一様流中の単独平板翼の後流渦に基づく空力音源の研究(流体工学, 流体機械)

抄録

The unsteady flow characteristics caused by the wake vortices generated from an isolated flat plate blade in a uniform flow were theoretically investigated with the discrete vortex method for elucidating the aeroacoustic source of the discrete frequency noise (DFN). We assumed that the DFN generated from the blade is originated by time fluctuation of the lift force caused by Karman vortex shedding. This calculation shows that the frequency and the intensity of velocity fluctuation in the wake can calculate accurately, and the half width of the wake is an important characteristic length to specify the periodic phenomena. The surface pressure, differentiated with respect to time, along the blade surface is closely related to the source, which gathers to the trailing edge. Then the chord wise correlation length calculated by integrating the distribution of the surface pressure data always conserved a constant value in all blades. The predicted DFN level agrees well with the experimental results.