## Turbine results |

Warning: | Turbines blades are relatively stiff; if blade internal load results are of interest, double precision logging should be enabled. |

For general information on selecting and producing results, see the producing results topic.

The position, relative to global axes, of a user-specified point $\vec{p}$ on the turbine. The point $\vec{p}$ is given in turbine local coordinates; if $\vec{p}=(0,0,0)$ then the position and orientation reported are those of the turbine origin.

The position of the user-specified point $\vec{p}$ on the turbine, relative to the static position of $\vec{p}$, and with respect to the static orientation of the turbine. By static position and static orientation we mean the position and orientation in the model's static state. So, if $\vec{p}_\textrm{inst}$ is the instantaneous position, and $\vec{p}_\textrm{static}$ is the static position, then these results report $\vec{p}_\textrm{inst} - \vec{p}_\textrm{static}$ with respect to the turbine's static axis directions.

These angles define the orientation of the turbine axes relative to global axes, with gamma defined as for line ends. Declination is in the range 0° to 180°. Range jump suppression is applied to the azimuth and gamma angles, so values outside the range -360° to +360° might be reported.

The orientation of the turbine relative to its static orientation. Considered as a vector, $\vec{R} = (Rx, Ry, Rz)$ defines the rotation from the static orientation to the instantaneous orientation. The rotation is about the direction of the vector $\vec{R}$, and has magnitude $\lvert\vec{R}\rvert$.

Acceleration, GX acceleration, GY acceleration, GZ acceleration

The magnitude and components of the velocity and acceleration of the turbine, relative to earth and with respect to the global axes, at the user-specified point $\vec{p}$ on the turbine.

x acceleration, y acceleration, z acceleration

The components of the velocity and acceleration of the turbine, relative to earth and with respect to the turbine axes, at the user-specified point $\vec{p}$ on the turbine.

Angular acceleration, x angular acceleration, y angular acceleration, z angular acceleration

The magnitude and components of the angular velocity and acceleration of the turbine, relative to earth and with respect to the turbine axes.

The magnitude of the total force applied to the turbine by the object to which it is connected, including structural inertia loads

The components, in the global axes directions, of the total force applied to the turbine by the object to which it is connected, including structural inertia loads.

The components, in the local turbine axes directions, of the total force applied to the turbine by the object to which it is connected, including structural inertia loads.

The magnitude of the total moment applied to the turbine by the object to which it is connected, including structural inertia loads.

The components, in the global axes directions, of the total moment applied to the turbine by the object to which it is connected, including structural inertia loads.

The components, in the local turbine axes directions, of the total moment applied to the turbine by the object to which it is connected, including structural inertia loads.

The angular velocity, about the turbine's $z$-axis, in the direction of the rotation sense, of the generator shaft relative to the turbine.

Note: | For a turbine with anticlockwise rotation sense, this does not obey the usual OrcaFlex right-handed convention. |

The torque, i.e. the moment about the turbine's $z$-axis, in the direction of the rotation sense, applied to the generator shaft by the generator.

Note: | For a turbine with anticlockwise rotation sense, this does not obey the usual OrcaFlex right-handed convention. |

The power, calculated as $-1 \times \text{generator angular velocity} \times \text{generator torque}$.

The torque, i.e. the moment about the turbine's $z$-axis, in the direction of the rotation sense, on the high speed shaft. This differs from the generator torque by the generator's inertial load. The torque is defined to be that applied from the generator side to the rotor side.

Note: | For a turbine with anticlockwise rotation sense, this does not obey the usual OrcaFlex right-handed convention. |

The angular velocity, about the turbine's $z$-axis, in the direction of the rotation sense, of the rotor relative to the turbine.

Note: |

The torque, i.e. the moment about the turbine's $z$-axis, in the direction of the rotation sense, on the main shaft. This differs from the high speed shaft torque due to the generator's gear ratio. The torque is defined to be that applied from the generator side to the rotor side.

Note: |

The angle of the blade 1 root $z$-axis, in the direction of the rotation sense, projected onto the turbine $xy$-plane, relative to the turbine $x$-axis and about the turbine $z$-axis. Reported in the range 0° to 360°.

Note: |

The components, in the local turbine axes directions, of the mean disturbed wind velocity, evaluated over all blade segments.

The skew angle, $\chi_0$, calculated as the angle between the mean disturbed wind velocity direction, evaluated over all blade segments, and the turbine's $z$-axis.

Weighting used to scale the induction factors.

Rotor aero Lx moment, rotor aero Ly moment, rotor aero Lz moment

The components, in the local turbine axes directions, of the net aerodynamic load relative to the turbine frame.

Note: | To calculated the net load acting at the turbine frame, as a result of the aerodynamic loading distributed over the blade segments, it is necessary to assume the rotor is instantaneously a rigid body. |

The aerodynamic power, calculated as $\text{main shaft angular velocity} \times \text{rotor aero Lz moment}$.

The instantaneous swept area, calculated as $\pi \times r\urm{x}^2$, where $r\urm{x}$ is the largest nodal displacement from the turbine origin (when projected onto the turbine $xy$-plane), evaluated over all nodes.

The aerodynamic thrust coefficient, calculated as \begin{equation} \frac{\text{rotor aero Lz force}}{\frac{1}{2} \rho \times \text{rotor swept area} \times (\text{disc z relative velocity})^2} \end{equation}

The aerodynamic power coefficient, calculated as \begin{equation} \frac{\text{rotor aero power}}{\frac{1}{2} \rho \times \text{rotor swept area} \times (\text{disc z relative velocity})^3} \end{equation}

The magnitude of the wind velocity, measured at the hub (i.e. the turbine frame origin), and relative to the hub.

The components, in the global axes directions, of the wind velocity, measured at the hub (i.e. the turbine frame origin), and relative to the hub.

The components, in the local turbine axes directions, of the wind velocity, measured at the hub (i.e. the turbine frame origin), and relative to the hub.

For a blade result you must specify, on the results form, the **blade** number and, for some results, the **position** on the blade at which you want the result reported. The position may be at one end of the blade, either end A (the root) or end B (the tip); or it may be in between and defined by **arc length** along the blade, measured from zero at end A.

Note: | The actual arc length at which blade results are reported might not correspond precisely to the specified value. OrcaFlex reports results for the nearest appropriate result position. |

The angle between the blade's fitting frame, which is fixed relative to the hub, and its root frame, which can be offset by an initial pitch and subject to pitch control in dynamics.

Note: | For a conventional turbine, with clockwise rotation sense, this does not obey the usual OrcaFlex right-handed convention. |

The magnitude of the total force applied to the blade root by the hub, including structural inertia loads.

The components, in the global axes directions, of the total force applied to the blade root by the hub, including structural inertia loads.

The components, in the local blade fitting frame axes directions, of the total force applied to the blade root by the hub, including structural inertia loads.

The magnitude of the total moment applied to the blade root by the hub, including structural inertia loads.

The components, in the global axes directions, of the total moment applied to the blade root by the hub, including structural inertia loads.

The components, in the local blade fitting frame axes directions, of the total moment applied to the blade root by the hub, including structural inertia loads.

Available at blade nodes. The global coordinates of the selected node.

Available at blade nodes. These angles report the local orientation of the node structural frame relative to global axes. The gamma angle is defined as for line ends.

Declination is in the range 0° to 180°. Range jump suppression is applied to azimuth and gamma, so it is possible for values outside the range -360° to +360° to be reported.

Node acceleration, Node GX acceleration, Node GY acceleration, Node GZ acceleration

Available at blade nodes. The magnitude and components (in the global axes directions) of the velocity and acceleration of the node, relative to earth.

Node x acceleration, Node y acceleration, Node z acceleration

Available at blade nodes. The components (in the node structural frame) of the velocity and acceleration of the node, relative to earth.

Node angular acceleration, Node x angular acceleration, Node y angular acceleration, Node z angular acceleration

Available at blade nodes. The magnitude and components of the angular velocity and acceleration of the node, with respect to the node structural frame.

Available if the blade DOFs are **free**, at mid-segment points and ends. The structural force along the blade's neutral axis. Positive values denote tension, negative values compression.

Available if blade DOFs are free, at mid-segment points and ends. The magnitude of the structural force normal to the blade axis and its local components. At end A, components are reported in the root node structural frame axes directions. At end B, i.e. the tip, the shear is always zero. At mid-segment, components are reported in the mid-segment frame axes directions.

Available if blade DOFs are free, at mid-segment points and ends. The magnitude of bend moment and its local components. At end A, components are reported in the root node structural frame axes directions. At end B, i.e. the tip, the moment is always zero. At mid-segment, components are reported in the mid-segment frame axes directions.

Available if blade DOFs are free, at mid-segment points and ends. The magnitude of curvature and its local components. At end A, components are reported in the root node structural frame axes directions. At end B, i.e. the tip, the curvature is always zero. At mid-segment, components are reported in the mid-segment frame axes directions.

Available if blade DOFs are free, at mid-segment points. The twist per unit length experienced by the *segment*, i.e. the additional twisting, due to the presence of torque, beyond the user-specified structural twist.

Available if blade DOFs are free, at mid-segment points and ends. The component of structural moment about the blade axis.

Available at mid-segment points. The axial and tangential induction factors. These factors could have been subject to induction scaling.

Available at mid-segment points. The axial induction factor corrected for wake skew. This factor could have been subject to induction scaling.

Available at mid-segment points. The components of the undisturbed flow velocity, relative to the aerodynamic centre. Components are reported in the nominal rotor plane frame axes directions.

Available at mid-segment points. The components of the disturbed wind velocity, relative to the aerodynamic centre. Components are reported in the nominal rotor plane frame axes directions.

Available at mid-segment points. The lift, drag, and moment coefficients respectively. If a UA model is selected, the modified unsteady coefficients are reported.

Available at mid-segment points. The lift force, drag force and pitching moment, per unit length, acting at the aerodynamic centre.

Available at mid-segment points. The local inflow angle.

Note: |

Available at mid-segment points. The incidence angle or angle of attack.

Note: |

Available if the tower influence is not **none**, at mid-segment points. Calculated as the distance between the blade segment's aerodynamic centre and its point of closest approach on the tower's axis, minus the tower's radius at the point of closest approach.

Note: | The tower clearance result does not account for the cross-sectional extent of the blade itself. |

Available if the model includes lines, at mid-segment points and ends. The shortest distances between the blade segment, or end, and the segments of lines in the model. The distance is the shortest distance between the blade segment's *axis*, or end node, and the outer edges of the line segments. The results selection form lets you choose how to report clearances:

- from the blade to all other lines
- from the blade to a specified line.

Note: | The line clearance result does not account for the cross-sectional extent of the blade itself. |

Available if blade DOFs are free, at blade nodes. The *deflection* is defined to be the node's position relative to its unstressed position. Its component in the turbine's $z$-axis direction, is reported as the *out of plane deflection*. Its component normal to both the turbine's $z$-axis direction and the blade's pitch axis, is reported as the *in plane deflection*.

Available at mid-segment points. For large angles of attack, or low inflow velocities, the UA models might become invalid. In such cases, the steady and unsteady aerofoil coefficients are blended using this weighting. If the UA weight is 1, the unsteady coefficients are used unblended. If the UA weight is 0, the steady coefficients are used unblended.

Available at mid-segment points. The local Mach number.