Steady calculations

Articles on this page:

• Assumptions in steady calculations
• Rotor diameter used to normalise coefficients

Problem

What simplifying assumptions do the steady calculations make in Bladed?

Solution

Various simplifying assumptions are made in the steady calculations, as summarised in the tables below. Note that the "aerodynamic information” and “performance coefficients” calculations only model the rotor (at zero tilt angle), whereas the other steady calculations model the whole turbine.

These assumptions are slightly different with the default aerodynamics and the new beta aerodynamics in Bladed 4.7, as shown in the tables.

Keywords

Steady calculations

Problem

What rotor diameter value is used to calculate the swept area for normalisation of Cp, Ct, Cq in the Performance Coefficients calculation?

Solution

The rotor diameter used is that of the unloaded rotor, which includes cone, pre-bend, and pre-sweep. Rotor deflections are included in the actual thrust/power/torque calculations, if you choose to include them. However, they are not taken into account when calculating the swept area for normalisation.

Keywords

Performance coefficients; pcoeffs; Rotor area; Rotor diameter; Cone