CN105317559A - Turbine rear force bearing case integrally connected to rectification blade cascade - Google Patents

Abstract

The connection structure of the turbine rear bearing casing and the rectifying blade cascade is integrated, and the shape of the turbine rear bearing casing part is the same as that of the conventional turbine rear bearing casing. Its difference and characteristics are: it adds a rectifying blade structure between the outer ring, inner ring and support plate of the conventional turbine back bearing casing, wherein the blade structure includes; blade upper edge plate, blade, blade flow channel plate, The blade lower edge plate and the front end baffle of the blade lower edge plate. The upper edge plate of the blade is fixed on the outer ring of the load-bearing casing through radial screws, and the rear end of the lower edge plate of the blade is positioned on the rear end flange of the inner ring of the load-bearing casing through special radial bolts; An air flow channel is formed among the flow channel plate, the vane, the upper edge plate of the vane and the supporting support plate. The invention realizes the integration of the turbine rear bearing casing and the rectifying blade cascade without greatly changing the structure of the turbine rear bearing casing and without affecting the strength, deformation coordination and support rigidity of the turbine rear bearing casing.

Description

Turbine rear bearing case integrally connected with rectifying cascade

technical field

The invention relates to an integrated connection structure of a turbine rear bearing casing and a rectifying blade cascade, and belongs to the technical field of aviation propulsion.

Background technique

In the current advanced aviation gas turbine engine, an afterburner is usually installed between the turbine and the exhaust nozzle to perform afterburning and afterburning, and continue to increase the thrust after the engine reaches the maximum thrust state. However, the airflow at the outlet of the low-pressure turbine usually cannot meet the requirements of the afterburner for the airflow angle at the outlet of the low-pressure turbine. Therefore, it is necessary to install rectifying blades between the rotor of the low-pressure turbine and the afterburner to rectify the airflow.

The above-mentioned design will cause the rear bearing casing to be moved backward to install additional outlet rectifying vanes, thereby increasing the axial length of the rotor and increasing the bearing support span. Correspondingly, the number of turbine components will be increased, resulting in an increase in engine weight, which is not conducive to improving the thrust-to-weight ratio of the engine.

When Pratt & Whitney USA designed the PW4000 engine, the section of the load-bearing support plate in the rear load-bearing casing (as shown in Figure 1) was designed as a leaf shape, and the load-bearing support plate can directly pass through the gas flow, that is, by using the bearing The support plate is used for rectification. However, there are many defects in the airfoil form of this support plate. For example, the support rigidity requirements of the rear load-bearing casing limit the number of force-bearing support plates, but in terms of aerodynamics, there must be enough blades to achieve good airflow. rectification effect.

Contents of the invention

In order to overcome the above-mentioned problems in the prior art, the present invention provides an integrated connection structure of the turbine rear bearing casing and the rectifying blade cascade, which does not significantly change the stress, deformation and support stiffness of the turbine rear bearing casing Next, the rectifying cascade structure can be connected and positioned with the rear bearing case.

In the integration scheme of the rear bearing casing and the rectifying blade cascade according to the present invention, the turbine rear bearing casing and the turbine final stage rectifying guide vane are designed as an integrated structure, which not only meets the requirements of the afterburner for low pressure The requirements for the turbine outlet airflow angle can also achieve the purpose of shortening the axial length of the low-pressure rotor, reducing weight and reducing the number of parts, thereby increasing the thrust-to-weight ratio of the engine.

Different from the traditional rectifying cascade structure, according to one aspect of the present invention, the blades in the integrated structure need to be discretely distributed in the circumferential direction between the support plates of the rear bearing casing, and to avoid the impact of the rectifying cascade structure on the rear bearing force. Due to the requirement that the strength and radial stiffness of the casing have too much influence, a "cantilever" blade fixing structure is adopted in which the upper edge of the blade is fixed, and the lower edge is only fixed along the axial and circumferential directions.

The advantage of the present invention compared with prior art is:

(1) The rectifying cascade structure is added without significantly affecting the strength and support stiffness of the original rear bearing casing;

(2) The rectifying cascade structure is added without affecting the deformation coordination of the original rear bearing casing;

(3) The rectifying cascade structure is added without the need to substantially modify the original rear bearing casing structure;

(4) The weight of the turbine components is reduced, the axial length of the turbine rotor is shortened, the thrust-to-weight ratio is increased, and the performance of the entire aero-engine is improved.

According to one aspect of the present invention, there is provided a turbine rear bearing casing with an integrated connection structure with the rectifying blade cascade, which is characterized in that it comprises: an outer ring of the rear bearing casing; an inner ring of the rear bearing casing; Load-bearing support plates; rectifying blade structures discretely installed between each load-bearing support plates and between the outer ring and the inner ring along the circumferential direction.

Description of drawings

Figure 1 is the rear bearing casing of Pratt & Whitney's PW4000 engine;

Fig. 2 is a sectional view of an integrated structure along a blade according to an embodiment of the present invention;

Fig. 3 is a three-dimensional schematic diagram of an integrated structure according to an embodiment of the present invention (1/N model, N is the number of supporting plates);

4A and 4B are schematic diagrams of radial bolt structure and assembly according to an embodiment of the present invention.

Explanation of symbols in the figure:

1—radial screw; 2—the outer ring of the rear bearing casing; 3—the upper edge plate of the blade;

4—blade; 5—blade runner plate; 6—blade lower edge plate;

7—radial bolts; 8—rear end flange of the inner ring of the rear bearing casing;

9—the inner ring of the rear bearing casing; 10—the front baffle of the lower edge plate of the blade;

11—rear load-bearing receiver support plate;

12—self-locking nut; 13—cylindrical part of radial bolt;

14—the bottom surface of the cylindrical part of the radial bolt;

15—the threaded portion of the radial bolt.

detailed description

The present invention provides an integrated connection structure between the turbine rear bearing casing and the rectifying blade cascade. The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 2 and Figure 3, in the integrated connection structure of the turbine rear bearing casing and the rectifying blade cascade according to an embodiment of the present invention, in addition to the rear bearing included in the existing turbine rear bearing casing structure In addition to the outer ring 2 of the force casing, the inner ring 9 of the rear force casing and the force-bearing support plate 11, the blades 4 are discretely installed between the force-bearing support plates 11 along the circumferential direction, and the cascade structure includes the upper edge of the blade Plate 3, blade 4, blade flow channel 5 and blade lower edge plate 6.

Open threaded holes at the upper edge plate 3 of the blade and open holes at the corresponding positions of the outer ring 2 of the rear bearing casing, and use radial screws 1 to completely connect and fix the upper edge plate 3 of the blade to the outer ring 2 of the rear bearing casing A baffle structure 10 is set at the front section of the lower edge plate 6 of the blade, and it is made into a whole to limit the axial displacement of the lower end of the blade 4 under the action of aerodynamic force; a flange 8 is set at the rear end of the inner ring 9 of the rear bearing casing , using a special radial bolt structure to connect the rear end of the blade lower edge plate 6 with the flange 8 .

As shown in Figure 4A and Figure 4B, it is the above-mentioned radial bolt structure and its assembly diagram; wherein, holes are respectively opened at the corresponding positions of the rear end of the blade lower edge plate 6 and the rear end flange 8 of the inner ring of the rear bearing casing , wherein the diameter R1 of the through hole on the lower edge plate 6 is larger than the diameter R2 of the through hole on the flange 8 . The radial bolt 7 is processed as follows: Unlike common bolts, the bolt 7 (see FIG. 4B ) includes a cylindrical portion 13 at the upper end and a threaded portion 15 at the lower end, and the diameter D1 of the cylindrical portion 13 is greater than the diameter of the threaded portion 15. diameter D2, the diameter relationship satisfies R1>D1>R2>D2. When assembling and installing, after aligning the through hole of the blade lower edge plate 6 with the through hole on the inner ring rear end flange 8 of the rear bearing casing 9, pass the bolt 7 from top to bottom in the radial direction, according to The diameter relationship R1>D1>R2>D2, the bolt cylindrical portion 13 will not be able to pass through the through hole on the flange 8 . The self-locking nut 12 is used for assembly, and the bolt 7 is fixed on the load-bearing casing flange 8 by using the bottom surface 14 of the bolt cylindrical part and the self-locking nut 12 . This bolt structure only constrains the axial and circumferential displacement of the blade lower edge plate 6, but the blade lower edge plate 6 can move freely along the centerline of the bolt 7, that is, a certain radial line of the turbine rear bearing casing.

The inventor has carried out the strength calculation of the rear bearing casing, and calculated the strength and deformation of the rear bearing casing under the thermal load of high-temperature gas behind the turbine. Among them, the ANSYS finite element analysis software is used, and the cyclic symmetry model of 1/N (N is the number of supporting plates) is adopted. Firstly, the convective heat transfer coefficients of different areas along the radial direction of the rear bearing casing and the surface of the blade are added. The working temperature field is calculated and simulated, and then the thermal-solid coupling method is adopted, and the temperature field is used as the temperature boundary condition of the model, and an axial constraint is added on the front end face of the outer ring of the rear bearing casing as the displacement boundary condition. Among them, the relative constraint between the blade and the rear bearing casing is added according to the method introduced in the invention, the upper edge plate of the blade is fully restrained relative to the outer ring of the rear bearing casing, and the rear end of the lower edge plate is added with a shaft relative to the rear bearing casing. The radial and circumferential constraints are used to simulate the fixation of radial screws and radial bolts. The strength calculation and analysis of the rear bearing receiver is carried out. The calculation of the strength of the original load-bearing casing shows that because the temperature at the load-bearing support plate is significantly higher than that of the inner and outer rings, the thermal deformation caused by the difference in thermal expansion is the main cause of stress. In the structure of the present invention, the cantilever design is adopted for the rectifying cascade, which can minimize further thermal deformation caused by the fact that the thermal expansion coefficient of the cascade material is different from that of the rear bearing casing material at the same temperature. Coordination problem, so it will not cause further increase in stress. The strength calculation carried out by the present invention shows that, with the integrated connection and positioning method of the present invention, the maximum radial stress of the integrated structure has almost no change compared with that of the rear bearing casing, and the maximum radial stress has increased by 4.25%.

In the inventor's calculation of the supporting stiffness of the rear bearing casing, the deformation of the rear bearing casing under the bearing load is mainly investigated, and the radial displacement difference of the radially corresponding positions of the inner and outer rings of the rear bearing casing is calculated. Calculate its support stiffness. Among them, the full model is used, and the relative constraints between the blade and the rear bearing casing are calculated with the same strength. Add an axial constraint to the front end of the outer ring of the rear bearing case, add an axial constraint to a point directly above the front end of the outer ring, and add a sinusoidally distributed unit force to the lower half ring of the inner ring of the rear bearing case to simulate the bearing load . The results show that, by adopting the integrated connection structure of the present invention, the support stiffness increases by an average of 1.545% at each position in the circumferential direction. Since the radial connection is only used at the outer ring of the load-bearing case and the upper edge plate of the blade, and only the axial and circumferential displacements are limited at the inner ring of the load-bearing case and the lower edge plate of the blade, the rectifier cascade After that, the supporting radial stiffness of the overall structure remains basically unchanged.

The above are only some specific implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be covered within the protection scope of the present invention.

Claims (6)

1. have with the turbine of the integrated linkage structure of rectification leaf grating after a support case, it is characterized in that comprising:

Rear support case outer shroud (2);

Rear support case inner ring (9);

Load support plate (11);

Circumferentially be arranged on the straightener(stator) blade structure between each load support plate (11) and between outer shroud (2) and inner ring (9) discretely.

2. support case after turbine according to claim 1, is characterized in that:

Described straightener(stator) blade structure comprises blade supramarginal plate (3), blade (4), blade passage plate (5), blade inframarginal (6) and blade inframarginal front end baffle (10);

After described turbine, support case has cascade structure, and this cascade structure comprises blade supramarginal plate (3), blade (4), blade passage (5) and blade inframarginal (6).

3. support case after turbine according to claim 2, is characterized in that:

The rear end of blade inframarginal (6) is positioned on the rear end boss (8) of support case inner ring (9) by radial bolts (7) along the axial and circumferential of support case after turbine;

Blade passage plate (5), blade (4), between blade supramarginal plate (3) and load support plate (11), form air-flow path.

4. support case after turbine according to claim 3, is characterized in that:

Blade supramarginal plate (3) is fixed on support case outer shroud (2) by radial screw (1),

And

Radial bolts (7) only carries out the location of axial and circumferential.

5. support case after turbine according to claim 3, is characterized in that:

Blade supramarginal plate (3) is fixed on support case outer shroud (2) by radial screw (1),

The corresponding position of the rear end boss (8) of the rear end of blade inframarginal (6) and rear support case inner ring (9) has through hole, through-hole aperture R1 on its Leaf inframarginal (6) is greater than the through-hole aperture R2 on rear end boss (8)

By under the state of the through hole alignment on the through hole of blade inframarginal (6) and rear end boss (8), radial bolts (7) along support case after turbine radial direction pass from outside to inside,

Radial bolts (7) comprises the cylindrical portion (12) of upper end and the screw section (14) of lower end, and the diameter D1 of cylindrical portion (12) is greater than the large footpath D2 of screw section (14), and diameter Relationship meets

R1>D1>R2>D2，

Cause relation for this reason, during erection, cylindrical portion (12) can not through the through hole on rear end boss (8).

6. support case after turbine according to claim 5, is characterized in that:

Use self-locking nut (11) to assemble, utilize the bottom surface of cylindrical portion (12) (13) and self-locking nut (11) to make bolt (7) be fixed on rear end boss (8),

Thus only prohibit the axial and circumferential displacement of blade inframarginal (6), but blade inframarginal (6) can move along the radial line of support case after the center line of bolt (7) and turbine.