RU2267018C1 - Turbine rotor support of high-temperature gas-turbine engine - Google Patents

Abstract

FIELD: mechanical engineering; high-temperature gas-turbine engines.

SUBSTANCE: according to invention, inner housing of support is made in form of three-layer envelope which forms, in addition to oil space, cooling air ring space enclosing oil space, also discharge air ring space. Load-bearing posts are rigidly connected with all three layers of inner housing envelope. Spaces of posts communicate with cooling air space and, through metering holes, with space formed between fairing, outer housing and inner housing with load-bearing posts. Pre-oil spaces communicate with discharge air ring space. Fairing consists of sectors installed for free thermal expansion.

EFFECT: increased strength reliability of support by excluding deformation processes in structural members.

6 cl, 8 dwg

Description

The invention relates to the field of aircraft engine manufacturing, and in particular to rotor bearings of turbines of a gas turbine engine located behind a compressor turbine, and can be used in transport and power engineering.

A well-known schematic diagram of the support, which includes two main structural parts: the bearing part and the bearing assembly. The bearing part consists of the outer and inner cases interconnected by radial power struts (see L.P. Lozitsky et al. Design and strength of aircraft gas turbine engines. - M .: Air transport, 1992, p. 173).

A support structure is known, including an outer casing, an inner casing connected with it with hollow power struts, a cowl, pipelines for supplying and draining oil, supplying cooling air and venting, bearing assemblies, seals (N.G. Gavrilov, N.I. Startsev. Design of axial turbines of gas turbine engines. - Kuibyshev: KuAI, 1984, p. 64-75).

As a prototype, the support of the turbine rotors of a high-temperature gas turbine engine located behind the compressor turbine (TV7-117C Turboprop engine. Technical operation manual 065.00.0300 RE, book 2, sections 072.53.00 and 072.54.00. - M. OJSC: Aviaizdat ", 2001). The support includes an outer housing, an inner housing associated with it with hollow power struts, a cowl, pipelines for supplying and draining oil, supplying cooling air and venting, bearing assemblies, oil and air seals. In the engine, the support is mounted with the front flange to the body of the combustion chamber, and the rear flange to the body of the free turbine. The main disadvantage of the support is its low strength reliability. When the engine is running on the fairing and power struts of the support, cracks occur, after disassembling the engine, warping of the outer and inner bodies is noted.

The objective of the invention is to increase the strength reliability of the support due to the exclusion of deformation processes in its structural elements.

The exclusion of deformation processes in the structural elements is achieved by the fact that in the support of the turbine rotors of a high-temperature gas turbine engine, including an outer casing, an inner casing with hollow power struts connected to it, a cowl, pipelines for supplying and draining oil, supplying cooling air and venting air from pre-oil cavities, bearing units, oil and air seals, according to the invention, the inner housing is made in the form of a three-layer shell with the formation of an oil cavity, covering e of the annular cavity of cooling air and the annular cavity of the exhaust air, while the power struts are rigidly connected to all three layers of the shell of the inner casing, and their cavities are in communication with the cavity of the cooling air and through the metering holes in the walls of the struts with a cavity formed between the cowling, the outer casing and internal housing with hollow power racks, pre-oil cavities communicated with the annular cavity of the exhaust air, in addition, the fairing is composed of sectors installed with the possibility of their freedom th thermal expansion in the axial, radial and circumferential directions. The outer casing and the inner casing with hollow power struts are made of titanium alloy. Each of the existing power racks, to which cooling air is supplied, is equipped with an internal heat shield. The fairing sectors on the side of the cavity formed between the fairing, the outer casing and the inner casing with hollow power struts are lined with heat-insulating screens. The connection of the outer casing with the hollow power struts is made by means of radial pins.

The fairing sectors, in order to ensure their free thermal expansion in the axial, radial and circumferential directions when the engine is running, must be installed with a gap relative to each other, while various options for their attachment to the outer and inner bearing housings are possible. For example, fairing sectors can be mounted on the outer casing with hooks in their rear outer part, while the collars of the rear inner shelves of the sectors are placed in the rear annular groove of the inner casing with axial clearance and secured with pins, the collars of the front inner shelves are inserted in the front annular the groove of the inner case, and the front outer parts of the sectors are joined by a floating ring having pins included in the corresponding grooves of the sectors.

The presence in the new support of two air annular cavities, one in the other, surrounding the oil cavity, as well as the connection of the cooling air cavity directly adjacent to the oil cavity, with the cavities of the power struts and through the metering holes provided in their walls with the cavity formed between the cowling, the outer case and the inner case with hollow power racks, compared with the prototype provide a reduction in temperature unevenness. Due to this, the value of thermal tension in the material of the housing of the power struts and the fairing is also reduced, due to the circumferential temperature unevenness of the gas flow in the flow part of the support formed by the fairing. In the prototype, the cooling air cavity and the exhaust air cavity are adjacent to the oil cavity, but only in small areas of the circle.

The performance of the fairing from sectors installed with the possibility of free thermal expansion in the axial, radial and peripheral directions, compared with the prototype, reduced the likelihood of thermal deformations in the fairing and the elements of the bearing part of the support. In the support, selected as a prototype, the fairing and the elements of the bearing part were combined into one all-welded structure.

The rigid connection of the power struts with all three layers of the shell of the inner casing significantly reduced the amount of vibration in the plane of this support, positively influenced the strength of the buildings, power struts and fairing.

A new effective air cooling scheme ensured a decrease in the temperature of the buildings and power racks by approximately 270 ° C, which made it possible to manufacture these structural elements from titanium alloys, which, in comparison with steel, have lower values of the coefficient of thermal expansion and specific gravity, which also reduced the level their possible deformations, as well as the mass of the support.

Equipping the power racks through which cooling air is transported with an internal heat shield reduced the level of unevenness in the thermal state of the power racks.

The heat-insulating screens mounted on the sectors of the fairing from the side of the cavity formed between the fairing, the outer casing and the inner casing with hollow power racks aligned and stabilized the temperature fields on the buildings and power racks.

The connection of the outer casing with the hollow power struts with the help of radial pins instead of the rigid welded joint, which takes place in the prototype support, provided the possibility of free thermal movements of these elements relative to each other, while eliminating the thermal spacing between them.

The invention is illustrated by drawings, on which:

Figure 1. Turbine rotor support for a high temperature gas turbine engine, fragment of a longitudinal section;

Figure 2. Cross section AA in Fig. 1 (bearing units removed);

Figure 3. A longitudinal section bB in figure 2;

Figure 4. Section BB in FIG. 3;

Figure 5. A longitudinal section DD in figure 2;

6. Fragment E in figure 1;

7. Fragment G in figure 1;

Fig. 8. Fragment K in figure 2.

The drawings show the support of the rotors of the turbines of a high-temperature gas turbine engine located behind the turbine of the engine compressor. The support includes an outer housing 1, an inner housing 2 with hollow power struts 3, a composite cowl 4, an oil supply pipe 5, an oil drain pipe 6, cooling air supply pipes 7 and 8, an air discharge pipe 9 from pre-oil cavities 19 and 20, bearing assemblies 10 and 11, oil seals 12 and 13, air seals 14 and 15.

The outer casing 1 and the inner casing 2 with welded power struts 3, forming the bearing part of the support, are interconnected by radial pins 16, which provide mutual alignment of these elements during thermal movement.

In the engine, the outer housing 1 of the support is connected by flange joints to the housing 17 of the combustion chamber and to the housing 18 of the free turbine.

The inner housing 2 is made in the form of a rigid three-layer shell. The inner layer of the casing encloses the oil cavity 27. An annular cavity 28 of cooling air is formed by the inner and middle layer of the casing. Between the middle and outer layer of the shell is placed an annular cavity 29 of the exhaust air. The support also contains air cavities 36 and 37 adjacent to pre-oil cavities 19 and 20, respectively.

The power racks 3 are welded with all three layers of the shell of the inner casing 2. The inner cavities of the power racks 3 are communicated through slotted openings 30 with the annular cavity 28 of cooling air and through the metering holes 31 in the walls of the power racks 3 with the cavity 32 formed between the fairing 4, the outer casing 1 and the inner casing 2 with power racks 3. The power racks 3, to which cooling air is supplied by pipelines 7 and 8, have internal heat shields 21 that prevent air from contacting the walls of these dots. The pre-oil cavities 19 and 20 are in communication with the annular cavity 29 of the air discharge and then through the pipe 9 with the flow part of the exhaust device (not shown in the drawings).

The composite fairing 4, in the form of a ring, has radial connectors (according to the number of racks) that divide it into identical sectors 22, each of which is worn on a power rack 3. Grooves are made in the joints of sectors 22, in which sealing plates 23 are installed. Clearances in joints compensate for thermal expansion of sectors in the circumferential direction. At the same time, the collars of 25 front internal shelves of the sectors are placed in the front annular groove of the inner casing 2 with a minimum clearance, and the collars 26 of the rear internal shelves of the sectors are placed in the rear annular groove with a clearance that compensates for the thermal expansion of the sectors in the axial direction. In the rear annular groove of the inner casing 2 there are five pins 33, which are located in the grooves of the collars 26. The collars 34 of the front external parts of the sectors 22 are combined with a free-floating ring 24 having pins included in the corresponding grooves of the sectors. Sectors 22 from the side of the cavity 32 are lined with heat-insulating shields 35 fixed to the sectors by resistance welding.

When the engine is running, air taken after the axial part of the centrifugal compressor enters through pipelines 7 and 8 for supplying cooling air to the cavity of the power struts 3 and then through slotted openings 30 to the annular cavity 28 of the cooling air.

The air from the annular cavity 28 of cooling air feeds the internal cavities of all five power racks 3, from where the air flows through the metering holes 32 into the cavity 32 and then through the perforation holes (not shown in the drawings) and leaks at the joints of the sectors 22 fall into the flow part formed by the composite fairing 4. The hydraulics of the power racks 3 are selected so that their thermal state is the same. This ensures a boost that prevents breakthrough of hot gases from the flow part into the cavity 32. The main part of the air from the annular cavity 28 through the bypass holes in the flange connections of the inner housing 2 with the air and oil seal housings (not shown in the drawings) enters the cavity 36 and 37. In these cavities, the air flow branches, providing cooling of rotor parts and pressurization of air seals 14, 15 and oil seals 12, 13.

From pre-oil cavities 19 and 20, through other bypass channels in the same flange connections, air enters the annular cavity 29 of the exhaust air, from where it is evacuated through the air discharge pipe 9 to the flow part of the outlet device (not shown in the drawings).

The rest of the air from the air cavities 36 and 37, ultimately, flows into the flow path of the engine.

The proposed support of the rotors of the turbines of a high temperature gas turbine engine has high strength reliability. In this case, the formation of cracks on the fairing and power racks is excluded, and after disassembling the engine, warping of the inner and outer bearing bodies is absent. According to the results of the thermal calculation, the temperature unevenness of the power racks does not exceed 45-50 ° C, while for the support selected as a prototype, this parameter has a value of 250-270 ° C. The temperature of the power racks in the new support is 430 ° C, and in the prototype - 680-700 ° C.

The absence of deformation in the inner and outer casing of the support ensures the coaxiality of these elements in the structure. The support does not require frequent reconditioning; it allows the possibility of modular replacement of a free turbine under operating conditions. It has a high level of production and operational manufacturability, maintainability. The use of the composite construction of the support made it possible to significantly simplify its assembly and disassembly, and also provided the ability to replace damaged parts of the support.

A new turbine rotor support for a high temperature gas turbine engine has been manufactured and has successfully passed lengthy bench tests as part of the engine. The test results indicate a stable and very low level of vibration in the plane of this support.

According to the results of micro-measurements of the engine support elements, which passed a long bench test, no changes in the geometry of the support were detected.

Claims (6)

1. The support of the turbine rotors of a high-temperature gas turbine engine, including an outer casing, an associated inner casing with hollow power struts, a cowl, pipelines for supplying and draining oil, supplying cooling air and venting air from pre-oil cavities, bearing assemblies, oil and air seals, characterized the fact that the inner case is made in the form of a three-layer shell with the formation of an oil cavity, covering it with an annular cavity of cooling air and an annular cavity of discharge air, wherein the power racks are rigidly connected with all three layers of the shell of the inner casing, and their cavities are connected with the cooling air cavity and through the metering holes in the walls of the racks with the cavity formed between the cowling, the outer casing and the inner case with hollow power racks, the pre-oil cavities are in communication with the annular cavity of the exhaust air, in addition, the fairing is composed of sectors installed with the possibility of their free thermal expansion in axial, radial and circumferential directions. 2. The support of the turbine rotors of the high-temperature gas turbine engine according to claim 1, characterized in that the outer casing and the inner casing with hollow power struts are made of titanium alloy. 3. The support of the rotors of the turbines of the high temperature gas turbine engine according to claim 1 or 2, characterized in that each of the existing power struts, to which cooling air is supplied, is equipped with an internal heat shield. 4. The support of the turbine rotors of the high-temperature gas turbine engine according to claim 3, characterized in that the sectors of the fairing from the cavity formed between it, the outer casing and the inner casing with hollow power racks are lined with heat-insulating screens. 5. The support of the rotors of the turbines of the high temperature gas turbine engine according to claim 4, characterized in that the connection of the outer casing with the hollow power racks is made using radial pins. 6. The support of the turbine rotors of the high-temperature gas turbine engine according to claim 1, characterized in that the cowl sectors are mounted on the outer casing by means of hooks in their rear outer part, while the shoulders of the rear inner shelves of the sectors are placed in the rear annular groove of the inner casing with an axial clearance and secured with pins, the collars of the front inner shelves are inserted into the front annular groove of the inner case, and the front external parts of the sectors are joined by a floating ring having pins included in the corresponding grooves sec tori.

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