초록 ▼

Existing pressure oscillations created by axial or centrifugal fans in a diverging shroud are utilized to power a passive, acoustic jet, the nozzle of which directs high momentum flux gas particles essentially tangentially into the boundary layer of the flow in a diffuser, or a duct, the fluid parti

Existing pressure oscillations created by axial or centrifugal fans in a diverging shroud are utilized to power a passive, acoustic jet, the nozzle of which directs high momentum flux gas particles essentially tangentially into the boundary layer of the flow in a diffuser, or a duct, the fluid particles in the resonant chamber of the passive acoustic jet being replenished with low momentum flux particles drawn from the fluid flow in a direction normal to the surface, thereby to provide a net time averaged flow of increased momentum flux particles to defer, even eliminate, the onset of boundary layer separation in the diffuser or duct. The passive acoustic jet is used in the vicinity of fan blade tips to alleviate undesirable flow effects in the tip region, such as leakage.

대표청구항 ▼

1. A fluid flow system, comprising:a fluid flow path having a surface and a stream of fluid flowing within said path, said fluid flow having a boundary layer adjacent said surface, said fluid flow having oscillatory pressure fluctuations; a passive acoustic chamber disposed near said surface; and a

1. A fluid flow system, comprising:a fluid flow path having a surface and a stream of fluid flowing within said path, said fluid flow having a boundary layer adjacent said surface, said fluid flow having oscillatory pressure fluctuations; a passive acoustic chamber disposed near said surface; and a fluid passage interconnecting said chamber with said fluid flow path at a small acute angle with respect to said surface, said chamber and said passage forming a resonant, passive acoustic jet of which said passage forms a nozzle, the resonant frequency of said acoustic jet being selected so that said oscillatory pressure fluctuations at the resonant frequency of said acoustic jet are of sufficient strength to provide pulses of fluid particles into said boundary layer.