TY - BOOK

T1 - Laminar-Turbulent transition on Wind Turbines

A1 - Martinez Hernandez,Gabriel Gerardo

AU - Martinez Hernandez,Gabriel Gerardo

A2 - Sørensen,Jens Nørkær

A2 - Shen,Wen Zhong

ED - Sørensen,Jens Nørkær

ED - Shen,Wen Zhong

PB - DTU Mechanical Engineering

PY - 2012

Y1 - 2012

N2 - The present thesis deals with the study of the rotational effects on the <br/>laminar-turbulent transition on wind turbine blades. <br/>Linear stability theory is used to formulate the stability equations that <br/>include the effect of rotation. The mean flow required as an input to stability <br/>computations is obtained by a similarity transformation technique. <br/>This approach allows to transform the boundary layer equations that have <br/>included the effect of the Coriolis and centrifugal forces into a set of couple <br/>partial differential equations, that are more convenient to solve numerically. <br/>The solution have been parametrized and adapted to an wind turbine rotor <br/>geometry. The blade is resolved in radial sections along which calculations <br/>are performed. The obtained mean flow is classified according to the parameters <br/>used on the rotating configuration, geometry and operational conditions. <br/>The stability diagrams have been obtained by solving the stability <br/>equations as an eigenvalue problem. The Keller box Scheme that is second <br/>order accurate was used as a numerical method. Have found to be stable and <br/>effective in terms of computing time. The solution of the eigenvalue problem <br/>provide connection between the parameters used to define the resultant wave <br/>magnitude and direction. The propagation of disturbances in the boundary <br/>layers in three dimensional flows is relatively a complicated phenomena. <br/>The report discusses the available methods and techniques used to predict <br/>the transition location. Some common wind turbine airfoils are selected to <br/>performe parametrical studies with rotational effects. Finally a wind turbine <br/>rotor is used for comparison with transition experiments. The relative <br/>motion between the flow and the blade geometry defines the response of <br/>the flow to disturbances. Have been found that flow on the suction side of <br/>the blade has a stabilizating effect, while on the region from the stagnation <br/>point to the rotor plane has a destabilizating effect on the boundary layer. <br/>The tendency is that rotational effect stabilize the boundary layer on the <br/>wind turbine blade.

AB - The present thesis deals with the study of the rotational effects on the <br/>laminar-turbulent transition on wind turbine blades. <br/>Linear stability theory is used to formulate the stability equations that <br/>include the effect of rotation. The mean flow required as an input to stability <br/>computations is obtained by a similarity transformation technique. <br/>This approach allows to transform the boundary layer equations that have <br/>included the effect of the Coriolis and centrifugal forces into a set of couple <br/>partial differential equations, that are more convenient to solve numerically. <br/>The solution have been parametrized and adapted to an wind turbine rotor <br/>geometry. The blade is resolved in radial sections along which calculations <br/>are performed. The obtained mean flow is classified according to the parameters <br/>used on the rotating configuration, geometry and operational conditions. <br/>The stability diagrams have been obtained by solving the stability <br/>equations as an eigenvalue problem. The Keller box Scheme that is second <br/>order accurate was used as a numerical method. Have found to be stable and <br/>effective in terms of computing time. The solution of the eigenvalue problem <br/>provide connection between the parameters used to define the resultant wave <br/>magnitude and direction. The propagation of disturbances in the boundary <br/>layers in three dimensional flows is relatively a complicated phenomena. <br/>The report discusses the available methods and techniques used to predict <br/>the transition location. Some common wind turbine airfoils are selected to <br/>performe parametrical studies with rotational effects. Finally a wind turbine <br/>rotor is used for comparison with transition experiments. The relative <br/>motion between the flow and the blade geometry defines the response of <br/>the flow to disturbances. Have been found that flow on the suction side of <br/>the blade has a stabilizating effect, while on the region from the stagnation <br/>point to the rotor plane has a destabilizating effect on the boundary layer. <br/>The tendency is that rotational effect stabilize the boundary layer on the <br/>wind turbine blade.

BT - Laminar-Turbulent transition on Wind Turbines

ER -