RU147353U1 - NOZZLE WITH CONTROLLED DRIVE VECTOR - Google Patents

Abstract

1. Nozzle with a controlled thrust vector containing the inlet channel, rotary shutters and the shutter control mechanism, characterized in that two flat plates are attached to the sides of the rectangular input channel, as an extension of these sides, on which three shutters are made, made in the form of a streamlined aerodynamic profile and forming between themselves at all working positions slotted channels 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% of the chord and the maximum riviznu 5% ÷ 15% of the chord profiles and the side flaps have a maximum thickness of 5% ÷ 20% of maximum curvature and chord 3% ÷ 5% .2. A nozzle with a controlled thrust vector according to claim 1, characterized in that the plates are made as a unit with the sides of the input channel.

Description

The utility model relates to the field of aviation, in particular, to devices for directional control and reactive torque compensation of the rotor of single-rotor helicopters.

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. For this purpose, at the very early stages of the development of helicopter industry, a wide variety of devices were considered: various kinds of aerodynamic surfaces, counterpropellers, jet nozzles, etc. In 1911, B.N. Yuryev obtained a patent for a single-rotor helicopter, in which reactive moment compensation and directional control were carried out using one or more small screws. The scheme of a single-rotor helicopter with a tail rotor is currently the most widespread. However, the tail rotor, with all its advantages, has a number of significant drawbacks. According to some reports, from 15% to 20% of helicopter accidents occur for reasons related to the tail rotor. This includes the destruction of the tail rotor or its transmission, the tail rotor blades touching foreign objects, the ground personnel falling under the tail rotor, etc. Very significant disadvantages of the tail rotor are also a high noise level, significant harmful resistance of the screw and its sleeve at high flight speeds, the presence of dangerous flight modes, for example, uncontrolled self-rotation of a helicopter.

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.

An alternative steering device is known, the so-called fenestron — a fan installed in a channel formed in a developed vertical tail unit (Davidson JK, Harvey S.T., Sherrib N.E. Fan-in-fin anti-torque concept study. USAAMRDL Tech. Rep. 72-44, US Army, July 1982). This design greatly alleviates operational safety issues.

The disadvantages of this solution include design complexity, increased power consumption, problems with handling in some flight modes, significant harmful resistance when flying at high speed.

It is known to use a propeller instead of a tail rotor with blades forming a cone with an opening angle of about 90 ° (Molyneux W.G. Observations on the highly coned propeller. Aeron J. v. 87, N 870, Dec. 1983). Independent control of the blades of such a propeller allows you to change the magnitude and direction of its thrust in a very wide range and use the thrust both to control the helicopter in roll and pitch, and to create propulsive force.

A device is known (Molyneux WG A vectored-thrust rotor for helicopter anti-torque applications. Aeron. J., 1983, XI, p. 87, N 869, p. 357-360), also providing the creation of both propulsive force and control moments on the course and pitch.

A significant drawback of the last two solutions is the complexity of technical solutions during their implementation and significant loads in the blades and control systems of devices.

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 drawbacks 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), which contains the input channel, 2 sets of plates forming side nozzles located on the rotary sections of the tail boom, as well as two rotary shutters, forming, when they open, a tail nozzle that creates propulsive force with the possibility of its rotation by a small angle and the control mechanism of the shutters. 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.

The objective of this utility model is to create a jet nozzle that efficiently (with low pressure loss) provides a lateral rotation of the jet of forced air in the hover mode and, as the flow velocity increases, a smooth rotation of the jet backward, providing the optimum ratio of lateral and propulsive forces for each mode flight.

The technical result consists in simplifying the design of the nozzle, in reducing the pressure loss in the nozzle and, correspondingly, increasing its efficiency, in ensuring the ratio of lateral and propulsive forces necessary for each flight mode.

The technical result is achieved in that the nozzle with a controlled thrust vector contains a rectangular input channel, pivoting flaps and a flap control mechanism, two flat plates are attached to the channel sides as an extension of these sides, on which three flaps are made, 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% of the chord and maxi cial curvature 5% ÷ 15% of the chord profiles and the side flaps have a maximum thickness of 5% ÷ 20% of maximum curvature and chord 3% ÷ 5% of the chord.

The technical result is also achieved by the fact that in the nozzle the plates are made as a single unit with the sides of the input channel.

The utility model is illustrated by illustrations:

FIG. 1 is a general view of a nozzle made in accordance with a utility model;

FIG. 2 - the relative position of the wings in different flight modes of the helicopter;

FIG. 3 - calculated pattern of streamlines in the nozzle channel;

FIG. 4 - visualization of the flow around the wings in the hanging mode;

FIG. 5 - dependence of the rotation angles of one of the side flaps depending on the angle of rotation of the central leaf;

FIG. 6 - the dependence of the angles of rotation of the second side flap depending on the angle of rotation of the Central leaf;

FIG. 7 - dependence of the angle of rotation of the thrust vector on the angle of rotation of the central wing;

FIG. 8 - dependence of nozzle thrust loss on the angle of rotation of the central wing.

In FIG. 1 shows one embodiment of a nozzle.

The jet nozzle as part of the jet control system of the helicopter has requirements that differ significantly from the requirements 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.

The input 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 relative position of the wings for the main flight modes is shown in FIG. 2.

The plates can be attached to the input channel or made with it as a whole.

The shape of the central wing is selected in such a way as to ensure a continuous flow in the nozzle channel in the main modes. In addition, to minimize pressure losses in the channel, a flow is provided such that the relatively slow flow is first rotated by the desired angle, and then accelerated to a given speed. To organize such a flow, the central wing should have an aerodynamic profile with a large curvature. If the profile is relatively thin in this case, then when switching from the hovering mode to the maximum speed mode, the formation of separation zones on the leading edge of the sash is inevitable. For this reason, the profile of the central leaflet has a significant thickness of at least 30% ÷ 50% of its chords, and the profiles of the lateral valves have a maximum thickness of 5% ÷ 20% of their chords and a maximum curvature of 3% ÷ 5% of their chords. However, then, in the hovering mode, a stagnant zone is formed in the corner between the leaves 4 and 5, which leads to significant pressure losses. To eliminate this effect, the flaps are turned in such a way that there is always a gap between them, which ensures the "drain" of the stagnant zone. At the same time, due to the large thickness of the central leaf and, accordingly, the large radius of its leading edge, the Coanda effect is realized on it: the air flowing through the slit gap adheres to the leaf surface and rotates almost along its entire surface, providing an additional lateral force. This is clearly seen from the calculated picture of the flow in the nozzle channel (Fig. 3) and when visualizing the flow by the silkworm method during tests in a wind tunnel (Fig. 4). During the tests, the mutual movements of the flaps were determined, ensuring a minimum level of nozzle thrust loss. In FIG. 5 and 6 show the optimal laws of variation of the rotation angles φ ₃ and φ _{5 of the} flaps 3 and 5, respectively, depending on the angle of rotation of the central wing φ ₄ . Moreover, as can be seen in FIG. 7, the rotation of the central leaf 4 in the range from -90 ° to 100 ° provides a sufficiently large range of the angle χ of rotation of the thrust vector R from -50 ° to 75 °.

In FIG. 8 shows the dependence of the ratio of the nozzle thrust to its ideal value R _id on the angle of rotation of the central wing φ ₄ . It can be seen that in this nozzle a very low level of thrust loss is achieved: in the main flight modes, the R / R _id value lies in the range 0.93 ÷ 0.98.

The final forms of execution of the flaps and nozzle as a whole depend on the specific configuration of the helicopter.

Thus, the simplification of the nozzle design is achieved by the fact that for the rotation of the jet in all flight modes, only three moving elements (wings) with fairly simple relationships of relative position are used. A decrease in pressure loss in the nozzle and an increase in its efficiency is achieved by the fact that the flaps are made in the form of a streamlined aerodynamic profile with a central flap having a greater relative thickness and curvature, and the side flap profiles have a smaller thickness and curvature, which ensures an uninterrupted flow in the channels formed by the flaps at all angles of rotation of the jet, as well as a favorable combination of rotation and acceleration of flow in the channels. Ensuring the necessary ratio of lateral and propulsive forces for each flight mode with a minimum increase in harmful resistance due to the loss of momentum taken from the external air flow is achieved by the fact that at all operating positions of the wings they form slotted channels, as a result of which no separation of the flow into the lateral and longitudinal jets, and the rotation of the total flowing jet by the desired angle.

Claims (2)

1. Nozzle with a controlled thrust vector containing the inlet channel, rotary shutters and the shutter control mechanism, characterized in that two flat plates are attached to the sides of the rectangular input channel, as an extension of these sides, on which three shutters are made, made in the form of a streamlined aerodynamic profile and forming between themselves at all working positions slotted channels 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% of the chord and the maximum riviznu 5% ÷ 15% of the chord profiles and the side flaps have a maximum thickness of 5% ÷ 20% of maximum curvature and chord 3% ÷ 5%. 2. A nozzle with a controlled thrust vector according to claim 1, characterized in that the plates are integral with the sides of the input channel.

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