RU2607687C1 - Nozzle of gas-jet helicopter control system - Google Patents

Abstract

FIELD: aircraft engineering.

SUBSTANCE: invention relates to aircraft engineering and can be used for helicopters with jet control system. Control mechanism of flaps of tricuspid nozzle with controlled thrust vector consists of toothed sector of middle flap position control, side flaps control levers, central rocker, engaged by rods with levers of side flaps. Central rocker is engaged with toothed sector of middle flap, wherein gear ratio from middle flap to central rocker is 0.70–0.78. Arms of central rocker have length of 0.3–0.4 width of nozzle inlet section and opening angle of arms 140–150°. Levers of side flaps have arms of length of 0.3–0.35 and 0.4–0.45 of nozzle inlet cross-section width and angle of inclination 50°–55° and 55°–60° respectively, and thrusts of levers of side flaps are 0.5–0.55 and 0.4–0.45 of nozzle inlet cross-section width.

EFFECT: reduced pressure losses in nozzle and improved its efficiency, providing required for each flight mode ratio of side and propulsion forces.

1 cl, 7 dwg

Description

The invention relates to the field of aviation, in particular to a gas-jet track control system and compensation of the reactive moment of the rotor of a single-rotor helicopter.

The vast majority of modern helicopters are single-rotor. A characteristic feature of this circuit is the need to compensate for the reactive moment of the rotor. The most widely used scheme is a single-rotor helicopter with a tail rotor. However, the tail rotor, with all its advantages, has a number of significant drawbacks. The presence of these shortcomings leads to constant (from the very initial period of development of helicopters to the present time) attempts to find an effective replacement for the tail rotor. One of the possible options for such a replacement may be the use of a gas-jet control system in a helicopter. Such a system can provide, in addition to the main function - reactive torque compensation and track control - a number of additional properties. In particular, it is possible to significantly reduce the noise level, increase the maneuverability characteristics, radically decrease the level of thermal visibility, increase the maximum flight speed, etc.

One of the main elements of a gas-jet helicopter control system is a jet nozzle with a controlled thrust vector. Such a nozzle creates an essential part of the lateral force that compensates for the reactive moment of the rotor, as well as the controlling lateral force and additional propulsive force in horizontal flight modes. Requirements for such a nozzle are substantially different from those for aircraft nozzles with a rotary thrust vector. First of all, this is a significantly increased range of jet rotation angles from 90 ° in the hover mode to ~ -40 ° in the autorotation mode. In this case, it is necessary to ensure the minimum possible loss of thrust, at least in two main modes - hovering (angle of rotation of the jet about 90 °) and flight at maximum speed (angle about 10 ° ÷ 20 °).

There are a large number of nozzle designs used on airplanes with rotation of the thrust vector, for example, a nozzle with a deflected thrust vector (patent No. RU 2168047 dated 05/27/2001, IPC F02K 1/12, F02K 9/84) containing converging flaps, divergent flaps, diverging thrusts cusps and control ring with suspension in the form of multi-link loops folding in radial planes, kinematically connected with rods of diverging cusps through parallelogram mechanisms. Each parallelogram mechanism between the driven lever and the leaf rods contains a second link in the form of a second driven lever mounted by a rotation support on the rocking arm pivotally mounted on the folding leaf, and the rods of the second link, the latter being fixed to the lever by spherical hinges. The main disadvantages of this variant of the nozzle are the relatively small range of angles of rotation of the thrust vector, insufficient for the gas-jet system of the helicopter, as well as the complex design of the mechanisms for controlling the elements of the nozzle.

Known application for compensation of the reactive moment of the rotor and for directional control of the jet nozzle located on the tail boom of a helicopter (Hanvey S.A. NOTAR - no tail rotor (circulation control tail boom) SETP Techn. Rev., 1982, p. 308-332). Such a system, in combination with supercirculation flow around the tail boom, is used, in particular, on the MD-900 helicopter and a number of other McDonnell Douglas helicopters. NOTAR system provides a number of advantages compared to the tail rotor in terms of flight safety and ground operation, noise reduction, improved handling, etc. The disadvantages of such a system include an increase in power consumed by the steering device and a significant increase in the harmful resistance of the helicopter body at high flight speeds.

Partially, these disadvantages are eliminated in the nozzle scheme with a controlled thrust vector (patent No. EP 2619087 (A1) - 2013-07-31 Propulsive Anti-Torque Nozzle System With External Rotating Sleeve For A Rotorcraft, IPC B64C 27/82 (2006.01)), which contains an input channel, 2 sets of plates forming side nozzles located on the rotary sections of the tail boom, as well as two rotary shutters, which, when opened, form the tail nozzle, which creates propulsive force with the possibility of its rotation by a small angle, and a shutter control mechanism. In this nozzle, air drawn from the external stream and pumped by the fan is mixed with the exhaust gases of the engine and, depending on the flight mode, is distributed between the rotary side nozzles and the tail nozzle flaps. Thus, the lateral force is created, which is necessary for directional control and to compensate for the reactive moment of the rotor, and (or) propulsive force, which reduces the resistance of the helicopter body. The disadvantages of this scheme include the complex design of the steering device with a large number of moving elements and a control system for these elements. If it is necessary to create both a lateral and a propulsive component of the nozzle traction force, dividing the injected flow into two parts, blown sideways and backward, is energetically worse than turning a single flow through an appropriate angle. In addition, the scheme under consideration does not allow turning the flow at large angles (close to 90 ° in the hovering mode) at an acceptable level of hydraulic losses. In addition, a large number of leaflets leads to increased pressure losses in the tract and, consequently, to increased power consumption.

A nozzle with a controlled thrust vector is known (patent No. RU 147353 U1 dated 11/22/2013, IPC B64C 27/82, B64C 19/02), which contains an input channel of rectangular cross section, pivoting flaps and a control mechanism for the flaps, two flat plates are attached to the sides of the channel , as a continuation of these sides, on which three wings are fixed, made in the form of a streamlined aerodynamic profile and forming gap channels with each other at all working positions, with a width of at least 3% of the chord of the central leaf, and the central leaf has a maximum thickness of 30 % ÷ 50% chords and a maximum curvature of 5% ÷ 15% chords, and the side-leaf profiles have a maximum thickness of 5% ÷ 20% chords and a maximum curvature of 3% ÷ 5% chords. This technical solution is taken as a prototype.

The disadvantage of this nozzle is the need to implement a coordinated rotation of the valves, ensuring minimal thrust loss in a wide range of flight modes.

The objective of the invention is to provide such a nozzle which, with relative simplicity of design, effectively (with low pressure loss) provides a sideways rotation of the jet of injected air laterally while hovering and, with increasing flight speed, a smooth backward rotation of the jet, providing an optimal ratio of lateral and propulsive forces for each flight mode.

The technical result consists in reducing the pressure loss in the nozzle and a corresponding increase in its efficiency, in ensuring the ratio of lateral and propulsive forces necessary for each flight mode.

The technical result is achieved by the fact that the nozzle of a gas-jet helicopter control system comprising an inlet channel, three rotary shutters, a shutter control mechanism, which consists of a gear sector for controlling the position of the middle shutter, control levers of the side shutters, a central rocker connected by rods with levers of the side shutters, the central rocking is connected by a gear transmission with the gear sector of the middle leaf, in addition, the gear ratio from the middle leaf to the central rocking is 0.70 ... 0. 78, the shoulders of the central rocking chair have a length of 0.3 ... 0.4 of the width of the nozzle inlet section and an opening angle of the shoulders of 140 ° ... 150 °, the levers of the side flaps have shoulders of 0.3 ... 0.35 and 0.4 ... 0.45 of the width of the nozzle inlet section and spell angles of 50 ° ... 55 ° and 55 ° ... 60 °, respectively, and the thrust levers of the side flaps have a length of 0.5 ... 0.55 and 0.4 ... 0.45 of the width of the inlet section of the nozzle.

The technical result is also achieved by the fact that in the nozzle of the gas-jet helicopter control system, the central rocking chair is connected to the middle wing using a cable transmission with a gear ratio of 0.7 ... 0.78.

The invention is illustrated by illustrations:

FIG. 1 - general view of the nozzle;

FIG. 2 - experimental dependence of the angle of rotation of the nozzle thrust vector on the angle of rotation of its middle leaf;

FIG. 3 - experimental dependence of the optimal angle of rotation of the left side flap on the angle of rotation of its middle leaf;

FIG. 4 - experimental dependence of the optimal angle of rotation of the right side flap on the angle of rotation of its middle leaf;

FIG. 5 is a general view of the mechanism for controlling the position of the nozzle flaps;

FIG. 6 - geometric parameters of the elements of the mechanism for controlling the position of the nozzle flaps;

FIG. 7 - the position of the nozzle flaps and the elements of the control mechanism in various flight modes.

Requirements for the jet nozzle as part of a helicopter jet control system are significantly different from those for aircraft nozzles with a rotary thrust vector. First of all, this is a significantly increased range of jet rotation angles from 90 ° in the hover mode to ~ -40 ° in the autorotation mode. In this case, it is necessary to ensure the minimum possible loss of thrust, at least in two main modes - hovering (angle of rotation of the jet about 90 °) and flight at maximum speed (angle about 10 ° ÷ 20 °). In addition, since the optimal pressure drop in the helicopter nozzle is much lower than in the aircraft nozzle, the sensitivity of the system to the level of pressure loss is much higher.

Based on these conditions, the proposed nozzle was developed. A general view of the nozzle is shown in FIG. 1. Inlet channel 1 provides a pair of the output section of the tail boom (usually round) with a rectangular section of the entrance directly to the nozzle. Further, the channel is limited from above and below by flat plates 2, between which the rotary valves 3, 4 and 5 are placed. The main element of the nozzle is the central valve 4, which mainly determines the angle of rotation of the jet. The experimental dependence of the angle of rotation of the jet χ on the angle of rotation of the central wing ϕ _{4 is} shown in FIG. 2. The nature of the flow in the nozzle and, accordingly, the pressure loss in it are largely determined by the relative position of the flaps at different operating modes. The relationship between the rotation angles of the valves, ensuring minimal loss of nozzle thrust in all operating modes, was determined by the results of experimental studies. In FIG. 3 shows the dependence of the angle ϕ _{3 of} rotation of the side flap 3, and in FIG. 4 - respectively, the angle ϕ _{5 of the} rotation of the side flap 5 from the angle ϕ _{4 of the} rotation of the central flap 4. The dotted line in the graphs shows the experimentally determined “corridor” of optimal values corresponding to the minimum pressure loss in the nozzle. This relationship is essentially nonlinear, which requires the use of a special mechanism for its implementation. The solid line in the graphs shows the dependencies provided by the mechanism of the proposed nozzle.

A diagram of this mechanism is shown in FIG. 5, and the designations of the geometric parameters of the mechanism elements are shown in FIG. 6. The sizes of all elements of the mechanism are given in the form of the ratio of the physical size to the characteristic size - the width of the inlet section of the nozzle L _in . The mechanism comprises a central two-arm rocker 6, rigidly connected to the gear sector 7, which transfers rotation through the gear sector 8 to the gear sector 9, rigidly connected to the central wing 4. The shoulders of the rocker 6 are connected via levers 10 and 12 to levers 11 and 13, rigidly connected with wings 3 and 5 respectively.

The mechanism works as follows. The control signal in the form of an angle of rotation is fed to the central rocking chair. Through the gear sectors 7, 8, 9, the rotation with the corresponding gear ratio i is transmitted to the middle wing, the position of which mainly determines the rotation of the thrust vector. Through the rods 10 and 12, the rotation of the rocker 6 is transmitted to the side flaps 3 and 5, respectively. The nature of the movements of the side flaps depending on the rotation of the rocker 6 and, respectively, of the central leaf 4 is determined by the ratio of the geometric parameters of the mechanism elements — the lengths of the rocking arms 6 - L ₀₃ and L ₀₅ , the angle of the arms ψ ₀ , as well as the lengths of the arms of the levers L ₃ and L ₅ and associated rods L ₃₀ and L ₅₀ . The sequence of changes in the position of the valves is shown in FIG. 7. In FIG. 7a shows the position of the cusps and mechanism elements in the hovering mode at ϕ ₄ ≈100 °. The ends of the rod 12 are located near the axis of the corresponding shoulder of the rocker 6 and at a small distance from the axis of rotation of the rocker. Because of this, as can be seen in FIG. 7b, the rotation of the rocker by a small angle practically does not lead to the rotation of the lever 13 and the leaf 5. However, the lever 11, the rod 10 and the corresponding rocking arm 6 form a parallelogram mechanism and the angle of rotation of the leaf 3 is almost proportional to the angle of rotation of the rocking 6 and the leaf 4. In FIG. 7c shows the position of the wings, approximately corresponding to the cruising flight mode. In this case, the movement of the sash 5 is gradually “activated” and the movement of the sash 3 is maintained. With a further rotation of the sash 4 corresponding to the autorotation mode, on the contrary, the movement of the sash 3 is practically blocked, and the sash 5 is “released”. As a result, the dependences of the rotation angles shown in FIG. 3 and 4.

An analysis of the parameters of the mechanism showed that the desired result is achieved in the following range of values of the main parameters:

- i = 0.70 ... 0.78

- ψ ₀ = 140 ° ... 150 °

- L ₀₅ / L _in = 0.3 ... 0.4

- L ₀₃ / L _I = 0.3 ... 0.4

- L ₃ / L _I = 0.3 ... 0.35

- L ₃₀ / L _in = 0.5 ... 0.55

- L ₅ / L _I = 0.4 ... 0.45

- L ₅₀ / L _I = 0.4 ... 0.45

The above results were obtained for the following geometric parameters: i = 0.74, ψ ₀ = 143 °, L ₀₅ / L _in = 0.367, L ₀₃ / L _in = 0.333, L ₃ / L _in = 0.333, L ₃₀ / L _in = 0.52 , L ₅ / L _in = 0,407, L ₅₀ / L _in = 0.433.

The connection of the central rocking chair with the middle leaf of the nozzle can also be carried out using a cable or belt drive with an appropriate gear ratio.

Thus, using a relatively simple mechanism, the implementation of a complex experimentally determined law of the optimal mutual movement of the nozzle flaps ensures minimal pressure loss and maximum nozzle efficiency in all flight modes, which is the technical result of the invention.

Claims (2)

1. The nozzle of a gas-jet control system of a helicopter containing an input channel, three rotary shutters, a shutter control mechanism, characterized in that the shutter control mechanism consists of a gear sector for controlling the position of the middle shutter, control levers of the side shutters, a central rocker connected by rods with levers of the side shutters moreover, the central rocking chair is connected by a gear transmission with the gear sector of the middle leaf, and the gear ratio from the middle leaf to the central rocking chair is 0.70 ... 0.78, the shoulders of the central rocking chair have a length of 0.3 ... 0.4 of the width of the inlet section of the nozzle and an angle of opening of the shoulders of 140 ° ... 150 °, the levers of the side flaps have shoulders of length 0.3 ... 0.35 and 0.4 ... 0.45 of the width of the inlet section of the nozzle and the spell angles 50 ° ... 55 ° and 55 ° ... 60 °, respectively, and the thrust levers of the side flaps have a length of 0.5 ... 0.55 and 0.4 ... 0.45 of the width of the inlet section of the nozzle. 2. The nozzle of the gas-jet helicopter control system according to claim 1, characterized in that the central rocking chair is connected to the middle wing using a cable transmission with a gear ratio of 0.7 ... 0.78.

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