Non-axisymmetric impeller hub design method for inhibiting secondary flow and impeller blade designed by non-axisymmetric impeller hub design method

Abstract

The invention relates to a design method of a non-axisymmetric impeller hub for restraining secondary flow and impeller blades designed by the non-axisymmetric impeller hub, the non-axisymmetric impeller hub comprises a hub body (2), a plurality of impeller blades (1) are uniformly distributed in the circumferential direction of the hub body (2), and each impeller blade (1) comprises a blade suction surface (3) and a blade pressure surface (4); every two adjacent impeller blades (1) form a blade channel (5); and in each blade channel (5), one side, close to the blade pressure surface (4), of the hub body (2) forms an upward convex shape so as to reduce the pressure, and one side, close to the blade suction surface (3), of the hub body (2) forms a downward concave shape so as to increase the pressure. Secondary flow in the impeller can be effectively restrained, and the energy efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of fluid machinery, and in particular relates to a design method for a non-axisymmetric impeller hub for suppressing secondary flow and an impeller blade designed therefor. Background Art

[0002] In recent years, fluid machinery has been developing towards high head and high efficiency. The secondary flow phenomenon in the impeller has become more and more obvious, which restricts the improvement of the impeller's energy efficiency. The traditional axisymmetric hub is weak in suppressing the secondary flow. Therefore, it is necessary to develop a new type of hub to suppress the secondary flow and improve the impeller efficiency. Summary of the invention

[0003] The purpose of the present invention is to provide a non-axisymmetric impeller hub design method for suppressing secondary flow and the impeller blades designed therewith, so as to quickly and effectively improve the impeller performance, effectively suppress the secondary flow and improve the efficiency.

[0004] The present invention provides a method for designing a non-axisymmetric impeller hub for suppressing secondary flow, wherein the non-axisymmetric impeller hub comprises a hub body, wherein the hub body is provided with a plurality of impeller blades evenly distributed in a circumferential direction, wherein the impeller blades comprise a blade suction surface and a blade pressure surface;

[0005] Two adjacent impeller blades form a blade channel; in each blade channel, the side of the hub body close to the blade pressure surface forms a convex shape to reduce the pressure, and the side of the hub body close to the blade suction surface forms a concave shape to increase the pressure.

[0006] Furthermore, in the blade channel, the structural modeling of the hub body is generated by a height distribution function z(x, y), and the height distribution function is composed of a circumferential modeling function f(y) and a radial modeling function A(x), wherein x is the radial position of the hub body; y is the circumferential position of the hub body.

[0007] Furthermore, the expression of the height distribution function z(x, y) is as follows:

[0008] z(x,y)=A(x)f(y).

[0009] Furthermore, the expression of the circumferential shaping function f(y) is as follows:

[0010]

[0011] Where y represents the circumferential position of the hub body, y1 represents the circumferential position of the blade suction surface, y2 represents the circumferential position where the concave shape near the blade suction surface ends, y3 represents the circumferential position where the convex shape near the blade pressure surface begins, y4 represents the circumferential position of the blade pressure surface, and y1 represents the circumferential position of the blade suction surface. <y2≤y3<y4。

[0012] Furthermore, the relative position of the concave and convex shapes along the circumferential direction can be adjusted by adjusting the sizes of y2 and y3.

[0013] Furthermore, the expression of the radial modeling function A(x) is as follows:

[0014]

[0015] Wherein, k is the coefficient, h represents the axial thickness of the hub body, x represents the radial position of the hub body, x1 represents the radial position of the blade inlet, and x2 represents the radial position of the blade outlet.

[0016] Furthermore, the concavity of the three-dimensional surface is adjusted by changing the value of the coefficient k.

[0017] The present invention also provides an impeller, comprising the non-axisymmetric impeller hub.

[0018] By means of the above scheme, through the non-axisymmetric impeller hub design method for suppressing secondary flow and the impeller blades designed therewith, the secondary flow in the impeller can be effectively suppressed, the secondary flow loss can be reduced, and the energy efficiency can be improved.

[0019] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of a non-axisymmetric impeller hub for suppressing secondary flow according to the present invention;

[0021] Figure 2 Schematic diagram of the circumferential shaping function f(y) according to an embodiment of the present invention.

[0022] Figure 3 Schematic diagram of a radial modeling function A(x) according to an embodiment of the present invention.

[0023] Reference numerals:

[0024] 1- impeller blades; 2- hub body; 3- blade suction surface; 4- blade pressure surface; 5- blade channel. DETAILED DESCRIPTION

[0025] The following further describes in detail the specific implementation manners of the present invention in conjunction with the accompanying drawings and embodiments. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0026] As shown Figure 1 in the figure, this embodiment provides a non-axisymmetric impeller hub design method for suppressing secondary flow. The non-axisymmetric impeller hub for suppressing secondary flow includes a hub body 2. A plurality of impeller blades 1 are evenly distributed circumferentially on the hub body 2. The impeller blades 1 include a blade suction surface 3 and a blade pressure surface 4; two adjacent impeller blades 1 form a blade passage 5; within each blade passage 5, one side of the hub body 2 close to the blade pressure surface 4 forms a convex shape to reduce the pressure, and one side of the hub body 2 close to the blade suction surface 3 forms a concave shape to increase the pressure. Thereby, the circumferential pressure gradient is reduced, achieving the purpose of suppressing secondary flow.

[0027] As shown Figure 2 and Figure 3 in the figure, within the blade passage 5, the structural shape of the hub body 2 is generated by a height distribution function z(x, y). The height distribution function is composed of a circumferential shaping function f(y) and a radial shaping function A(x), where x is the radial position of the hub body; y is the circumferential position of the hub body.

[0028] The expression of the height distribution function z(x, y) is as follows:

[0029] z(x, y) = A(x)f(y).

[0030] Specifically, the expression of the circumferential shaping function f(y) is as follows:

[0031]

[0032] In the formula, y represents the circumferential position of the hub body, y1 represents the circumferential position of the blade suction surface, y2 represents the circumferential position where the concave shaping near the blade suction surface ends, y3 represents the circumferential position where the convex shaping near the blade pressure surface starts, y4 represents the circumferential position of the blade pressure surface, and y1 < y2 ≤ y3 < y4. The relative position of the concave and convex shaping along the circumference can be adjusted by adjusting the magnitudes of y2 and y3.

[0033] Specifically, the expression of the radial shaping function A(x) is as follows:

[0034]

[0035] In the formula, k is a coefficient, h represents the axial thickness of the hub body, x represents the radial position of the hub body, x1 represents the radial position of the blade inlet, and x2 represents the radial position of the blade outlet. The concavity and convexity of the three-dimensional surface can be adjusted by changing the value of the coefficient k.

[0036] This embodiment also provides an impeller, which adopts the non-axisymmetric impeller hub.

[0037] By using the non-axisymmetric impeller hub design method for suppressing secondary flow and the impeller blades designed therein, it is possible to achieve in each blade channel that the hub near the pressure side of the blade is convex, the pressure is reduced, and the hub near the suction side of the blade is concave, the pressure is increased, thereby reducing the circumferential pressure gradient, suppressing the secondary flow, reducing the secondary flow loss, and improving the energy efficiency.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the technical principles of the present invention, and these improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for designing a non-axisymmetric impeller hub for suppressing secondary flow, characterized in that: The non-axisymmetric impeller hub comprises a hub body (2), a plurality of blades (1) are evenly distributed in the circumferential direction of the hub body (2), and the impeller blades (1) comprise a blade suction surface (3) and a blade pressure surface (4); Two adjacent impeller blades (1) form a blade channel (5); in each blade channel (5), the side of the hub body (2) close to the blade pressure surface (4) forms a convex shape to reduce pressure, and the side of the hub body (2) close to the blade suction surface (3) forms a concave shape to increase pressure.

2. A non-axisymmetric impeller hub design method for suppressing secondary flow according to claim 1, characterized in that: In the blade channel (5), the structural modeling of the hub body (2) is generated by a height distribution function z(x, y), and the height distribution function is composed of a circumferential modeling function f(y) and a radial modeling function A(x), wherein x is the radial position of the hub body; y is the circumferential position of the hub body.

3. A non-axisymmetric impeller hub design method for suppressing secondary flow according to claim 2, characterized in that: The expression of the height distribution function z(x,y) is as follows: z(x,y)=A(x)f(y).

4. A method for designing a non-axisymmetric impeller hub for suppressing secondary flow according to claim 3, characterized in that: The expression of the circumferential shaping function f(y) is as follows: Where y represents the circumferential position of the hub body, y1 represents the circumferential position of the blade suction surface, y2 represents the circumferential position where the concave shape near the blade suction surface ends, y3 represents the circumferential position where the convex shape near the blade pressure surface begins, y4 represents the circumferential position of the blade pressure surface, and y1 represents the circumferential position of the blade suction surface. <y2≤y3<y4。 5. A method for designing a non-axisymmetric impeller hub for suppressing secondary flow according to claim 3, characterized in that: The relative position of the concave and convex shapes along the circumferential direction can be adjusted by adjusting the sizes of y2 and y3.

6. A method for designing a non-axisymmetric impeller hub for suppressing secondary flow according to claim 5, characterized in that: The expression of the radial modeling function A(x) is as follows: Wherein, k is the coefficient, h represents the axial thickness of the hub body, x represents the radial position of the hub body, x1 represents the radial position of the blade inlet, and x2 represents the radial position of the blade outlet.

7. A method for designing a non-axisymmetric impeller hub for suppressing secondary flow according to claim 5, characterized in that: The concavity of the three-dimensional surface can be adjusted by changing the value of the coefficient k.

8. An impeller, characterized in that: The invention comprises the non-axisymmetric impeller hub as claimed in any one of claims 1 to 7.

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