Axial seam treatment casing based on B spline curve

Abstract

The invention relates to the technical field of gas compressor casing treatment, and discloses an axial seam treatment casing based on a B spline curve, the treatment casing is applied to a gas compressor, a rotor blade of the gas compressor is arranged in the treatment casing, the free end edge of the rotor blade faces the side wall of an inner cavity of the treatment casing, and a blade tip gap is formed between the free end edge of the rotor blade and the side wall of the inner cavity of the treatment casing; a plurality of axial seams parallel to the axis of the treatment casing are formed in the side wall of an inner cavity of the treatment casing, and notches of the axial seams all face the circumferential side wall and the front edge side wall of the rotor blade. In a radial cross section view of the compressor rotor basin, the contour section shape of the radial cross section is controlled by using six constraint points; according to the method, the axial seam section is constructed by utilizing the geometrical characteristics of the high-pressure compressor; two acute angles are formed between a curve formed by the B splines and the wall face of the casing, so that blade tip airflow enters the groove more easily from the rear portion of the processing seam and returns to the blade tip at the front portion of the processing groove in the downstream direction, and the purposes of reducing in-seam circulation loss and enhancing upstream jet flow are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of compressor casing treatment, and particularly to an axial slot treatment casing based on B-spline curves. Background Art

[0002] The flow process in the clearance region of a gas turbine compressor is very complex, and the losses caused by the clearance flow account for a large proportion of the total energy losses of the moving blades and the compressor stage. Moreover, the performance of the compressor is highly sensitive to the tip clearance. During operation, an increase in the clearance usually leads to a decline in the performance of the compressor. During actual service, the tip clearance may increase temporarily or permanently, thus affecting the economy and stability of the operation of the gas turbine.

[0003] Endwall treatment technology is a compressor clearance flow control method that has been studied and successfully applied earlier. It can effectively broaden the compressor stability margin and has been widely used in many actual engine models, such as the JT-9D engine, CFM-56 engine in the United States, the ЛН-31Ф engine in Russia, and the WP-14 aero-gas turbine engine in China. Schematic diagrams of basic axial slot types and axial slot endwall treatments are shown in Figure 1 and Figure 2 as shown.

[0004] Generally speaking, the effect of axial slot type casing treatment in broadening the compressor stability margin is stronger than that of circumferential groove type casing treatment, but it has a greater impact on efficiency. This is due to the large circulation losses in the slot and the mixing losses between the flow in the slot and the mainstream. Therefore, reasonably organizing the internal shape of the axial slot and reducing the circulation losses and mixing losses in the slot can enhance the stability expansion ability while keeping the efficiency loss as small as possible. Summary of the Invention

[0005] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, the abstract of the specification and the title of the invention of this application to avoid obscuring the purpose of this part, the abstract of the specification and the title of the invention, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0006] In view of the problems existing in the above-mentioned existing axial slot treatment casings, the present invention is proposed.

[0007] Therefore, the purpose of the present invention is to provide an axial slot treatment casing based on B-spline curves, which uses B-spline curve modeling to make the profile of the axial slot transition smoothly, thereby reducing the circulation losses in the slot and enabling the fluid to flow into and out of the axial slot at a more reasonable angle.

[0008] To solve the above technical problems, the present invention provides the following technical solution: an axial slot treatment casing based on B-spline curves, which is applied to a compressor. The rotor blades of the compressor are arranged inside the treatment casing, and the free end edges of the rotor blades face the inner cavity side wall of the treatment casing, and there is a tip clearance between the two. A plurality of axial slots parallel to its axis are opened on the inner cavity side wall of the treatment casing, and the notches of the axial slots all face the circumferential side wall and the leading edge side wall of the rotor blades; in the radial cross-sectional view of the compressor rotor flow field, 6 constraint points are used to control the profile shape of its radial cross-section.

[0009] As a preferred scheme of the axial slot treatment casing based on B-spline curves of the present invention, among them: the 6 constraint points include the intersection points P1 and P2 of the notch of the axial slot C and the side wall of the treatment casing. The intersection point P1 is arranged at 5% - 10% Cx,tip on the front side upstream of the leading edge side wall, and the intersection point P2 is arranged at 10% - 20% Cx,tip on the rear side upstream of the leading edge side wall. Here, Cx,tip is the axial chord length of the rotor blade, and the midpoint of the line connecting the intersection points P1 and P2 is P0.

[0010] As a preferred scheme of the axial slot treatment casing based on B-spline curves of the present invention, among them: the 6 constraint points include the limiting points F1 and F2 that constrain the depth of the axial slot C and the basic profile. The limiting point F1 is arranged at the vertical position between the intersection point P1 and the midpoint P0, and the limiting point F2 is arranged at the vertical position between the midpoint P0 and the intersection point P2.

[0011] As a preferred scheme of the axial slot treatment casing based on B-spline curves of the present invention, among them: the radial distance between the limiting point F1 and the line connecting the intersection points P1 and P2 is h1, and the radial distance between the limiting point F2 and the line connecting the intersection points P1 and P2 is h2. Here, the value range of h1 is 5τ - 20τ, the value range of h2 is 5τ - 20τ, and h1 ≥ h2, where τ is the width of the tip clearance F.

[0012] As a preferred scheme of the axial slot treatment casing based on B-spline curves of the present invention, among them: the 6 constraint points further include the limiting points F3 and F4 that constrain the jet outlet and suction inlet angles of the axial slot C. The limiting point F3 is arranged at the vertical position upstream of the intersection point P1, and the limiting point F4 is arranged at the vertical position between the limiting point F2 and the intersection point P2.

[0013] As a preferred scheme of the axial slot treatment casing based on B-spline curves of the present invention, among them: the vertical distance between the limiting point F3 and the line connecting the intersection points P1 and P2 is h3, and the vertical distance between the limiting point F2 and the line connecting the intersection points P1 and P2 is h4. Here, h3 < h1, h4 < h2.

[0014] As a preferred embodiment of the axial slot processing casing based on B-spline curves in the present invention, the following steps are involved: construct a B-spline curve by successively passing through P1, F3, F1, F2, F4, and P2, and the formed B-spline curve is the radial cross-sectional profile of the cavity of the axial slot C.

[0015] As a preferred embodiment of the axial slot processing casing based on B-spline curves in the present invention, the following holds: the number N of the axial slots C opened is 3 to 5 times the number of the rotor blades 200.

[0016] As a preferred embodiment of the axial slot processing casing based on B-spline curves in the present invention, the circumferential opening ratio of the axial slot C is 30% - 70%, and the circumferential inclination angle β is 30° - 60°.

[0017] As a preferred embodiment of the axial slot processing casing based on B-spline curves in the present invention, the compressor applied is a single-stage or multi-stage radial flow, mixed flow, or axial flow compressor.

[0018] Advantages of the present invention:

[0019] The design configuration method of the present invention is simple and is easy to use the geometric features of the high-pressure compressor to construct the axial slot profile; the curve formed by the B-spline forms two acute angles with the casing wall surface, making it easier for the tip flow to enter the slot from the rear of the processing slot and return to the tip in the direction pointing downstream at the front of the processing slot, achieving the purpose of reducing the circulation loss in the slot and enhancing the upstream jet flow, thereby broadening the stable margin of the compressor on the premise of having a relatively small impact on the efficiency. Description of the drawings

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. Among them:

[0021] The figure is a schematic diagram of the conventional circumferential slot casing processing structure, where Figure 1 (a) is the front view, Figure 1 (b) is the cross-sectional view.

[0022] Figure 2 It is a schematic diagram of the conventional axial slot casing processing structure, where Figure 2 (a) is the front view, Figure 2 (b) is the cross-sectional view.

[0023] Figure 3 It is a schematic diagram of the radial cross-sectional plane structure of the axial slot processing casing based on B-spline curves in the present invention.

[0024] Figure 4 This is a schematic diagram of the internal top view structure of the axial slot processing casing based on B-spline curves according to the present invention.

[0025] Figure 5 This is a schematic diagram of a partial structure of the radial section of the axial slot processing casing based on B-spline curves according to the present invention.

[0026] Figure 6 This is a schematic diagram of the specific processing parameters of the axial slot casing based on B-spline curve modeling designed for a certain compressor rotor.

[0027] Figure 7 This is a graph of the isentropic efficiency - normalized mass flow rate relationship of the compressor for Comparative Example 2.

[0028] Figure 8 This is a graph of the total pressure ratio - normalized mass flow rate relationship of the compressor for Comparative Example 2. Detailed implementation manners

[0029] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific implementation manners of the present invention will be given in conjunction with the drawings of the specification.

[0030] In the following description, many specific details are set forth to facilitate a thorough understanding of the present invention. However, the present invention may be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the spirit of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0031] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation manner of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that excludes other embodiments.

[0032] Furthermore, the present invention is described in detail with reference to the schematic diagrams. When describing the embodiments of the present invention in detail, for the sake of clarity, the cross-sectional views showing the device structure may be enlarged locally out of proportion, and the schematic diagrams are only examples and should not limit the scope of protection of the present invention herein. In addition, in actual production, three-dimensional spatial dimensions including length, width, and depth should be included.

[0033] Embodiment 1

[0034] Refer to Figures 3 to 5 , which is the first embodiment of the present invention, providing an axial slot processing casing based on B-spline curves. This casing is applied to a compressor, and the compressor to which it is applied is a single-stage or multi-stage radial flow, mixed flow, or axial flow compressor.

[0035] Furthermore, the rotor blades 200 of the compressor are distributed and installed on the edge of the middle rotor shaft, and are integrally arranged in the processing casing 100 and rotate in the casing with the rotor; the free end edge of the rotor blade 200 faces the inner cavity side wall of the processing casing 100 and has no contact with the inner cavity side wall of the casing, and a tip clearance F is formed therebetween; this is conducive to the flow of the air flow in the casing.

[0036] A plurality of axial slots C parallel to its axis are provided on the inner cavity side wall of the processing casing 100, and the notches of the axial slots Z all face the circumferential side wall Z and the leading edge side wall Q of the rotor blade 200; in the radial cross-sectional view of the compressor rotor flow field, the contour profile shape of its radial cross-section is controlled by 6 constraint points.

[0037] Specifically, the 6 constraint points include two intersection points P1 and P2, that is, the intersection of the notch of the axial slot C and the side wall of the processing casing 100. Among them, the intersection point P1 is set at 5% - 10% C x,tip at the upstream front side of the leading edge side wall Q, and the intersection point P2 is set at 10% - 20% C x,tip at the upstream rear side of the leading edge side wall Q, where C x,tip is the axial chord length of the rotor blade 200, and the midpoint of the line connecting the intersection points P1 and P2 is P0.

[0038] The 6 constraint points also include 4 limit points, which are the limit points F1 and F2 for constraining the depth of the axial slot C and the basic contour. Among them, the limit point F1 is set at the vertical position between the intersection point P1 and the midpoint P0, and the limit point F2 is set at the vertical position between the midpoint P0 and the intersection point P2.

[0039] Furthermore, the radial distance between the limit point F1 and the line connecting the intersection points P1 and P2 is h1, and the radial distance between the limit point F2 and the line connecting the intersection points P1 and P2 is h2. Among them, the value range of h1 is 5τ - 20τ, the value range of h2 is 5τ - 20τ, and h1 ≥ h2, where τ is the width of the tip clearance F.

[0040] The other 2 limit points are the limit points F3 and F4 for constraining the jet outlet and suction inlet angles of the axial slot C. The limit point F3 is set at the vertical position upstream of the intersection point P1, and the limit point F4 is set at the vertical position between the limit point F2 and the intersection point P2.

[0041] Furthermore, the vertical distance between the limit point F3 and the line connecting the intersection points P1 and P2 is h3, and the vertical distance between the limit point F2 and the line connecting the intersection points P1 and P2 is h4. Among them, h3 < h1 and h4 < h2.

[0042] Construct a B-spline curve successively passing through P1, F3, F1, F2, F4, P2, and the formed B-spline curve is the radial cross-sectional profile of the cavity of the axial slot C; the transition of the axial slot C surface of this shape is smooth, reducing the circulation loss in the slot, and enabling the fluid to flow into and out of the axial slot at a more reasonable angle, reducing the mixing loss between the flow in the slot and the mainstream, so that the treatment slot can improve the stability expansion ability with as little efficiency loss as possible.

[0043] Furthermore, for the number N of the axial slots C opened, the preferred number is 3 to 5 times the number of the rotor blades 200. And the circumferential opening ratio is preferably 30% - 70%, and the circumferential inclination angle β is preferably 30° - 60°. Among them, the circumferential opening ratio refers to the ratio of the opening area of the treatment slot (axial slot C) on the casing to the area of the inner surface of the casing within the axial range where the treatment slot is located.

[0044] Embodiment 2

[0045] Referring to Figure 6 , this is the second embodiment of the present invention, and the effects are described by taking the first-stage rotor and its casing of a certain gas turbine high-pressure compressor as an example.

[0046] Some design parameters of this compressor rotor are shown in Table 1.

[0047] Table 1 Some design parameters of the first-stage rotor of a certain gas turbine high-pressure compressor.

[0048]

[0049] Perform the following design according to the design method in the invention content:

[0050] In the radial cross-sectional view of the rotor flow domain, first determine the two intersection points P1 and P2 of the cross-sectional profile of the axial slot C and the treatment casing. Among them, the axial chord length C x,tip of the rotor blade 200 = 60mm, the intersection point P1 is set at 5% - 10% C x,tip in the front side upstream of the leading edge side wall Q, take 10% C x,tip = 6mm, the intersection point P2 is set at 10% - 20% C x,tip in the downstream of the leading edge side wall Q, take 20% C x,tip = 12mm, then the connection line of the intersection points P1 and P2 is the width of the treatment slot on the inner side wall of the casing, which is 18mm.

[0051] In the radial cross-sectional view, use two control points F1 and F2 to control the depth and basic profile of the treatment slot. Let the midpoint of the connection line of P1 and P2 be P0, the axial position of F1 is located between P1 and P0, and the axial position of F2 is located between P0 and P2.

[0052] The radial distance between the limiting point F1 and the connecting line between the intersection points P1 and P2 is h1, and h1 is taken as 8τ = 5.6 mm; the radial distance between F2 and the connecting line between the intersection points P1 and P2 is h2, and h2 is taken as 5τ = 3.5 mm; τ is the width of the tip clearance F, which is 0.7 mm.

[0053] In the radial cross-sectional view, two control points F3 and F4 are used to control the angles of the treatment slot jet outlet and the suction inlet. The axial position of F3 is upstream of P1, and the vertical distance from the connecting line between the intersection points P1 and P2 is h3, h3 < h1, and h3 is taken as 4 mm.

[0054] The limiting point F4 is located between F2 and P2, and the vertical distance from the connecting line between the intersection points P1 and P2 is h4, h4 < h2, and h4 is taken as 2 mm.

[0055] Construct a B-spline curve successively passing through P1, F1, F2, F3, F4, and P2, then the formed B-spline curve is the required axial slot radial cross-sectional profile. The axial slot type casing treatment formed with this profile, the number of treatment slots is taken as 4 times the number of rotor blades, which is 172 per week, the circumferential opening ratio is taken as 50%, and the circumferential inclination angle β is taken as 45°.

[0056] The B-spline curve constructed based on these 6 control points is located above the leading edge of the blade, sucking the blocked fluid downstream from the leading edge, and spraying the fluid downstream at high speed upstream of the leading edge.

[0057] Combined with the attached Figure 7 and Figure 8 As shown in, before the present invention is used, the dimensionless flow rate at the near stall point of the prototype compressor is 0.94. After the present invention is used, the near stall flow rate drops to 0.90, and the stall margin is significantly improved, and the efficiency at the design point remains almost unchanged.

[0058] The axial slot type casing treatment designed according to the above method, with the B-spline curve as the required axial slot meridian profile, enables the tip fluid to smoothly flow into the treatment slot from the rear of the treatment slot and inject into the upstream of the leading edge from the front of the treatment slot, achieving the purpose of reducing flow loss while improving the margin broadening ability.

[0059] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limitations. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A casing for axial seam processing based on B-spline curve, characterized by: include, Applied to a compressor, the rotor blade (200) of the compressor is arranged in a processing casing 100, the free end edge of the rotor blade (200) faces the inner cavity side wall of the processing casing 100, and there is a blade tip gap F between the two; A plurality of axial slots (C) parallel to the axis of the inner cavity of the processing casing 100 are provided on the inner cavity side wall, and the slots of the axial slots Z are all oriented toward the circumferential side wall (Z) and the leading edge side wall (Q) of the rotor blade (200); In the radial cross-section view of the compressor rotor flow domain, six constraint points are used to control the profile shape of the radial cross-section.

2. The axial seam processing casing based on B-spline curve according to claim 1, characterized in that: The six restraint points include intersections P1 and P2 of the notch of the axial seam (C) and the side wall of the processing casing 100. The intersection P1 is set at 5% to 10% C of the upstream front side of the leading edge side wall (Q). x,tip The intersection point P2 is set at 10% to 20% C of the upstream rear side of the leading edge side wall (Q). x,tip Where, C x,tip is the axial chord length of the rotor blade (200), and the midpoint of the line connecting the intersection points P1 and P2 is P0.

3. The axial seam processing casing based on B-spline curve according to claim 2, characterized in that: The six constraint points include constraint points F1 and F2 for constraining the depth of the axial seam (C) and the base profile. The constraint point F1 is set at a vertical position between the intersection point P1 and the midpoint P0, and the constraint point F2 is set at a vertical position between the midpoint P0 and the intersection point P2.

4. The axial seam processing casing based on B-spline curve according to claim 3, characterized in that: The radial distance between the limiting point F1 and the line between the intersection points P1 and P2 is h1, and the radial distance between the limiting point F2 and the line between the intersection points P1 and P2 is h2, wherein the value range of h1 is 5τ~20τ, the value range of h2 is 5τ~20τ, and h1≥h2, wherein τ is the width of the blade tip gap F.

5. The axial seam processing casing based on B-spline curve according to claim 4, characterized in that: The six constraint points also include constraint points F3 and F4 for constraining the angles of the jet outlet and suction inlet of the axial slot (C). The constraint point F3 is set at a vertical position upstream of the intersection point P1, and the constraint point F4 is set at a vertical position between the constraint point F2 and the intersection point P2.

6. The axial seam processing casing based on B-spline curve according to claim 5, characterized in that: The vertical distance between the limit point F3 and the line connecting the intersection points P1 and P2 is h3, and the vertical distance between the limit point F2 and the line connecting the intersection points P1 and P2 is h4, wherein h3<h1, h4<h2.

7. The axial seam processing casing based on B-spline curve according to claim 6, characterized in that: A B-spline curve is constructed sequentially through P1, F3, F1, F2, F4, and P2, and the formed B-spline curve is the radial cross-sectional profile of the groove cavity of the axial seam (C).

8. The axial seam processing casing based on B-spline curve according to claim 7, characterized in that: The number N of the axial slots (C) is 3 to 5 times the number of the rotor blades (200).

9. The axial seam processing casing based on B-spline curve according to claim 8, characterized in that: The circumferential opening ratio φ of the axial slot (C) is 30%-70%, and the circumferential inclination angle β is 30°-60°.

10. The axial seam processing casing based on B-spline curve according to claim 9, characterized in that: The compressor used is a radial flow, mixed flow or axial flow compressor of single-stage or multi-stage structure.

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