CN110159358B

CN110159358B - Interstage casing

Info

Publication number: CN110159358B
Application number: CN201810151538.0A
Authority: CN
Inventors: 李蓓; 范宜龙; 侯伟涛
Original assignee: AECC Commercial Aircraft Engine Co Ltd
Current assignee: AECC Commercial Aircraft Engine Co Ltd
Priority date: 2018-02-14
Filing date: 2018-02-14
Publication date: 2022-02-08
Anticipated expiration: 2038-02-14
Also published as: CN110159358A

Abstract

The invention provides an interstage casing which comprises an upper flow passage, a lower flow passage and a rectifying blade, wherein the rectifying blade is connected between the upper flow passage and the lower flow passage, a fillet which is asymmetric back and forth along the axial direction is arranged at the joint of the rectifying blade and the upper flow passage, the fillet comprises a first chamfer positioned at the front part of the rectifying blade along the axial direction and a second chamfer positioned at the rear part of the rectifying blade along the axial direction, the first chamfer and the second chamfer are connected through a connecting surface, and a plurality of cold air holes are formed in the connecting surface and used for improving a flow field. The turbine interstage casing of the invention utilizes the cold air between the rectifying blades and the bearing support plates, blows off high-loss low-energy fluid in an angle area through the hole-opened cold air, increases the local flow velocity, weakens the local axial and radial pressure gradients, and achieves the purpose of improving the local flow field.

Description

Interstage casing

Technical Field

The invention relates to the field of gas turbine engines, in particular to an interstage casing.

Background

With the increase of the bypass ratio of the civil aircraft engine, both the increase of the diameter of the fan and the reduction of the size of the core engine, the radial drop between the outlet of the high-pressure turbine and the inlet of the low-pressure turbine is increased. This tends to increase the divergence angle of the pitch diameter of the high and low pressure turbine interstage casings. Meanwhile, the axial length of the interstage casing is required to be shortened as much as possible so as to reduce the weight of the interstage casing and further reduce the weight of the engine. Generally, the Mach number of the outlet of the high-pressure turbine is higher and can reach 0.3-0.5. Under the same Mach number, the flow coefficient corresponding to the inlet stage of the low-pressure turbine is too high, so that the efficiency of the low-pressure turbine is low. In order to ensure the performance of the low-pressure turbine, the inlet mach number of the low-pressure turbine is generally much smaller than that of the outlet of the high-pressure turbine. The low pressure turbine inlet area is therefore often higher than the high pressure turbine outlet area, with an expanding design from inlet to outlet for the interstage casing. Therefore, the civil aircraft engine turbine interstage casing tends to realize the design of a large-divergence-angle ultra-compact interstage casing with larger radial drop and shorter axial length.

In addition, the flow field in the interstage casing is very complex. Fig. 1 is a schematic view of a prior art S-type interstage casing. Fig. 2 is a schematic diagram of an S-type interstage casing in the prior art. FIG. 3 is a schematic illustration of a prior art interstage casing flow separation. FIG. 4 is a schematic illustration of a prior art interstage casing flow separation. As shown in fig. 1 to 4, at the first bend of the S-shaped flow path, the lower flow path increases in pressure and decreases in flow velocity, and the upper flow path decreases in pressure and increases in flow velocity. Due to the radial balance, a pressure gradient is created from the casing (low pressure) to the hub (high pressure). This pressure gradient is superimposed on the counter pressure gradient due to the increased flow area, i.e., the counter pressure gradient region created after the fluid is accelerated through the first bend of the S-shaped interstage casing. In the second bend of the S-shaped flow channel of the interstage casing, the flow is turned back to the axial direction, the static pressure of the casing is high, the static pressure of the hub is low, and further a radial pressure gradient and an axial counter pressure gradient are generated, so that the diffusion deceleration of the fluid is caused, and the flow separation of the flow surface of S2 shown in the right diagram of fig. 4 is easily caused.

Various supporting, lubricating oil and oil return pipes are arranged in the bearing support plate of the interstage casing, the bearing support plate is wrapped by the rectifying blades, and a cold air cooling oil pipe is led between the bearing support plate and the rectifying blades. Constrained by the diameter of the pipeline, the maximum thickness of the interstage casing rectifying blade is thick, and the relative thickness is even up to 30%. For pneumatic design, the addition of the rectifying blades causes strong secondary flow in the interstage casing, the contraction of a flow passage area before the maximum thickness of the rectifying blades reduces flow speed, increases pressure, expands the flow passage area after the maximum thickness of the rectifying blades increases flow speed, reduces pressure, complicates a flow field of the interstage casing, and facilitates flow separation after the maximum thickness of the rectifying blades.

Generally, the flow separation caused by the S-shaped flow channel is mainly suppressed by adjusting the position and amplitude of two bending points of the flow channel. After the support plate is in the maximum thickness, the flow separation caused by the fluid deceleration is mainly improved by adjusting the shape of the rectifying blade, the outlet angle of the high-pressure turbine and the like. The airflow angle of the high-pressure turbine outlet close to the root part and the tip part deviates from the axial direction due to the leakage flow of the blade tip clearance of the last-stage movable blade of the high-pressure turbine, the wake of the high-pressure turbine and the like, the radius of the front edge of the blade is increased through the conventional blade profile improved design, and the blade can adapt to the inflow attack angle deviating from the axial direction, but brings more blade profile losses. And the installation angle of the rectifying blade is adjusted to meet the airflow angle at the inlet, so that the blade has twisting direction along the radial direction, and the arrangement of a pipeline system is not facilitated. If the thicknesses of the bearing support plate and the rectifying blades are increased for the convenience of arranging pipelines, higher blade profile loss is brought.

Therefore, the flow separation of the rectifying blade close to the upper flow channel and the lower flow channel is difficult to improve by a conventional method, particularly after the rectifying blade is in the maximum thickness, the flow area of the flow channel is increased more by combining the concave design of the second bending part of the upper flow channel of the interstage casing, and the corner area separation of the tail edge of the rectifying blade close to the upper flow channel area is further intensified.

Fig. 5 is a front view of a single channel interstage casing of the prior art. Fig. 6 is a side view of a prior art interstage casing. As shown in fig. 5 and 6, the conventional interstage casing is composed of an upper flow passage 10, a lower flow passage 11 and a rectifying blade 12, and the rectifying blade 12 forms a fillet 13 with the upper flow passage 10 and the lower flow passage 11. A designer improves the flow field inside the interstage casing through optimization of molded lines of the upper flow channel 10 and the lower flow channel 11 and aerodynamic shape design of the rectifying blades 12.

When the height difference between the high-pressure turbine outlet and the low-pressure turbine inlet is large, so that the radial divergence angle of the interstage casing is larger than 35 degrees, or when the requirement of a pipeline system for equal radius of an oil pipe is too high, so that the relative thickness of the rectifying blade of the interstage casing is larger than 25 percent, the flow separation of the tail edge of the rectifying blade close to the upper flow passage part is difficult to eliminate by the conventional means.

Disclosure of Invention

The invention aims to overcome the defect that flow separation in an interstage casing is difficult to eliminate in the prior art, and provides the interstage casing.

The invention solves the technical problems through the following technical scheme:

an interstage casing, characterized in that the interstage casing comprises an upper flow channel, a lower flow channel and a rectifying blade, the rectifying blade is connected between the upper flow channel and the lower flow channel, a junction of the rectifying blade and the upper flow channel is provided with a fillet which is asymmetric back and forth along the axial direction, the fillet comprises a first chamfer positioned on the front part of the rectifying blade along the axial direction and a second chamfer positioned on the rear part of the rectifying blade along the axial direction, the first chamfer and the second chamfer are connected through an interface, and the interface is provided with a plurality of cold air holes for improving a flow field.

According to an embodiment of the invention, the area of the first chamfer is 45-80% of the axial length of the straightening vane.

According to an embodiment of the invention, the area of the second chamfer is 55-90% of the axial length of the straightening vane.

According to an embodiment of the invention, the first chamfer has an area rounding radius which is larger than an area rounding radius of the second chamfer.

According to an embodiment of the invention, the difference between the first and second chamfer area rounding radii is greater than or equal to 2 mm.

According to one embodiment of the invention, the shape of the cold air holes is circular, square, triangular or trapezoidal.

According to one embodiment of the invention, the cold air hole is provided on at least one side of the interface.

According to one embodiment of the invention, the interface is a flat surface or a beveled surface.

According to one embodiment of the present invention, the interface is a curved surface.

According to one embodiment of the invention, the interstage casing is a turbine interstage casing or a compressor interstage casing.

The positive progress effects of the invention are as follows:

the interstage casing of the invention utilizes a hole pattern design arranged at the chamfer of the rectifying blade of the interstage casing to improve flow separation in the interstage casing of the turbine. The cold air between the rectifying blades and the bearing support plates is utilized, and the cold air is guided through the holes to blow off high-loss low-energy fluid in the corner area, so that the local flow velocity is increased, and the local axial and radial pressure gradients are weakened, thereby achieving the purpose of improving the local flow field.

Drawings

The above and other features, properties and advantages of the present invention will become more apparent from the following description of the embodiments with reference to the accompanying drawings in which like reference numerals denote like features throughout the several views, wherein:

fig. 1 is a schematic view of a prior art S-type interstage casing.

Fig. 2 is a schematic diagram of an S-type interstage casing in the prior art.

FIG. 3 is a schematic illustration of a prior art interstage casing flow separation.

FIG. 4 is a schematic illustration of a prior art interstage casing flow separation.

Fig. 5 is a front view of a single channel interstage casing of the prior art.

Fig. 6 is a side view of a prior art interstage casing.

Figure 7 is a side view of a first embodiment of an interstage casing of the invention.

Fig. 8 is a rear view of a first embodiment of an interstage casing of the invention.

Fig. 9 is an enlarged view of a portion a in fig. 8.

Fig. 10 is a top view of a first interstage casing embodiment of the invention.

Fig. 11 is an enlarged view of a portion B in fig. 10.

Fig. 12 is a partial enlarged rear view of a second embodiment of an interstage casing of the invention.

Fig. 13 is a partial enlarged rear view of a third embodiment of an interstage casing of the invention.

Fig. 14 is a partial enlarged rear view of a fourth embodiment of an interstage casing of the invention.

Fig. 15 is a first enlarged partial view of a fifth embodiment of an interstage casing of the invention from the rear.

Fig. 16 is a second enlarged partial view of a fifth embodiment of an interstage casing of the invention from the rear.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

Further, although the terms used in the present invention are selected from publicly known and used terms, some of the terms mentioned in the description of the present invention may be selected by the applicant at his or her discretion, the detailed meanings of which are described in relevant parts of the description herein.

Furthermore, it is required that the present invention is understood, not simply by the actual terms used but by the meaning of each term lying within.

The first embodiment is as follows:

figure 7 is a side view of a first embodiment of an interstage casing of the invention. Fig. 8 is a rear view of a first embodiment of an interstage casing of the invention. Fig. 9 is an enlarged view of a portion a in fig. 8. Fig. 10 is a top view of a first interstage casing embodiment of the invention. Fig. 11 is an enlarged view of a portion B in fig. 10.

As shown in fig. 7 to 11, the present invention discloses a turbine interstage casing which comprises an upper flow passage 20, a lower flow passage 30 and a rectifying blade 40, wherein the rectifying blade 40 is connected between the upper flow passage 20 and the lower flow passage 30, and a junction of the rectifying blade 40 and the upper flow passage 20 is provided with a fillet which is asymmetric back and forth in the axial direction, the fillet comprising a first chamfer 41 at a front portion of the axial rectifying blade 40 and a second chamfer 42 at a rear portion of the axial rectifying blade 40. Meanwhile, the first chamfer 41 and the second chamfer 42 are connected by an interface 50, and a plurality of cold air holes 51 are formed on the interface 50 for improving the flow field. A chamfer 43 is formed between the straightening vane 40 and the lower flow passage 30.

Preferably, the area of the first chamfer 41 is 45-80% of the axial length of the straightening vane 40. The area of the second chamfer 41 is 55-90% of the axial length of the straightening vane 40. Further, the area rounding radius of the first chamfer 41 is larger than the area rounding radius of the second chamfer 42. The difference between the area rounding radius of the first chamfer 41 and the area rounding radius of the second chamfer 42 is greater than or equal to 2 mm.

In addition, the shape of the cold air hole 51 in the present embodiment may preferably be circular. In this embodiment, the number of the cold air holes 51 is 2, but other numbers of cold air holes are also possible, and all the cold air holes are within the protection scope of the present invention.

Example two:

As shown in fig. 12, the structure of the present embodiment is substantially the same as that of the first embodiment, except that: the shape of the cold air hole 51 in this embodiment is a square.

Example three:

As shown in fig. 13, the structure of the present embodiment is substantially the same as that of the first embodiment, except that: the shape of the cold air hole 51 in this embodiment is triangular.

Example four:

As shown in fig. 14, the structure of the present embodiment is substantially the same as that of the first embodiment, except that: the shape of the cold air hole 51 in the present embodiment is trapezoidal. In addition, the cold air hole 51 may have another shape, and the cold air hole 51 is provided on at least one side interface 50.

Example five:

fig. 15 is a first enlarged partial view of a fifth embodiment of an interstage casing of the invention from the rear. Fig. 16 is a second enlarged partial view of a fifth embodiment of an interstage casing of the invention from the rear.

As shown in fig. 15 and 16, the structure of the present embodiment is substantially the same as that of the first embodiment, except that: it is within the scope of the present invention that the interface 50 be planar, beveled, or have other complex curved structures. The curved structure forms an intersection line 52 with the end wall and the fairing blades.

According to the structural description, aiming at the flow separation, the turbine interstage casing is designed based on the front and back asymmetrical filleting angles along the axial direction, the traditional interstage casing filleting angle is split into a front part and a back part along the axial direction rectifying blade, namely, the radius of the fillet along the front part of the axial direction rectifying blade is slightly larger, the radius of the fillet along the back part of the axial direction rectifying blade is slightly smaller, and the different fillet radii of the front part and the back part form an interface surface in a main flow passage. The cold air holes are designed on the interface, and the secondary air flow jetted from the cold air holes is utilized to increase the local flow velocity, so that the local pressure is reduced, the axial and radial pressure gradient is reduced, and the flow separation caused by low-speed fluid near the interface is improved.

In summary, the turbine interstage casings of the present invention utilize a bore design disposed at the chamfered corners of the interstage casing fairing blades to improve flow separation within the turbine interstage casings. The cold air between the rectifying blades and the bearing support plates is utilized, and the cold air is guided through the holes to blow off high-loss low-energy fluid in the corner area, so that the local flow velocity is increased, and the local axial and radial pressure gradients are weakened, thereby achieving the purpose of improving the local flow field. The structure of the turbine interstage casing can obviously improve the flow separation of the trailing edge of the rectifying blade of the interstage casing close to an upper flow channel, improve the aerodynamic performance of the interstage casing and provide better inflow conditions for a low-pressure turbine.

While specific embodiments of the invention have been described above, it will be appreciated by those skilled in the art that these are by way of example only, and that the scope of the invention is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the spirit and scope of the invention, and these changes and modifications are within the scope of the invention.

Claims

1. An interstage casing, comprising an upper flow passage, a lower flow passage and a rectifying blade, wherein the rectifying blade is connected between the upper flow passage and the lower flow passage, the junction of the rectifying blade and the upper flow passage is provided with a rounding off which is asymmetric back and forth along the axial direction, the rounding off comprises a first rounding off at the front part of the rectifying blade along the axial direction and a second rounding off at the rear part of the rectifying blade along the axial direction, the first rounding off and the second rounding off are connected through an interface, and a plurality of cold air holes are arranged on the interface for improving the flow field.

2. The interstage casing of claim 1, wherein a region of the first chamfer is 45% -80% of an axial length of the rectifier blade.

3. The interstage casing of claim 2, wherein the area of the second chamfer is 55% -90% of an axial length of the rectifier blade.

4. The interstage casing of claim 1, wherein an area fillet radius of the first chamfer is greater than an area fillet radius of the second chamfer.

5. The interstage casing of claim 4, wherein a difference between an area fillet radius of the first chamfer and an area fillet radius of the second chamfer is greater than or equal to 2 mm.

6. The interstage casing of claim 1, wherein the shape of the cold air hole is circular, square, triangular or trapezoidal.

7. The interstage casing of claim 6, wherein the cold gas holes are disposed on at least one side of the interface.

8. The interstage casing of claim 1, wherein the interface is planar or beveled.

9. The interstage casing of claim 1, wherein the interface is curved.

10. The interstage casing of any one of claims 1-9, wherein the interstage casing is a turbine interstage casing or a compressor interstage casing.