RU2792994C1 - Propeller with external annular frame and tension blades - Google Patents

Abstract

FIELD: aviation; wind energy.

SUBSTANCE: invention relates to the design of propellers. The propeller consists of a hub located on the axis of rotation, and two-row blades, more than two in number, mounted radially. The blades are mechanically connected by the butt part with the propeller hub, have a variable angle of inclination of the profile to the plane of rotation along the span - angle of twist. The propeller blades are made of a thin profile of small curvature. The blade tips are mechanically connected to the outer annular frame so that the upper and lower blades of the two-row propeller mechanically stretch the outer annular frame radially and in different directions along the propeller rotation axis.

EFFECT: reduction in the diameter and weight of the propeller.

1 cl

Description

The invention relates to propellers used in aviation and wind energy.

A propeller, a propeller, is a bladed propeller in which radially arranged profiled blades rotated by a power plant discard air and thereby create thrust. The propeller of a wind turbine converts wind energy into mechanical rotational energy.

The idea of a propeller was proposed in 1475 by Leonardo da Vinci, and it was first used to create thrust in 1754 by M.V. Lomonosov in a model of an instrument for meteorological research. By the middle of the 19th century, propellers were used on steamships, working similarly to propellers. In the 20th century, propellers began to be used on airships, airplanes, helicopters, snowmobiles, and hovercraft. In 1892-1910, Russian research engineer and inventor S. K. Dzhevetsky developed the theory of an isolated blade element, and in 1910-1911, Russian scientists B. N. Yuryev and G. Kh. Sabinin developed this theory. In 1912-1915, N. E. Zhukovsky created a vortex theory that gives a visual physical representation of the operation of a screw and other bladed devices and establishes a mathematical relationship between forces, velocities, and geometric parameters in such devices. A significant role in the further development of this theory, its engineering applications and research into the strength of the propeller belongs to V. P. Vetchinkin. The theory of an optimal propeller with a finite number of blades was first created by the German scientist A. Betz (1919) and the English scientist S. Goldstein (1929). In 1956, the vortex theory of the propeller was extended to the main rotor of a helicopter by the Soviet scientist G.I. Maikopar.

The propeller consists of a hub located on the engine shaft and blades having different cross-sectional profiles along the span and a variable angle of inclination of the profile to the plane of rotation - twist. In flight, due to the addition of the translational speed, the linear speed of rotation and the additional speed of the flow caused by the operation of the propeller, the air runs into each elementary section of the blade at a certain angle of attack. In this case, the total aerodynamic force arising from all sections of all blades forms the thrust force of the propeller and the force of resistance to its rotation. Depending on the amount of power consumed, propellers with a different number of blades are used - two-, three-, four-, and more bladed, as well as coaxial propellers rotating in opposite directions. The first propellers had a fixed pitch in flight, determined by a constant blade angle. In order to maintain a sufficiently high efficiency over the entire range of flight speeds and engine power, as well as to obtain the least drag of the propeller in the event of a forced engine stop in flight (vane mode) or negative thrust in order to slow down the aircraft during landing (reverse mode), air in-flight variable pitch propellers. In such propellers, the blades are rotated in the sleeve relative to the longitudinal axis by a mechanical, hydraulic or electric mechanism controlled by a centrifugal regulator, which maintains a constant given number of revolutions. By design, propellers are divided into single, coaxial, double-row, propeller in the ring and propfans. A single propeller has one row of blades. The coaxial propeller consists of two single propellers located one after the other on coaxial shafts rotating in opposite directions. A twin-row propeller, unlike a coaxial propeller, has single propellers that rotate in the same direction. The propeller in the ring has a profiled ring to create additional thrust, and is effective at speeds up to 200 km/h. Propfans are distinguished by a large number of wide thin saber-shaped blades. Depending on the location on the aircraft, there are pulling and pushing propellers. To increase thrust and efficiency at low translational speed and high power, the propeller is placed in a profiled ring, in which the jet velocity in the plane of rotation is greater than that of an isolated propeller, and the ring itself creates additional thrust due to the speed circulation. For the same purpose, the sectional profile of the propeller blade is given a large curvature. The diameter of propellers reaches 6-7 meters . Propeller blades are made from duralumin, steel and composite materials. At flight speeds of 600–800 km/h, the propeller efficiency reaches 0.9–0.8, respectively. At high speeds, under the influence of air compressibility, the efficiency drops. The main way to reduce power losses from air compressibility is the use of thin profiles of small curvature.

The main disadvantages of existing propellers are: excessive elongation of the blades, leading to collisions with the blade, with the fuselage of the aircraft, with the design of the wind turbine; - large mass; - susceptibility to flutter and self-destruction; - decrease in efficiency at high speeds under the influence of air compressibility. The propeller, as a technical system, in its development has approached the threshold of a technical contradiction: to increase lift, thrust, the diameter of the propeller must be large, and must be small in order to meet the requirements of strength and safety.

To eliminate this technical contradiction, I propose to use thin profiles of small curvature as double-row propeller blades, installed radially, mechanically connected by the butt part with the propeller hub, and the blade tips are mechanically connected to the outer annular frame. The upper and lower blades of a two-row propeller mechanically stretch the outer annular frame radially and in different directions along the axis of rotation of the propeller. The additional tension of the blades occurs due to the centrifugal force created by the rotation of the propeller.

Due to the use of thin profiles of small curvature, a reduction in mass is achieved, an increase in the efficiency of the propeller. Double-row blades increase thrust, lift with a smaller diameter propeller. The outer annular frame, stretched by the blades radially and in different directions along the axis of rotation of the propeller, increases the strength of the propeller structure.

Bibliography

Literature: Yuryev B. N. Propellers. M.; L., 1933; Zhukovsky N. E. Vortex theory of the propeller // Zhukovsky N. E. Poln. coll. op. M.; L., 1937. T. 6; Vetchinkin V.P., Polyakov N.N. Theory and calculation of an air propeller. M., 1940; Alexandrov V. L. Air screws. M., 1951; Frankl F. I. Selected Works on Gas Dynamics. M., 1973; TsAGI. Main stages of scientific activity, 1918–1968 M., 1976.

Claims (1)

A propeller consisting of a hub located on the axis of rotation and two-row blades, more than two in number, mounted radially, mechanically connected by the butt of the blade with the hub of the propeller, having a variable angle of inclination of the profile to the plane of rotation along the span - a twist, characterized in that the blades The propeller is made of a thin profile of small curvature, the tips of the blade feather are mechanically connected to the outer annular frame so that the upper and lower blades of the two-row propeller mechanically stretch the outer annular frame radially and in different directions along the axis of rotation of the propeller.