Posterior edge separation vortex high-lift force high speed laminar flow airfoil

Abstract

The invention relates to a high lift fore and high-speed laminar-flow airfoil with a posterior margin separation vortex. The airfoil has an accelerating pressure gradient segment (A') on the upper surface of the airfoil from a grid origin to a point positioned at 60 percent of chord length away from the costal margin, and the upper surface of the airfoil keeps a positive small curvature segment(A);in order to ensure that the posterior margin pressure of the airfoil recovers smoothly, two adverse pressure gradient segments( B') are adopted behind the accelerating pressure gradient segment, andthe curvature is turned into small negative curvature from small positive curvature; the posterior margin of the airfoil is a separated slope(C) to separate the flow at the posterior margin, and the position of the separated slope is positioned near 95 percent of the chord length away from the costal margin. The separation does not go further along an attack angle and Mach number because of the action of the separated slope, and the circulation around the airfoil is increased by the posterior margin separation vortex to ensure that the airfoil has high lift force. The technical proposal adopted by the airfoil ensures that the separation vortex appears at the posterior margin, the airfoil has the possibility of supporting the longer accelerating pressure gradient on the upper surface, simultaneously the long accelerating pressure gradient ensures that the laminar flows more stably, and the lift force of the airfoil is improved by the increase of the circulation caused by the separationvortex at the posterior margin.

Description

1. Technical field [0001] The invention relates to the research of a laminar flow airfoil, in particular to a trailing edge separation vortex high-lift high-speed laminar flow airfoil. 2. Background technology [0002] In the development of modern commercial airliners, the fuel problem has been paid more and more attention, and drag reduction is an important means to solve this problem. Especially for modern wide-body large civil aircraft, frictional resistance accounts for about 40% of the total resistance. For smaller civil aircrafts, the proportion of frictional resistance in the total resistance is even larger. Cost reduction is of great significance. Because the frictional resistance of turbulent flow is greater than that of laminar flow, the use of laminar airfoil is an important research direction in various methods of drag reduction. [0003] Although the discussion and research of laminar flow technology has a long history, it is rarely applied in engineering prac...

AI Technical Summary

Problems solved by technology

The laminar flow airfoil with a certain reverse pressure gradient has better tail pressure recovery, no large reverse pressure gradient, and is not easy to cause separation of the trailing edge, but the anti-interference ability is weak, and it is easy to be affected by the surface roughness and noise of the airfoil. Due to the influence of other factors, the flow transition occurs in advance, which seriously affects the aerodynamic performance of the laminar airfoil; for the laminar airfoil with a forward pressure gradient, since the forward subgradient can control the growth of the T-S wave disturbance, it is relatively stable and not easy The airfoil is disturbed, but the pressure recovery at the tail of the airfoil often has a large reverse pressure gradient, which will cause the occurrence of trailing edge separation, and with the increase of the angle of attack and Mach number, the trailing edge separation will move forward rapidly, making the airfoil The aerodynamic performance of the

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