CN110005631B - Centrifugal impeller rear bearing cooling and sealing structure - Google Patents
Centrifugal impeller rear bearing cooling and sealing structure Download PDFInfo
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- CN110005631B CN110005631B CN201910324334.7A CN201910324334A CN110005631B CN 110005631 B CN110005631 B CN 110005631B CN 201910324334 A CN201910324334 A CN 201910324334A CN 110005631 B CN110005631 B CN 110005631B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/05—Shafts or bearings, or assemblies thereof, specially adapted for elastic fluid pumps
- F04D29/056—Bearings
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/05—Shafts or bearings, or assemblies thereof, specially adapted for elastic fluid pumps
- F04D29/056—Bearings
- F04D29/0563—Bearings cartridges
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/08—Sealings
- F04D29/083—Sealings especially adapted for elastic fluid pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/58—Cooling; Heating; Diminishing heat transfer
- F04D29/582—Cooling; Heating; Diminishing heat transfer specially adapted for elastic fluid pumps
- F04D29/5846—Cooling; Heating; Diminishing heat transfer specially adapted for elastic fluid pumps cooling by injection
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- Sealing Using Fluids, Sealing Without Contact, And Removal Of Oil (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
The invention discloses a centrifugal impeller rear bearing cooling and sealing structure, which comprises: the bearing cylinder seat is equipped with bearing chamber, ring in the bearing cylinder seat and locates the outer annular runner of interior annular runner and ring outside the ring locating interior annular runner, and the both ends of bearing chamber are equipped with interior structure of obturating respectively, and the both ends of interior annular runner are equipped with middle structure of obturating respectively, and the both ends of outer annular runner are equipped with outer structure of obturating respectively. The inner annular flow passage is communicated with a first draft tube and is used for introducing low-temperature airflow at the blade top of the inlet of the centrifugal impeller into the inner annular flow passage. The outer annular flow passage is communicated with a second draft tube and used for leading mixed airflow formed by mixing in the outer annular flow passage to high-temperature parts of the engine. The cooling and sealing structure for the rear bearing of the centrifugal impeller can reduce the heat load of the bearing cylinder seat, inhibit the coking of lubricating oil in the bearing cavity, reduce the heat stress of the bearing seat, reduce the temperature rise of the lubricating oil in the bearing cavity and effectively solve the cooling and sealing problems of the rear bearing of the centrifugal impeller of the medium and small aircraft engine with high supercharging ratio.
Description
Technical Field
The invention relates to the field of aircraft engines, in particular to a centrifugal impeller rear bearing cooling and sealing structure.
Background
In a double-rotor small and medium-sized aviation gas turbine engine, at least three bearing fulcrums are required, so that bearing cavities are inevitably required to be arranged at high-temperature parts such as a combustion chamber, a turbine and the like, and the difficulty is brought to cooling and sealing of a bearing seat by the peripheral high-temperature environment. The design form of a single-stage centrifugal compressor is often adopted, a middle high-pressure rotor bearing is arranged between the centrifugal compressor and a gas turbine, and an engine combustion chamber is arranged right above the centrifugal compressor and has a large thermal load, so that the cooling and sealing design of the bearing at the position is greatly challenged.
Cooling and obturating of a centrifugal impeller rear bearing are shown in fig. 1, air is introduced from the root of a centrifugal impeller outlet, and reaches a centrifugal impeller back cavity through a rotor-stator radial gap, then air flow is divided into two paths, one path is used for obturating the left side of a bearing cavity through graphite sealing, the other path is divided into two paths through holes H1 and H2 on a bearing seat, the bearing seat is divided into two paths after being ventilated and cooled, one path is used for obturating the right side of the bearing cavity through graphite sealing on the right side, and the other path is used for cooling and obturating the high-pressure rotor disc through a high-pressure turbine disc neck hole H3.
With the improvement of the thermodynamic cycle parameters of the aircraft engine, particularly after the pressure increase ratio of the air compressor reaches 24, the outlet temperature of the centrifugal impeller can reach 550 ℃, the radial internal flow of the back cavity of the centrifugal impeller has large wind resistance and temperature rise, the outlet temperature of the back cavity reaches 630 ℃, if the conventional design means shown in figure 1 is adopted, the high-temperature air is used for cooling the bearing seat and sealing the bearing cavity, the cooling effect cannot be achieved, but the lubricating oil in the bearing seat and the bearing cavity can be heated, so that the lubricating oil is coked, the thermal stress of the bearing seat is too large, the working environment of the bearing is deteriorated, and the normal work of the engine is seriously influenced.
Disclosure of Invention
The invention provides a centrifugal impeller rear bearing cooling and sealing structure, which aims to solve the technical problem that the existing centrifugal impeller rear bearing cooling and sealing structure is not suitable for cooling and sealing a centrifugal impeller rear bearing of a medium-small aircraft engine with a high supercharging ratio.
The technical scheme adopted by the invention is as follows:
a centrifugal impeller rear bearing cooling and sealing structure comprising: the bearing device comprises a bearing cylinder seat, wherein a bearing cavity for mounting a rear bearing, an inner annular flow passage annularly arranged outside the bearing cavity and an outer annular flow passage annularly arranged outside the inner annular flow passage are arranged in the bearing cylinder seat; the inner annular flow passage is communicated with a first drainage tube, and the first drainage tube is used for introducing low-temperature airflow at the blade top of the inlet of the centrifugal impeller into the inner annular flow passage so as to cool the bearing cylinder seat and seal the bearing cavity through the inner sealing structure; mixing the low-temperature airflow entering the outer annular flow channel through the middle sealing structure and the high-temperature airflow entering the root part of the centrifugal impeller outlet of the outer annular flow channel through the outer sealing structure to form mixed airflow; the outer annular flow passage is communicated with a second drainage pipe, and the second drainage pipe is used for guiding mixed airflow formed by mixing in the outer annular flow passage to a high-temperature part at the rear part of the engine to relieve pressure of the outer annular flow passage and cool the high-temperature part.
Furthermore, the inflow end of the first drainage tube is communicated with the inlet blade top of the centrifugal impeller, and the outflow end of the first drainage tube is communicated with one end, close to the centrifugal impeller, in the inner annular runner; the inflow end of the second drainage tube is communicated with one end, close to the centrifugal impeller, in the outer annular flow channel, and the outflow end of the second drainage tube is communicated with a rear-stage part of the centrifugal impeller.
Furthermore, the number of the first drainage tubes is multiple, and the multiple first drainage tubes are sequentially arranged at intervals along the circumferential direction of the inner annular flow channel; the quantity of second drainage tube is many, and many second drainage tubes set up along outer annular runner's circumference interval in proper order.
Furthermore, the end surfaces of the two ends of the bearing cylinder seat are respectively provided with a corresponding circle of inner runner through holes and a corresponding circle of outer runner through holes, and the outer runner through holes are annularly arranged outside the inner runner through holes; part of low-temperature airflow in the inner annular flow channel penetrates through the inner flow channel through hole and then enters the bearing cavity through the inner sealing structure, and the rest part of low-temperature airflow penetrates through the inner flow channel through hole and then enters the outer annular flow channel through the middle sealing structure and the outer flow channel through hole; the high-temperature airflow at the root of the centrifugal impeller outlet passes through the outer sealing structure and then passes through the outer runner through hole to enter the outer annular runner.
Further, the bearing cylinder seat is divided into an inner shaft cylinder, a middle shaft cylinder and an outer shaft cylinder which are sequentially arranged from inside to outside under the action of the bearing cavity, the inner annular flow passage and the outer annular flow passage; a sealing shaft barrel fixed with a rotating shaft of the centrifugal impeller is rotatably arranged in the bearing cavity; the inner sealing structure is arranged between the sealing shaft barrel and the inner shaft barrel; the middle sealing structure is arranged between the sealing shaft barrel and the middle shaft barrel; the outer sealing structure is arranged between the sealing shaft barrel and the outer shaft barrel.
Further, the inner sealing structure is a graphite sealing structure; the middle sealing structure is a straight-through grate tooth sealing structure, and the sealing gap is 0.1-0.3 mm; the outer sealing structure is a step type grate tooth sealing structure, and the sealing gap is 0.1-0.3 mm.
Further, the inner sealing structure is a graphite sealing structure; the middle sealing structure and the outer sealing structure are brush type sealing structures or fingertip sealing structures.
Furthermore, the sealing shaft barrel is of an integral structure, and the rear bearing is arranged on the outer circle of the sealing shaft barrel; or the rear bearing is arranged on the excircle of the rotating shaft; the sealing shaft barrel comprises a front sealing ring barrel and a rear sealing ring barrel, the front sealing ring barrel and the rear sealing ring barrel are arranged at intervals along the axial direction, and the end parts of the front sealing ring barrel and the rear sealing ring barrel respectively prop against the two ends of the rear bearing.
Further, the bearing cylinder seat is connected to the mounting channel of the bearing casing; a first throttling hole and a second throttling hole communicated with the first throttling hole are formed in the bearing casing; after the high-temperature air flow at the root of the outlet of the centrifugal impeller is throttled sequentially through the first throttling hole and the second throttling hole, part of the high-temperature air flow enters the outer annular flow channel through the outer sealing structure, and the rest of the high-temperature air flow enters the high-pressure turbine disc behind the centrifugal impeller and is used for sealing the rear stage of the high-pressure turbine disc.
Furthermore, the number of the first throttle holes and the number of the second throttle holes are both multiple, and the multiple first throttle holes and the multiple second throttle holes are respectively arranged at intervals in sequence along the circumferential direction of the bearing casing; the throttle areas of the first throttle hole and the second throttle hole are both 2 mm-4 mm.
The invention has the following beneficial effects:
in the cooling and sealing structure of the centrifugal impeller rear bearing, low-temperature airflow at the blade top of the centrifugal impeller inlet enters an inner annular flow passage through a first drainage tube to form an annular heat insulation layer in a bearing cylinder seat to reduce the heat load of the bearing cylinder seat, part of the low-temperature airflow entering the inner annular flow passage passes through the inner sealing structure to seal a bearing cavity, so that the high-temperature airflow at the root of the centrifugal impeller outlet is prevented from entering the bearing cavity, further the bearing cavity is subjected to oil sliding, excessive temperature rise and coking, even combustion and ignition and other hazards are avoided, the rest part of the low-temperature airflow enters an outer annular flow passage through an intermediate sealing structure and is mixed with the high-temperature airflow entering the root of the centrifugal impeller outlet in the outer annular flow passage from the outer sealing structure to form mixed airflow, the mixed airflow forms a second annular heat insulation layer in the bearing cylinder seat to further reduce the heat load of the bearing cylinder seat, and meanwhile the mixed airflow in the outer annular flow passage is led to rear-stage parts of the centrifugal impeller through a second drainage The rear-stage parts are cooled, and meanwhile, the pressure of the outer annular flow channel is relieved, so that low-temperature airflow in the inner annular flow channel enters the outer annular flow channel through the middle sealing structure under the action of pressure difference, and high-temperature airflow is further prevented from entering the inner annular flow channel and the bearing cavity through the middle sealing structure.
In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic view of a cooling and sealing structure of a rear bearing of a conventional centrifugal impeller;
fig. 2 is a schematic view of a centrifugal impeller rear bearing cooling and sealing structure in accordance with a preferred embodiment of the present invention.
Description of the figures
10. A bearing cartridge seat; 101. a bearing cavity; 102. an inner annular flow passage; 103. an outer annular flow passage; 104. an inner runner through hole; 105. an outer flow passage through hole; 11. an inner shaft cylinder; 12. a middle shaft cylinder; 13. an outer shaft barrel; 20. a rear bearing; 30. an inner seal structure; 40. a middle sealing structure; 50. an outer seal structure; 60. a first draft tube; 70. a centrifugal impeller; 71. an inlet blade top of the centrifugal impeller; 72. the root of the centrifugal impeller outlet; 73. a rotating shaft; 80. a second draft tube; 90. tightly sealing the shaft cylinder; 110. a bearing housing; 111. a first orifice; 112. a second orifice.
Detailed Description
The embodiments of the invention will be described in detail below with reference to the accompanying drawings, but the invention can be embodied in many different forms, which are defined and covered by the following description.
Referring to fig. 2, a preferred embodiment of the present invention provides a centrifugal impeller rear bearing cooling and sealing structure, including: bearing cylinder seat 10, be equipped with the bearing chamber 101 that is used for installing rear bearing 20 in the bearing cylinder seat 10, the ring is located the outer interior annular runner 102 of bearing chamber 101 and the outer annular runner 103 of annular runner 102 is located to the ring, the both ends of bearing chamber 101 are equipped with the interior structure 30 of obturating that is used for sealing bearing chamber 101 respectively, the both ends of interior annular runner 102 are equipped with the middle structure 40 of obturating that is used for obturating interior annular runner 102 respectively, the both ends of outer annular runner 103 are equipped with the outer structure 50 of obturating that is used for the outer annular runner 103 of obturating respectively. The inner annular flow passage 102 is communicated with a first draft tube 60, and the first draft tube 60 is used for introducing low-temperature airflow at the inlet blade top 71 of the centrifugal impeller into the inner annular flow passage 102 so as to cool the bearing cylinder seat 10 and seal the bearing cavity 101 after passing through the inner sealing structure 30. The low-temperature airflow entering the outer annular flow passage 103 through the middle sealing structure 40 and the high-temperature airflow entering the centrifugal impeller outlet root 72 of the outer annular flow passage 103 through the outer sealing structure 50 are mixed to form mixed airflow; the outer annular flow passage 103 is communicated with a second draft tube 80, and the second draft tube 80 is used for guiding mixed airflow formed by mixing in the outer annular flow passage 103 to high-temperature parts at the rear part of the engine to relieve pressure of the outer annular flow passage 103 and cool the parts at the rear stage.
In the cooling and sealing structure for the rear bearing of the centrifugal impeller, low-temperature airflow at the blade top 71 at the inlet of the centrifugal impeller enters the inner annular flow channel 102 through the first draft tube 60 to ventilate and cool the bearing cylinder seat 10 and form an annular heat-insulating layer to reduce the heat load of the bearing cylinder seat 10, part of the low-temperature airflow entering the inner annular flow channel 102 passes through the inner sealing structure 30 to seal the bearing cavity 101, the rest part of the low-temperature airflow enters the outer annular flow channel 103 through the middle sealing structure 40 and is mixed with high-temperature airflow entering the root 72 of the outlet of the centrifugal impeller in the outer annular flow channel 103 from the outer sealing structure 50 to form mixed airflow, the mixed airflow forms a second annular heat-insulating layer in the bearing cylinder seat 10 to further reduce the heat load of the bearing cylinder seat 10, and meanwhile, the mixed airflow in the outer annular flow channel 103 is led to high-temperature parts at the rear part of the engine through the second draft tube 80 communicated with the mixed airflow to cool the high-temperature, meanwhile, the pressure of the outer annular flow passage 103 is relieved, so that low-temperature airflow in the inner annular flow passage 102 enters the outer annular flow passage 103 through the middle sealing structure 40 under the action of pressure difference, high-temperature airflow at the root 72 of the centrifugal impeller outlet is further inhibited from directly entering the bearing cavity 101, and the risk of coking caused by excessive temperature rise of lubricating oil is avoided.
According to the cooling and sealing structure for the rear bearing of the centrifugal impeller, a low-temperature airflow is introduced to ventilate and cool the bearing cylinder seat 10 and seal the bearing cavity 101, and meanwhile, the effect of inhibiting the high-temperature airflow at the root 72 of the outlet of the centrifugal impeller from entering the bearing cavity 101 is achieved, so that the heat load of the bearing cylinder seat 10 is reduced, the purpose of reducing the temperature rise of lubricating oil in the bearing cavity 101 is achieved, the risks of coking of the lubricating oil in the bearing cavity and overlarge local thermal stress of the bearing seat are avoided, and the cooling and sealing problems of the rear bearing of the centrifugal impeller of the aero-engine with a high supercharging ratio are effectively solved.
Alternatively, as shown in FIG. 2, the inflow end of the first draft tube 60 communicates with the centrifugal impeller inlet tip 71 and the outflow end of the first draft tube 60 communicates with the end of the inner annular flow passage 102 adjacent the centrifugal impeller 70. Because the temperature of the end of the inner annular flow passage 102 close to the centrifugal impeller 70 is higher than the temperature of the end of the inner annular flow passage 102 far from the centrifugal impeller 70, when the outflow end of the first draft tube 60 is communicated with the end of the inner annular flow passage 102 close to the centrifugal impeller 70, the heat load of the end of the bearing cartridge 10 close to the centrifugal impeller 70 can be effectively reduced, and the heat load of the bearing cartridge 10 is uniform. The inflow end of the second draft tube 80 is communicated with one end of the outer annular flow passage 103 close to the centrifugal impeller 70, and the outflow end of the second draft tube 80 is communicated with the rear-stage parts of the centrifugal impeller 70. Similarly, since the temperature of the end of the outer annular flow passage 103 close to the centrifugal impeller 70 is higher than the temperature of the end of the outer annular flow passage 103 far from the centrifugal impeller 70, when the inflow end of the second draft tube 80 is communicated with the end of the outer annular flow passage 103 close to the centrifugal impeller 70, the heat load of the end of the bearing cartridge 10 close to the centrifugal impeller 70 can be effectively reduced, and the heat load of the bearing cartridge 10 is uniform.
Preferably, the number of the first draft tubes 60 is multiple, and the multiple first draft tubes 60 are sequentially arranged at intervals along the circumferential direction of the inner annular flow channel 102, so as to ensure the circumferential temperature uniformity of the air flow of the inner annular flow channel 102 and the bearing cavity 101. Specifically, the number of the first draft tubes 60 is 2, and the pipe diameter of each first draft tube 60 is 10mm to 12 mm. Preferably, the number of the second draft tubes 80 is multiple, and the multiple second draft tubes 80 are sequentially arranged at intervals along the circumferential direction of the outer annular flow passage 103, so that the uniformity of the circumferential temperature of the airflow of the outer annular flow passage 103 is ensured. Specifically, the number of the second draft tubes 80 is 2, and the pipe diameter of each second draft tube 80 is 10mm to 12 mm.
Alternatively, as shown in fig. 2, the end surfaces of the two ends of the bearing cylinder 10 are respectively provided with a corresponding circle of inner flow passage through holes 104 and a corresponding circle of outer flow passage through holes 105, and the outer flow passage through holes 105 are arranged outside the inner flow passage through holes 104. Part of the low-temperature airflow in the inner annular flow passage 102 penetrates through the inner flow passage through hole 104 and then enters the bearing cavity 101 through the inner sealing structure 30 to seal the bearing cavity 101, and the rest of the low-temperature airflow penetrates through the inner flow passage through hole 104 and then enters the outer annular flow passage 103 through the middle sealing structure 40 and the outer flow passage through hole 105. The high temperature air flow at the centrifugal impeller outlet root 72 passes through the outer sealing structure 50 and then through the outer flow passage through hole 105 into the outer annular flow passage 103.
Alternatively, as shown in fig. 2, the bearing cartridge 10 is divided into an inner shaft tube 11, an intermediate shaft tube 12 and an outer shaft tube 13, which are arranged in sequence from inside to outside, by a bearing cavity 101, an inner annular flow passage 102 and an outer annular flow passage 103. A sealing shaft cylinder 90 fixed with the rotating shaft 73 of the centrifugal impeller 70 is rotatably arranged in the bearing cavity 101. The inner sealing structure 30 is disposed between the sealing shaft cylinder 90 and the inner shaft cylinder 11. The intermediate sealing structure 40 is disposed between the sealing sleeve 90 and the intermediate sleeve 12. The outer sealing structure 50 is disposed between the sealing shaft cylinder 90 and the outer shaft cylinder 13.
In a first embodiment of this alternative, as shown in fig. 2, the inner sealing structure 30 is a graphite sealing structure, which is a structure commonly used in the prior art for sealing a gap by the cooperation of a moving graphite ring and a stationary graphite ring. The middle sealing structure 40 is a straight-through grate tooth sealing structure, the sealing gap is 0.1 mm-0.3 mm, and low-temperature airflow in the inner annular flow channel 102 can conveniently enter the outer annular flow channel 103 after smoothly passing through the straight-through grate tooth sealing structure. Specifically, the intermediate sealing structure 40 includes 2-pass straight-through sealing castors disposed on the sealing shaft cylinder 90 and a castors ring disposed on the intermediate shaft cylinder 12 in a matching manner. The outer sealing structure 50 is a stepped grate tooth sealing structure, the sealing gap is 0.1 mm-0.3 mm, and the stepped grate tooth sealing structure can reduce the pressure of airflow at the root 72 of the outlet of the centrifugal impeller, so that the airflow is mixed with the airflow at the inner annular flow passage 102 at the position of the middle sealing structure 40 and is discharged through an external pipeline to be used for cooling high-temperature parts at the rear part of the engine. Specifically, the outer sealing structure 50 includes 6 stepped sealing grate teeth disposed at one end of the sealing shaft cylinder 90, a grate ring disposed on the outer shaft cylinder 13 in a matching manner, 5 stepped sealing grate teeth disposed at the other end of the sealing shaft cylinder 90, and a grate ring disposed on the outer shaft cylinder 13 in a matching manner.
In a second embodiment of this alternative, not shown, the inner sealing structure 30 is a graphite sealing structure, which is a structure commonly used in the prior art for sealing the gap by the cooperation of a moving graphite ring and a stationary graphite ring. The middle sealing structure 40 and the outer sealing structure 50 are brush type sealing structures or fingertip sealing structures, and the brush type sealing structures and the fingertip sealing structures are common sealing structures used for sealing gaps in the prior art.
Optionally, the sealing shaft cylinder 90 is of an integral structure, the rear bearing 20 is installed on the outer circle of the sealing shaft cylinder 90, the overall structural strength of the sealing shaft cylinder 90 is high, and the assembly and the fixation are simple. Or the rear bearing 20 is installed on the outer circle of the rotation shaft 73. The sealing shaft cylinder 90 comprises a front sealing ring cylinder and a rear sealing ring cylinder, the front sealing ring cylinder and the rear sealing ring cylinder are arranged at intervals along the axial direction, and the end parts of the front sealing ring cylinder and the rear sealing ring cylinder respectively prop against the two ends of the rear bearing 20.
Alternatively, as shown in fig. 2, the bearing cartridge 10 is attached to the mounting channel of the bearing housing 110. The bearing housing 110 has a first orifice 111 and a second orifice 112 communicating with the first orifice 111. After a part of high-temperature airflow at the root 72 of the centrifugal impeller outlet passes through the first throttling hole 111 and the second throttling hole 112 in sequence, part of the high-temperature airflow enters the outer annular flow passage 103 through the outer sealing structure 50, and the rest of the high-temperature airflow enters a high-pressure turbine disc behind the centrifugal impeller 70 for rear-stage sealing of the high-pressure turbine disc. The arrangement of the first throttle hole 111 and the second throttle hole 112 is used for throttling and depressurizing high-temperature air flow, so that the pressure in the outer annular flow passage 103 is reduced while the back sealing pressure of the high-pressure turbine disc is ensured.
Preferably, the number of the first throttle holes 111 and the second throttle holes 112 is multiple, and the multiple first throttle holes 111 and the multiple second throttle holes 112 are sequentially arranged at intervals along the circumferential direction of the bearing housing 110, so as to ensure uniformity of circumferential inflow and outflow of the bearing housing 110. Specifically, the flow areas of the first throttle hole 111 and the second throttle hole 112 are designed to ensure that the pressure drop of the airflow along the way and the pressure at the high-pressure turbine disc can meet the sealing requirement of the rear stage gap of the high-pressure turbine disc, so in a preferred scheme of the invention, the circumferential hole number ranges of the first throttle hole 111 and the second throttle hole 112 are 15-20, and the throttle areas of the first throttle hole 111 and the second throttle hole 112 are 2 mm-4 mm.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The utility model provides a centrifugal impeller rear bearing cooling and structure of obturating which characterized in that includes:
the bearing device comprises a bearing cylinder seat (10), wherein a bearing cavity (101) for mounting a rear bearing (20), an inner annular runner (102) annularly arranged outside the bearing cavity (101) and an outer annular runner (103) annularly arranged outside the inner annular runner (102) are arranged in the bearing cylinder seat (10), inner sealing structures (30) for sealing the bearing cavity (101) are respectively arranged at two ends of the bearing cavity (101), middle sealing structures (40) for sealing the inner annular runner (102) are respectively arranged at two ends of the inner annular runner (102), and outer sealing structures (50) for sealing the outer annular runner (103) are respectively arranged at two ends of the outer annular runner (103);
the inner annular flow channel (102) is communicated with a first draft tube (60), and the first draft tube (60) is used for introducing low-temperature airflow at the inlet blade top (71) of the centrifugal impeller into the inner annular flow channel (102) so as to cool the bearing cylinder seat (10) and seal the bearing cavity (101) through the inner sealing structure (30);
the low-temperature airflow entering the outer annular flow passage (103) through the middle sealing structure (40) and the high-temperature airflow entering the centrifugal impeller outlet root (72) of the outer annular flow passage (103) through the outer sealing structure (50) are mixed to form mixed airflow;
the outer annular flow passage (103) is communicated with a second draft tube (80), and the second draft tube (80) is used for guiding mixed airflow formed by mixing in the outer annular flow passage (103) to high-temperature parts at the rear part of an engine to relieve pressure of the outer annular flow passage (103) and cool the high-temperature parts at the same time.
2. The centrifugal impeller rear bearing cooling and sealing structure as recited in claim 1,
the inflow end of the first draft tube (60) is communicated with the inlet blade top (71) of the centrifugal impeller, and the outflow end of the first draft tube (60) is communicated with one end, close to the centrifugal impeller (70), in the inner annular flow passage (102);
the inflow end of the second draft tube (80) is communicated with one end, close to the centrifugal impeller (70), in the outer annular flow passage (103), and the outflow end of the second draft tube (80) is communicated with a rear-stage part of the centrifugal impeller (70).
3. The centrifugal impeller rear bearing cooling and sealing structure as recited in claim 2,
the number of the first drainage tubes (60) is multiple, and the multiple first drainage tubes (60) are sequentially arranged at intervals along the circumferential direction of the inner annular flow channel (102);
the number of the second drainage tubes (80) is multiple, and the second drainage tubes (80) are sequentially arranged at intervals along the circumferential direction of the outer annular flow passage (103).
4. The centrifugal impeller rear bearing cooling and sealing structure as recited in claim 1,
the end surfaces of two ends of the bearing cylinder seat (10) are respectively provided with a corresponding circle of inner runner through holes (104) and a corresponding circle of outer runner through holes (105), and the outer runner through holes (105) are annularly arranged outside the inner runner through holes (104);
part of low-temperature airflow in the inner annular flow passage (102) penetrates out of the inner flow passage through hole (104) and then enters the bearing cavity (101) through the inner sealing structure (30), and the rest of low-temperature airflow penetrates out of the inner flow passage through hole (104) and then enters the outer annular flow passage (103) through the middle sealing structure (40) and the outer flow passage through hole (105);
and the high-temperature airflow at the root (72) of the centrifugal impeller outlet passes through the outer sealing structure (50) and then enters the outer annular flow passage (103) through the outer flow passage through hole (105).
5. The centrifugal impeller rear bearing cooling and sealing structure as recited in claim 1,
the bearing cylinder seat (10) is divided into an inner shaft cylinder (11), a middle shaft cylinder (12) and an outer shaft cylinder (13) which are sequentially arranged from inside to outside under the action of the bearing cavity (101), the inner annular flow passage (102) and the outer annular flow passage (103);
a sealing shaft barrel (90) fixed with a rotating shaft (73) of the centrifugal impeller (70) is rotatably arranged in the bearing cavity (101);
the inner sealing structure (30) is arranged between the sealing shaft barrel (90) and the inner shaft barrel (11);
the middle sealing structure (40) is arranged between the sealing shaft barrel (90) and the middle shaft barrel (12);
the outer sealing structure (50) is arranged between the sealing shaft barrel (90) and the outer shaft barrel (13).
6. The centrifugal impeller rear bearing cooling and sealing structure as recited in claim 5,
the inner sealing structure (30) is a graphite sealing structure;
the middle sealing structure (40) is a straight-through grate tooth sealing structure, and the sealing gap is 0.1-0.3 mm;
the outer sealing structure (50) is a step type grate tooth sealing structure, and the sealing gap is 0.1-0.3 mm.
7. The centrifugal impeller rear bearing cooling and sealing structure as recited in claim 5,
the inner sealing structure (30) is a graphite sealing structure;
the middle sealing structure (40) and the outer sealing structure (50) are brush type sealing structures or fingertip sealing structures.
8. The centrifugal impeller rear bearing cooling and sealing structure as recited in claim 5,
the sealing shaft cylinder (90) is of an integral structure, and the rear bearing (20) is arranged on the outer circle of the sealing shaft cylinder (90); or
The rear bearing (20) is arranged on the excircle of the rotating shaft (73);
the sealing shaft barrel (90) comprises a front sealing ring barrel and a rear sealing ring barrel, the front sealing ring barrel and the rear sealing ring barrel are arranged at intervals along the axial direction, and the end parts of the front sealing ring barrel and the rear sealing ring barrel respectively prop against the two ends of the rear bearing (20).
9. The centrifugal impeller rear bearing cooling and sealing structure as recited in claim 1,
the bearing cylinder seat (10) is connected to the mounting channel of the bearing casing (110);
a first throttle hole (111) and a second throttle hole (112) communicated with the first throttle hole (111) are formed in the bearing casing (110);
after the high-temperature air flow at the root (72) of the centrifugal impeller outlet is throttled sequentially through the first throttling hole (111) and the second throttling hole (112), part of the high-temperature air flow enters the outer annular flow passage (103) through the outer sealing structure (50), and the rest of the high-temperature air flow enters a high-pressure turbine disc behind the centrifugal impeller (70) and is used for rear-stage sealing of the high-pressure turbine disc.
10. The centrifugal impeller rear bearing cooling and sealing structure as claimed in claim 9,
the number of the first throttle holes (111) and the number of the second throttle holes (112) are both multiple, and the multiple first throttle holes (111) and the multiple second throttle holes (112) are respectively arranged at intervals in sequence along the circumferential direction of the bearing casing (110);
the throttle areas of the first throttle hole (111) and the second throttle hole (112) are both 2 mm-4 mm.
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