RU70315U1 - TURBO-FAN ENGINE - Google Patents

Abstract

The utility model relates to gas turbine engines. In the proposed turbofan engine, gas from two or more gas generators rotates a common two-stage turbine that rotates in different directions and transmits torques using shafts and two-stage gearboxes with spur gears to a turbofan having a nacelle.

Description

The proposed utility model relates to mechanical engineering and can be used as an aircraft turbofan engine, or as a gas turbine ground installation.

Known turboprop engine (see. Double-circuit turbojet, turbofan and turboprop engines. A.L. Klyachkin. Riga Institute of Civil Air Fleet Engineers named after the Lenin Komsomol. Riga-1963 p. 298 Fig. IV g2 and p. 295) the main components of which are:

1. The input device.

2. The compressor.

3. The combustion chamber.

4. The turbine.

5. The exhaust (jet) nozzle.

6. Propeller.

7. Differential planetary gear.

The disadvantage of this engine is the presence of a shaft passing through the entire engine, which greatly complicates its design: increases the size of the hubs of the compressor disks and the turbine, complicates the design of the supports. The outer diameter of the shaft is structurally limited, which leads to high revolutions for the transmission of the required power, while maintaining the permissible voltage at the shaft. Long shafts are not rigid, so it is almost impossible to balance them accurately. Therefore, it is very difficult to get rid of vibrations and defects (touching the shafts) during the evolution of the aircraft (impact during landing, for example).

For a single-shaft turbine, the differential planetary gearbox is optimal (see Foreign Science and Technology News No. 11 1988, p. 19, section “gearbox”).

Differential planetary gearboxes operate reliably only up to a thrust of 18 tons. This is due to the fact that the satellite gears create large centrifugal forces and wear out the bearings on which they rotate. The disadvantages of this gearbox can also include high oil consumption, the lowest efficiency among gear reducers (low efficiency due to the fact that the satellite gears, together with the housing on which they are located, rotate in an air - oil environment). Differential planetary gearboxes are sensitive to the quality, temperature and pressure of the oil, lubricating teeth and gear bearings. In the event of a slight increase in temperature and a drop in oil pressure, the gearbox will collapse immediately. Due to the presence of a ring gear with internal teeth, helical, chevron, and other gears cannot be used, which does not allow reducing the size of the gearbox. Closest to the proposed engine is a jet propulsion system for aircraft (see England patent, No. 1020145, class F1G dated December 7, 1964), containing at least two gas generators consisting of an axial compressor, a combustion chamber and a turbine located along a common air flow, a common compressor supplying compressed air to individual compressors, a common turbine rotated from the exhaust gases of gas generators, which rotates the common compressor and nozzle. The disadvantage of this engine is the design complexity. This engine can be compared in design with a twin-shaft gas turbine engine of the same size, thrust and specific fuel consumption. The presence of a large number of compressor stages in a jet engine does not in itself give significant differences between them in mass or characteristics (see News of foreign science and technology No. 11 of 1988 p.19,

left column, 20-23 rows from the top). Since gas generators are located inside the air stream, they must be streamlined so as not to create resistance. Each gas generator must be controlled by control units, which have nowhere to place, unless on the outside of the entire engine, which will significantly increase the transverse area of the engine, which will create a lot of air resistance during flight. The disadvantages of this engine include the need for accurate synchronization of the passage of air through gas generators. If one of the gas generators does not synchronously reach the preset mode, then the compressor surges are very likely (i.e., air flow disruption and compressor failure). It is very difficult to isolate the compressor surge in conventional gas turbine engines with one gas generator, and with several gas generators connected by a single air stream, this will make it much more difficult, if at all possible (see the Handbook of Aviation Engineering. Third Edition, revised. And add., P.S. Shevelko, Military Publishing, 1974. P. 250, Computational modes of compressor operation). Failure or simple misregistration of one of the gas generators will lead to an immediate breakdown of the entire engine. In the engine (see England patent, No. 1020145, class F1G dated Dec. 7, 1964), it is impossible to integrate the thrust reverse, therefore its operation is difficult. The objective of the proposed utility model is the ability to create a highly economical, reliable engine with any maximum thrust.

The task is achieved in that the engine contains a common two-stage turbine rotating in different directions and transmitting torques using shafts and two-stage gearboxes with spur gears to a fan heater having a nacelle.

Figure 1, Figure 2, Figure 3, schematically shows a turbofan engine: front view, view from the entrance and a top view, respectively.

The engine contains two gas generators 1, consisting of an axial compressor 2, a combustion chamber 3 and a turbine 4, a common two-stage turbine 5, rotating in different directions, shafts 6, a two-stage gearbox with cylindrical gears 7, a fan heater 8, a nozzle 9, a nacelle of a fan heater 10, a nacelle gas generators 11.

When the engine is running, the air entering the compressor 2 is compressed and enters the combustion chamber 3, the combustion products of which pass through the turbines 4, which rotate the compressor 2 and through the common two-stage turbine 5, rotating in different directions, enter the nozzle 9. The turbine 5 through shafts 6 transmits torques to two-stage gearboxes 7 having a common housing and from it a fan fan 8 having a nacelle 10 that creates traction, throwing air back.

The advantages of the proposed turbofan engine design. The use of a fan-driven fan with a nacelle in the engine makes it possible to obtain a specific fuel consumption of up to 0.6 kg / kgf hour at a speed of M = 0.8 (see Foreign Science and Technology News No. 11, 1988, p. 15 Fig. 1).

The use of a two-stage turbine rotating in different directions allows the use of a simple two-stage gearbox with cylindrical gears, for any transmitted power. The gearbox consists of two gearboxes independent of each other. Failure of one of them will not lead to breakage of the other. Stopping one gearbox will stop one fan stage, which will only result in loss of traction. A drop in oil pressure lubricating the gearbox will not damage the gearbox. The gearbox will work for quite some time without breaking, like a normal gearbox in an automobile engine. The teeth of the gears can be of any profile and design (chevron, helical, etc.), which will reduce the size (and hence weight) of the gears and increase their reliability (since the contact of the gear teeth can be made shock-free) compared to a planetary gear .

The gearbox oil consumption in the scheme I have proposed is an order of magnitude lower than that of a planetary gearbox. And less oil - less weight. Due to the fact that in the proposed gearbox there are no satellite gears, the adjustment of the position of the blades of the fan heater through it is simplified. Due to the possibility of installing the blades at an optimal angle at different engine operating modes, a high flight efficiency is achieved the plane. In addition, by simply turning the blades, you can get reverse thrust. Since the shafts are located between the gas generators, they are not limited in the size of the outer diameter, which allows them to be made rigid and light. If the shafts are rigid, then they can be very precisely balanced, which will avoid vibrations. Gas generators are not interconnected by gas-air flow, which allows you to debug the operation of gas generators independently of each other. Stopping one gas generator will not stop the entire engine. The engine will lose only 30% of thrust due to forcing another gas generator. Gas generators do not have a complex power removal system for rotating a current generator. Power can be removed directly from the gearbox. The control units of gas generators can be immediately on two gas generators and located in the opening between the gas generators, protected by a nacelle of gas generators. The gas generator nacelle has flaps, which allows easy and quick access to control units and gas generators for routine engine maintenance. Due to the fact that gas generators do not have mechanical connection through shafts with each other and with the engine, they can be easily replaced right under the wing of the aircraft without removing the entire engine.

The design of the engine I proposed consists of easily interchangeable modules: gas generators, a fan heater with a fan fan nacelle, a reducer, a free turbine with shafts, and nozzles. The manufacture of these engine modules has been mastered by the aviation industry. There are no technological difficulties in the manufacture of the engine. Moreover,

manufacturing will be easier. Separation of the engine into modules simplifies the assembly of the engine, making it maintainable.

An important factor in the dignity of the engine is cheap engine refinement. It is enough to bring one gas generator, which will take half as much fuel. It is possible to use existing gas generators from already brought, well-proven engines. For example, to create an engine with a thrust of 40 tons, there are already excellent gas generators with a thrust of 20 tons. To create heavy-duty engines will not require special new equipment. The noise of the proposed engine will be significantly less than that of a similar gas turbine engine. In addition, it is impossible, in principle, to produce a turbofan engine with a thrust of 40 tons of another design. If the turbofan engine is three-shaft, then two shafts should belong to the gas generator. Twin-shaft gas generators are optimal and have the best characteristics. The third shaft is used to transmit torque from the gas generator through the gearbox to the fan heater. But the gearbox must be differential planetary. But planetary gears cannot yet be with a thrust of more than 18 tons. Four-shaft engines have not yet been made by anyone.

Claims (1)

Turbofan engine containing at least two gas generators, consisting of an axial compressor, a combustion chamber and a turbine located along a common air stream and nozzle, characterized in that it contains a common nacelle for gas generators, a common two-stage free turbine rotating in different directions and transmitting torques with the help of shafts and two-stage gearboxes with spur gears, a fan heater having a nacelle.