RU2371598C2 - Turbo-fan engine - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: turbo-fan engine comprises two gas generators consisting of axial compressor, combustion chamber and turbine arranged along shared airflow, and nozzles. Additionally, it incorporates nacelle shared by aforesaid gas generators, common two-stage free turbine mounted between gas generators and running in opposite directions to transmit torques with the help of two one-stage reductions gears and two shafts mounted in parallel between gas generators and to auger-type fan mounted in nacelle.

EFFECT: higher reliability and operating economy.

4 dwg

Description

The present invention relates to mechanical engineering and can be used as an aircraft turbofan engine, and 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 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 the defect of 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 gears 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, it is impossible to use helical, chevron, and other gears, which does not allow reducing the size of the gearbox. The British patent GB 594207, 11/05/1947 is known, in which a turboprop engine with two coaxial screws is described, in which a gas generator, deaxially located relative to them, serves as a rotation drive of a free biotational turbine. The disadvantage of this technical solution is the impossibility of industrial application. The GB 594207 engine has a huge cross-sectional area, which creates great resistance to the incoming air flow. Due to the fact that the gas duct is located not along the air flow, but across it, gas-dynamic losses increase. It is also impossible to integrate a gas duct into an airplane without aerodynamic losses.

Closest to the proposed engine is a jet propulsion system for aircraft (see England patent No. 1020145, class F01G 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 stream air, 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 Foreign Science and Technology News No. 11, 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 to the air stream. 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 great resistance to air flow 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 detach from compressor surges 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 immediate damage to the entire engine.

The objective of the invention is the ability to create a highly economical, reliable engine with any maximum thrust.

The objective is achieved in that the engine contains a common nacelle for gas generators, a common two-stage free turbine located between the gas generators, rotating in opposite directions and transmitting torques using two single-stage gearboxes and two shafts parallel to each other between the gearboxes, a propeller fan having a nacelle.

Figure 1, Figure 2, Figure 3, Figure 4 schematically shows a turbofan engine: front view, a cross section from above, a view from the entrance and a cross section, respectively.

The engine contains two gas generators 1, a common two-stage turbine 2, rotating in opposite directions, shafts 3, single-stage gearboxes 4 and 5, a fan fan 6, a nozzle 8, a fan fan nacelle 7, gas generator nacelle 9.

When the engine is running, air enters the gas generators 1, where it turns into gas with high pressure and high temperature, through a common two-stage turbine 2, rotating in different directions, the gas enters the nozzle 8. The turbine 2 transmits torques to the single-stage gearbox 5, from it through two spaced shaft 3 to a single-stage gearbox 4, and from it a fan heater 6 having a nacelle 10, which creates traction, throwing air back.

The advantages of the proposed turbofan engine design.

The use of a propeller 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 News of foreign science and technology No. 11, 1988, p. 15, Fig. 1).

The use of a two-stage turbine rotating in opposite directions allows the use of simple single-stage gearboxes with spur gears for any transmitted power.

Gearboxes 4 and 5 consist of two gearboxes independent of each other.

In the case of the use of a parasite gear in the front gearbox 4, it is possible to simply synchronize the rotation of the fan 6.

Due to the fact that the shafts 3 are spaced from each other and are located above and below the horizontal axis of the engine, it is possible to move the gas generators almost to contact, which will reduce the cross-sectional area of the engine and therefore reduce resistance to the incoming air flow. The design of the shaft bearings is also greatly simplified. 3. A drop in the oil pressure lubricating the gearbox will not damage the gearboxes. Gearboxes will work for quite some time without breaking, like a normal gearbox in an automobile engine. The gear teeth 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 unshocked) compared to the planetary gearbox. 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 there are no satellite gears in the proposed gearbox, it is easier to adjust the position of the blades of the fan heater through it. 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 a reverse thrust.

The shafts 3 are located between the gas generators and 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 from gearboxes. The control units of gas generators can be in one instance at once 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 directly under the wing of the aircraft without removing the entire engine.

The design of the engine I proposed consists of easily replaceable modules: gas generators, a fan heater with a fan fan nacelle, gearboxes, a free turbine, shafts, 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 become easier.

Separation of the engine into modules simplifies the assembly of the engine, making it maintainable.

An important factor in the dignity of the proposed 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. Say, 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. The gearbox must be a differential planetary. And planetary gearboxes cannot yet be with a thrust of more than 18 tons.

Four-shaft engines have not been done yet by anyone.

Claims (1)

A turbofan engine containing two gas generators, consisting of an axial compressor, a combustion chamber and a turbine located along a common air stream and a nozzle, characterized in that it contains a common nacelle for gas generators, a common two-stage free turbine located between the gas generators, rotating in opposite directions and transmitting torques with the help of two single-stage gearboxes and two shafts located parallel to each other between gearboxes, a fan heater having a nacelle.

Images