A flow transition passive control device using surface openings/grooves

Abstract

The invention discloses a flow transition passive control device using surface openings / grooves. The flow transition passive control device has a double-layer structure, including an upper layer of metal material and a lower layer of sound-absorbing material. The flow transition Microholes and / or microgrooves are arranged on the surface of the passive control device, and the microholes and / or microgrooves penetrate the metal material layer and extend to the sound-absorbing material layer. Adopting a flow transition passive control device using surface openings / grooves of the present invention, the size of surface micropores or microgrooves is larger than traditional porous sound-absorbing materials, which is easy to process; the two-layer structure improves the absorption of acoustic disturbances Efficiency can control boundary layer transition more effectively; the control effect is highly robust and can reduce frictional resistance.

Description

technical field [0001] The invention relates to a flow transition passive control device utilizing surface openings / grooves, and belongs to the technical field of aerodynamics. Background technique [0002] During the interaction between fluids (such as air and water) and solids, the thin layer outside the solid wall—the boundary layer—plays the main role. Boundary layer flow in nature has two distinct states: laminar flow and turbulent flow. There are huge differences between the two in terms of frictional resistance, noise, heat flow and mixing. The transition between laminar flow and turbulent flow is called transition, and transition control is of great significance to the design of aircraft, engines and underwater ships. For example, adding a transition device before the inlet of a hyperramjet engine can promote the flow transition from laminar flow to turbulent flow, thereby improving engine efficiency and is also critical to preventing engine failure. If the long-e...

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Problems solved by technology

There are huge differences in frictional resistance, noise, heat flow and mixing between the two

[0004] Based on this principle, opening holes or grooves on the surface can also suppress the growth of the acoustic mode and delay the transition of the boundary layer. Some researches have been carried out in this area at home and abroad, but there are still some problems and deficiencies: holes or grooves The size is too small and difficult to process; its suppression of the growth of acoustic disturbance is limited; the effect of suppressing modal growth depends on specific working conditions, and its robustness is poor

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