Circumferential groove treatment casing based on B spline curve

Abstract

The invention relates to the technical field of gas compressor casing treatment, and discloses a circumferential groove treatment casing based on a B spline curve, the treatment casing is applied to a gas compressor, rotor moving blades of the treatment casing are arranged in the treatment casing, the free end edges of the moving blades face the side wall of an inner cavity of the treatment casing, and a blade tip gap is formed between the free end edges of the moving blades and the side wall of the inner cavity of the treatment casing; a circumferential groove is formed in the side wall of an inner cavity of the treatment casing, and a groove opening of the circumferential groove faces the circumferential side wall and the front edge side wall of the moving blade; in the meridian plane view of the compressor rotor basin, the contour section shape of the axial section is controlled by using the six constraint points; the section of the circumferential groove is constructed by utilizing the geometric characteristics of the gas compressor; the arc based on the B-spline curve model enables blade tip airflow to enter the groove from the rear portion of the processing groove more easily and return to the blade tip at the front portion of the processing groove in the downstream direction, the purposes of reducing the circulation loss in the groove and enhancing the upstream jet flow are achieved, and therefore the stability margin of the gas compressor is widened on the premise that the effect on efficiency is small.

Description

Technical Field

[0001] The present invention relates to the technical field of compressor casings, and particularly to a circumferential groove treatment casing based on B-spline curves. Background Art

[0002] In the field of gas turbines, the performance of compressors is crucial, and the compressor performance is highly sensitive to tip clearances. On the one hand, a large tip clearance will lead to a reduction in compressor efficiency, which not only reduces the work capacity of the mainstream but also generates additional energy losses. On the other hand, tip clearances may also cause flow instability phenomena, such as the generation and development of tip vortices, further affecting the performance and reliability of compressors. During actual service, the tip clearance may increase temporarily or permanently, thus affecting the economy and stability of gas turbine operation.

[0003] Although traditional design optimization and control strategies can alleviate the problems caused by tip clearances to a certain extent, they have limitations, such as complex structures and efficiency losses. Casing treatment technology is an early studied and successfully applied compressor clearance flow control method, which can effectively improve the stability and performance of compressors without significantly increasing the complexity of gas turbines. Basic casing treatments include circumferential groove types and axial slot types of casing treatments, and schematic diagrams are as shown in Figure 1 and Figure 2 shown.

[0004] Generally speaking, the adverse effect of circumferential groove type casing treatment on compressor efficiency is less than that of axial slot type casing treatment, but the stability expansion ability is weak, which is due to the small space in the circumferential groove and the inability to form a jet with strong energy. If the design characteristics of axial slot type casing treatment are borrowed to enhance the jet intensity of the circumferential groove of the compressor, the effect of enhancing the stability expansion ability can be achieved 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, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this part, the abstract, and the title, but such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the problems existing in the existing circumferential groove treatment casings, the present invention is proposed.

[0007] Therefore, the purpose of the present invention is to provide a circumferential groove treatment casing based on B-spline curves, which uses B-spline curve modeling to make the profile of the circumferential groove transition smoothly, so that the fluid flows into and out of the circumferential groove at a more reasonable angle, improving the overall stability expansion ability of the casing and reducing the flow loss.

[0008] To solve the above technical problems, the present invention provides the following technical solution: a circumferential groove treatment casing based on B-spline curve, which is applied to a compressor. The moving blades of the compressor rotor are arranged in the treatment casing. The free end edge of the moving blade faces the inner cavity side wall of the treatment casing, and there is a tip clearance between the two. A circumferential groove is formed on the inner cavity side wall of the treatment casing, and the notch of the circumferential groove faces the circumferential side wall and the leading edge side wall of the moving blade. In the meridional plane view of the compressor rotor flow domain, the contour profile of its axial section is controlled by 6 constraint points.

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

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

[0011] As a preferred scheme of the circumferential groove treatment casing based on B-spline curve of the present invention, among them: the radial distance between the limiting point F1 and the connection line of the intersection points P1 and P2 is h1, and the radial distance between the limiting point F2 and the connection line of the intersection points P1 and P2 is h2. Among them, the value range of h1 is 3τ - 10τ, the value range of h2 is 3τ - 10τ, and h1 ≥ h2, where τ is the width of the tip clearance.

[0012] As a preferred scheme of the circumferential groove treatment casing based on B-spline curve 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 circumferential groove. The limiting point F3 is arranged at the axial position upstream of the intersection point P1, and the limiting point F4 is arranged at the axial position between the limiting point F2 and the intersection point P2.

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

[0014] As a preferred embodiment of the circumferential groove treatment casing based on B-spline curves according to the present invention, specifically: construct a B-spline curve successively passing through P1, F3, F1, F2, F4, and P2, and the formed B-spline curve is the meridional plane profile of the groove cavity of the circumferential groove.

[0015] As a preferred embodiment of the circumferential groove treatment casing based on B-spline curves according to the present invention, specifically: the compressor applied is a radial flow, mixed flow or axial flow compressor with a single-stage or multi-stage structure.

[0016] Advantages of the present invention:

[0017] The design configuration method of the present invention is simple and easy to construct the circumferential groove profile by using the geometric characteristics of the compressor; the circular arc based on the B-spline curve modeling enables the tip flow to more easily enter the groove from the rear of the treatment groove and return to the tip in the front of the treatment groove in the direction pointing downstream, achieving the purpose of reducing the circulation loss in the groove and enhancing the upstream jet, thereby broadening the stable margin of the compressor on the premise of having less impact on the efficiency. Description of the drawings

[0018] In order 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, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0019] Figure 1 It is a schematic diagram of the conventional circumferential groove casing treatment structure, where Figure 1 (a) is the front view, Figure 1 (b) is the sectional view.

[0020] Figure 2 It is a schematic diagram of the conventional axial slot casing treatment structure, where Figure 2 (a) is the front view, Figure 2 (b) is the sectional view.

[0021] Figure 3 It is a schematic diagram of the meridional plane structure of the circumferential groove treatment casing based on B-spline curves according to the present invention.

[0022] Figure 4 It is a schematic diagram of the fluid inhalation and ejection of the tip of the moving blade and the inner wall of the casing of the circumferential groove treatment casing based on B-spline curves according to the present invention.

[0023] Figure 5 It is a schematic diagram of the specific treatment parameters of the jet-enhanced circumferential groove casing designed for a certain compressor rotor.

[0024] Figure 6 Efficiency - dimensionless flow rate relationship of the compressor in Comparative Prototype for Example 2 Figure 1 .

[0025] Figure 7 Efficiency - dimensionless flow rate relationship of the compressor in Comparative Prototype for Example 2 Figure 2 . Specific implementation manners

[0026] To make the above - mentioned objects, features and advantages of the present invention more obvious and understandable, the specific implementation manners of the present invention will be described in detail below with reference to the accompanying drawings of the specification.

[0027] In the following description, many specific details are set forth to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0028] Secondly, the so - called "one embodiment" or "embodiment" herein refers to a specific feature, structure or characteristic that can 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.

[0029] Furthermore, the present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention in detail, for the convenience of explanation, the cross - sectional views showing the device structure will be enlarged locally out of the general 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.

[0030] Example 1

[0031] Referring to Figure 3 and 4 , for the first embodiment of the present invention, a circumferential groove - treated casing based on B - spline curves is provided. 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.

[0032] Furthermore, the compressor rotor is installed on the central axis inside the casing, and the moving blades 200 on its circumferential sidewall are also located inside the treated casing 100 and rotate inside the casing with the rotor. The free - end edge of the moving blade 200 faces the inner - cavity sidewall of the treated casing 100 and has no contact with the inner - cavity sidewall of the casing, forming a tip clearance F to facilitate the flow of air in the casing.

[0033] A circumferential groove D is formed on the inner cavity side wall of the casing 100, and the notch of the circumferential groove D faces the circumferential side wall Z and the leading edge side wall Q of the moving blade 200; in the meridional plane view of the compressor rotor flow field, the profile shape of the axial section of the circumferential groove D is specifically controlled by six constraint points.

[0034] Specifically, the six constraint points include two intersection points P1 and P2, that is, the intersection points of the notch of the circumferential groove D and the side wall of the 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 moving blade 200 of the rotor, and the midpoint of the line connecting the intersection points P1 and P2 is P0.

[0035] The six constraint points include four limit points, namely the limit points F1 and F2 used to constrain the depth and basic profile of the circumferential groove D. Among them, the limit point F1 is set at the axial position between the intersection point P1 and the midpoint P0, and the limit point F2 is set at the axial position between the midpoint P0 and the intersection point P2.

[0036] 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 3τ - 10τ, the value range of h2 is 3τ - 10τ, and h1 ≥ h2, where τ is the width of the tip clearance F.

[0037] The other two limit points are the limit points F3 and F4 used to constrain the jet outlet and suction inlet angles of the circumferential groove D. The limit point F3 is set at the axial position upstream of the intersection point P1, and the limit point F4 is set at the axial position between the limit point F2 and the intersection point P2.

[0038] Furthermore, the axial distance between the limit point F3 and the line connecting the intersection points P1 and P2 is h3, and the axial 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.

[0039] A smooth B-spline curve is constructed successively through P1, F3, F1, F2, F4, and P2. The formed B-spline curve is the meridional plane contour of the groove cavity of the circumferential groove D. The arc shape in the downstream of this curve contour enables the tip flow to smoothly enter the treatment groove from the downstream, with low flow loss; the tip fluid entering the groove, after circulating through the smooth transition curve, is injected into the mainstream from the upstream of the tip leading edge, significantly enhancing the jet effect, improving the margin broadening ability, and having a simple profile design.

[0040] Embodiment 2

[0041] Reference Figures 5 to 7 This is the second embodiment of the present invention. Taking the first-stage rotor blade of a certain gas turbine compressor and its casing as an example, the effects will be described below.

[0042] Some design parameters of the compressor rotor blade are shown in Table 1.

[0043] Table 1 Some design parameters of the first-stage rotor blade of a certain gas turbine compressor.

[0044]

[0045] According to the design parameters in the above Embodiment 1, the following design is carried out:

[0046] In the meridional plane view of the rotor flow field, first determine the two intersection points P1 and P2 of the circumferential groove D profile and the treatment casing 100; where the axial chord length C of the rotor blade 200 x,tip = 60 mm, the intersection point P1 is set at 5% - 10% C upstream and in front of the leading-edge side wall Q x,tip , taking 10% C x,tip = 6 mm, the intersection point P2 is set at 10% - 20% C downstream of the leading-edge side wall Q x,tip , taking 20% C x,tip = 12 mm, then the connection line between the intersection points P1 and P2 is the width of the treatment seam on the casing profile, which is 18 mm.

[0047] In the meridional plane view, use two limit points F1 and F2 to control the depth and basic profile of the treatment groove. The midpoint of the connection line between the intersection points P1 and P2 is P0. The axial position of the limit point F1 is between the intersection point P1 and the midpoint P0, and the axial position of the limit point F2 is between P0 and P2.

[0048] The radial distance between the limit point F1 and the connection line (casing profile) between the intersection points P1 and P2 is h1, and h1 is taken as 4τ = 2.8 mm; the radial distance between F2 and the connection line (casing profile) between the intersection points P1 and P2 is h2, and h2 is taken as 3τ = 2.1 mm; τ is the width of the tip clearance F, which is 0.7 mm.

[0049] In the meridional plane view, use two limit points F3 and F4 to control the angles of the treatment groove jet outlet and suction inlet. The axial position of the limit point F3 is upstream of the intersection point P1, and the axial distance from the casing profile is h3, h3 < h1, and h3 is taken as 2 mm.

[0050] The axial position of the limit point F4 is between F2 and P2, and the axial distance from the casing profile is h4, h4 < h2, and h4 is taken as 1.5 mm.

[0051] Construct a B-spline curve successively passing through P1, F3, F1, F2, F4, P2, then the formed B-spline curve is the required meridional contour of the circumferential groove. 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 upstream of the leading edge and ejecting the fluid downstream at high speed upstream of the leading edge.

[0052] Combined with the attached Figure 6 and Figure 7 As shown in, when using the prototype smooth-wall casing, the dimensionless flow rate at the near-stall point of the compressor is 0.78. After using the circumferential groove casing, the near-stall flow rate drops to 0.75, the stall margin increases, and the efficiency at the design point (dimensionless flow rate 0.88) remains unchanged.

[0053] The circumferential groove treatment casing designed according to the above method uses a B-spline curve as the required meridional contour of the circumferential groove, enabling the tip fluid to smoothly flow into the treatment groove from the rear of the treatment groove and inject into the upstream of the leading edge from the front of the treatment groove, achieving the purpose of reducing flow losses while improving the margin broadening ability.

[0054] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. 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 processing circumferential grooves based on B-spline curves, characterized in that: include, Applied to a compressor, the moving blades (200) of the compressor rotor are arranged in a processing casing (100), the free end edges of the moving blades face the inner cavity side wall of the processing casing (100), and there is a blade tip gap (F) between the two; A circumferential groove (D) is provided on the inner cavity side wall of the processing casing (100), and the notch of the circumferential groove (D) faces the circumferential side wall (Z) and the leading edge side wall (Q) of the moving blade (200); In the meridian view of the compressor rotor flow domain, six constraint points are used to control the profile shape of its axial section.

2. The circumferential groove processing casing based on B-spline curve according to claim 1, characterized in that: The six restraint points include intersection points P1 and P2 of the notch of the circumferential groove (D) and the side wall of the processing casing (100), and the intersection point 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 circumferential groove processing casing based on B-spline curve according to claim 2, characterized in that: The six constraint points include limit points F1 and F2 for constraining the depth and basic profile of the circumferential groove (D). Limit point F1 is set at an axial position between the intersection point P1 and the midpoint P0, and limit point F2 is set at an axial position between the midpoint P0 and the intersection point P2.

4. The circumferential groove processing casing based on B-spline curve according to claim 3 is 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 3τ~10τ, the value range of h2 is 3τ~10τ, and h1≥h2, wherein τ is the width of the blade tip gap (F).

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

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

7. The circumferential groove 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 meridian profile of the groove cavity of the circumferential groove (D).

8. The circumferential groove processing casing based on B-spline curve according to claim 7, 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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