초록 ▼

A method is provided for hypersonic laminar flow control which uses the effect of boundary layer stabilization by an ultrasonically transparent coating. A hypersonic body surface is covered by the coating which absorbs the flow disturbance energy and does not trip the boundary layer flow. In one emb

A method is provided for hypersonic laminar flow control which uses the effect of boundary layer stabilization by an ultrasonically transparent coating. A hypersonic body surface is covered by the coating which absorbs the flow disturbance energy and does not trip the boundary layer flow. In one embodiment, the coating is made from a porous material of regular structure containing cylindrical blind microholes normal to the body surface. In another embodiment, the porous material has random distributions of pore shape and orientation. Extraction of the flow disturbance energy by pores causes stabilization of the boundary layer on the coated surface and leads to laminar-turbulent transition delay. The method can be used to decrease the aerodynamic drag of hypersonic vehicles and reduce heat transfer on vehicle surfaces.

대표청구항 ▼

[ We claim:] [1.] A body capable of providing laminar flow control while exposed to a hypersonic flow, a surface of said body and said hypersonic flow defining a hypersonic boundary layer, said body comprising:an absorptive material for providing ultrasonic absorption of acoustic energy while expose

[ We claim:] [1.] A body capable of providing laminar flow control while exposed to a hypersonic flow, a surface of said body and said hypersonic flow defining a hypersonic boundary layer, said body comprising:an absorptive material for providing ultrasonic absorption of acoustic energy while exposed to hypersonic flow, said absorptive material having an absorption coefficient (A) such that disturbances in the hypersonic boundary layer are stabilized, said absorptive material providing acoustic absorption due to dissipation mechanisms.