \eta \zeta } )} \right] =T\left[ {P(\vec {\omega }_{{\textit{xyz}}} )} \right] T^{t}+\dot{T}T^{t}\nonumber \\ \end{aligned}$$
(A.5)

In Eq. (A.4), the angular acceleration of each coordinate system is obtained directly by taking the partial derivative of each angular velocity component of Eq. (A.5), as follows:

$$\begin{aligned} \left[ {P(\vec {\alpha }_{{\textit{xyz}}} )} \right] =\frac{\partial }{\partial t}\left[ {P(\vec {\omega }_{{\textit{xyz}}} )} \right] ; \left[ {P(\vec {\alpha }_{\xi \eta \zeta } )} \right] =\frac{\partial }{\partial t}\left[ {P(\vec {\omega }_{\xi \eta \zeta } )} \right] \nonumber \\ \end{aligned}$$
(A.6)

Moreover, \(\left[ {J_1 } \right] \) and \(\left[ {J_2 } \right] \) in Eq. (6) are as follows:

$$\begin{aligned} \left[ {J_1 } \right] =\int _A {\left[ {P(\vec {r})} \right] \mathrm{d}A,} \left[ {J_2 } \right] =\int _A {\left[ {P(\vec {r})} \right] ^{t}\left[ {P(\vec {r})} \right] \mathrm{d}A}\nonumber \\ \end{aligned}$$
(A.7)

The variational vector of Eq. (23), constructed by using the modal coordinate variables, is expressed as [21]

$$\begin{aligned}&\left\{ {\delta \psi } \right\} _{11\times 1}^t =\left[ Q \right] _{11\times N} \left\{ {\delta q_i } \right\} _{N\times 1}^t\nonumber \\&\quad =\left( {{\begin{array}{ccccc} {2\sum _{i=1}^N {\mathfrak {R}{a}_{1i} q_i } }&{}\quad {2\sum _{i=1}^N {\mathfrak {R}{a}_{2i} q_i } }&{}\quad {2\sum _{i=1}^N {\mathfrak {R}{a}_{3i} q_i } }&{}\quad {\ldots }&{}\quad {2\sum _{i=1}^N {\mathfrak {R}{a}_{Ni} q_i } } \\ {2\sum _{i=1}^N {\mathfrak {R}{b}_{1i} q_i } }&{}\quad {2\sum _{i=1}^N {\mathfrak {R}{b}_{2i} q_i } }&{}\quad {2\sum _{i=1}^N {\mathfrak {R}{b}_{3i} q_i } }&{}\quad {\ldots }&{}\quad {2\sum _{i=1}^N {\mathfrak {R}{b}_{Ni} q_i } } \\ {2\sum _{i=1}^N {\mathfrak {R}{c}_{1i} q_i } }&{}\quad {2\sum _{i=1}^N {\mathfrak {R}{c}_{2i} q_i } }&{}\quad {2\sum _{i=1}^N {\mathfrak {R}{c}_{3i} q_i } }&{}\quad {\ldots }&{}\quad {2\sum _{i=1}^N {\mathfrak {R}{c}_{Ni} q_i } } \\ {Q_{1v} }&{}\quad {Q_{2v} }&{}\quad {Q_{3v} }&{}\quad {\ldots }&{}\quad {Q_{Nv} } \\ {{Q}'_{1v} }&{}\quad {{Q}'_{2v} }&{}\quad {{Q}'_{3v} }&{}\quad {\ldots }&{}\quad {{Q}'_{Nv} } \\ {{Q}''_{1v} }&{}\quad {{Q}''_{2v} }&{}\quad {{Q}''_{3v} }&{}\quad {\ldots }&{}\quad {{Q}''_{Nv} } \\ {Q_{1w} }&{}\quad {Q_{2w} }&{}\quad {Q_{3w} }&{}\quad {\ldots }&{}\quad {Q_{Nw} } \\ {{Q}'_{1w} }&{}\quad {{Q}'_{2w} }&{}\quad {{Q}'_{3w} }&{}\quad {\ldots }&{}\quad {{Q}'_{Nw} } \\ {{Q}''_{1w} }&{}\quad {{Q}''_{2w} }&{}\quad {{Q}''_{3w} }&{}\quad {\ldots }&{}\quad {{Q}''_{Nw} } \\ {Q_{1\phi } }&{}\quad {Q_{2\phi } }&{}\quad {Q_{2\phi } }&{}\quad {\ldots }&{}\quad {Q_{N\phi } } \\ {{Q}'_{1\phi } }&{}\quad {{Q}'_{2\phi } }&{}\quad {{Q}'_{3\phi } }&{}\quad {\ldots }&{}\quad {{Q}'_{N\phi } } \\ \end{array} }} \right) \left\{ {\begin{array}{l} \delta q_1 \\ \delta q_2 \\ \delta q_3 \\ \cdot \\ \cdot \\ \cdot \\ \delta q_N \\ \end{array}} \right\} \end{aligned}$$
(A.8)

where \(\mathfrak {R}{a}_{ji} \), \(\mathfrak {R}{b}_{ji} \) and \(\mathfrak {R}{c}_{ji} \) are the components of matrices \([\mathfrak {R}{a}]\), \([\mathfrak {R}{b}]\) and \([\mathfrak {R}{c}]\), which are represented as follows:

$$\begin{aligned} \left\{ {\begin{array}{l} {}[\mathfrak {R}{a}]_{N\times N} =-\frac{1}{2}\int \limits _0^s {\left[ {\left\{ {{Q}'_v } \right\} ^{t}\left\{ {{Q}'_v } \right\} +\left\{ {{Q}'_w } \right\} ^{t}\left\{ {{Q}'_w } \right\} } \right] _{N\times N} \mathrm{d}s} \\ {}[\mathfrak {R}{b}]_{N\times N} =-\frac{1}{2}\left[ {\left\{ {{Q}'_v } \right\} ^{t}\left\{ {{Q}'_v } \right\} +\left\{ {{Q}'_w } \right\} ^{t}\left\{ {{Q}'_w } \right\} } \right] _{N\times N} \\ {}[\mathfrak {R}{c}]_{N\times N} =-\frac{1}{2}\left[ \left\{ {{Q}''_v } \right\} ^{t}\left\{ {{Q}'_v } \right\} +\left\{ {{Q}'_v } \right\} ^{t}\left\{ {{Q}''_v } \right\} \right. \\ \left. +\left\{ {{Q}''_w } \right\} ^{t}\left\{ {{Q}'_w } \right\} +\left\{ {{Q}'_w } \right\} ^{t}\left\{ {{Q}''_w } \right\} \right] _{N\times N} \\ \end{array}} \right. \nonumber \\ \end{aligned}$$
(A.9)

The vectors of variational multipliers for the kinetic energy \(\left\{ {R^{\tilde{T}}} \right\} \), potential energy \(\left\{ {R^{\varPi }} \right\} \) and the external work performed by the aerodynamic forces \(\left\{ {R^{W_{\mathrm{aero}} }} \right\} \) are obtained as follows:

$$\begin{aligned}&\left\{ {R^{\tilde{T}}} \right\} :\left\{ {\begin{array}{ll} R_2^{\tilde{T}} =R_3^{\tilde{T}} =R_6^{\tilde{T}} =R_9^{\tilde{T}} =R_{11}^{\tilde{T}} =0; \\ R_1^{\tilde{T}} =\rho A\left( {\begin{array}{ll} s\varOmega ^{2}+2\varOmega \dot{v}\epsilon +\left( {-\ddot{u}+u\varOmega ^{2}-s\varOmega ^{2}\beta _\mathrm{c}^2 -\beta _\mathrm{c} w\varOmega ^{2}+z_G \left( {\ddot{w}^{\prime }-\varOmega ^{2}(w^{\prime }+\beta _\mathrm{c} )-2\dot{\phi }\varOmega } \right) +y_G \left( {\ddot{v}^{\prime }-\varOmega ^{2}v^{\prime }} \right) } \right) \epsilon ^{2} \\ +\,\left( {-\dot{v}\varOmega \beta _\mathrm{c}^2 -y_G \varOmega \left( \phi ^{2}+v^{\prime 2} \right) ^{\cdot }-z_G \varOmega w^{\prime }\dot{v}^{\prime }} \right) \epsilon ^{3} \\ \end{array}} \right) ; \\ R_4^{\tilde{T}} =\rho A\left( {\begin{array}{ll} (-\ddot{v}+\varOmega ^{2}v+y_G \varOmega ^{2})\epsilon +(-2\varOmega \dot{u}+2\beta _\mathrm{c} \varOmega \dot{w}+z_G (\ddot{\phi }-\phi \varOmega ^{2}+2\varOmega \dot{w}^{\prime })+2y_G \varOmega \dot{v}^{\prime })\epsilon ^{2} \\ +\,(-2z_G \varOmega (\phi v^{\prime })^{.}+2y_G \varOmega (w^{\prime }+\beta _\mathrm{c} )\dot{\phi })\epsilon ^{3} \\ \end{array}} \right) ; \\ R_5^{\tilde{T}} =(-y_G \rho As\varOmega ^{2}\epsilon +\rho A(z_G s\varOmega ^{2}\phi -2y_G \varOmega \dot{v})\epsilon ^{2}+(2z_G \rho A\varOmega \dot{v}\phi +2\rho J_{yz} \dot{\phi }\varOmega )\epsilon ^{3}); \\ R_7^{\tilde{T}} =\rho A((-\ddot{w}-s\varOmega ^{2}\beta _\mathrm{c} )\epsilon +(-2\beta _\mathrm{c} \varOmega \dot{v}-y_G \ddot{\phi })\epsilon ^{2}+2z_G \beta _\mathrm{c} \varOmega \dot{\phi }\epsilon ^{3}); \\ R_8^{\tilde{T}} =(-z_G \rho As\varOmega ^{2}\epsilon +\rho A(-y_G s\varOmega ^{2}\phi -2z_G \varOmega \dot{v})\epsilon ^{2}+(-2\rho Ay_G \varOmega \dot{v}\phi +2\rho J_{yy} \dot{\phi }\varOmega )\epsilon ^{3}); \\ R_{10}^{\tilde{T}} =\left( {\begin{array}{ll} -\varOmega ^{2}J_{yz} \rho +(-\rho J_{xx} \ddot{\phi }+\rho (J_{yy} -J_{zz} )\phi \varOmega ^{2}-2\rho J_{yz} \varOmega \dot{v}^{\prime }-2\rho J_{yy} \varOmega \dot{w}^{\prime })\epsilon \\ +\,\rho A(y_G (-\ddot{w}-s\varOmega ^{2}(w^{\prime }+\beta _\mathrm{c} ))+z_G (\ddot{v}-\varOmega ^{2}(sv{)}'))\epsilon ^{2}+\rho A\varOmega \dot{v}(-2y_G (w^{\prime }+\beta _\mathrm{c} )+2z_G v^{\prime })\epsilon ^{3} \\ \end{array}} \right) ; \\ \end{array}} \right. \nonumber \\ \end{aligned}$$
(A.10)
$$\begin{aligned}&\left\{ {R^{\varPi }} \right\} :\left\{ {\begin{array}{l} R_1^\varPi =R_2^\varPi =R_3^\varPi =R_4^\varPi =R_7^\varPi =0; \\ R_5^\varPi =\epsilon ^{2}\left( {-.5GI_{xx} \phi ^{\prime }w^{\prime \prime }} \right) +\epsilon ^{3}\left( {\begin{array}{l} EI_{zz} v^{\prime \prime 2}v^{\prime }+.25GI_{xx} w^{\prime \prime 2}v^{\prime }+.5EI_{yz} (w^{\prime }v^{\prime \prime 2}+w^{\prime }w^{\prime \prime 2}+w^{\prime \prime }v^{\prime }v^{\prime \prime }) \\ +(.5E-.25G)I_{xx} w^{\prime }v^{\prime \prime }w^{\prime \prime } \\ \end{array}} \right) ; \\ R_6^\varPi =\epsilon \left( {EI_{zz} v^{\prime \prime }+EI_{yz} w^{\prime \prime }} \right) +\epsilon ^{2}\left( {-E(I_{yy} -I_{zz} )w^{\prime \prime }\phi +.5GI_{xx} w^{\prime }\phi ^{\prime }-2EI_{yz} \phi v^{\prime \prime }} \right) \\ +\,\epsilon ^{3}\left( {\begin{array}{l} EI_{zz} v^{\prime \prime }v^{\prime 2}+E(I_{yy} -I_{zz} )v^{\prime \prime }\phi ^{2}+(.5E-.25G)I_{xx} v^{\prime }w^{\prime }w^{\prime \prime }+.25GI_{xx} w^{\prime 2}v^{\prime \prime } \\ +EI_{yz} (.5w^{\prime \prime }w^{\prime 2}+.5w^{\prime \prime }v^{\prime 2}-2w^{\prime \prime }\phi ^{2}+v^{\prime }v^{\prime \prime }w^{\prime }) \\ \end{array}} \right) ; \\ R_8^\varPi =\epsilon ^{2}(.5GI_{xx} \phi ^{\prime }v^{\prime \prime })+\epsilon ^{3}\left( {\begin{array}{l} EI_{yy} w^{\prime \prime 2}w^{\prime }+.25GI_{xx} v^{\prime \prime 2}w^{\prime }+.5EI_{yz} (v^{\prime }w^{\prime \prime 2}+v^{\prime }v^{\prime \prime 2}+w^{\prime \prime }w^{\prime }v^{\prime \prime }) \\ +(.5E-.25G)I_{xx} v^{\prime \prime }v^{\prime }w^{\prime \prime } \\ \end{array}} \right) ; \\ R_9^\varPi =(EI_{yy} w^{\prime \prime }+EI_{yz} v^{\prime \prime })\epsilon +\epsilon ^{2}(-.5GI_{xx} v^{\prime }\phi ^{\prime }-E(I_{yy} -I_{zz} )v^{\prime \prime }\phi +2EI_{yz} w^{\prime \prime }\phi ) \\ +\,\epsilon ^{3}\left( {\begin{array}{l} .25GI_{xx} v^{\prime 2}w^{\prime \prime }+EI_{yz} (.5v^{\prime \prime }v^{\prime 2}+.5w^{\prime 2}v^{\prime \prime }+v^{\prime }w^{\prime \prime }w^{\prime }-2v^{\prime \prime }\phi ^{2}) \\ -E(I_{yy} -I_{zz} )\phi ^{2}w^{\prime \prime }+(.5E-.25G)I_{xx} v^{\prime }v^{\prime \prime }w^{\prime }+EI_{yy} w^{\prime \prime }w^{\prime 2} \\ \end{array}} \right) ; \\ R_{10}^\varPi =\epsilon ^{2}(-E(I_{yy} -I_{zz} )w^{\prime \prime }v^{\prime \prime }+EI_{yz} (-v^{\prime \prime 2}+w^{\prime \prime 2}))+\epsilon ^{3}(E(I_{yy} -I_{zz} )(v^{\prime \prime 2}-w^{\prime \prime 2})\phi -4EI_{yz} w^{\prime \prime }\phi v^{\prime \prime }); \\ R_{11}^\varPi =\epsilon (GI_{xx} \phi ^{\prime })+\epsilon ^{2}(-.5GI_{xx} (v^{\prime \prime }w^{\prime }-v^{\prime }w^{\prime \prime })); \\ \end{array}} \right. \nonumber \\ \end{aligned}$$
(A.11)
$$\begin{aligned}&\left\{ {R_{\mathrm{C}}^{W_{\mathrm{aero}} } } \right\} :\left\{ {\begin{array}{l} R_{\mathrm{C},1}^{W_{\mathrm{aero}} } ,R_{\mathrm{C},2}^{W_{\mathrm{aero}} } ,R_{\mathrm{C},3}^{W_{\mathrm{aero}} } =0; R_{\mathrm{C},4}^{W_{\mathrm{aero}} } =\frac{\rho _\mathrm{a} c_{\mathrm{L}\alpha } c}{2}\left( {\begin{array}{l} \left( {(\dot{w}+W_i )^{2}-s\varOmega (\phi +\phi _\mathrm{p} )(\dot{w}+W_i )} \right) \epsilon ^{2} \\ +\left( {\begin{array}{l} -.25c(1-2a)(\dot{\phi }+\varOmega (w^{\prime }+\beta _\mathrm{c} ))W_i +2.W_i \varOmega v(w^{\prime }+\beta _\mathrm{c} ) \\ -\dot{v}W_i (\phi +\phi _\mathrm{p} )-2s\varOmega W_i \chi -W_i \varOmega w^{\prime }v^{\prime }s \\ +\left( {s\varOmega (\phi +\phi _\mathrm{p} )-2W_i } \right) (w^{\prime }+\beta _\mathrm{c} )V_i \mathrm{sin}(\varOmega t)\\ -V_i W_i (\phi +\phi _\mathrm{p} )\mathrm{cos}(\varOmega t) \\ \end{array}} \right) \\ \end{array}} \right) \epsilon ^{3}; \\ R_{\mathrm{C},5}^{W_{\mathrm{aero}} } =\frac{\rho _\mathrm{a} c_{\mathrm{L}\alpha } c}{2}\left( {cs\varOmega w^{\prime }W_i (1+2a)/8} \right) ; R_{\mathrm{C},8}^{W_{\mathrm{aero}} } =\frac{\rho _\mathrm{a} c_{\mathrm{L}\alpha } c}{2}\left( {-\frac{1}{8}cv^{\prime }\varOmega sW_i (2a+1)} \right) \epsilon ^{3};R_{\mathrm{C},6}^{W_{\mathrm{aero}} },R_{\mathrm{C},9}^{W_{\mathrm{aero}} } =0 \\ R_{\mathrm{C},7}^{W_{\mathrm{aero}} } =\frac{\rho _\mathrm{a} c_{\mathrm{L}\alpha } c}{2}\left( {\begin{array}{l} -s\varOmega \left( {\begin{array}{l} \dot{w}+W_i \\ -s\varOmega (\phi +\phi _\mathrm{p} +\epsilon \chi ) \\ \end{array}} \right) \epsilon +\left( {\begin{array}{l} s\varOmega \dot{v}(\phi +\phi _\mathrm{p} +\epsilon \chi )-\dot{v}((\dot{w}+W_i ) \\ -s\varOmega (\phi +\phi _\mathrm{p} ))+.25c\dot{\phi }s\varOmega (1-2a) \\ +.25cs\varOmega ^{2}(1-2a)(w^{\prime }+\beta _\mathrm{c} ) \\ -s\varOmega ^{2}v(w^{\prime }+\beta _\mathrm{c} )+.5\varOmega ^{2}s^{2}w^{\prime }v^{\prime } \\ +s\varOmega (w^{\prime }+\beta _\mathrm{c} )V_i \mathrm{sin}(\varOmega t) \\ +\left( {2s\varOmega (\phi +\phi _\mathrm{p} +\epsilon \chi )-(\dot{w}+W_i )} \right) V_i \mathrm{cos}(\varOmega t) \\ \end{array}} \right) \epsilon ^{2} \\ +\left( {\begin{array}{l} 0.5s\varOmega W_i (w^{\prime }+\beta _\mathrm{c} )^{2}+.5s\varOmega \dot{v}w^{\prime }v^{\prime }-\varOmega \dot{v}v(w^{\prime }+\beta _\mathrm{c} )+.25c(1-2a)\varOmega \dot{v}(w^{\prime }+\beta _\mathrm{c} ) \\ +\left( {v^{\prime }W_i +\dot{v}(w^{\prime }+\beta _\mathrm{c} )-2.s\varOmega v^{\prime }(\phi +\phi _\mathrm{p} )} \right) V_i \mathrm{sin}(\varOmega t) \\ +\left( {\begin{array}{l} 2(\phi +\phi _\mathrm{p} )\dot{v}+.25c(1-2a)\dot{\phi }-\varOmega v(w^{\prime }+\beta _\mathrm{c} ) \\ +s\varOmega w^{\prime }v^{\prime }+0.25(1-2a)c\varOmega (w^{\prime }+\beta _\mathrm{c} ) \\ \end{array}} \right) V_i \mathrm{cos}(\varOmega t) \\ +V_i^2 (w^{\prime }+\beta _\mathrm{c} )\mathrm{sin}(\varOmega t)\mathrm{cos}(\varOmega t)+\mathrm{cos}(\varOmega t)^{2}V_i^2 (\phi +\phi _\mathrm{p} ) \\ \end{array}} \right) \epsilon ^{3} \\ \end{array}} \right) ; \\ R_{\mathrm{C},10}^{W_{\mathrm{aero}} } =\frac{\rho _\mathrm{a} c_{\mathrm{L}\alpha } c}{2}\left( {\begin{array}{l} 0.25c(1+2a)\left( {\varOmega s(\phi +\phi _\mathrm{p} )-(\dot{w}+W_i )} \right) \epsilon ^{2} \\ +\left( {\begin{array}{l} c(1+2a)\dot{v}\left( {-.25W_i +s\varOmega (\phi +\phi _\mathrm{p} )} \right) +c^{2}s\varOmega a(1-2a)\dot{\phi }/8 \\ +.25c(1+2a)s\varOmega (w^{\prime }+\beta _\mathrm{c} )V_i \mathrm{sin}(\varOmega t) \\ +\left( {-W_i +2\varOmega s(\phi +\phi _\mathrm{p} )} \right) c(1+2a)V_i \mathrm{cos}(\varOmega t)/4 \\ \end{array}} \right) \epsilon ^{3}; \\ \end{array}} \right) ; \\ \end{array}} \right. \nonumber \\&\left\{ {R_{\mathrm{NC}}^{W_{\mathrm{aero}} } } \right\} :\left\{ {\begin{array}{l} R_{\mathrm{NC},1}^{W_{\mathrm{aero}} } ,R_{\mathrm{NC},2}^{W_{\mathrm{aero}} } ,R_{\mathrm{NC},3}^{W_{\mathrm{aero}} },R_{\mathrm{NC},5}^{W_{\mathrm{aero}} },R_{\mathrm{NC},6}^{W_{\mathrm{aero}} },R_{\mathrm{NC},8}^{W_{\mathrm{aero}} },R_{\mathrm{NC},9}^{W_{\mathrm{aero}} },R_{\mathrm{NC},11}^{W_{\mathrm{aero}} } =0; \\ R_{\mathrm{NC},4}^{W_{\mathrm{aero}} } =\frac{\rho _\mathrm{a} c_{\mathrm{L}\alpha } c}{2}\left( {\left( {-s^{2}\varOmega ^{2}c_{\mathrm{D}} /c_{\mathrm{L}\alpha } } \right) \epsilon ^{2}+\left( {\begin{array}{l} -.25c\dot{\phi }s\varOmega (\phi +\phi _\mathrm{p} )-2s\varOmega \dot{v}c_{\mathrm{D}} /c_{\mathrm{L}\alpha } -1/c_{\mathrm{L}\alpha } c_{\mathrm{L}0} \varOmega sW_i \\ -2s\varOmega c_{\mathrm{D}} /c_{\mathrm{L}\alpha } V_i \mathrm{cos}(\varOmega t) \\ \end{array}} \right) \epsilon ^{3}} \right) ; \\ R_{\mathrm{NC},7}^{W_{\mathrm{aero}} } =\frac{\rho _\mathrm{a} c_{\mathrm{L}\alpha } c}{2}\left( {\begin{array}{l} \left( {-.25c\ddot{w}+.25cs\varOmega ^{2}(w^{\prime }+\beta _\mathrm{c} )+.25c\dot{\phi }s\varOmega +s^{2}\varOmega ^{2}c_{\mathrm{L}0} /c_{\mathrm{L}\alpha } } \right) \epsilon ^{2} \\ +\left( {\begin{array}{l} -s\varOmega W_i c_{\mathrm{D}} /c_{\mathrm{L}\alpha } +2\varOmega s\dot{v}c_{\mathrm{L}0} /c_{\mathrm{L}\alpha } +.25s\varOmega c\dot{v}^{\prime }w^{\prime } \\ -.25c\varOmega (\phi +\phi _\mathrm{p} )V_i \mathrm{sin}(\varOmega t) \\ \left( {.25c\dot{\phi }+.5c\varOmega (w^{\prime }+\beta _\mathrm{c} )+2s\varOmega c_{\mathrm{L}0} /c_{\mathrm{L}\alpha } } \right) V_i \mathrm{cos} (\varOmega t) \\ \end{array}} \right) \epsilon ^{3} \\ \end{array}} \right) ; \\ R_{\mathrm{NC},10}^{W_{\mathrm{aero}} } =\frac{\rho _\mathrm{a} c_{\mathrm{L}\alpha } c}{2}\left( {-c^{2}s\varOmega a(1-2a)\dot{\phi }/16} \right) \epsilon ^{3}; \\ \end{array}} \right. \nonumber \\ \end{aligned}$$
(A.12)
$$\begin{aligned}&\left\{ {R_{\mathrm{C}}^{W_{\mathrm{aero}} } } \right\} :\left\{ {\begin{array}{l} R_{\mathrm{C},1}^{W_{\mathrm{aero}} } ,R_{\mathrm{C},2}^{W_{\mathrm{aero}} },R_{\mathrm{C},3}^{W_{\mathrm{aero}} } R_{\mathrm{C},5}^{W_{\mathrm{aero}} },R_{\mathrm{C},6}^{W_{\mathrm{aero}} } , R_{\mathrm{C},8}^{W_{\mathrm{aero}} } ,R_{\mathrm{C},9}^{W_{\mathrm{aero}} } =0; \\ R_{\mathrm{C},4}^{W_{\mathrm{aero}} } =\frac{\rho _\mathrm{a} c_{\mathrm{L}\alpha } c}{2}\left( {\left( {W^{2}-s\varOmega W_i \phi _\mathrm{p} } \right) \epsilon ^{2}+\left( {\begin{array}{l} -.25c\beta _\mathrm{c} \varOmega (1-2a)W_i -V_i W_i \phi _\mathrm{p} \mathrm{cos}(\varOmega t) \\ +\left( {s\varOmega \phi _\mathrm{p} -2W_i } \right) \beta _\mathrm{c} V_i \mathrm{sin}(\varOmega t) \\ \end{array}} \right) } \right) \epsilon ^{3}; \\ R_{\mathrm{C},7}^{W_{\mathrm{aero}} } =\frac{\rho _\mathrm{a} c_{\mathrm{L}\alpha } c}{2}\left( {\begin{array}{l} -s\varOmega \left( {W_i -s\varOmega \phi _\mathrm{p} } \right) \epsilon +\left( {\begin{array}{l} +.25\beta _\mathrm{c} cs\varOmega ^{2}(1-2a)+s\varOmega \beta _\mathrm{c} V_i \mathrm{sin}(\varOmega t) \\ +\left( {2s\varOmega \phi _\mathrm{p} -W_i } \right) V_i \mathrm{cos}(\varOmega t) \\ \end{array}} \right) \epsilon ^{2} \\ +\left( {\begin{array}{l} 0.5s\varOmega W_i \beta _\mathrm{c} ^{2}+0.25\beta _\mathrm{c} (1-2a)c\varOmega V_i \mathrm{cos}(\varOmega t) \\ +V_i^2 \beta _\mathrm{c} \mathrm{sin}(\varOmega t)\mathrm{cos}(\varOmega t)+\mathrm{cos}(\varOmega t)^{2}V_i^2 \phi _\mathrm{p} \\ \end{array}} \right) \epsilon ^{3} \\ \end{array}} \right) ; \\ R_{\mathrm{C},10}^{W_{\mathrm{aero}} } =\frac{\rho _\mathrm{a} c_{\mathrm{L}\alpha } c}{2}\left( {\left( {c(1+2a)\left( {s\varOmega \phi _\mathrm{p} -W_i } \right) /4} \right) \epsilon ^{2}+\left( {\begin{array}{l} +.25\beta _\mathrm{c} c(1+2a)s\varOmega V_i \mathrm{sin}(\varOmega t) \\ +\left( {-W_i +2s\varOmega \phi _\mathrm{p} } \right) c(1+2a)V_i \mathrm{cos}(\varOmega t)/4 \\ \end{array}} \right) \epsilon ^{3};} \right) ; \\ \end{array}} \right. \nonumber \\&\left\{ {R_{\mathrm{NC}}^{W_{\mathrm{aero}} } } \right\} :\left\{ {\begin{array}{l} R_{\mathrm{NC},1}^{W_{\mathrm{aero}} } ,R_{\mathrm{NC},2}^{W_{\mathrm{aero}} } ,R_{\mathrm{NC},3}^{W_{\mathrm{aero}} } ,R_{\mathrm{NC},5}^{W_{\mathrm{aero}} } ,R_{\mathrm{NC},6}^{W_{\mathrm{aero}} } ,R_{\mathrm{NC},8}^{W_{\mathrm{aero}} } ,R_{\mathrm{NC},9}^{W_{\mathrm{aero}} } ,R_{\mathrm{NC},10}^{W_{\mathrm{aero}} } ,R_{\mathrm{NC},11}^{W_{\mathrm{aero}} } =0; \\ R_{\mathrm{NC},4}^{W_{\mathrm{aero}} } =\frac{\rho _\mathrm{a} c_{\mathrm{L}\alpha } c}{2}\left( {\left( {-s^{2}\varOmega ^{2}c_{\mathrm{D}} /c_{\mathrm{L}\alpha } } \right) \epsilon ^{2}-2s\varOmega c_{\mathrm{D}} V_i \mathrm{cos}(\varOmega t)\epsilon ^{3}/c_{\mathrm{L}\alpha } } \right) ; \\ R_{\mathrm{NC},7}^{W_{\mathrm{aero}} } =\frac{\rho _\mathrm{a} c_{\mathrm{L}\alpha } c}{2}\left( {\left( {.25cs\varOmega ^{2}\beta _\mathrm{c} +s^{2}\varOmega ^{2}c_{\mathrm{L}0} /c_{\mathrm{L}\alpha } } \right) \epsilon ^{2}+\left( {\begin{array}{l} -s\varOmega W_i c_{\mathrm{D}} /c_{\mathrm{L}\alpha } -.25c\varOmega \phi _\mathrm{p} V_i \mathrm{sin}(\varOmega t) \\ \left( {.5c\varOmega \beta _\mathrm{c} +2s\varOmega c_{\mathrm{L}0} /c_{\mathrm{L}\alpha } } \right) V_i \mathrm{cos} (\varOmega t) \\ \end{array}} \right) \epsilon ^{3}} \right) ; \\ \end{array}} \right. \nonumber \\ \end{aligned}$$
(A.13)

In Eqs. (A.10) through (A.13), the magnitude orders of the terms are indicated by an arbitrary parameter of \(\epsilon =1\), and the components of free-stream velocity \(V_{{\mathrm{wind}}} \) and \(W_{{\mathrm{wind}}} \) are denoted by \(V_i \) and \(W_i \), respectively. Moreover, the related circulatory and non-circulatory terms of the aerodynamic equation are defined by Eqs. (A.12) and (A.13), respectively, through which the overall aerodynamic equation is expressed as \(\left\{ {R^{W_{\mathrm{aero}} }} \right\} =C\mathrm{(k)}\left\{ {R_{\mathrm{C}}^{W_{\mathrm{aero}} } } \right\} +\left\{ {R_{\mathrm{NC}}^{W_{\mathrm{aero}} } } \right\} \).

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Rezaei, M.M., Behzad, M., Haddadpour, H. et al. Aeroelastic analysis of a rotating wind turbine blade using a geometrically exact formulation. Nonlinear Dyn 89, 2367–2392 (2017). https://doi.org/10.1007/s11071-017-3591-1

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