RU2748769C1 - Device for jet drive of the main rotor - Google Patents

Abstract

FIELD: aviation.SUBSTANCE: invention relates to the field of aviation, in particular to the designs of the main rotor drives of rotorcraft. The device of main rotor jet drive consists of power plant (1), compressor (2) with a control valve of air pressure, main rotor sleeve (3), blades (4), pipelines (5), slot nozzles (6), the long side of which is located along the rear edge of the blades. The transverse axis of the slot nozzles is located at a distance of 0.7 of the radius of the rotor from the axis of rotation. The angle of gas ejection from the nozzles is αez=45° relatively to the chord of the cross-section profile of the rotor blade. The setting angle of the blade profile is within 18°<φ<25°.EFFECT: increase in the specific thrust of the rotor, reduction in the weight and dimensions of the device are achieved.1 cl, 2 dwg

Description

The invention relates to the field of aviation, in particular to the designs of rotary-wing aircraft, and can be used in aircraft heavier than air with vertical take-off or landing with a vertical position of the longitudinal axis during landing, incl. and in unmanned aerial vehicles.

From the prior art, a jet-slotted blade (variants) of a rotor of a helicopter with a jet drive and a starter-generator are known from the description for patent RU 2362707 C2, class. В64С 11 \ 00 (2006.01), В64С 27 \ 18 (2006.01), publ. 07/27/2009, bul. No. 21, in which a longitudinal air duct is made, connected to the longitudinal slots of the air intake and outlet nozzle, opposite which guide blades are located, having combinations of the placement of the air intake and the outlet nozzle relative to the butt and end parts of the blade, while the areas of reduced pressure on the lower surface of the blade are connected areas of increased pressure on the upper surface of the blade, thereby controlling the circulation around the blade profile. To create torque and supercirculation, ramjet engines with a fuel supply system are placed in the cavities of the blades.

The disadvantage of this technical solution is a rather complex design of the blades, a large construction height of the profile, the use of heat-resistant materials, significant energy losses due to high hydraulic resistance during the movement of the gas mixture and combustion products inside the cavities of the blade.

Also known is a vertical take-off and landing aircraft (jet helicopter) from the description of the invention to the patent RU 2656780 C2, CL. В64С 27 \ 18, publ. 06.06.2018, bul. No. 16, a helicopter with a jet rotor drive with technical support for the rotation of the rotor blades without a gearbox. Jet engines are placed inside the blades along their axes with the movement of the gas flow through the engines in the direction from the propeller axis to the periphery of the blades with the gas outlet towards the trailing edge of the rotor blades. Additional jet engines are located on the rotor hub with the gas flow through the engines in the direction from the rotor axis in the direction opposite to the rotor rotation direction.

, здесь: Т - тяга несущего винта, N - мощность силовой установки.The disadvantage of this device is the sufficient bulkiness and complexity of the design and insufficiently high energy characteristics, in particular the specific thrust

, here: T is the rotor thrust, N is the power of the power plant.

The closest analogue (prototype) in its technical essence to the proposed invention is a control device for the jet drive of the main rotor of the helicopter patent RU 2569233 C1, class. В64С 27 \ 18 (2006.01), publ. 20.112015, bul. No. 32, containing a power plant and a compressor for producing high-pressure gas, a system for transporting compressed gas in the propeller cavity, slotted nozzles installed on the trailing edges of the blade at an angle α <45 ° relative to the plane passing through the longitudinal axis and the chord of its cross-sectional profile, as well as slotted nozzles located on the line of maximum relative thicknesses of the profile of the cross-sections of the blade, the axes of which are directed downward perpendicular to the above plane, and valves for regulating the value of the gas pressure in the slotted nozzles.

As a result of the analysis of the above and other devices, it was revealed that in order to improve (increase) the main energy indicator of a propeller with a jet drive - specific thrust q, it is necessary, first of all, to reduce energy losses in the propeller jet, i.e. to increase the efficiency of the screw η _{0 by} various design measures, which is a rather complex technical problem.

The objective and the technical result of the invention is to increase the specific thrust of the device, as well as to simplify the design and reduce the weight and dimensions by reducing energy losses in the propeller jet.

The solution to the problem and the technical result of the invention are achieved by the fact that in the rotor rotor drive device, which includes a power plant and a compressor for producing high-pressure gas, a system for transporting compressed gas to nozzles, a valve for regulating gas pressure, rectangular nozzles are placed on the trailing edges of the blades, one on each blade and directed at an angle α _рз = 45 ° relative to the plane passing through the longitudinal axis and the chord of its cross-sectional profile, the transverse axis of each slotted nozzle is at a distance of 0.7 of the propeller radius from the axis of rotation, and the blades have an installation angle (the angle between the plane of rotation of the screw and the plane passing through the longitudinal axis and the chord of the cross-sectional profile) 18 ° <ϕ <25 °.

This arrangement of nozzles and the design parameters of the propeller create the effect of a jet flap (A.K. Martynov Applied aerodynamics. M .: Mashinostroenie, 1972, pp. 284-285), the flow around the propeller profile changes and the coefficient of the lifting force of the profile with _y can reach large values especially in the characteristic section (at a distance of 0.7 of the radius of the screw from the axis of rotation).

FIG. 1 shows a diagram of the rotor jet drive device.

The device consists (Fig. 1) of a power plant 1, a compressor 2 with an air pressure regulating valve, a rotor sleeve 3, blades 4, pipelines 5, slotted nozzles 6, the long side of which is located along the trailing edge of the blades, and the length of the slotted nozzle b _slot ≈ b, and the width of the nozzle δ _slit ≈ 0.1 b.

Using the relations known from the impulse theory of the propeller (B.N. Yuriev Aerodynamic calculation of helicopters M .: Oborongiz, 1956, pp. 171, 193-201, 260), the specific thrust of a conventional isolated propeller when it is operating in place can be written in the following form

where: T is the propeller thrust, R is the radius of the propeller, ω is the angular velocity of rotation

b ₇ - the value of the chord of the screw at a distance of 0.7R from the axis of rotation

Su ₇ - coefficient of lift of the propeller profile at a distance of 0.7R from the axis of rotation

k is the number of propeller blades, F is the area swept by the propeller, ρ is the air density at a given temperature and atmospheric pressure

здесь: χ=0,75-0,9 - коэффициент концевых потерь, η₀ - КПД винта, учитывающий потери энергии в струе винта ≈ 0,6÷0,75 (для обычных винтов)

here: χ = 0.75-0.9 is the coefficient of end losses, η ₀ is the efficiency of the propeller, taking into account the energy losses in the propeller jet ≈ 0.6 ÷ 0.75 (for conventional propellers)

In addition, it follows from the impulse theory (BN Yuriev Aerodynamic calculation of helicopters M .: Oborongiz, 1956, pp. 260-262) that for a medium-shaped propeller operating in place, the propeller efficiency can be written in the form

- коэффициент заполнения винта на расстоянии 0,7R от оси вращенияhere: χ is the screw end loss coefficient (it is practically constant for a given screw), C _x7 , C _y7 are the coefficients of the drag and the lift force of the cross-sectional profile at a distance of 0.7 of the screw radius R from the screw rotation axis (characteristic section),

- filling factor of the screw at a distance of 0.7R from the axis of rotation

.From equalities (1), (2) it follows that the efficiency of the propeller η ₀ with the constancy of other defining parameters depends significantly on the ratio

...

The location of the slotted nozzle on the trailing edge of the propeller blade so that the transverse axis of the nozzle is at a distance of 0.7R from the axis of rotation of the rotor and at α _pz = 45 °, and the longitudinal axis runs along the trailing edge of its blades, creates the greatest effect of the jet flap, i.e. ... significantly increases the lift coefficient C _y7 . As for the drag coefficient C _x7 , two factors are at work. According to the method of determining the drag using the impulse theorem (A.K. Martynov Applied aerodynamics. M .: Mashinostroenie, 1972, pp. 293-295), the airfoil drag has two terms: the drag created by the forces of surface pressure and the drag created by the forces friction of the air flow on the surface of the screw. FIG. 2 shows a diagram describing the drag of the propeller profile by the impulse method. As is known from hydromechanics, the impulse of the force is equal to the second change in the momentum of the medium contained in the trickle and the difference in the pressure forces acting in the considered sections of the trickle. This impulse of force will be equal to the frontal resistance of the X profile in the plane of the ABCD contour (Fig. 2).

Here AB is the contour line crossing the wake behind the airfoil, р ₀ , ν _{0 are the} static pressure and the velocity of the undisturbed flow in front of the airfoil, respectively, р, ρ are the static pressure and density at any point of the flow, u, ν are the velocity components at any point of the flow directed along the flow axis (x) and along the perpendicular axis (y), ú is the horizontal velocity component for the airfoil without a jet flap. The aerodynamic wake behind the airfoil characterizes the loss of momentum, and is thus related to drag.

Experimental verification has shown that at small swirl angles (at least up to ϕ = 20 °), the first term in equality (3) can be neglected, the second term can take extreme values depending on the difference between the quantities (ν ₀ - u) and the absolute value quantities ν ₀ . The propeller profile in the characteristic section (at a distance of 0.7 R from the axis of rotation) has the minimum drag at 18 ° <ϕ <25 ° and α _pz = 45 °

при вышеуказанных параметрах становится минимальным и, соответственно, КПД винта η₀ и удельная тяга устройства q становятся максимальными.Attitude

with the above parameters becomes minimum and, accordingly, the efficiency of the propeller η ₀ and the specific thrust of the device q become maximum.

The device works as follows. The power plant 1 drives the compressor 2, which generates high-pressure gas and transports it through the control valve to the screw sleeve 3 through the pipelines 5 to the hollow blades 4 and then to the slotted nozzles 6 to create a reactive force T _p , the horizontal component of which T _px creates a torque the moment of the main rotor, and the vertical component T _ru contributes to the creation of thrust (lift) of the rotor (Fig. 1).

The jets of gas under overpressure? P ₀ of nozzles expire at medium speed ν _slit at one second mass flow rate m _c, installed control valve (density and gas pressure at the expiry of the nozzle equal to atmospheric _and P, ρ _a). The outflow occurs from nozzles located along the trailing edges of the blades, at an angle α _рз = 45 ° relative to the plane passing through the longitudinal axis of the rotor and the chord of the blade profile. When the propeller rotates, an aerodynamic force T _ae arises (due to the vortex circulation around the airfoil), which also contributes to the creation of the rotor thrust: T = T _ru + T _e , and the magnitude of this force increases significantly due to the jet flap effect created by the air jets flowing out of the slotted nozzles.

The stationary mode of propeller rotation occurs when the torque of the reactive component of the force is balanced by the moment of the aerodynamic drag of the propeller blades.

Thus, the achievement of the technical result is based on the fact that the number and special arrangement of slotted nozzles on the rotor blades, as well as the choice of the optimal ratio of such defining parameters as the setting angle of the blade ϕ and the angle of ejection of the gas jet from the nozzle α _рз , the maximum increase in the specific thrust of the rotor is achieved q, which cannot be obtained in the prototype because of the significantly higher profile drag caused by the gas jets ejected from the nozzles perpendicular to the plane of rotation of the screw, the greater headroom of the profile and, as a consequence, the high power consumption.

Estimated calculations and experimental verification also showed that, at least for a propeller with a constant blade width and low twist (σ = σ ₇ = const), the specific thrust of the propeller with slotted nozzles at the blade ends (jet flap) of the proposed scheme is (40-50 )% more than the same propeller without a jet flap and driven by a conventional power plant (for example, from an electric motor or internal combustion engine).

Claims (1)

A rotor jet drive device containing a power plant and a compressor for generating high-pressure gas, rectangular nozzles for generating jet thrust, rotating blades, located on the trailing edges of the blades at an angle α _pz = 45 ° relative to the plane passing through the longitudinal axis and the chord of their profile cross-section, a system for transporting compressed gas to nozzles, a valve for regulating the value of gas pressure in slotted nozzles, characterized in that on each blade there is only one nozzle, the transverse axis of which is at a distance of 0.7 of the radius of the screw from the axis of rotation, as well as the setting the cross-sectional angle of each propeller blade is within 18 ° <ϕ <25 °, which significantly increases the efficiency of the propeller and, accordingly, increases the specific thrust of the device.

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