Unsteady Vortex Loop/Dipole Theory Applied to the Work and Acoustics of an Ideal Low Speed Propeller.

摘要

The vortex loop/dipole singularities used to simulate blade lift and thickness in potential flow models of turbomachines are examined in an unsteady form. The three-dimensional potential fields created as these singularities rotate in the absolute frame are shown to provide the input forces, ideal work and wake energy for an incompressible fluid, as well as the tonal acoustics for slight compressibility. For typical low Mach number propellers the sound field is dominated by the lift force and exhibits large cancellation effects with multiple blades. It is concluded that the unsteady formulation illustrates well the physics of a turbomachine, and in addition, highlights some basic principles of potential flow.... Energy conversion, Power sources, Turbomachines physics, Acoustics, Fluid mechanics.