JPH0656131B2 - Method and apparatus for controlling cooling flow pressure in a thrust booster liner in a mixed flow variable cycle gas turbine engine - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a gas turbine engine with a thrust booster, and more particularly to a method of controlling cooling flow pressure in a thrust booster liner.

BACKGROUND OF THE INVENTION Gas turbine engines generally drive a compressor for compressing air flowing through the engine, a combustor for mixing and igniting compressed air with a fuel to produce a high energy gas stream, and a compressor. Has a turbine for
One type of aircraft gas turbine engine is the turbojet, which is powered by a high velocity gas stream exiting the turbine.

Another type of aircraft gas turbine engine is a turbofan with a fan located in front of the compressor and driven by a second or power turbine located downstream of the first turbine. is there.
The pressurized airflow generated by such a fan is split into two parts. The first part enters the outer bypass duct and bypasses the main engine, while the second part enters the compressor of the main engine. One of the advantages that turbofan engines have over turbojet engines is that they can move more air, thereby increasing the thrust of the engine.

Another means that can be utilized to increase thrust in a gas turbine engine is a thrust augmentor. In a gas turbine engine with a thrust enhancer, an exhaust duct is provided downstream of the turbine, and additional fuel is injected into the exhaust duct to ignite it, thereby increasing the energy of the gas flow. The thrust enhancement of the engine is achieved by ejecting such a gas flow from the exhaust nozzle.

One type of engine that has the characteristics of both a turbofan engine and an engine with a thrust booster is a mixed-flow engine in which the fan airflow is mixed with the gas flow from the main engine behind the turbine and in front of the thrust booster. is there. One of the features of turbofan engines, especially high bypass ratio turbofan engines, is that they have a relatively low specific fuel consumption at subsonic speeds. Further, one of the characteristics of the turbojet engine and the turbofan engine having a relatively low bypass ratio is that the specific thrust characteristic at supersonic speed is relatively large.

To meet the desire to operate aircraft efficiently over a wide range of subsonic and supersonic speeds, so-called variable cycle engines have been developed. A feature of such a variable cycle engine is that the bypass ratio of the engine can be changed during operation. For example, US Pat. No. 4010
A variable cycle engine is disclosed in the specification of US Pat. No. 608 and US Pat. No. 4,175,384. Each of the variable cycle engines disclosed therein, along with an outer bypass duct, includes a variable area bypass injector for regulating flow within the bypass duct to vary the engine cycle.

Such thrust augmenters for variable cycle engines are typically located in the exhaust duct of the engine. To protect the exhaust duct from the extremely high temperatures associated with the gas flow in the thrust augmentation device, a cooling liner can be placed inside the duct to form a cooling plenum therebetween.
In that case, cooling is achieved by diverting a portion of the bypass flow into such a plenum.

The basic problem when designing a thrust enhancer liner is
The pressure difference that may exist between the cooling flow in the plenum and the gas flow inside the liner. Such problems are especially acute when the pressure inside the liner suddenly drops. For example, a sudden reduction in fuel entering the combustor (a sudden change in throttle) causes the main engine to decelerate and the pressure in the thrust booster to drop faster than the pressure in the bypass air. Therefore, when designing the liner, some means must be taken to prevent the liner from collapsing inward.

Conventionally, various techniques have been proposed to solve this problem. For example, suitable supports (e.g., hanging fittings or connecting fittings) may be installed to hold the liner in the duct. However, such a solution results in increased complexity and weight as well as increased manufacturing costs for the liner. Also, US Pat.
According to another control means described in U.S. Pat. No. 7, the plenum is divided into a plurality of compartments and the flow to each chamber is regulated by a flange which limits the air flow and regulates the pressure. While such devices are effective, they require extra structural members to achieve the desired end. Another solution to the above problem is US Pat. No. 4,720,720.
A valve is used to regulate the air flow to the thrust enhancer liner, as described in '08. This patent discloses effective means for adjusting the pressure in the plenum. However, the above-mentioned US Pat.
Both the means disclosed in 866417 and 407,2008 add some structure to the liner, which results in higher costs.

OBJECTS OF THE INVENTION One of the objects of the present invention is to provide a new and improved method for adjusting the thrust flow liner cooling flow pressure in a gas turbine engine.

It is also an object of the present invention to provide a lightweight and inexpensive means for adjusting the cooling flow pressure of a thrust booster liner in a gas turbine engine.

SUMMARY OF THE INVENTION According to one aspect of the invention, there is provided a method of regulating bypass flow pressure in a mixed flow variable cycle gas turbine engine. The engine in this case has means for having a bypass flow and for changing the pressure of the bypass flow,
It also includes a liner thrust augmentation device with a portion of the bypass flow supplied as a coolant. The method of the present invention senses the pressure P _{1 of the} coolant and the pressure P ₂ in the thrust enhancer, and the pressure of the bypass flow P ₁ ,
It consists of varying as a function of P ₂ or both.

DETAILED DESCRIPTION OF THE INVENTION The drawings show a mixed flow variable cycle gas turbine engine 10
It is shown. The main engine 12 of such a gas turbine engine 10 includes a compressor 14 for compressing air flowing therein, a combustor 16 for mixing fuel with air to produce a high energy gas stream, and such gas stream. Includes a turbine 18 for extracting energy from the compressor 14 to drive it. A gas stream 20 is generated by such a main engine 12.

The gas turbine engine 10 also includes a first turbine 18
It also includes a front fan 22 driven by a second turbine 24 located aft of the. The front fan 22 is located inside the air intake 26 and is effective in pressurizing the air 28 entering the intake 26. Front fan 22
A rear fan 30 is located on the downstream side of the. The rear fan 30 is driven by the turbine 18. However, it will be appreciated that the present invention is not limited to such an arrangement and that the rear fan 30 may be driven by a second turbine 24 or a third turbine (not shown). . The rear fan 30 serves to further pressurize the air passing through it.

The outer duct 32 guides the first airflow 34 around the rear fan 30. The inner duct 36 guides a second airflow 38 from the rear fan 30 into a central bypass duct 40.
In this way, the second air stream 38 is transferred to the first air stream 34.
Is mixed with to form a bypass stream 42.

Adjusting means for varying the bypass flow pressure in bypass duct 40 are shown as 44 and 46. According to one embodiment of the present invention, such adjusting means may include as shunt valve 46 as disclosed in US Pat. No. 4,068,471. According to another embodiment of the present invention, the adjusting means described above is disclosed in US Pat. No. 4,175.
It may include a variable area bypass injector as disclosed in US Pat. That is, such a variable area bypass injector includes a dual bypass selection valve as 44 and a static pressure valve as 46. According to yet another embodiment of the present invention, the adjusting means may further include a rear variable area bypass injector (VABI) 47, which effectively reduces the area of the bypass duct 40.

Other adjustment means should be conceivable to a person skilled in the art,
All of them are included within the scope of the present invention. The feature of such adjusting means is that the outer duct 32 and the inner duct 36 are
Of the turbofan system can be realized by completely opening the same, and by completely closing one of the outer duct 32 and the inner duct 36 and completely opening the other, a low turbojet cycle operation similar to a pure turbojet cycle can be realized. It is to be able to realize turbofan operation with a bypass ratio. Furthermore, such adjusting means can be in an intermediate position to provide a bypass flow 42 consisting of air flows 34 and 38. In short, the features of the present invention are
One is that the areas of the outer duct 32 and the inner duct 36 can be changed. Another feature of the adjusting means is that the valve 46 can be configured such that by varying the area of the inner duct 36, the cross-sectional area of the inner duct 36 through which the airflow 38 flows changes rapidly. . In this way, a sharp pressure drop occurs for the airflow 38 flowing therein. If rear VABI is used,
When the pressure of the air flow 38 drops, the pressure of the bypass flow can be lowered while opening it to keep the mass flow rate substantially constant.

Behind the main engine 12, a thrust augmentation device 48 surrounded by an exhaust duct 50 is located. A cooling liner 52 is located inside the exhaust duct 50, and a cooling plenum 54 is formed therebetween. Liner 5
At the front end of 2, a portion 58 of the bypass flow 42 is attached to the plenum 5
Introducing means 56 for introducing into 4 is located. A mixing means 60 for mixing the bypass flow 42 with the gas flow 20 is located behind the main engine 12 and in front of the thrust augmentation device 48. According to one embodiment of the invention, a variable geometry mixer as disclosed in US Pat. No. 4,069,661 is used as the mixing means 60.

The pressure P ₁ in the plenum 54 by the first sensing means 62
Is sensed. For example, the sensing means 62 can be a pressure transducer or other means known in the art. Similarly, the pressure P ₂ in the thrust augmentation device 48 is sensed by the second sensing means 64. The controller 66 controls the pressure signal P ₁
And P ₂ and then valves 46 and / or 4
A signal for activating 4 is sent to the adjusting means. If P
_{If 1} is greater than P ₂ by a predetermined value or more, the valve 46 may be moved toward the closed position. In this way, the air flow 38 from the inner duct 36 to the bypass duct 40 will experience a pressure drop. Such a pressure drop will reduce P ₁ relative to P ₂ , thereby reducing the radial force acting inwardly on liner 52.

It is also possible to develop a control device that monitors only _one of P _{1 and} P ₂ . For example, controller 66 may be responsive to sudden changes in the maximum value of P ₁ or the value of P ₂ . Furthermore, in order to control the pressure P ₁ by varying the bypass flow pressure in the bypass duct 40, the controller 66 may adjust only the valve 44 or valves 44 and 4 may be used.
It will be obvious that both 6 may be adjusted.

Another feature of the invention is that the pressure drop created in the front bypass duct can result in improved performance. Total thrust is the product of mass flow rate and flow velocity. In the engine as shown, airflow is limited by the maximum Mach in mixer 60. The pressure drop caused by valve 46 causes the total pressure in bypass flow 42 to drop. Since the total pressure is a function of the Mach number, reducing the total pressure also reduces the Mach number in the mixer. Accordingly, the speed of the gas turbine engine 10 can be increased, thereby increasing the Mach number of the bypass flow through the mixer 60. Higher gas turbine engine 10 speeds increase mass flow through the engine, which in turn increases thrust.

As will be apparent to those of skill in the art, the present invention is not limited to only the particular embodiments described herein.
On the contrary, the invention is equally applicable to any variable cycle engine equipped with means to regulate bypass flow in the engine.

Also, the dimensions and the rational or structural relationships shown in the drawings are for the purpose of illustration only, and the dimensions and ratios that are actually used in the variable cycle engine of the present invention. Needless to say, it should not be understood as a structural relationship.

Furthermore, various modifications and changes may be made or equivalents may be used in whole or in part without departing from the spirit and scope of the present invention.

[Brief description of drawings]

1 is a schematic cross-sectional view of a mixed flow variable cycle gas turbine engine according to the present invention. In the figure, 10 is a mixed flow type variable cycle gas turbine engine, 12 is a main engine, 14 is a compressor, 16 is a combustor,
18 is a first turbine, 20 is a gas flow, 22 is a front fan, 24 is a second turbine, 26 is an air intake, 28 is air, 30 is a rear fan, 32 is an outer duct, 34 is a first turbine. Air flow, 36 an inner duct, 38 a second air flow,
40 is a bypass duct, 42 is a bypass flow, 44, 46
And 47 are adjusting means, 48 is a thrust augmenting device, 50 is an exhaust duct, 52 is a cooling liner, 54 is a cooling plenum, 5
6 is an introducing means, 60 is a mixing means, 62 is a first sensing means, 64 is a second sensing means, and 66 is a controller.

Claims (7)

[Claims] 1. A mixed flow variable cycle gas turbine engine having a bypass flow and means for varying the pressure of the bypass flow, and including a thrust enhancer and a liner, wherein a portion of the bypass flow is supplied as coolant. in senses the pressure P ₂ of the coolant pressure P ₁ and in the augmentor of the pressure of the bypass flow P _1, P ₂
Alternatively, a method of adjusting the bypass flow pressure, which is characterized in that it is changed as a function of both of them. 2. A main engine for generating a gas flow, a front fan for pressurizing air, a rear fan for further pressurizing the air discharged from the front fan, and a rear fan for supplying a first air flow. An outer duct for directing the periphery of the air duct, an inner duct for forming a bypass flow with the first air flow by directing a second air flow from the rear fan into the central bypass duct, the pressure of the bypass flow Means for changing the thrust, a thrust augmentation device located behind the main engine, an exhaust duct surrounding the thrust augmentation device, and a cooling plenum disposed inside the exhaust duct and between the exhaust duct and the exhaust duct. A cooling liner, means for introducing a portion of the bypass flow into the plenum,
And a gas turbine engine including means for mixing the bypass flow with the gas flow, sensing a pressure P ₁ in the plenum and a pressure P ₂ in the thrust augmentation device, the inner duct, the outer duct or A method for adjusting bypass flow pressure, characterized in that the area of both of them is changed as a function of P ₁ , P ₂ or both of them. 3. The method of claim 2 wherein the areas of the inner duct, the outer duct, or both are varied as a function of the difference between P ₁ and P ₂ . 4. A main engine for generating a gas flow, a front fan for pressurizing air, a rear fan for further pressurizing air discharged from the front fan, a central bypass duct, and the rear fan. An outer duct for guiding a first air flow through the periphery into the bypass duct, an inner duct for guiding a second air flow from the rear fan into the bypass duct, located behind the main engine A thrust augmentation device, an exhaust duct surrounding the thrust augmentation device, a cooling liner disposed inside the exhaust duct to form a cooling plenum with the exhaust duct, and a portion of the bypass flow introduced into the plenum. Means, a means for mixing the bypass flow with the gas flow, a first sensing means for sensing a pressure P ₁ in the plenum, the thrust augmentation device A second sensing means for sensing a pressure P ₂ in the bypass duct, and a regulation means for varying the pressure of the flow in the bypass duct as a function of P ₁ , P ₂ or both. And a gas turbine engine. 5. The gas turbine engine according to claim 4, wherein the adjusting means includes means for changing the area of the inner duct and means for changing the area of the outer duct. 6. A gas turbine engine according to claim 5, wherein said adjusting means includes means for varying the area of said bypass bus duct. 7. A gas turbine engine according to claim 4 wherein said adjusting means includes means for causing a rapid pressure drop in said inner duct.