Measurements of the Early Development of Trailing Vorticity from a Rotor

摘要: Abstract : The wake behind a two-bladed model rotor in light climb was measured using particle image velocimetry, with particular emphasis on the development of trailing vortex during first revolution rotor. distribution vorticity distinguished from slightly elliptical swirl pattern. Peculiar dynamics within "void" region may explain why peak appeared to shift away center as aged, suggesting onset instability. and axial velocities (which reached 44% 12% tip speed, respectively) were found be asymmetric relative center. In particular, flow composed two concentrated zones moving opposite directions. radial circulation rapidly increased magnitude until reaching point just beyond core radius, after which rate growth decreased significantly. core-radius age, but large-radius remain relatively constant. distributions velocity exhibit self-similar behaviors, especially core. diameter initially about 10% rotor-blade chord, more than doubled its size one