A design method of multi-stage centrifugal pump streamline space guide vane

Abstract

The application provides a design method for a streamlined space guide vane of a multistage centrifugal pump, and belongs to the technical field of hydraulic machinery. The design method for the streamlined space guide vane of the multistage centrifugal pump directly controls the guide vane profile according to a curve equation, can adapt to various change conditions, significantly improves the guide vane design efficiency under the condition of controlling the direction of the inlet and outlet flow passages, and has extremely important role and value for improving the hydraulic performance of the space guide vane. The positive and negative guide vanes of the design method for the streamlined space guide vane of the multistage centrifugal pump are an integral streamline, have obvious optimization effect, are simple in design calculation, and are high in adaptability.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic machinery technology, specifically relating to a design method for streamlined spatial guide vanes in a multi-stage centrifugal pump. Background Technology

[0002] Guide vanes in multistage centrifugal pumps are crucial energy conversion components. They collect the liquid flowing out of the impeller, reducing its velocity and converting it into pressure energy, which is then transported to the suction inlet of the next stage impeller. Guide vanes must ensure the axisymmetry of the fluid exiting the impeller, minimizing hydraulic losses within the impeller. During liquid transport, guide vanes must eliminate the rotational motion of the liquid exiting the impeller, reducing any resulting hydraulic losses. Types of guide vanes include radial guide vanes, axial guide vanes, reverse guide vanes, flow channel guide vanes, and spatial guide vanes. Because the liquid flow direction from the impeller to the next stage impeller involves two 90° turns, losses are significant, accounting for 40%–50% of pump losses, severely impacting the efficiency of the centrifugal pump. Multistage centrifugal pumps are widely used and hold a vital position in the national economy. With the continuous development of my country's economy, the market demands increasingly higher technical performance from multistage centrifugal pump products, and the pursuit of high efficiency is of great significance for energy conservation and environmental protection.

[0003] Due to the flow direction change, the traditional design of multistage pump guide vanes is divided into three sections: the guide vane inlet section, the transition section, and the outlet section. The flow transition is not coordinated, resulting in a large hydraulic loss in the guide vane. Therefore, the design of spatial streamlined guide vanes overcomes the drawbacks of the traditional design method and can improve the efficiency of the whole pump by reducing hydraulic loss. The design of spatial streamlined guide vanes under the existing technology has the following problems: (1) Invention patent CN201811254069.1 discloses a design method of spatial guide vanes for mixed flow pumps, which does not belong to the application scope of multistage centrifugal pumps. The positive and negative guide vanes adopt a segmented interpolation method, which has the defect of unsmooth transition between the positive and negative guide vanes. When the interpolation control point is changed, the entire function needs to be recalculated. The calculation process is complicated and the amount of calculation is large, which is very inconvenient for modifying the curve type later. (2) Invention patent CN201510593425.2 discloses a hydraulic design method for a space guide vane centrifugal pump. It uses Bézier curves to segmentally control the shape of the guide vane axial surface and the blade profile. The Bézier curves only determine the control points through the blade inlet and outlet placement angles, without analyzing the relationship between the flow channel and the blade, and lacking specific design for the flow channel and curved surface shape. (3) Invention patent CN201510674177.4 discloses a design method for matching the inner and outer edge streamlines of a guide vane. It designs the inner and outer edge streamlines as concentric circles, adopts a segmented design for the transition section of the inner and outer edge streamlines, and then uses the wrap angle two-wing transformation drawing method to design the streamlines. The design is relatively complicated and the transition at the segment is not smooth. Summary of the Invention

[0004] This invention is made to solve the above-mentioned problems. In view of the excessive hydraulic loss of existing centrifugal pump guide vanes and the unsmooth transition caused by the segmented control of the forward and reverse guide vanes, the purpose of this invention is to provide a design method for streamlined spatial guide vanes of multi-stage centrifugal pumps.

[0005] This invention provides a design method for streamlined spatial guide vanes of a multi-stage centrifugal pump, used to design the structure of the spatial guide vanes of the centrifugal pump. The spatial guide vane includes a disc with an arc-shaped outer edge, several blades evenly arranged on the disc and perpendicular to it, and an outer cover plate covering the outer periphery of the blades. The intersection line of the blades and the disc is denoted as the inner edge line, and the intersection line of the blades and the outer cover plate is denoted as the outer edge line. The area between two adjacent blades, from the blade inlet to the maximum outer edge line, is the inlet flow channel, and from the maximum outer edge line to the blade outlet, is the outlet flow channel. The method includes the following steps: S10, based on the performance requirements, strength requirements, and given impeller dimensions of the centrifugal pump, calculate the inlet placement angle α1, the outlet placement angle α2, the number of blades, and the several wrap angles β of the blades at the inner edge line. n-1 The diameters of the blades at the inner and outer edges, respectively, where n ≥ 3; S20, through the wrap angle β n-1 S30: Calculate the positions of n control points on different planes of the wheel; S40: Calculate the three-dimensional curve equation fitted by the n control points based on their positions, thereby completing the blade profile design. The three-dimensional curve equation is a Bézier curve or a spline curve, and the three-dimensional curve equation is of order n-1; S50: Based on the inlet installation angle α1, the outlet installation angle α2, and the diameter of the blade at the inner and outer edges respectively, translate and stretch the lines of the three-dimensional curve equation to generate the blade surface. Then, add the blade thickness to form the blade solid; S60: Based on the number of blades, evenly distribute the solid blades around the wheel to complete the design of the spatial guide vane.

[0006] The streamlined spatial guide vane design method for multi-stage centrifugal pumps provided by this invention may also have the following features: in steps S10 to S20, the n control points of the same blade include at least a first reference control point P0, a second reference control point P1, and a third reference control point P2. The first reference control point P0 is the farthest end of the diameter of the blade at the inner edge line. The second reference control point P1 and the third reference control point P2 are the intersection points of the inlet flow channel and the outlet flow channel of the spatial guide vane with the impeller, respectively, and are located on the inlet base circle with diameter D1 and the outlet base circle with diameter D3 of the impeller, respectively, where D1 > D3.

[0007] The multi-stage centrifugal pump streamlined spatial guide vane design method provided by the present invention may also have the following feature: when n=4, the control point also includes a first intermediate control point P3, which is the intersection of the circular arc surface of the wheel and the front and side planes.

[0008] The multi-stage centrifugal pump streamlined spatial guide vane design method provided by the present invention may also have the following features: when n≥5, the control points also include n-3 intermediate control points, including the first intermediate control point P3 and the second intermediate control point P4, the first intermediate control point P3 and the second intermediate control point P4 being the intersection of the arc surface of the wheel and the front and back planes, respectively.

[0009] The streamlined spatial guide vane design method for multi-stage centrifugal pumps provided by this invention can also have the following feature: when n≥6, the intermediate control points further include n-5 auxiliary control points P. m 5≤m≤n-1, auxiliary control point P m Distance control point P n-m The nearest point, auxiliary control point P m The position is determined by the wrap angle β m control.

[0010] The streamlined spatial guide vane design method for multi-stage centrifugal pumps provided by this invention may also have the following feature: the curve of the three-dimensional curve equation is a smooth transition complete streamline.

[0011] The streamlined spatial guide vane design method for multi-stage centrifugal pumps provided by this invention may also have the following feature: In step S20, the curve of the three-dimensional curve equation is a cubic spline curve, and the fitting method is: the points between each pair of adjacent control points are piecewise fitted using a cubic polynomial parametric equation, where the cubic polynomial parametric equation is: P i (t)=[1-3(t / t1) 2 +2(t / t1) 3 ]P i +[3(t / t1) 2 -2(t / t1) 3 ]P i+1 +[(t / t1)-2(t / t1) 2 +(t / t1) 3 ]P i ’ +[-(t / t1) 2 +(t / t1) 3 ]P i+1 ’ P i For the i-th control point (i≤n), t i Let P be the line segment i P i+1 The length of P (i≤n-1) i ’ Let t be the tangential guide of the i-th control point, and t be the chord length between points P1 and P.

[0012] The streamlined spatial guide vane design method for multi-stage centrifugal pumps provided by this invention may also have the following feature: the outer edge line and the inner edge line of the same blade form a plane, which is the working surface of the blade, and the angle γ between the working surface and the impeller is 90°.

[0013] The streamlined spatial guide vane design method for multi-stage centrifugal pumps provided by this invention may also have the following feature: the flow directions of the inlet flow channel and the outlet flow channel are opposite in the plane, with an included angle of 180°.

[0014] The streamlined spatial guide vane design method for multi-stage centrifugal pumps provided by this invention may also have the following features: the blade height gradually decreases from the inside to the outside, and the interior area of ​​two adjacent blades along the flow channel direction perpendicular to the spatial guide vane is equal to the cross-sectional area formed by the flow channel.

[0015] The role and effect of invention

[0016] According to the multi-stage centrifugal pump streamlined spatial guide vane design method of the present invention, the structure of the spatial guide vane of the centrifugal pump is designed. The spatial guide vane includes a disc with an arc-shaped outer edge, a number of blades uniformly arranged on the disc and perpendicular to it, and an outer cover plate covering the outer periphery of the blades. The intersection line of the blades and the disc is denoted as the inner edge line, and the intersection line of the blades and the outer cover plate is denoted as the outer edge line. The area between two adjacent blades, from the blade inlet to the maximum outer edge line, is the inlet flow channel, and from the maximum outer edge line to the blade outlet is the outlet flow channel. The method includes the following steps: S10, based on the performance requirements, strength requirements of the centrifugal pump and the given impeller size, calculate the inlet placement angle α1, the outlet placement angle α2, the number of blades, and the number of wrap angles β of the blades at the inner edge line. n-1 The diameters of the blades at the inner and outer edges, respectively, where n ≥ 3; S20, through the wrap angle β n-1 Calculate the positions of n control points on different planes of the wheel; S30, calculate the three-dimensional curve equation fitted by the n control points based on their positions to complete the blade profile design. The three-dimensional curve equation is a Bézier curve or a spline curve, and the three-dimensional curve equation is of order n-1; S40, based on the inlet installation angle α1, the outlet installation angle α2, and the diameter of the blade at the inner and outer edges respectively, translate and stretch the lines of the three-dimensional curve equation to generate the blade surface, and then add the blade thickness to form the blade solid; S50, based on the number of blades, evenly distribute the solid blades around the wheel to complete the design of the spatial guide vane.

[0017] Therefore, the streamlined spatial guide vane design method for multi-stage centrifugal pumps of this invention achieves direct control of the guide vane blade profile based on the curve equation, adapting to various changing conditions. Under the condition of controlling the inlet and outlet flow direction, it significantly improves the guide vane design efficiency, playing a crucial role and value in enhancing the hydraulic performance of spatial guide vanes. The forward and reverse guide vanes of the streamlined spatial guide vane design method of this invention form a single, complete streamline, exhibiting significant optimization effects, simple design calculations, and strong adaptability. Attached Figure Description

[0018] Figure 1 This is an assembly diagram of the multi-stage centrifugal pump in Embodiment 1 of the present invention;

[0019] Figure 2 This is an exploded view of the structure of the multi-stage centrifugal pump in Embodiment 1 of the present invention;

[0020] Figure 3 This is a schematic diagram of the streamlined spatial guide vane design of the multi-stage centrifugal pump in Embodiment 1 of the present invention;

[0021] Figure 4 This is a front view of the streamlined spatial guide vane in Embodiment 1 of the present invention;

[0022] Figure 5 This is a rear view of the streamlined spatial guide vane in Embodiment 1 of the present invention;

[0023] Figure 6 This is a perspective view of the streamlined spatial guide vane in Embodiment 1 of the present invention.

[0024] Figure 7 This is a comparison chart of the performance experimental data of a centrifugal pump using a conventional guide vane when the streamlined spatial guide vane obtained by the multi-stage centrifugal pump streamlined spatial guide vane design method in Embodiment 1 of the present invention is applied to a centrifugal pump. Detailed Implementation

[0025] To make the technical means, creative features, objectives and effects of this invention easy to understand, the following embodiments, in conjunction with the accompanying drawings, specifically illustrate a method for designing streamlined spatial guide vanes for a multi-stage centrifugal pump according to this invention.

[0026] <Example>

[0027] Figure 1 This is an assembly diagram of the multi-stage centrifugal pump in Embodiment 1 of the present invention; Figure 2 This is an exploded view of the structure of the multi-stage centrifugal pump in Embodiment 1 of the present invention.

[0028] like Figure 1 and Figure 2As shown, this embodiment provides a multi-stage centrifugal pump 100, including a front cover plate 10 of the pump casing, a rear cover plate 20 of the pump casing, an impeller 30, a spatial guide vane 40, and a support 50.

[0029] The front cover plate 10 and the rear cover plate 20 of the pump casing have a fluid inlet 11 and a fluid outlet 21, respectively, for introducing and discharging fluid.

[0030] Several impellers 30 and several spatial guide vanes 40 are spaced apart from each other and pass through the shaft 60, thus being rotatably disposed between the front cover plate 10 and the rear cover plate 20 of the pump casing.

[0031] The space guide vane 40 includes a disk 41 with an arc-shaped outer edge, a number of blades 42 evenly arranged on the disk 41 and perpendicular to it, and an outer cover plate 43 covering the outer periphery of the blades 42.

[0032] The bracket 50 is located at the bottom of the front cover plate 10 and the rear cover plate 20 of the pump casing, and is used to support the entire multistage centrifugal pump 100.

[0033] Figure 3 This is a schematic diagram of the streamlined spatial guide vane design of the multi-stage centrifugal pump in Embodiment 1 of the present invention; Figure 4 This is a front view of the streamlined spatial guide vane in Embodiment 1 of the present invention;

[0034] Figure 5 This is a rear view of the streamlined spatial guide vane in Embodiment 1 of the present invention; Figure 6 This is a perspective view of the streamlined spatial guide vane in Embodiment 1 of the present invention.

[0035] like Figures 1-6 As shown, this embodiment provides a design method for streamlined spatial guide vanes of a multi-stage centrifugal pump, used to design the structure of the spatial guide vane 40 of the centrifugal pump 100.

[0036] The line of intersection between blade 42 and disk 41 is denoted as inner edge line 42a, and the line of intersection between blade 42 and outer cover plate 43 is denoted as outer edge line 42b.

[0037] The region between two adjacent blades 42, from the inlet of blade 42 to the maximum outer edge line, is the inlet flow channel 42c, and the region from the maximum outer edge line to the outlet of blade 42 is the outlet flow channel 42d.

[0038] The plane formed by the outer edge line 42b and the inner edge line 42a of the same blade 42 is the working surface of the blade, and the angle γ between the working surface and the disk 41 is 90°.

[0039] The inlet flow channel 42c and outlet flow channel 42d of the space guide vane 40 have opposite flow directions in the plane, with an included angle of 180°.

[0040] The blade height of the blade 42 gradually decreases from the inside to the outside, and the interior of two adjacent blades has the same cross-sectional area as any flow channel formed by the flow channel along the direction perpendicular to the spatial guide vane 40.

[0041] The streamlined spatial guide vane design method for multi-stage centrifugal pumps in this embodiment includes the following steps:

[0042] S10, based on the performance and strength requirements of the centrifugal pump 100 and the given dimensions of the impeller 30, calculate the inlet placement angle α1, outlet placement angle α2, number of blades 42, and several wrap angles β of the blades 42 at the inner edge line 42a on the impeller 41. n-1 The diameters of the blades at the inner edge line 42a and the outer edge line 42b, respectively, where n≥3.

[0043] The inlet placement angle α1, outlet placement angle α2, and wrap angle β in this step are... n-1 The method for determining it is as follows:

[0044] The inlet diameter of blade 42 is D1 = D a +(2~5)mm

[0045] The outlet diameter of blade 42 is D3 = D j

[0046] The inlet flow angle α3' of blade 42 is equal to arctan(v). m3 / v u3 )

[0047] The circumferential velocity component v at the inlet of blade 42 u3 =v u2 (R2 / R3)

[0048] axial velocity v at blade exit 42 m3 =Q / (S3Ψ3)

[0049] Blade 42 inlet displacement coefficient Ψ3=1-(ZS) u3 ) / (D3π)

[0050] Blade 42 Inlet placement angle α1=α3'+Δα

[0051] The axial length L of blade 42 is (0.5~0.7)D a

[0052] Blade 42 inlet width b3 = b2 + (3~5) mm

[0053] In the above formula: D a D is the outlet diameter of impeller 30. j The inlet diameter of the impeller is 30, v u2R1 is the circumferential velocity at the outlet of impeller 30, R2 is the outlet radius of impeller 30, R3 is the radius of the calculation point at the inlet edge of blade 42, Q is the pump's given flow rate, S3 is the cross-sectional area of ​​the liquid flowing through the axial surface at the inlet of blade 42, and Z is the circumferential velocity at the outlet of impeller 30. a S represents the number of leaves (42). u3 S represents the circumferential thickness at the inlet of blade 42. u3 =δ3 / sinα3', where δ3 is the actual thickness value, Δα is the inlet angle of attack, and b2 is the outlet thickness of impeller 30 (including front and rear cover plates).

[0054] According to the two-dimensional axial streamline design method of spatial guide vane blades, in the design of spatial guide vanes for multi-stage pumps, in order to ensure that the fluid can flow smoothly between the spatial guide vane 40 and the impeller 30 and avoid excessive fluid energy hydraulic loss due to obstructed flow, the outlet placement angle α2 is usually selected from 80° to 95°.

[0055] Enclosure angle β n-1 The range is usually controlled between 70° and 150° to reduce friction and thus reduce hydraulic loss, enhance the ability to control the fluid, and improve efficiency and stability.

[0056] Specifically, the design parameters of the space guide vane 40 in this embodiment are shown in Table 1 below.

[0057] Table 1 (Design parameters of Space Guide Vane 40)

[0058] Geometric design parameters numerical values <![CDATA[Import diameter D1 (mm) of blade 42]]> 163 <![CDATA[Outlet diameter D3 (mm) of blade 42]]> 82 Axial length L (mm) of blade 42 35.4 Number of leaves Z 42 8 <![CDATA[Import installation angle α1 (°)]]> 13 <![CDATA[Outlet placement angle α2 (°)]]> 80 <![CDATA[Inlet width b3 (mm) of blade 42]]> 12 <![CDATA[Wrapping angle β n-1 (°)]]> 110

[0059] S20, via the wrap angle β n-1 Calculate n control points P on different planes of the roulette wheel 41. n-1 Their respective locations.

[0060] Specifically, such as Figure 3 As shown, in this embodiment, n=7, and control point P n-1 It includes the first reference control point P0, the second reference control point P1, the third reference control point P2, the first intermediate control point P3, the second intermediate control point P4, the auxiliary control point P5, and the auxiliary control point P6.

[0061] The first reference control point P0 is the farthest point of the diameter of blade 42 at the inner edge line 42a.

[0062] The second reference control point P1 and the third reference control point P2 are the intersections of the inlet flow channel 42c and the outlet flow channel 42d of the space guide vane 40 with the wheel disk 41, respectively. They are located on the inlet base circle with diameter D1 and the outlet base circle with diameter D3 of the wheel disk 41, respectively, where D1 > D3.

[0063] The first intermediate control point P3 and the second intermediate control point P4 are the intersection points of the arc surface of the roulette wheel 41 and the front and back planes, respectively.

[0064] Auxiliary control point P5 is a point closer to control point P2, and its position is controlled by the wrap angle β5; auxiliary control point P6 is a point closer to control point P1, and its position is controlled by the wrap angle β6.

[0065] In this embodiment, 7 control points P are selected. n-1 The coordinates are shown in Table 2 below.

[0066] Table 2 (7 control points P) n-1 (coordinates)

[0067] Control Points coordinate <![CDATA[P1]]> (-63.3743，51.4249，0) <![CDATA[P2]]> (-44.3788，74.0269，0) <![CDATA[P3]]> (-30.3011，85.8506，0) <![CDATA[P0]]> (0，97.3366，-6.2954) <![CDATA[P4]]> (39.9182，81.8232，-13) <![CDATA[P5]]> (48.8158，55.7865，-13) <![CDATA[P6]]> (35.736，20.8972，-13)

[0068] S30, based on control point P n-1 Calculate the location of 7 control points P n-1 The fitted three-dimensional curve equation completes the blade profile design. The three-dimensional curve equation is a Bézier curve or a spline curve, and the three-dimensional curve equation is of order n-1.

[0069] Specifically, in this embodiment, the three-dimensional curve equation is defined as a cubic spline curve, which is a smooth, complete streamline, and n control points P are used. n-1 Piecewise fitting of points between adjacent pairs is performed using a cubic polynomial parametric equation, which is:

[0070] P i (t)=[1-3(t / t1) 2 +2(t / t1) 3 ]P i +[3(t / t1) 2 -2(t / t1) 3 ]P i+1 +[(t / t1)-2(t / t1) 2 +(t / t1) 3 ]

[0071] P i ’ +[-(t / t1) 2 +(t / t1) 3 ]P i+1 ’

[0072] In the above formula, P i For the i-th control point (i≤n), t i Let P be the line segment i P i+1 The length of P (i≤n-1) i’ Let t be the tangential guide of the i-th control point, and t be the chord length between points P1 and P.

[0073] S40, based on the inlet placement angle α1, the outlet placement angle α2, and the diameters of the blade 42 at the inner edge line 42a and outer edge line 42b respectively, the lines of the three-dimensional curve equation are "offset" vertically outward by a distance equal to the blade inlet width b3, and rotated 25° towards the axis. This yields the outer edge line 42b of the intersection of the spatial guide vane blade 42 and the outer cover plate 43. Using the modeling software Preo / Creo, commands such as "boundary blending," "extending," and "thickening" are applied to the inner edge line 42a and outer edge line 42b to complete the forming model of the blade 42. Subsequently, the model of the cover plate 43 is completed based on its parameters.

[0074] S50, based on the number of blades 42, the design of the space guide vane 40 is completed by evenly distributing the solid bodies of several blades 42 around the wheel 41.

[0075] Figure 7 This is a comparison chart of the performance experimental data of a centrifugal pump using a conventional guide vane when the streamlined spatial guide vane obtained by the multi-stage centrifugal pump streamlined spatial guide vane design method in Embodiment 1 of the present invention is applied to a centrifugal pump.

[0076] like Figure 7 As shown, when the pump flow rate is 3m³ / h 3 / h~12m 3 When the streamlined spatial guide vane obtained by the multi-stage centrifugal pump streamlined spatial guide vane design method in this embodiment is applied to the centrifugal pump, the efficiency performance of the centrifugal pump is better than that of the centrifugal pump using conventional guide vanes in the flow range.

[0077] <Example 2>

[0078] This embodiment provides a method for designing streamlined spatial guide vanes for a multi-stage centrifugal pump. The steps are largely similar to those in Embodiment 1, with the only difference being that n=3 in step S20 and the control point P. n-1 It includes only the first reference control point P0, the second reference control point P1, and the third reference control point P2.

[0079] <Example 3>

[0080] This embodiment provides a method for designing streamlined spatial guide vanes for a multi-stage centrifugal pump. The steps are largely similar to those in Embodiment 1, with the only difference being that n=4 in step S20 and the control point P. n-1 It includes only the first reference control point P0, the second reference control point P1, the third reference control point P2, and the first intermediate control point P3.

[0081] The first intermediate control point P3 is the intersection of the arc surface of the roulette wheel 41 and the front and side planes.

[0082] The role and effect of the embodiments

[0083] According to the embodiment of this invention, a streamlined spatial guide vane design method for a multi-stage centrifugal pump is provided for designing the structure of the spatial guide vane of the centrifugal pump. The spatial guide vane includes a disc with an arc-shaped outer edge, several blades evenly arranged on the disc and perpendicular to it, and an outer cover plate covering the outer periphery of the blades. The intersection line between the blades and the disc is denoted as the inner edge line, and the intersection line between the blades and the outer cover plate is denoted as the outer edge line. The area between two adjacent blades, from the blade inlet to the maximum outer edge line, is the inlet flow channel, and from the maximum outer edge line to the blade outlet is the outlet flow channel. The method includes the following steps: S10, based on the performance requirements, strength requirements, and given impeller dimensions of the centrifugal pump, calculate the inlet placement angle α1, the outlet placement angle α2, the number of blades, and the several wrap angles β of the blades at the inner edge line. n-1 The diameters of the blades at the inner and outer edges, respectively, where n ≥ 3; S20, through the wrap angle β n-1 Calculate the positions of n control points on different planes of the wheel; S30, calculate the three-dimensional curve equation fitted by the n control points based on their positions to complete the blade profile design. The three-dimensional curve equation is a Bézier curve or a spline curve, and the three-dimensional curve equation is of order n-1; S40, based on the inlet installation angle α1, the outlet installation angle α2, and the diameter of the blade at the inner and outer edges respectively, translate and stretch the lines of the three-dimensional curve equation to generate the blade surface, and then add the blade thickness to form the blade solid; S50, based on the number of blades, evenly distribute the solid blades around the wheel to complete the design of the spatial guide vane.

[0084] Therefore, the streamlined spatial guide vane design method for multi-stage centrifugal pumps in this embodiment achieves direct control of the guide vane blade profile based on the curve equation. It can adapt to various changing conditions and significantly improves guide vane design efficiency while controlling the inlet and outlet flow directions. This method plays a crucial role and has significant value in improving the hydraulic performance of spatial guide vanes. The forward and reverse guide vanes in this embodiment are a single, complete streamline, exhibiting significant optimization effects, simple design calculations, and strong adaptability.

[0085] The streamlined spatial guide vane design method for multi-stage centrifugal pumps in this embodiment offers simple and flexible curve calculation. It allows for faster design of suitable guide vane shapes, and the resulting streamlined shape better conforms to liquid flow laws, is supported by fluid mechanics theory, effectively reduces flow process losses, and improves hydraulic efficiency.

[0086] This embodiment uses cubic spline curves, and the positive and negative guide vanes are formed in one step. The formula is simple, easy to modify, and the streamline transition is smooth.

[0087] In this embodiment, the inlet and outlet flow directions are opposite in the plane, with an included angle of 180°, and the angle γ between the guide vane working surface and the impeller is 90°. Simultaneously, the blade height gradually decreases from the inside to the outside, and the cross-sectional areas formed by any section perpendicular to the flow channel within two adjacent blades are equal. Furthermore, this embodiment only requires designing one guide vane curve, which can be controlled by a single curve equation; the remaining curves can be obtained through three-dimensional transformation. This embodiment analyzes the relationship between the flow channel and the blades, and provides specific design details for the surface shapes of the flow channel and blades.

[0088] This embodiment adopts a combination of control points and spline curves for development and design, optimizing the segmented design method into a streamline that controls the blade profile as a whole. The design is simple and easy to control, with no unsmooth transition sections, and is supported by relevant fluid mechanics theories.

[0089] This embodiment realizes direct control of the guide vane blade profile based on the curve equation, which can adapt to various changes. Under the condition of controlling the direction of the inlet and outlet flow channels, it significantly improves the design efficiency of the guide vane and plays an extremely important role and value in improving the hydraulic performance of the space guide vane.

[0090] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for designing streamlined spatial guide vanes for a multi-stage centrifugal pump, used to design the structure of spatial guide vanes for a centrifugal pump. The spatial guide vane includes a disk with an arc-shaped outer edge, a plurality of blades evenly arranged on the disk and perpendicular to it, and an outer cover plate covering the periphery of the blades. The intersection line between the blades and the disk is denoted as the inner edge line, and the intersection line between the blades and the outer cover plate is denoted as the outer edge line. The region between two adjacent blades, extending from the blade inlet to the maximum outer edge, is the inlet flow channel, and extending from the maximum outer edge to the blade outlet, is the outlet flow channel. Its features are, Includes the following steps: S10, based on the performance requirements and strength requirements of the centrifugal pump and the given impeller dimensions, calculate the inlet placement angle α1, the outlet placement angle α2, the number of blades, and the several wrap angles β of the blades at the inner edge of the impeller. n-1 The diameters of the blades at the inner edge and the outer edge, respectively, wherein n≥3; S20, via the wrap angle β n-1 Calculate the positions of n control points on different planes of the roulette wheel; S30, calculate the three-dimensional curve equation fitted by n control points based on the position of the control points, thereby completing the blade profile design. The three-dimensional curve equation is a Bézier curve or a spline curve, and the three-dimensional curve equation is of order n-1. S40, based on the inlet placement angle α1, the outlet placement angle α2, and the diameters of the blades at the inner and outer edges respectively, the lines of the three-dimensional curve equation are translated and stretched to generate the blade surface, and then the blade thickness is added to form the solid of the blade; S50, according to the number of blades, the solid bodies of several blades are evenly distributed around the wheel to complete the design of the space guide vane.

2. The method for designing streamlined spatial guide vanes for a multi-stage centrifugal pump according to claim 1, characterized in that: in, In steps S10 to S20, the n control points of the same blade include at least a first reference control point P0, a second reference control point P1, and a third reference control point P2. The first reference control point P0 is the farthest point of the diameter of the blade at the inner edge line. The second reference control point P1 and the third reference control point P2 are the intersections of the inlet flow channel and the outlet flow channel of the spatial guide vane with the wheel disk, respectively. They are located on the inlet base circle with diameter D1 and the outlet base circle with diameter D3 of the wheel disk, respectively, where D1 > D3.

3. The method for designing streamlined spatial guide vanes for a multi-stage centrifugal pump according to claim 2, characterized in that: in, When n=4, the control point also includes a first intermediate control point P3, which is the intersection of the arc surface of the wheel and the front and side planes.

4. The method for designing streamlined spatial guide vanes for a multi-stage centrifugal pump according to claim 2, characterized in that: in, When n≥5, the control points also include n-3 intermediate control points. The intermediate control points include a first intermediate control point P3 and a second intermediate control point P4. The first intermediate control point P3 and the second intermediate control point P4 are the intersection points of the arc surface of the wheel and the front and back planes, respectively.

5. The method for designing streamlined spatial guide vanes for a multi-stage centrifugal pump according to claim 4, characterized in that: in, When n≥6, the intermediate control point also includes n-5 auxiliary control points P. m , 5≤m≤n-1, Auxiliary control point P m Distance control point P n-m The nearest point, auxiliary control point P m The position is determined by the wrap angle β m control.

6. The method for designing streamlined spatial guide vanes for a multi-stage centrifugal pump according to claim 1, characterized in that: in, The curve in the three-dimensional curve equation is a smooth, complete streamline.

7. The method for designing streamlined spatial guide vanes for a multi-stage centrifugal pump according to any one of claims 1 to 6, characterized in that: in, In step S20, the curve of the three-dimensional curve equation is a cubic spline curve, and the fitting method is: the points between each pair of adjacent control points are piecewise fitted using a cubic polynomial parametric equation. The parametric equation of the cubic polynomial is: P i (t)=[1-3(t / t1) 2 +2(t / t1) 3 ]P i +[3(t / t1) 2 -2(t / t1) 3 ]P i+1 +[(t / t1)-2(t / t1) 2 +(t / t1) 3 ] P i ’ +[-(t / t1) 2 +(t / t1) 3 ]P i+1 ’ , P i For the i-th control point (i≤n), t i Let P be the line segment i P i+1 The length of P (i≤n-1) i ’ Let t be the tangential guide of the i-th control point, and t be the chord length between points P1 and P.

8. The method for designing streamlined spatial guide vanes for a multi-stage centrifugal pump according to claim 1, characterized in that: in, The plane formed by the outer edge line and the inner edge line of the same blade is the working surface of the blade, and the angle γ between the working surface and the disk is 90°.

9. The method for designing streamlined spatial guide vanes for a multi-stage centrifugal pump according to claim 1, characterized in that: in, The inlet and outlet channels flow in opposite directions in the plane, with an included angle of 180°.

10. The method for designing streamlined spatial guide vanes for a multi-stage centrifugal pump according to claim 1, characterized in that: in, The blade height gradually decreases from the inside to the outside, and the interior of two adjacent blades has the same cross-sectional area as any flow channel formed by the flow channel along the direction perpendicular to the spatial guide vane.

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