RU2313680C2 - Silencing nozzle of air-jet engine (versions) - Google Patents

Abstract

FIELD: aircraft industry.

SUBSTANCE: invention relates to aircraft nozzles with devices for silencing noise of jets of air-jet engine. Three versions of silencing nozzle are proposed. According to first design version, channel of constricting flat nozzle of air-jet engine with cutouts in shell in area of throat section is divided by partitions into row of small nozzles. Edges of upper shells of small nozzle are displaced relative to corresponding edges of lower shell of small nozzles either forward or backward along axis of nozzle channel. Direction of displacement of edges of upper and lower shells of small nozzles alternates. According to second design version, channel of constricting axially symmetrical nozzle of air-jet engine with cutout of shell in area of troat section is divided into sectors by pylons directed from shell to axis of nozzle channel and they do not reach opposite wall of nozzle. Edges of shells between pylons of adjacent sector opposite wall of nozzle. Edges of shells between pylons of adjacent sectors are displaced relative to each other either forward or backward along axis of nozzle channel. Direction of displacement of edges of shells of adjacent sectors alternates. According to third design version, pylons are installed at exit section of axially symmetrical nozzle of air-jet engine containing shell and central body. Said pylons are installed between central body and shell, dividing channel of nozzle into row of small channels, and deflecting flaps are arranged on surface of central body on every other small channel. Front edge of flaps is hinge-connected to central body near throat section of nozzle.

EFFECT: reduced noise of jet owing to creating different direction of velocity vector at nozzle exit.

4 cl, 27 dwg

Description

The invention relates to the field of aviation, in particular to nozzles of jet engines of aircraft with devices for reducing noise.

One of the main requirements for engines of civilian aircraft is the low noise level on takeoff and landing. Noise reduction is especially relevant for supersonic passenger aircraft (ATP), for which the noise on the ground is determined by the noise of the engine jets.

Known nozzle for ATP with reduced noise due to the flow of external air during takeoff through hollow pylons. In this case, the supersonic part of the nozzle performs the function of an ejector. In cruise supersonic flight mode, the pylons are retracted, the supersonic part of the nozzle is formed by flaps located on the inner surface of the ejector (AIAA Paper N 80-0165, 1980. Flight and wind tunnel test results of a mechanical jet noise suppressor nozzle. RDFitzSimmons, RAMcKinnon and ESJohnson Douglas Aircraft Company McDonnell Douglas Corporation and JR Brooks Rolls-Royce, Limited). Studies of this nozzle showed that with a decrease in noise on take-off and landing by 16 EPNdB, thrust loss is 5-6%. At the same time, the nozzle design is complex, with three groups of movable elements (subsonic flaps regulating the critical section, retractable pylons, supersonic flaps) and, as a result, has a lot of weight.

Known nozzle for ATP containing an axisymmetric tapering nozzle and ejector (UK patent No. 1207194 "United Aircraft Corp.", IPC B64D 330/06, 1967). With high traction characteristics of this nozzle, the noise reduction is negligible, because in a short ejector, without dividing the main jet into a series of small ones, it is impossible to provide an ejection coefficient sufficient to significantly reduce the speed of the outflowing jet and, accordingly, noise.

A nozzle with a reduced noise level is known, containing a shell and a central body, between which there are hollow pylons that separate the main channel of the nozzle into a number of channels, as well as an ejector, each pylon is equipped with two panels, movably connected to the pylon along the edges, and a panel rotation mechanism ( U.S. Patent No. 2940252, IPC F02K 1/26, 1960). The disadvantage of this nozzle is that the fastening of the panels to the edges of the pylons extends the internal channel of the nozzle by the length of the panels along the axis of the nozzle, which reduces the mixing length of the internal flow and external air in the ejector and, accordingly, reduces the level of noise reduction. In addition, the supersonic part of the nozzle is formed by a single panel, which does not allow optimally adjusting the nozzle in a wide range of flight modes and leads to additional thrust losses.

A sound-damping jet engine nozzle is known that contains an ejector, a shell and a central body, between which there are hollow pylons that divide the main channel of the nozzle into a number of sectors, and a pair of panels movably connected to the pylon along the edges, and rotation mechanisms designed to change the shape of the sectors between the pylons. The nozzle feature is that it is additionally equipped with several panels movably connected to each other and installed behind each pylon (RF patent No. 2092708, IPC F02K 1/34, 1993). The disadvantage of this nozzle is the design complexity.

A sound-damping jet engine nozzle is known, comprising a rim, corrugated nozzle, peripheral channels, an ejector (US Pat. No. 3,749,316, Sound Suppressing Thrust Augmenting Apparatus, IPC B64D 33/06; F01N 1/14; F01N 1/16; 1972). The disadvantages of the nozzle are its unregulated, inapplicability on supersonic aircraft.

Known flat ejector nozzle for a jet engine containing a shell, an internal corrugated nozzle, ejector, baffles in the ejector, which are made of sound-absorbing material (UK, application No. 1345786, Ejectors; jet propulsion nozzles BERTIN & CIE, 1971). The disadvantages of the nozzle are its unregulated, inapplicability on supersonic aircraft.

Known nozzle containing a shell, a tapering channel, corrugations, movably connected to a tapering channel, ejector air intakes, supersonic nozzle panels, outer nozzle panels and side walls of the nozzle (Jet mixing characteristics for a supersonic ejector. T. Oishi, T. Watanabe, Y. Udagawa, Y.Nacamura, IHI Aero-Engine & Space Operations, Tokyo, Japan, 6 ^{th International Conference on LASER ANEMOMETRY, August} 13-18, 1995. The Westin Resort, Hilton Head Island, South Carolina, USA). The disadvantage of this nozzle is that the presence of one set of corrugations does not allow to completely mix the nozzle stream with the external flow in the ejector. The noise reduction is about 10 EPNdb (AIAA N 96-1668. 2 ^nd AIAA / CEAS AeroAcoustics Conference May 6-8, 1996 / State College, PA. An experimental study of 2-d mixer-ejector noise and thrust characteristics. S .Ju.Krasheninnikov, AKMironov CIAM, Moscow, Russia, EVPaulukov, VKZitenev TsAGI, Zukovskiy, Russia, J.Julliard, E.Maingre SNECMA Villaroche, Moissy Cramayel, France).

Known flat noise suppressing nozzle of an jet engine (RF Patent No. 2153091, IPC F02K 1/46, 2000). The nozzle consists of a shell, a tapering channel, corrugations, an ejector, supersonic panels, and air intakes. The nozzle is provided with additional channels connecting the internal cavity of the tapering channel of the nozzle with the ejector. Additional channels are equipped with valves that block the gas flow in flight modes without sound attenuation. The corrugation ledges face the outside of the nozzle and are located between the additional channels, and the ejector duct is divided into parts by supersonic panels. This nozzle design reduces noise during take-off. The disadvantage of the nozzle is the complexity of the design.

The objective of the invention is to reduce the noise level of the jet at take-off and landing.

There are three options for nozzles with sound attenuation.

In the first and second embodiments of the device, a flat and axisymmetric sound-damping chevron nozzles of an air-jet engine (US Patent No. 6360528, Chevron exhaust nozzle for a gas turbine engine, General Electric Co, 2002), which include a channel for a gas jet flow, are selected as the prototype. jets. A series of adjacent chevrons located at the nozzle exit limit the exhaust port. The presence of chevrons at the nozzle exit leads to a decrease in jet noise due to a change in the turbulence structure in the mixing layer of the jet with the external flow. If the chevrons are located at a small angle to the jet, then they do not lead to an increase in thrust loss in the nozzle. The disadvantage of the prototype is the insufficient effect of chevrons on the jet, and with an increase in the angle of installation of the chevron to the jet, the thrust loss in the nozzle increases.

In the first embodiment of the device, the solution of the problem and the technical result are achieved by the fact that in the tapering flat nozzle of the jet engine with cutouts on the shell, the nozzle channel in the region of the critical section of the nozzle is divided by partitions into a series of small nozzles, the edges of the upper shells of which are offset relative to the corresponding edges of the lower shells either forward or backward along the axis of the nozzle channel, with adjacent small nozzles alternating in the direction of displacement of the edges of the upper and lower shells. This leads to the fact that the velocity vector of the outflow from neighboring small nozzles are directed at an angle to each other.

Figure 1 shows a flat nozzle with sound attenuation (1st version of the device).

Figure 2 shows a longitudinal section of a flat sound attenuating nozzle in section AA.

Figure 3 shows a longitudinal section of a flat sound attenuating nozzle in section BB.

Figure 4 shows the angle between the directions of the flow velocity vectors in adjacent small nozzles.

Figure 5 shows a right side view of a flat sound attenuating nozzle.

Figure 6 shows a top view of a flat sound attenuating nozzle.

The flat noise-attenuating nozzle in the first embodiment of the device (Figs. 1-3) consists of a shell 1, partitions 2 located in the vicinity of the critical section, and side walls of the nozzle 3.

и

направлены под углом φ друг к другу за счет чередования вырезов на обечайке (фиг.2-4). Различное направление скоростей потоков газа на выходе из сопла приводит к снижению шума реактивной струи. Глубину вырезов и количество перегородок можно оптимизировать для каждого отдельного конструктивного применения.The nozzle operates as follows. A gas stream flows through the nozzle channel. At the exit of the nozzle, the gas is separated by partitions 2 into a series of flows. The presence of the cutout 4 on the shell 1 leads to the inclination of the cut of the nozzle 5 and the deviation of the flow velocity vector. In adjacent channels of the flow velocity vector

and

are directed at an angle φ to each other due to the alternation of cutouts on the shell (Fig.2-4). Different direction of gas flow rates at the exit of the nozzle leads to a decrease in jet noise. The depth of cuts and the number of partitions can be optimized for each individual structural application.

In the second embodiment of the device that implements the proposed method, the solution of the problem and the technical result are achieved by the fact that the channel of the tapering axisymmetric nozzle of the jet engine with cutouts on the shell in the region of the critical section is divided by pylons directed from the shell to the axis of the nozzle channel and not reaching the opposite the nozzle walls, into sectors, and the edges of the shells between the pylons of neighboring sectors are displaced relative to each other either forward or backward along the axis of the nozzle channel, and edovanie direction of displacement edges of shells adjacent sectors.

Figure 7 shows a longitudinal section of a "sector" nozzle with sound attenuation (2nd version of the device) in section BB.

On Fig shows a right side view of the "sector" nozzle with sound attenuation.

Figures 9-10 are views of a longitudinal section D of a nozzle showing different directions of the velocity vector in adjacent sectors of the nozzle.

Figure 11 shows the combination of types G and D and the angle between the directions of the flow velocity vectors in neighboring sectors of the nozzle.

12 is a photograph of a model of a “sector” tapering nozzle with sound attenuation.

On Fig.13-15 shows the results of experimental studies of traction and acoustic characteristics of the "sector" nozzle with sound attenuation.

"Sector" nozzle in the second embodiment of the device consists of a shell 1 and pylons 2 (Fig.7-11). The number of pylons and their configuration may be different. 7-12 depict a "sector" nozzle with 12 pylons.

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в соседних секторах сопла. Созданное таким образом различное направление скорости струи на срезе сопла приводит к снижению шума реактивной струи без заметных потерь тяги сопла.The nozzle operates as follows. A gas stream flows through the nozzle channel. At the exit of the nozzle, the gas is separated by pylons 2 into zones with smaller jets, in which the velocity vectors of the adjacent jets are directed at an angle to each other. Cutout 4 of the edge of the shell 1 on the "even" sectors upstream, relative to the edge (without cutout) 6 of the shell 1 on the "odd" sectors, leads to the inclination of the cut of the nozzle 5 and deviates part of the jet from the axis of the nozzle (Fig.9-10). 11 shows the angle φ between the directions of the flow velocity vectors

and

in adjacent nozzle sectors. The thus created different direction of the jet velocity at the nozzle exit leads to a decrease in the jet noise without significant nozzle loss.

As shown by experimental studies of the traction characteristics of the “sector” nozzle in TsAGI, the thrust loss in such a nozzle is at the level of thrust loss in the standard axisymmetric nozzles (Fig. 13), and the noise reduction efficiency increases with increasing pressure drop across the nozzle exit. The highest efficiency reaches 1-3 dB in the region of the maximum noise spectrum (Figs. 14-15).

In the third embodiment of the device, an axisymmetric nozzle with a central body with a reduced noise level, containing a shell, a central body with hollow pylons located around it, through which external air passes (Thrust performance of isolate d plug nozzles with two tipes of 40-spoke noise), was selected as the prototype suppressor at mach numbers from 0 to 0.45. by DE Harrington and JJScbloemer, NASA TM X-2951, 1974). In the nozzle, the main gas jet stream is separated by hollow pylons through which external air passes into a series of smaller jets. The disadvantage of this nozzle is that when separating the main jet using hollow pylons, small jets are located at some distance from each other. Moreover, the presence of the bottom region leads to the fact that the loss of thrust of the nozzle in flight modes with noise attenuation increases to 16% of the ideal thrust of the nozzle.

In the third embodiment of the device, the solution of the problem and the technical result are achieved by the fact that on the cut of the axisymmetric nozzle of the jet engine containing the shell and the central body, pylons are installed dividing the nozzle channel into a number of small channels, and the thickness of the pylons is not more than 0.2L _p where L _p - maximum distance between the pillars and the surface of the central body through a small passage located deflectable flap length is not less than L _c = 0.2H _* (H _* - height of the nozzle throat), with an angle rejected I from the surface of the central body in the range from 0 to 30 °, wherein the cutting edge flaps hingedly attached to the central body in the vicinity of the nozzle throat.

On Fig shows a longitudinal section of a "sector" sound-attenuating nozzle with a Central body (the third version of the device) with the position of the moving parts in the take-off mode with sound attenuation in cross-section EE.

On Fig shows a right side view of the "sector" soundproof nozzle with a Central body.

On Fig shows a longitudinal section of a "sector" soundproofing nozzle with a Central body with the position of the moving parts in flight mode without sound attenuation in cross-section EE.

On Fig shows a longitudinal section of part of the "sector" soundproof nozzle with a Central body in the region of the critical section in M 2: 1.

On Fig shows a General diagram of the mechanisms for moving the valves inside the Central body.

Figure 21 shows a photograph of a model of a "sector" sound-attenuating nozzle with a central body.

Figure 22 shows a photograph of interchangeable parts of a model of a "sector" sound-attenuating nozzle with a central body with various protrusions. (In experimental studies, the leaflets were imitated by protrusions).

On Fig shows a flow diagram in a "sector" soundproofing nozzle with a Central body.

In Fig.24-27 presents the results of experimental studies of traction and acoustic characteristics of the "sector" soundproof nozzle with a Central body.

The axisymmetric "sector" sound-attenuating nozzle with a central body in the third embodiment of the device (Fig. 16) consists of a shell 1, a central body 7 with wings 8 and pylons 2 located between the central body 7 and the shell 1. The configuration and dimensions of the wings can be different ( Fig. 22) and can be optimized for each individual structural application. The number of pylons can also be different. The movement of the sections 8 is carried out by a power system consisting of hydraulic cylinders 9 and a system of levers 10 (Fig. 20).

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в соседних секторах (со створками и без створок). В рассматриваемой схеме угол между направлениями векторов скорости в соседних секторах составляет ~20°. На режиме полета без шумоглушения механизмы перемещения убирают створки 8 внутрь центрального тела 7 (фиг.18). Такая перестройка приводит к уменьшению потерь тяги сопла.The nozzle operates as follows. In take-off mode, the gas flow from the engine is divided by pylons 2 into a series of flows in small nozzles (in this model there were 18 nozzles). Shutters 8 on the central body 7, installed through one small nozzle, lead to a deviation of the flow velocity vector in small nozzles (sectors) with shutters. 23 shows a flow diagram in a “sector” nozzle with a central body and an angle φ between the directions of the flow velocity vectors

and

in neighboring sectors (with and without wings). In the scheme under consideration, the angle between the directions of the velocity vectors in neighboring sectors is ~ 20 °. In flight mode without sound attenuation, the movement mechanisms remove the shutters 8 inside the central body 7 (Fig. 18). This adjustment leads to a decrease in nozzle thrust loss.

The mechanisms for moving the valves are similar to the known mechanisms for regulating nozzles and other casement structures of modern aircraft.

At TsAGI, traction and acoustic characteristics of “sector” nozzles with sound attenuation were studied. In experimental studies, deflected leaflets were simulated by protrusions mounted on the central body. Studies of a “sector” sound-damping nozzle with a central body showed that thrust loss without an external nozzle flow without protrusions amounted to about 3% of the ideal nozzle thrust in the range of the available degree of pressure reduction in the nozzle π _c = 1.8-3.5, π _c = P _OS / P _N where R _OS - the total gas pressure at the nozzle inlet P _H - atmospheric pressure. The presence of protrusions of different sizes leads to an increase in traction loss by 0.5-2% (Fig.24-25). The presence of protrusions reduces the noise of the jet. The efficiency of noise reduction increases with increasing pressure drop, the largest decrease in the region of the maximum of the spectrum of the jet is 6-8 dB, while discrete noise components are suppressed (Figs. 26-27).

Claims (3)

1. A tapering flat nozzle of an aircraft engine with cutouts on the shell, characterized in that the nozzle channel in the critical section is divided by partitions into small nozzles, the edges of the upper shells of which are offset relative to the corresponding edges of the lower shells either forward or backward along the axis of the nozzle channel, moreover, in adjacent small nozzles there is an alternation of the direction of displacement of the edges of the upper and lower shells. 2. Tapering axisymmetric nozzle of the jet engine with cutouts on the shell, characterized in that the nozzle channel in the critical section is divided by pylons directed from the shell to the nozzle channel axis and not reaching the opposite wall of the nozzle into sectors, and the edges of the shells between the pylons neighboring sectors are displaced relative to each other either forward or backward along the axis of the nozzle channel, and there is an alternation of the direction of displacement of the edges of the shells of the neighboring sectors. 3. An axisymmetric jet engine nozzle containing a shell, a central body, pylons dividing the nozzle channel into a series of small channels, characterized in that the pylon thickness is not more than 0.2L _p , where L _p is the maximum distance between the pylons, and deflectable flaps with a length of at least L _c = 0.2H ^* (H ^* is the height of the critical section of the nozzle) are located on the surface of the central body through one small channel, the angle of deviation of the flaps from the surface of the central body can be in the range from 0-30 °, with the leading edge sash hinges fixedly attached to the central body in the vicinity of the critical section of the nozzle.

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