0 a flat, narrow part of a fan, propeller, etc. that turns because of the pressure of air or liquid against it -- （風扇、螺旋槳等的）葉片，翼
The helical vortex precesses about the tube centreline in the same direction as the rotation imparted by the swirl vanes.
Examples include heart valve leaflets, parachute canopies, thin airfoils (including bird, insect, or bat wings), sails, kites, flags, and weather vanes.
The vortex centre and free stagnation point were found using the vane probe.
This effect would be minimized if the vanes are made perfectly symmetric.
A turbo molecular pump, backed by a rotary vane pump is connected to the chamber.
Nevertheless, it is important to remember here that the vane was of k i t e size; a 1.0 cm square.
This is a very thin vane, normally 1 x 1cm, mounted on a spindle so that the vane can rotate.
If this idea was completely correct the vane would have reversed its direction of rotation as it was moved into the core.
