CN114458619A

CN114458619A - Design method of leakage-proof structure of axial flow compressor

Info

Publication number: CN114458619A
Application number: CN202210142858.6A
Authority: CN
Inventors: 马婧媛; 林峰
Original assignee: Jimei University
Current assignee: Jimei University
Priority date: 2022-02-16
Filing date: 2022-02-16
Publication date: 2022-05-10
Also published as: LU503361B1

Abstract

The invention has proposed a axial compressor and prevented leaking the structural design method, regard trailing edge or median of the rotatable blade as the rotating shaft, the rotating shaft rotates a circle around the compressor axis and forms the circular ring, confirm the blade top camber line of the blade with the excircle, after dividing the excircle averagely according to the blade quantity, rotate 180 degrees or 360 degrees respectively around the rotating shaft with every section of curves and get the semicircular convexity or circular convexity, can get the peripheral surface of the cartridge receiver above the blade; and determining a corresponding hub line below the blade root by using the inner circle, and obtaining the circumferential surface of the hub below the blade root by the same rotating method. The design method can enable the blade top curved surface to be completely attached to the upper casing without a gap, the gap between the blade root curved surface and the lower hub is uniform and as small as possible, leakage flow in a blade top area is avoided when the blade rotates, and leakage flow in a blade root area is reduced.

Description

Design method of leakage-proof structure of axial flow compressor

Technical Field

The invention relates to the field of axial flow compressors, in particular to a design method of a leakage-proof structure of an axial flow compressor.

Background

CN203488438U discloses a high-efficiency flow rate adjusting device of a compressor, which is characterized in that a guide vane is connected with a main shaft, an inlet guide vane rotating shaft is sleeved on the main shaft and fixed by a set screw, and a nut is arranged at the upper end of the main shaft and fixed between the guide vane and a rolling bearing to form an air inlet channel. Although the scheme can reduce the clearance between the guide vane and the casing to a certain extent by the upward bulge of the casing above the rotatable guide vane, the clearance cannot be completely closed, and the leakage flow loss still exists.

CN208431176U discloses a magnetic suspension compressor flow regulating device, which can prevent leakage in magnetic suspension design, but the device is very complex and difficult to process, and the device has heavy weight and high cost, and is difficult to popularize and apply.

Fig. 5 shows a flow regulation diagram of an axial compressor which closes an inlet passage by rotating a rotatable vane 1 to achieve flow regulation. When the rotatable blades rotate for a certain angle, a gap is formed between the rotatable blades and the casing and the hub, so that the leakage problem is caused, and the working efficiency of the axial flow compressor is influenced.

Disclosure of Invention

The invention aims to provide a design method of a leakage-proof structure of an axial flow compressor, which aims to solve the problems. Therefore, the invention adopts the following specific technical scheme:

a leakage prevention design method of an axial flow compressor can comprise the following steps:

s1, selecting a rotating shaft and determining the position of the rotating shaft in the axial direction of a gas compressor, wherein the rotating shaft is perpendicular to the axis of the gas compressor;

s2, rotating the rotating shaft by 360 degrees around the axis of the compressor to obtain a circular ring, wherein the excircle of the circular ring is a connecting line of blade top arcs of rotatable blades, namely a casing line, the inner circle is a hub line below a blade root, and the inner circle is shortened upwards by a preset distance and is a connecting line of blade root arcs;

s3, equally dividing the circular rings according to the number of the rotatable blades in the full circumference, thereby determining the size of each rotatable blade;

s4, respectively rotating each rotatable blade along a rotating shaft to form an upper semicircular convex curved surface and a lower semicircular convex curved surface or a full-circular convex curved surface; and

s5, connecting the upper and lower semicircular convex curved surfaces or the full-circular convex curved surface respectively, and completing the rest areas to finally form a casing circumferential surface which is in seamless fit with the blade top of the rotatable blade and a hub circumferential surface which is in uniform clearance fit with the blade root.

Further, in S1, the trailing edge or the middle line of the rotatable blade is selected as the rotation axis.

Further, in S4, each of the rotatable blades is rotated 180 ° or 360 ° around the rotation axis.

Further, in S1, when the rotation shaft is a trailing edge of the rotatable blade, the position of the rotation shaft in the compressor axial direction is equal to the preset pitch, and when the rotation shaft is a center line of the rotatable blade, the position of the rotation shaft in the compressor axial direction is equal to a blade chord length of +1/2 of the preset pitch.

Further, in S2, the preset distance is less than 1 mm.

Further, in S3, the number of the rotatable blades in the full circumference is equal to the number of the rotatable blades in the closing region ÷ the size of the closing region × 360.

By adopting the technical scheme, the invention has the beneficial effects that: no matter how many angles the rotatable blade rotates, there is no clearance between the rotatable blade and the upper casing, and the clearance between the rotatable blade and the lower hub is uniform and can be as small as possible, and at the same time, no additional device is needed, and the weight and the cost are not increased.

Drawings

To further illustrate the various embodiments, the invention provides the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the embodiments. Those skilled in the art will appreciate still other possible embodiments and advantages of the present invention with reference to these figures. Elements in the figures are not drawn to scale and like reference numerals are generally used to indicate like elements.

FIG. 1 is a flow chart of a design method of a leakage-proof structure of an axial flow compressor of the present invention;

FIG. 2 is a schematic view of a rotatable blade design;

FIG. 3 is a schematic view of the upper case and the lower hub rotated 180 with the trailing edge of the rotatable blade as the axis of rotation;

FIG. 4 is a schematic view of the upper case and the lower hub rotated 360 about the centerline of the rotatable blades as the axis of rotation;

fig. 5 is a schematic view of an axial flow compressor.

Detailed Description

The invention will now be further described with reference to the accompanying drawings and detailed description.

As shown in fig. 1, a method for designing a leakage-proof structure of an axial flow compressor may include the following steps:

s1, selecting the tail edge or the middle line of a rotatable blade as a rotating shaft and determining the position of the rotating shaft in the axial direction of the axial flow compressor, wherein the rotating shaft needs to be selected to be perpendicular to the axial line of the axial flow compressor, namely in the radial direction of the axial flow compressor. It should be understood that the axis of rotation may also be the line on any blade between the trailing edge and the centerline. When the rotating shaft is a trailing edge of the rotatable blade, the position of the rotating shaft in the axial direction of the axial compressor is equal to a preset pitch (a pitch between the rotatable blade and the movable blade when the width direction of the rotatable blade coincides with the axial direction of the axial compressor), and when the rotating shaft is a center line of the rotatable blade, the position of the rotating shaft in the axial direction of the axial compressor is equal to a blade chord length of a preset pitch + 1/2.

S2, rotating the rotating shaft by 360 degrees around the axis of the compressor to obtain a circular ring, wherein the excircle of the circular ring is a connecting line of blade top arcs of rotatable blades, namely a casing line, the inner circle is a hub line below a blade root, and the inner circle is upwardly reduced by a preset distance (a gap between the blade and the hub) and is a connecting line of blade root arcs; typically, the clearance between the blades and the hub is as small as possible, for example less than 1 mm, to reduce leakage.

S3, equally dividing the circular rings according to the number of the rotatable blades in the full circumference, thereby determining the size of each rotatable blade, as shown in FIG. 2; wherein the number of rotatable blades in the full circumference is equal to the number of rotatable blades in the closed area ÷ the size of the closed area × 360. For example, if there are 6 vanes in the 90 ° closing region, the number of rotatable vanes in the full circumference is 6 ÷ 90 × 360 ═ 24.

S4, respectively rotating each rotatable blade along the rotating shaft, for example, rotating 180 degrees by taking the tail edge of the rotatable blade as the rotating shaft to form an upper semicircular convex curved surface and a lower semicircular convex curved surface (as shown in A and B in figure 3), or rotating 360 degrees by taking the center line of the rotatable blade as the rotating shaft to form an upper full circular convex curved surface and a lower full circular convex curved surface (as shown in A 'and B' in figure 4).

And S5, respectively connecting the upper semicircular convex curved surface and the lower semicircular convex curved surface or the full-circular convex curved surface, and completing the rest areas to finally form a casing circumferential surface 100 and a hub circumferential surface 200 which are matched with the blade top and the blade root of the rotatable blade in a leakage-free manner, as shown in figures 3 and 4. Fig. 3 is a schematic view of an upper casing and a lower hub rotated by 180 ° with a trailing edge of a rotatable blade as a rotation axis, and fig. 4 is a schematic view of an upper casing and a lower hub rotated by 360 ° with a center line of a rotatable blade as a rotation axis.

The design method can ensure that no matter how many angles the rotatable blade rotates, the rotatable blade and the upper casing are completely attached without a gap, the gap between the rotatable blade and the lower hub is uniform and can be as small as possible, leakage flow in the blade top area is avoided when the blade rotates, and leakage flow in the blade root area is reduced. Meanwhile, additional devices are not needed, and the weight and the cost are not increased.

While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A design method of a leakage-proof structure of an axial flow compressor is characterized by comprising the following steps:

2. A method for designing a leakage preventing structure of an axial compressor, as claimed in claim 1, wherein in S1, the trailing edge or the middle line of the rotatable blade is selected as the rotation axis.

3. A leakage preventing structure design method for an axial flow compressor as claimed in claim 2, wherein each of the turnable vanes is turned 180 ° or 360 ° around the rotation axis in S4.

4. A leakage preventing structure design method for an axial flow compressor as claimed in claim 2, wherein in S1, when the rotation axis is the trailing edge of the rotatable blade, the position of the rotation axis in the axial direction of the compressor is equal to the preset pitch, and when the rotation axis is the center line of the rotatable blade, the position of the rotation axis in the axial direction of the compressor is equal to the preset pitch +1/2 chord length of the blade.

5. A method for designing a leakage preventing structure of an axial flow compressor as claimed in claim 1, wherein in S2, the predetermined distance is less than 1 mm.

6. A leakage preventing structure design method for an axial flow compressor as claimed in claim 1, wherein in S3, the number of the turnable vanes in the whole circumference is equal to the number of the turnable vanes in the closed region divided by the size of the closed region x 360.