초록 ▼

Retarding of the point of transition from laminar flow to turbulent flow in aerodynamic boundary layers on the surfaces of aircraft is accomplished by radiating acoustic energy at frequencies greater than twice the critical Tollmein-Schlichting frequency into the boundary layer. The acoustic energy

Retarding of the point of transition from laminar flow to turbulent flow in aerodynamic boundary layers on the surfaces of aircraft is accomplished by radiating acoustic energy at frequencies greater than twice the critical Tollmein-Schlichting frequency into the boundary layer. The acoustic energy interferes with the formation of Tollmein-Schlichting waves, thereby increasing the incidence of laminar flow and reducing aerodynamic drag.

대표청구항 ▼

A method for retarding the onset of turbulent boundary layer flow around an airfoil moving with respect to an air mass through the infusion of acoustic energy into the boundary layer comprising the steps of: (a) electronically generating acoustic energy at or near the surface of an airfoil moving th

A method for retarding the onset of turbulent boundary layer flow around an airfoil moving with respect to an air mass through the infusion of acoustic energy into the boundary layer comprising the steps of: (a) electronically generating acoustic energy at or near the surface of an airfoil moving through an air mass and having a laminar flow boundary layer over at least a portion of said surface of said airfoil, (b) providing a plurality of predetermined acoustic energy emitting locations upon said airflow surface over which said boundary layer flow is laminar, and (c) directing said electronically generated acoustic energy into said boundary layer from said plurality of predetermined acoustic energy emitting locations, wherein the step of electronically generating includes generating said acoustic energy as a band of random noise having wavelengths not greater than one half of a predetermined critical wavelength of Tollmien-Schlichting oscillatory disturbance waves present within said boundary layer in the absence of said generated acoustic energy, such that said band of random noise forms wave patterns that destructively interfere with the formation of said Tollmien-Schlichting oscillatory disturbance waves.