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Caradonna-Tung rotor in hover
Example simulation of a rotor in hover
A simulation of rotor in hover is considered. The rotor has two untwisted, untapered, rectangular blades with a NACA0012 airfoil. The rotor radius is
m and the aspect ratio is
. The rotor has a collective pitch of
deg, and is rotating at
rpm, corresponding to a tip Mach number of
. A structured mesh with 40 panels in the chordwise and 20 panels in the spanwise direction (for each blade) is used. The mesh is scaled so that the chord of the rotor blades
equals 1 and the span
equals 6. The resulting rotational velocity is then adjusted to
rad/s. The results are obtained with an azimuthal step of
s) for 10 revolutions. From
s the rotational velocity is increased gradually from
rad/s. The gradual increase of the rotational velocity allows the wake to develop without numerical instabilities. The image below shows the pressure coefficient distribution and the developed wake.
The animation below shows the development of the wake.
Caradonna-Tung rotor wake development
The images below show the pressure coefficient at
. The experimental results from Caradonna and Tung  are shown for comparison.
Overall, good agreement between the simulation and the experimental results is observed.
 Caradonna, F.X. and Tung, C., "Experimental and Analytical Studies of a Model Helicopter Rotor in Hover", NASA Technical Memorandum 81232, 1981