High lift-drag ratio laminar flow aerofoil profile suitable for low altitude and low speed unmanned aerial vehicle

Abstract

The invention belongs to the technical field of unmanned aerial vehicle aerofoil profile design and specifically relates to a high lift-drag ratio laminar flow aerofoil profile suitable for a low altitude (H is less than 5000 m) and low speed (Ma is less than 0.1) unmanned aerial vehicle. The maximum thickness of the aerofoil profile is 10%C, the chord position corresponding to the maximum thickness is 34%C, the maximum camber is 3.76%C, the chord position corresponding to the maximum camber is 41%C, and the thickness of a trailing edge is 0.3% C, wherein C is the chord length of the aerofoilprofile. According to the high lift-drag ratio laminar flow aerofoil profile suitable for the low altitude and low speed unmanned aerial vehicle, the upper surface of the aerofoil profile can generateflow transition at the 70-80% chord length under a working condition of 500 thousand order of Reynolds number; laminar flow gradually evolves into turbulent flow, namely, is transitioned first and then is separated; laminar flow separating bubbles are not generated; in a design state, the aerofoil profile has low resistance and high lift-drag ratio and possesses stable stalling characteristic andexcellent torque characteristic; and each performance index of the light unmanned aerial vehicle during low altitude and low speed long flight can be satisfied.

Description

technical field [0001] The invention belongs to the technical field of UAV airfoil design, and in particular relates to a laminar flow airfoil with high lift-to-drag ratio suitable for low-altitude (H<5000m) and low-speed (Ma<0.1) UAVs. Background technique [0002] Low-altitude and low-speed UAVs generally refer to light UAVs with a flying altitude below 5,000 meters and a cruising speed not exceeding Mach 0.1. Compared with conventional aviation UAVs, low-altitude and low-speed UAVs have particularity in aerodynamic design and analysis. The specific contents include: (1) The cruising speed of such UAVs is small (no more than 0.1Ma, about 50-120km / h), while the Reynolds number is proportional to the speed, and its cruising Reynolds number is about 500,000, which involves the separation of the laminar boundary layer and the transition from laminar flow to turbulent flow, which are easily caused by low Reynolds number flow. The airfoil lift-to-drag ratio is greatly red...

AI Technical Summary

Problems solved by technology

[0003] For low-altitude and low-speed light UAVs in China, traditional aviation airfoils are usually used, and their stall characteristics and lift-drag characteristics are poor, making the aircraft's maximum take-off weight, endurance time and other key indicators far less than the design value

In addition, there are few studies on laminar airfoil design, representative ones are: Patent No. CN201510106270.5 and CN200810017364.5, which are mainly designed for high-speed flow with Mach number around 0.6, not for low altitude, low speed and low Reynolds number conditions ; Patent No. CN201310354010.0, its main extremely low speed (10m / s), extremely small Reynolds number (260,000) full-wing solar unmanned aerial vehicle, for photovoltaic energy can be shaped with the aircraft body, its airfoil at 10% ~70% of the chord length range is a single shape, which is not suitable for conventional low-altitude and low-speed light drones except for solar drones; patent No. CN201610164763.9, which developed a 14% thickness The airfoil has a design Reynolds number of 1.1 million and a design Mach number of 0.226. This invention is mainly aimed at high-altitude and long-endurance UAVs with a flight height greater than 18,000 meters. The thickness of 14% airfoil is too thick for light UAVs. Large, it will greatly increase the empty weight of the wings and the whole aircraft, and then reduce the mounting performance of this type of drone

[0004] The above airfoils are not suitable for low-altitude (H<5000m) and low-speed (Ma<0.1) light UAVs. In view of this, this invention is proposed to solve the gaps in the design of low-altitude and low-speed airfoils.

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