RU2729312C1 - Double-flow engine - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to engine building, particularly, to output devices of double-flow engine. Known double-circuit engine comprising fan, high pressure compressor, combustion chamber, outer circuit path, multi-stage cooled turbine with low-pressure turbine impeller with cooled working blades, cooling channels of which by their outlets are interconnected with turbine gas path, and by inputs - with supply line passing through internal cavities of radial posts located behind turbine, wherein supply line through air intakes turned by their inputs to engine input is communicated with path of the air circuit, according to invention is equipped with mixer located behind radial posts behind turbine and made in form of channels alternating along perimeter, forming outlet cavity of external circuit and the inner cavity outlet cavity, wherein the outer cavity outlet cavity is interconnected with the outer circuit path, and the inner circuit outlet cavity is interconnected with the turbine gas path, wherein the air intakes are arranged along the outer circuit path before the mixer. Besides, the ratio of the outward cavity area of the outer outline to the inner cavity outlet cavity area in the radial plane can be equal to

where F_outOC is the output cavity of outer circuit area; F_outIC - output cavity of inner circuit area.

EFFECT: implementation of the invention makes it possible to increase reliability of the turbine working blade and to reduce operating costs due to increased efficiency of cooling of the turbine at modes with maximum temperature of gas, and consequently, to increase service life of both the working blade and the engine as a whole.

1 cl, 3 dwg

Description

The invention relates to engine building, in particular to the output devices of a two-circuit engine.

Known is a two-circuit engine containing a fan, a high-pressure compressor, a combustion chamber, an external circuit path, a multistage cooled turbine with a low-pressure turbine impeller with cooled rotor blades, the cooling channels of which are connected with their outputs to the turbine gas path, and the inputs with a supply line passing through through the inner cavities of the radial struts located behind the turbine, while the supply line through the air intakes, turned by their inputs to the engine inlet, is connected to the outer loop.

/ RF patent No. 2143574, IPC F02C 7/12, publ. 12/27/1999

, где

- полное давление на входе в воздухозаборники магистрали подвода охлаждающего воздуха из тракта наружного контура; P_вых - статическое давление в газовоздушном тракте двигателя за турбиной, существенно снижает возможность интенсификации процессов охлаждения.The disadvantage of this solution is that in this scheme the existing pressure drop in the cooling system of the low-pressure turbine rotor blade is minimal,

where

- total pressure at the inlet to the air intakes of the cooling air supply line from the external circuit; P _out - static pressure in the gas-air path of the engine behind the turbine, significantly reduces the possibility of intensifying the cooling processes.

;

- температура газа; Т_ст - температура стенки пера лопатки;

- температура охлаждающего воздуха. Однако, за счет низкой температуры охлаждаемого воздуха, отбираемого из тракта наружного контура, происходит приемлемое охлаждение пера рабочей лопатки. Тем самым температура охлаждающего воздуха (300…400°С) компенсирует низкую эффективность охлаждения.Therefore, the cooling efficiency is Θ = 0.18 ... 0.2, where

;

- gas temperature; T _st is the temperature of the wall of the blade airfoil;

- the temperature of the cooling air. However, due to the low temperature of the cooled air taken from the external circuit path, acceptable cooling of the airfoil of the rotor blade occurs. Thus, the temperature of the cooling air (300 ... 400 ° C) compensates for the low cooling efficiency.

If the engine reaches high-speed modes, especially with an increase in flight altitude, where the gas temperature reaches its maximum, it is required to increase the active drop in the cooling system of the low-pressure turbine rotor blade, which increases the cooling air speed, thereby intensifying the cooling processes in the rotor blade. In this scheme, while maintaining the source of cooling air, solving this problem is difficult.

The objective of the invention is to improve the efficiency of turbine cooling.

The expected technical result is an increase in the active drop in the cooling system of the turbine rotor blade at high-speed conditions, especially when the flight altitude is increased.

The expected technical result is achieved by the fact that a two-circuit engine containing a fan, a high-pressure compressor, a combustion chamber, an external circuit path, a multistage cooled turbine with a low-pressure turbine impeller with cooled rotor blades, the cooling channels of which are connected with their outputs to the turbine gas path, and inputs with a supply line passing through the inner cavities of the radial struts located behind the turbine, while the supply line through the air intakes, turned by their inputs to the engine inlet, communicates with the external circuit path, according to the proposal, is equipped with a mixer located behind the radial struts behind the turbine, and made in the form of channels alternating along the perimeter, forming the outlet cavity of the outer contour and the outlet cavity of the inner contour, while the outlet cavity of the outer contour is communicated with the path of the outer contour, and the outlet cavity of the inner contour is communicated with the gas path of the turbine , while the air intakes are located along the path of the external circuit in front of the mixer.

In addition, the ratio of the area of the outlet cavity of the outer contour to the area of the outlet cavity of the inner contour in the radial plane can be equal to:

Where

F _outNK - area of the outlet cavity of the outer contour;

F _outVK - area of the outlet cavity of the inner contour.

повышается, т.е. повышается активный перепад

в системе охлаждения рабочей лопатки турбины низкого давления, что обеспечивает при том же самом источнике охлаждающего воздуха повышение эффективности охлаждения рабочей лопатки.The supply of a by-pass engine with a mixer located behind the radial struts behind the turbine at high-altitude speed modes of engine operation, where the gas temperature is maximum, and there is a need to have a high cooling efficiency of the low-pressure turbine rotor blade in the absence of the possibility to change the source of cooling air, allows to reduce the static pressure in the gas path turbine (P _out ), which becomes equal to the static pressure at the outlet from the external circuit. At the same time, since in these modes the degree of bypass of the engine is higher than in terrestrial modes, while the degree of bypass is adopted in the well-known range for engines with mixing, then a greater air flow passes through the outer loop, the flow rate from the outer loop increases and, with equality static pressures downstream of the mixer, total pressure in the external circuit path

increases, i.e. active drop increases

in the cooling system of the rotor blade of a low-pressure turbine, which provides an increase in the cooling efficiency of the rotor blade with the same source of cooling air.

The execution of the mixer in the form of channels alternating along the perimeter, forming the outlet cavity of the outer loop and the outlet cavity of the inner loop, provides, on the one hand, the required mixing of flows with equalization of the static pressure in the area behind the mixer, and on the other hand, provides a minimum mass of the structure, since in this case the mixer can be made from sheet material.

Communication of the outlet cavity of the external circuit with the tract of the external circuit and the outlet cavity of the internal circuit with the gas tract of the turbine provides a connection between the internal and external circuits, since in this design the mixer plays the role of an ejector, where the ejected working fluid is air from the channel of the external circuit, and the ejecting working fluid is the body is the gas from the internal circuit, since it has a greater flow energy (higher temperature and flow rate). Thus, the main property of ejection is fulfilled when, under the action of the energy of the ejected flow, the static pressure at the outlet of the mixer becomes lower than the total pressure of the ejected flow. Under the influence of the pressure difference, the ejected flow rushes into the mixer, at the outlet of which, ultimately, the ejected and ejected flows are mixed with equalization of parameters at the outlet of the mixer.

является оптимальным соотношением, при котором с одной стороны, скорости истечения из выходных полостей наружного и внутреннего контура, потери по внутреннему контуру находятся в оптимальной точке, когда полное давление смешения становится максимальным, статическое давление максимально падает и эжектирующая способность внутреннего контура повышается, тем самым повышается активный перепад в системе охлаждения рабочей лопатки турбины.Area ratio

is the optimal ratio at which, on the one hand, the flow rates from the outlet cavities of the outer and inner contour, the losses along the inner contour are at the optimal point, when the total mixing pressure becomes maximum, the static pressure drops to the maximum and the ejection capacity of the inner contour increases, thereby increasing active differential in the turbine rotor blade cooling system.

The location of the air intakes along the path of the external circuit in front of the mixer unambiguously determines that the area of cooling air intake for cooling the turbine rotor blade will be with a higher total pressure than in the area behind the mixer.

The invention is illustrated by graphic materials.

FIG. 1 - longitudinal section of a by-pass engine;

FIG. 2 - longitudinal section of the last stage of the turbine;

FIG. 3 - cross section of the mixer.

The two-circuit engine contains a fan 1, a high-pressure compressor 2, a combustion chamber 3, an external circuit path 4, a multistage cooled turbine 5 with an impeller 6 of a low-pressure turbine 7 with cooled rotor blades 8. The cooling channels 9 of the rotor blades 8 are connected to the gas path 11 of the turbine 7, and inlets 12 through the channels of the disk 13, the inlet guide vane 14 and the inner cavities 15 located behind the turbine 7 of the radial struts 16 with the path of the outer circuit 4 of the engine. Moreover, the channels of the disk 13, the inlet guide vane 14 and the inner cavities 15 of the radial struts 16 form a line for supplying 17 cooling air from the path of the external circuit 4 to the inputs 12 of the cooling channels 9 of the rotor blade 8 of the low pressure turbine 7.

Also, the bypass engine is equipped with a mixer 18 located behind the radial struts 16 behind the turbine 7, and is made in the form of channels 19 alternating along the perimeter, forming the outlet cavity of the outer loop 20 and the outlet cavity of the inner loop 21. In this case, the outlet cavity of the outer loop 20 is in communication with the outer circuit 4, and the outlet cavity of the inner circuit 21 is in communication with the gas path of the turbine 11.

The inlets of the line of the cooling air lead 17 are made in the form of air intakes 22, turned by their inputs 23 to the engine inlet and located along the path of the external circuit 4 in front of the mixer 18.

The engine works as follows:

When the engine is running, the air from the fan 1 is divided into two streams: one of them enters the high-pressure compressor 2, and the other enters the path of the outer circuit 4. From the path of the outer circuit 4, the cooling air enters the air intakes 22, which are turned by their inputs 23 to the engine inlet ... In this case, the pressure for bleeding the cooling air from the tract of the external circuit 4 corresponds to the braking pressure of the air in the air intakes 22. Further, the air along the cooling air supply line 17 through the internal cavities 15 located behind the turbine 7 radial struts 16, the inlet guide vane 14 and the channels of the disk 13 enters the inputs 12 cooling channels 9 rotor blades 8, cooling their internal cavities. Further, the air through the outlets 10 is discharged into the gas path 11 of the turbine 7, and, mixing with the gas, enters the outlet cavity of the inner loop 21.

The mixer 18 equalizes the static pressures of the flows from the outlet cavity of the external circuit 20 and from the outlet cavity of the internal circuit 21. Since the outlet cavity of the internal circuit 21 is in communication with the gas path 11 of the turbine 7, the same static pressure is established there. The pressure difference required to ensure the cooling of the rotor blades 8 is the sum of the pressure difference between the total selection pressure from the external circuit 4 and the static pressure in the 11 turbine 7 gas path.

When the engine is operating at high-speed modes, a larger amount of air passes through the tract of the outer circuit 4 than in the terrestrial mode. Thus, the flow rate of the cooling air into the outlet cavity of the outer circuit 20 is increased. It is known that with increasing speed, while the static pressure is constant, the total flow pressure increases. Therefore, the total pressure of the selection of cooling air from the tract of the external circuit 4 increases, while maintaining the equality of the static pressures of the outlet cavity of the external circuit 20 and the outlet cavity of the internal circuit 21, thereby increasing the active differential in the cooling system of the rotor blades 8 of the low-pressure turbine 7.

Implementation of the invention makes it possible to increase the reliability of the turbine rotor blade and reduce operating costs by increasing the efficiency of turbine cooling at the maximum gas temperature modes, and, consequently, to increase the resource of both the rotor blade itself and the engine as a whole.

Claims (6)

1. A two-circuit engine containing a fan, a high-pressure compressor, a combustion chamber, an external circuit path, a multistage cooled turbine with a low-pressure turbine impeller with cooled rotor blades, the cooling channels of which are connected with their outputs to the turbine gas path, and the inputs with the supply line, passing through the inner cavities of the radial struts located behind the turbine, while the supply line through the air intakes, turned by their inputs to the engine inlet, is communicated with the external circuit path, characterized in that it is equipped with a mixer made in the form of channels alternating along the perimeter forming the output cavity of the external of the circuit and the outlet cavity of the inner loop, and located behind the radial struts behind the turbine, the outlet cavity of the outer loop is communicated with the path of the outer loop, and the outlet cavity of the inner loop is communicated with the gas path of the turbine, while the air intakes are located along the bunk path in front of the mixer. 2. The double-circuit engine according to claim 1, characterized in that the ratio of the area of the outlet cavity of the outer contour to the area of the outlet cavity of the inner contour in the radial plane is equal to:

Where F _outNK - area of the outlet cavity of the outer contour; F _outVK - area of the outlet cavity of the inner contour.

Images